Question:
What do these two changes have in common?
dry ice sublimating and becoming a gas
water freezing into ice

Choices:
A. Both are caused by cooling.
B. Both are caused by heating.
C. Both are only physical changes.
D. Both are chemical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Dry ice is solid carbon dioxide. When dry ice gets warm, it changes state and becomes carbon dioxide gas. This change of state, from solid to gas, is called sublimation.
Dry ice becoming a gas is a physical change. A change of state does not form a different type of matter.
Water freezing into ice is a change of state. So, it is a physical change. The water changes from solid to liquid. But the ice is still made of the same type of matter as the liquid water.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Dry ice sublimating is caused by heating. But water freezing into ice is not.
Both are caused by cooling.
Water freezing is caused by cooling. But dry ice sublimating is not.

natural science


Question:
What do these two changes have in common?
breaking a ceramic plate
knitting yarn into a scarf

Choices:
A. Both are only physical changes.
B. Both are chemical changes.
C. Both are caused by cooling.
D. Both are caused by heating.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Breaking a ceramic plate is a physical change. The plate gets broken into pieces. But each piece is still made of the same type of matter.
Knitting yarn into a scarf is a physical change. The yarn gets a different shape, but it is still made of the same type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science

local parquet snapshot does not include README/license metadata; verify upstream before public upload


Question: Select the invertebrate.

Choices:
A. cardinalfish
B. earthworm
C. green sea turtle
D. black howler

Hint: Insects, spiders, and worms are invertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A black howler is a mammal. Like other mammals, a black howler is a vertebrate. It has a backbone.
A green sea turtle is a reptile. Like other reptiles, a green sea turtle is a vertebrate. It has a backbone.
An earthworm is a worm. Like other worms, an earthworm is an invertebrate. It does not have a backbone. It has a soft body.
A cardinalfish is a fish. Like other fish, a cardinalfish is a vertebrate. It has a backbone.

natural science


Question:
What do these two changes have in common?
a banana getting ripe on the counter
saliva breaking down a piece of bread

Choices:
A. Both are chemical changes.
B. Both are caused by cooling.
C. Both are only physical changes.
D. Both are caused by heating.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
A banana getting ripe on the counter is a chemical change. As a banana ripens, the type of matter in it changes. The peel changes color and the inside becomes softer and sweeter.
Saliva breaking down a piece of bread is a chemical change. Bread is made up mostly of a chemical called starch. Saliva breaks the bonds between atoms in the starch molecules.
The atoms then link together to form smaller, simpler molecules of sugar. The sugar is a different type of matter than the starch.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: What is the probability that a cockatiel produced by this cross will have bright orange cheeks?

Choices:
A. 2/4
B. 1/4
C. 4/4
D. 3/4
E. 0/4

In a group of cockatiels, some individuals have bright orange cheeks and others have pale orange cheeks. In this group, the gene for the cheek color trait has two alleles. The allele for bright orange cheeks (R) is dominant over the allele for pale orange cheeks (r).
This Punnett square shows a cross between two cockatiels.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science

Use Punnett squares to calculate probabilities of offspring types


Question: Select the fish below.

Choices:
A. piranha
B. olive toad
C. sea otter
D. American bullfrog

Fish live underwater. They have fins, not limbs.
Fish are cold-blooded. The body temperature of cold-blooded animals depends on their environment.
A goldfish is an example of a fish.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

An American bullfrog is an amphibian. It has moist skin and begins its life in water.
Frogs live near water or in damp places. Most frogs lay their eggs in water.
A sea otter is a mammal. It has fur and feeds its young milk.
Sea otters have very thick fur. Their fur keeps them warm in cold water.
An olive toad is an amphibian. It has moist skin and begins its life in water.
Toads do not have teeth! They swallow their food whole.
A piranha is a fish. It lives underwater. It has fins, not limbs.
Piranhas have sharp teeth. Piranhas hunt in groups. A group of piranhas can eat a large animal.

natural science

Identify mammals, birds, fish, reptiles, and amphibians


Question:
What do these two changes have in common?
getting a haircut
sawing a log in half

Choices:
A. Both are caused by heating.
B. Both are caused by cooling.
C. Both are chemical changes.
D. Both are only physical changes.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Getting a haircut is a physical change. Your hair is shorter after a haircut. But it is still made of the same type of matter.
Sawing a log in half is a physical change. The log splits into two pieces. But the pieces are still made of the same type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the vertebrate.

Choices:
A. white-spotted octopus
B. locust
C. whiptail lizard
D. peacock butterfly

Hint: Mammals, birds, fish, reptiles, and amphibians are vertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A whiptail lizard is a reptile. Like other reptiles, a whiptail lizard is a vertebrate. It has a backbone.
Like other octopuses, a white-spotted octopus is an invertebrate. It does not have a backbone. It has a soft body.
A peacock butterfly is an insect. Like other insects, a peacock butterfly is an invertebrate. It does not have a backbone. It has an exoskeleton.
A locust is an insect. Like other insects, a locust is an invertebrate. It does not have a backbone. It has an exoskeleton.

natural science


Question: Select the solid.

Choices:
A. air inside a tire
B. eraser
C. air inside a bubble
D. coffee

Solid, liquid, and gas are states of matter. Matter is anything that takes up space. Matter can come in different states, or forms.
When matter is a solid, it has a definite volume and a definite shape. So, a solid has a size and shape of its own.
Some solids can be easily folded, bent, or broken. A piece of paper is a solid. Also, some solids are very small. A grain of sand is a solid.
When matter is a liquid, it has a definite volume but not a definite shape. So, a liquid has a size of its own, but it does not have a shape of its own. Think about pouring juice from a bottle into a cup. The juice still takes up the same amount of space, but it takes the shape of the bottle.
Some liquids do not pour as easily as others. Honey and milk are both liquids. But pouring honey takes more time than pouring milk.
When matter is a gas, it does not have a definite volume or a definite shape. A gas expands, or gets bigger, until it completely fills a space. A gas can also get smaller if it is squeezed into a smaller space.
Many gases are invisible. Air is a gas.

Coffee is a liquid. A liquid takes the shape of any container it is in. If you pour coffee into a different container, the coffee will take the shape of that container. But the coffee will still take up the same amount of space.
The air inside a tire is a gas. A gas expands to fill a space. The air in a tire expands to fill all the space inside the tire. If air leaks out, it will expand into the space around the tire.
The air inside a bubble is a gas. A gas expands to fill a space. The air inside a bubble fills all the space in the bubble. If the bubble pops, the air will expand to fill a much larger space.
An eraser is a solid. You can bend an eraser. But it will still have a size and shape of its own.

natural science


Question: Select the bird below.

Choices:
A. barn owl
B. black howler
C. gray tree frog
D. zebra

Birds have feathers, two wings, and a beak.
Birds are warm-blooded. Warm-blooded animals can control their body temperature.
A turkey vulture is an example of a bird.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A barn owl is a bird. It has feathers, two wings, and a beak.
Barn owls live on every continent except Antarctica.
A black howler is a mammal. It has hair and feeds its young milk.
Howler monkeys have loud calls, or howls. Their calls can be heard over three miles away!
A zebra is a mammal. It has hair and feeds its young milk.
Zebras eat mostly grass. But they sometimes eat other types of plants, such as shrubs or tree bark.
A gray tree frog is an amphibian. It has moist skin and begins its life in water.
There are many kinds of tree frogs. Most tree frogs are very small. They can walk on thin branches.

natural science


Question: Select the mammal below.

Choices:
A. koala
B. mandarinfish
C. helmeted iguana
D. bald eagle

Mammals have hair or fur and feed their young milk.
Mammals are warm-blooded. Warm-blooded animals can control their body temperature.
A rabbit is an example of a mammal.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A koala is a mammal. It has fur and feeds its young milk.
Koalas sleep for up to 20 hours a day!
A bald eagle is a bird. It has feathers, two wings, and a beak.
Bald eagles live in trees near water. They build nests that can be up to 13 feet wide!
A mandarinfish is a fish. It lives underwater. It has fins, not limbs.
Mandarinfish often live near coral reefs. They eat small worms, snails, and fish eggs.
A helmeted iguana is a reptile. It has scaly, waterproof skin.
Iguanas are a type of lizard. Iguanas eat plants and fruit.

natural science


Question: What is the probability that a cow produced by this cross will have solid coloring?

Choices:
A. 3/4
B. 4/4
C. 0/4
D. 1/4
E. 2/4

In a group of cows, some individuals have solid coloring and others have white spots. In this group, the gene for the coat pattern trait has two alleles. The allele for white spots (a) is recessive to the allele for solid coloring (A).
This Punnett square shows a cross between two cows.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question: Select the vertebrate.

Choices:
A. yellow jacket
B. dung beetle
C. black orb weaver spider
D. harvest mouse

Hint: Mammals, birds, fish, reptiles, and amphibians are vertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A yellow jacket is an insect. Like other insects, a yellow jacket is an invertebrate. It does not have a backbone. It has an exoskeleton.
A harvest mouse is a mammal. Like other mammals, a harvest mouse is a vertebrate. It has a backbone.
Like other spiders, a black orb weaver spider is an invertebrate. It does not have a backbone. It has an exoskeleton.
A dung beetle is an insect. Like other insects, a dung beetle is an invertebrate. It does not have a backbone. It has an exoskeleton.

natural science


Question: Select the chemical formula for this molecule.

Choices:
A. PCl5N
B. P2Cl6
C. Cl6
D. PCl5

Every substance around you is made up of atoms. Atoms can link together to form molecules. The links between atoms in a molecule are called chemical bonds. Different molecules are made up of different chemical elements, or types of atoms, bonded together.
Scientists use both ball-and-stick models and chemical formulas to represent molecules.
A ball-and-stick model of a molecule is shown below.
The balls represent atoms. The sticks represent the chemical bonds between the atoms.
Notice how each ball is labeled with a symbol made of one or more letters. The symbol is an abbreviation for a chemical element. The ball represents one atom of that element.
Every chemical element is represented by its own symbol. For some elements, that symbol is one capital letter. For other elements, it is one capital letter followed by one lowercase letter. For example, the symbol for the element boron is B and the symbol for the element chlorine is Cl.
The molecule shown above has one boron atom and three chlorine atoms. A chemical bond links each chlorine atom to the boron atom.
The chemical formula for a molecule contains the symbol for each chemical element in the molecule. Many chemical formulas use subscripts. A subscript is text that is smaller and placed lower than the normal line of text.
In chemical formulas, the subscripts are numbers. The subscript is always written after the symbol for an element. The subscript tells you how many atoms that symbol represents. If the symbol represents just one atom, then no subscript is included.
The symbols in the chemical formula for a molecule match the symbols in the ball-and-stick model for that molecule. The ball-and-stick model shown before and the chemical formula shown above represent the same substance.

P is the symbol for phosphorus. Cl is the symbol for chlorine. This ball-and-stick model shows a molecule with one phosphorus atom and five chlorine atoms.
The chemical formula will contain the symbols P and Cl. There is one phosphorus atom, so P will not have a subscript. There are five chlorine atoms, so Cl will have a subscript of 5.
The correct formula is PCl5.
The diagram below shows how each part of the chemical formula matches with each part of the model above.

natural science

Match chemical formulas to ball-and-stick models


Question: What is the expected ratio of offspring with black eyes to offspring with red eyes? Choose the most likely ratio.

Choices:
A. 4:0
B. 0:4
C. 3:1
D. 1:3
E. 2:2

In a group of koi fish, some individuals have red eyes and others have black eyes. In this group, the gene for the eye color trait has two alleles. The allele for red eyes (E) is dominant over the allele for black eyes (e).
This Punnett square shows a cross between two koi fish.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

To determine how many boxes in the Punnett square represent offspring with black eyes or red eyes, consider whether each phenotype is the dominant or recessive allele's version of the eye color trait. The question tells you that the E allele, which is for red eyes, is dominant over the e allele, which is for black eyes.
Black eyes is the recessive allele's version of the eye color trait. A koi fish with the recessive version of the eye color trait must have only recessive alleles for the eye color gene. So, offspring with black eyes must have the genotype ee.
There are 0 boxes in the Punnett square with the genotype ee.
Red eyes is the dominant allele's version of the eye color trait. A koi fish with the dominant version of the eye color trait must have at least one dominant allele for the eye color gene. So, offspring with red eyes must have the genotype EE or Ee.
All 4 boxes in the Punnett square have the genotype EE or Ee.
So, the expected ratio of offspring with black eyes to offspring with red eyes is 0:4. This means that, based on the Punnett square, this cross will never produce offspring with black eyes. Instead, this cross is expected to always produce offspring with red eyes.

natural science

Use Punnett squares to calculate ratios of offspring types


Question: Select the amphibian below.

Choices:
A. human
B. gray wolf
C. great white shark
D. red-spotted newt

Amphibians have moist skin and begin their lives in water.
Amphibians are cold-blooded. The body temperature of cold-blooded animals depends on their environment.
A gray tree frog is an example of an amphibian.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A human is a mammal. It has hair and feeds its young milk.
Humans are a type of animal called a primate. Monkeys and apes are also primates.
A gray wolf is a mammal. It has fur and feeds its young milk.
Wolves often live in family groups. A wolf mother, father, and their children travel together.
A great white shark is a fish. It lives underwater. It has fins, not limbs.
Great white sharks can live for up to 70 years.
A red-spotted newt is an amphibian. It has moist skin and begins its life in water.
Some newts live in water. Other newts live on land but lay their eggs in water.

natural science


Question: How long is a tennis racket?

Choices:
A. 26 feet
B. 26 miles
C. 26 inches
D. 26 yards

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a tennis racket is 26 inches.
26 feet, 26 yards, and 26 miles are all too long.

natural science

Choose customary units of distance, mass, and volume


Question:
What do these two changes have in common?
breaking a ceramic plate
mixing chocolate syrup into milk

Choices:
A. Both are caused by cooling.
B. Both are chemical changes.
C. Both are only physical changes.
D. Both are caused by heating.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Breaking a ceramic plate is a physical change. The plate gets broken into pieces. But each piece is still made of the same type of matter.
Mixing chocolate syrup into milk is a physical change. The chocolate syrup and milk make a mixture. Making a mixture does not form a different type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the invertebrate.

Choices:
A. macaw
B. atlas moth
C. dyeing dart frog
D. piranha

Hint: Insects, spiders, and worms are invertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A macaw is a bird. Like other birds, a macaw is a vertebrate. It has a backbone.
A dyeing dart frog is an amphibian. Like other amphibians, a dyeing dart frog is a vertebrate. It has a backbone.
A piranha is a fish. Like other fish, a piranha is a vertebrate. It has a backbone.
An atlas moth is an insect. Like other insects, an atlas moth is an invertebrate. It does not have a backbone. It has an exoskeleton.

natural science


Question: Select the fish below.

Choices:
A. mandarinfish
B. green iguana
C. water buffalo
D. red-headed poison frog

Fish live underwater. They have fins, not limbs.
Fish are cold-blooded. The body temperature of cold-blooded animals depends on their environment.
A salmon is an example of a fish.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A green iguana is a reptile. It has scaly, waterproof skin.
Iguanas are a type of lizard. Iguanas eat plants and fruit.
A water buffalo is a mammal. It has hair and feeds its young milk.
Water buffaloes live in Asia. Some people raise water buffaloes for their milk.
A red-headed poison frog is an amphibian. It has moist skin and begins its life in water.
Poison dart frogs come in many bright colors. Their bright color warns other animals that these frogs are poisonous.
A mandarinfish is a fish. It lives underwater. It has fins, not limbs.
Mandarinfish often live near coral reefs. They eat small worms, snails, and fish eggs.

natural science


Question: Select the living thing.

Choices:
A. roller skate
B. the Great Sphinx of Giza
C. cave
D. kelp

All living things are made up of cells. Plants, animals, and some fungi have many cells. Other living things are made up of just one cell.
All living things need food and water. Water helps living things break down food and remove waste. Food gives living things energy. They use energy from food to grow and change.
All living things sense changes in their environment. Living things might sense changes by seeing, smelling, hearing, or feeling. Living things can respond to the changes they sense.

A cave is not a living thing.
A cave may have animals or plants living inside. But a cave does not have all the traits of a living thing. A cave does not need food or water.
The Great Sphinx of Giza is not a living thing.
The Great Sphinx of Giza is a statue of a mythical sphinx, a creature with a lion's body and a human head. The Great Sphinx does not have all of the traits of a living thing. It does not grow or respond to the world around it. It does not need food or water.
Kelp is a living thing.
Kelp grows and responds to its environment. It needs food and water. It is made up of many cells.
Kelp uses energy from sunlight to make food. Kelp plants have special air pockets that bring their leaves close to the surface.
A roller skate is not a living thing.
Roller skates do not have all of the traits of living things. They do not grow or respond to their environment. They do not need food or water.

natural science


Question: What is the expected ratio of offspring with a yellow ground spot to offspring with a white ground spot? Choose the most likely ratio.

Choices:
A. 1:3
B. 4:0
C. 2:2
D. 3:1
E. 0:4

This passage describes the ground spot color trait in watermelon plants:
Watermelon plants grow with their fruit resting on the ground. Over time, the bottom of each fruit develops a white or yellow spot called a ground spot. In some types of watermelon plants, the color of the ground spot is an inherited trait.
In a group of watermelon plants, some individuals have a yellow ground spot and others have a white ground spot. In this group, the gene for the ground spot color trait has two alleles. The allele for a white ground spot (g) is recessive to the allele for a yellow ground spot (G).
This Punnett square shows a cross between two watermelon plants.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

To determine how many boxes in the Punnett square represent offspring with a yellow ground spot or a white ground spot, consider whether each phenotype is the dominant or recessive allele's version of the ground spot color trait. The question tells you that the g allele, which is for a white ground spot, is recessive to the G allele, which is for a yellow ground spot.
A yellow ground spot is the dominant allele's version of the ground spot color trait. A watermelon plant with the dominant version of the ground spot color trait must have at least one dominant allele for the ground spot color gene. So, offspring with a yellow ground spot must have the genotype GG or Gg.
All 4 boxes in the Punnett square have the genotype GG or Gg.
A white ground spot is the recessive allele's version of the ground spot color trait. A watermelon plant with the recessive version of the ground spot color trait must have only recessive alleles for the ground spot color gene. So, offspring with a white ground spot must have the genotype gg.
There are 0 boxes in the Punnett square with the genotype gg.
So, the expected ratio of offspring with a yellow ground spot to offspring with a white ground spot is 4:0. This means that, based on the Punnett square, this cross will always produce offspring with a yellow ground spot. This cross is expected to never produce offspring with a white ground spot.

natural science


Question: How long is a basketball court?

Choices:
A. 29 miles
B. 29 yards
C. 29 inches
D. 29 feet

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a basketball court is 29 yards.
29 inches and 29 feet are too short. 29 miles is too long.

natural science


Question: Which organ stores solid waste before it is released from the body?

Choices:
A. esophagus
B. trachea
C. large intestine
D. muscles

natural science


Question: What is the probability that a rat produced by this cross will have a dwarf body?

Choices:
A. 1/4
B. 2/4
C. 4/4
D. 0/4
E. 3/4

In a group of rats, some individuals have a normal-sized body and others have a dwarf body. In this group, the gene for the body size trait has two alleles. The allele for a dwarf body (b) is recessive to the allele for a normal-sized body (B).
This Punnett square shows a cross between two rats.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question: Select the fish.

Choices:
A. manta ray
B. elongated tortoise
C. albatross
D. green sea turtle

Fish live underwater. They have fins, not limbs.

A manta ray is a fish. It lives underwater. It has fins, not limbs.
Rays have a different shape than many other fish. Rays are large and flat. They have wide, triangle-shaped fins that help them swim long distances.
A green sea turtle is a reptile. It has scaly, waterproof skin.
Sea turtles live in the water, but they lay their eggs on land.
An albatross is a bird. It has feathers, two wings, and a beak.
Albatrosses live near the ocean. They hunt squid, fish, and other small animals.
An elongated tortoise is a reptile. It has scaly, waterproof skin.
A tortoise's shell protects it from predators. When a tortoise feels threatened, it can pull its head and legs inside its shell.

natural science


Question: Select the amphibian below.

Choices:
A. zebra
B. horned frog
C. green moray eel
D. koala

Amphibians have moist skin and begin their lives in water.
Amphibians are cold-blooded. The body temperature of cold-blooded animals depends on their environment.
A red-spotted newt is an example of an amphibian.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A koala is a mammal. It has fur and feeds its young milk.
Koalas sleep for up to 20 hours a day!
A zebra is a mammal. It has hair and feeds its young milk.
Zebras eat mostly grass. But they sometimes eat other types of plants, such as shrubs or tree bark.
A green moray eel is a fish. It lives underwater. It has fins, not limbs.
Eels are long and thin. They may have small fins. They look like snakes, but they are fish!
A horned frog is an amphibian. It has moist skin and begins its life in water.
Frogs live near water or in damp places. Most frogs lay their eggs in water.

natural science


Question: What is the probability that a chicken produced by this cross will be heterozygous for the leg color gene?

Choices:
A. 4/4
B. 3/4
C. 2/4
D. 1/4
E. 0/4

In a group of chickens, some individuals have white legs and others have yellow legs. In this group, the gene for the leg color trait has two alleles. The allele for yellow legs (l) is recessive to the allele for white legs (L).
This Punnett square shows a cross between two chickens.

Offspring genotypes: homozygous or heterozygous?
How do you determine whether an organism is homozygous or heterozygous for a gene? Look at the alleles in the organism's genotype for that gene.
An organism with two identical alleles for a gene is homozygous for that gene.
If both alleles are dominant, the organism is homozygous dominant for the gene.
If both alleles are recessive, the organism is homozygous recessive for the gene.
An organism with two different alleles for a gene is heterozygous for that gene.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype.
Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4

natural science


Question:
What do these two changes have in common?
sediment settling to the bottom of a muddy puddle
shaking up salad dressing

Choices:
A. Both are chemical changes.
B. Both are caused by heating.
C. Both are only physical changes.
D. Both are caused by cooling.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Loose matter such as sand and dirt is called sediment. Sediment settling to the bottom of a muddy puddle is a physical change.
The sediment sinks, and the water above becomes clearer. This separates the water from the sediment. But separating a mixture does not form a different type of matter.
Shaking up salad dressing is a physical change. The different parts mix together, but they are still made of the same type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: How long is the Golden Gate Bridge?

Choices:
A. 2,750 millimeters
B. 2,750 kilometers
C. 2,750 meters
D. 2,750 centimeters

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using metric units, length can be written with units of millimeters, centimeters, meters, or kilometers. One meter contains 100 centimeters or 1,000 millimeters. So, 1 meter is larger than 1 centimeter, and 1 centimeter is larger than 1 millimeter.
The tip of the pencil shown here is only 1 millimeter wide, but the pencil is about 16 centimeters long.
A red fox is about 1 meter long. The Sydney Harbour Bridge in Australia is about 1,000 meters, or 1 kilometer, in length.

The best estimate for the length of the Golden Gate Bridge is 2,750 meters.
2,750 millimeters and 2,750 centimeters are too short. 2,750 kilometers is too long.

natural science

Choose metric units of distance, mass, and volume


Question: Which of the following organisms is the primary consumer in this food web?

Choices:
A. kelp
B. sea otter
C. plainfin midshipman
D. phytoplankton

Below is a food web from an ocean ecosystem in Monterey Bay, off the coast of California.
A food web models how the matter eaten by organisms moves through an ecosystem. The arrows in a food web represent how matter moves between organisms in an ecosystem.

A food web is a model.
A food web shows where organisms in an ecosystem get their food. Models can make things in nature easier to understand because models can represent complex things in a simpler way. If a food web showed every organism in an ecosystem, the food web would be hard to understand. So, each food web shows how some organisms in an ecosystem can get their food.
Arrows show how matter moves.
A food web has arrows that point from one organism to another. Each arrow shows the direction that matter moves when one organism eats another organism. An arrow starts from the organism that is eaten. The arrow points to the organism that is doing the eating.
An organism in a food web can have more than one arrow pointing from it. This shows that the organism is eaten by more than one other organism in the food web.
An organism in a food web can also have more than one arrow pointing to it. This shows that the organism eats more than one other organism in the food web.

Primary consumers eat producers. So, in a food web, primary consumers have arrows pointing to them from producers.
The phytoplankton does not have any arrows pointing to it. So, the phytoplankton is not a primary consumer.
The plainfin midshipman has an arrow pointing to it from the phytoplankton. The phytoplankton is a producer, so the plainfin midshipman is a primary consumer.
The sea otter has an arrow pointing to it from the sea urchin. The sea urchin is not a producer. So, the sea otter is not a primary consumer.
The kelp does not have any arrows pointing to it. So, the kelp is not a primary consumer.
The kelp bass has an arrow pointing to it from the kelp. The kelp is a producer, so the kelp bass is a primary consumer.

natural science


Question: Select the mammal below.

Choices:
A. loon
B. Tasmanian devil
C. great white shark
D. albatross

Mammals have hair or fur and feed their young milk.
Mammals are warm-blooded. Warm-blooded animals can control their body temperature.
A koala is an example of a mammal.

Birds, mammals, fish, reptiles, and amphibians are groups of animals. Scientists sort animals into each group based on traits they have in common. This process is called classification.
Classification helps scientists learn about how animals live. Classification also helps scientists compare similar animals.

A loon is a bird. It has feathers, two wings, and a beak.
Loons usually live near lakes. They dive in the water to hunt for food.
An albatross is a bird. It has feathers, two wings, and a beak.
Albatrosses live near the ocean. They hunt squid, fish, and other small animals.
A Tasmanian devil is a mammal. It has fur and feeds its young milk.
Tasmanian devils are meat-eating marsupials. They live on the island of Tasmania, near Australia.
A great white shark is a fish. It lives underwater. It has fins, not limbs.
Great white sharks can live for up to 70 years.

natural science


Question: What is the probability that a scarlet rosemallow plant produced by this cross will have white flowers?

Choices:
A. 4/4
B. 2/4
C. 3/4
D. 0/4
E. 1/4

In a group of scarlet rosemallow plants, some individuals have red flowers and others have white flowers. In this group, the gene for the flower color trait has two alleles. The allele for white flowers (f) is recessive to the allele for red flowers (F).
This Punnett square shows a cross between two scarlet rosemallow plants.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question:
What do these two changes have in common?
rust forming on a metal gate
burning food on a stove

Choices:
A. Both are chemical changes.
B. Both are only physical changes.
C. Both are caused by cooling.
D. Both are caused by heating.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Rust forming on a metal gate is a chemical change. As the gate rusts, the metal turns into a different type of matter called rust. Rust is reddish-brown and falls apart easily.
Burning food on a stove is a chemical change. When the food burns, the type of matter in it changes. The food turns black and gives off smoke.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Burning is caused by heating. But rust forming on a metal gate is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question:
What do these two changes have in common?
mixing sand and water
sediment settling to the bottom of a muddy puddle

Choices:
A. Both are caused by cooling.
B. Both are chemical changes.
C. Both are caused by heating.
D. Both are only physical changes.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Mixing sand and water is a physical change. Adding water makes the sand wet. But both the sand and water are still made of the same type of matter as before.
Loose matter such as sand and dirt is called sediment. Sediment settling to the bottom of a muddy puddle is a physical change.
The sediment sinks, and the water above becomes clearer. This separates the water from the sediment. But separating a mixture does not form a different type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question:
What do these two changes have in common?
melting wax
knitting yarn into a scarf

Choices:
A. Both are caused by heating.
B. Both are only physical changes.
C. Both are chemical changes.
D. Both are caused by cooling.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Melting wax is a change of state. So, it is a physical change. The wax changes from solid to liquid. But it is still made of the same type of matter.
Knitting yarn into a scarf is a physical change. The yarn gets a different shape, but it is still made of the same type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Wax melting is caused by heating. But knitting yarn is not.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question:
What do these two changes have in common?
breaking a ceramic plate
water vapor condensing on a bathroom mirror

Choices:
A. Both are chemical changes.
B. Both are only physical changes.
C. Both are caused by cooling.
D. Both are caused by heating.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Breaking a ceramic plate is a physical change. The plate gets broken into pieces. But each piece is still made of the same type of matter.
Water vapor condensing on a bathroom mirror is a change of state. So, it is a physical change. The water changes state from gas in the air to liquid water on the mirror. But the water vapor and the liquid water are both made of water.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Water vapor condensing is caused by cooling. But breaking a ceramic plate is not.

natural science


Question: Select the invertebrate.

Choices:
A. cricket
B. cockatoo
C. minnow
D. whiptail lizard

Hint: Insects, spiders, and worms are invertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A whiptail lizard is a reptile. Like other reptiles, a whiptail lizard is a vertebrate. It has a backbone.
A cockatoo is a bird. Like other birds, a cockatoo is a vertebrate. It has a backbone.
A minnow is a fish. Like other fish, a minnow is a vertebrate. It has a backbone.
A cricket is an insect. Like other insects, a cricket is an invertebrate. It does not have a backbone. It has an exoskeleton.

natural science


Question: What is the probability that a Labrador retriever produced by this cross will have brown fur?

Choices:
A. 3/4
B. 0/4
C. 1/4
D. 4/4
E. 2/4

In a group of Labrador retrievers, some individuals have black fur and others have brown fur. In this group, the gene for the fur color trait has two alleles. The allele for black fur (F) is dominant over the allele for brown fur (f).
This Punnett square shows a cross between two Labrador retrievers.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question: How long is the Amazon River?

Choices:
A. 4,000 inches
B. 4,000 miles
C. 4,000 yards
D. 4,000 feet

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of the Amazon River is 4,000 miles.
4,000 inches, 4,000 feet, and 4,000 yards are all too short.

natural science


Question: Select the vertebrate.

Choices:
A. moon jellyfish
B. fly
C. greater flamingo
D. ladybug

Hint: Mammals, birds, fish, reptiles, and amphibians are vertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A greater flamingo is a bird. Like other birds, a greater flamingo is a vertebrate. It has a backbone.
Like other jellyfishes, a moon jellyfish is an invertebrate. It does not have a backbone. It has a soft body.
A ladybug is an insect. Like other insects, a ladybug is an invertebrate. It does not have a backbone. It has an exoskeleton.
A fly is an insect. Like other insects, a fly is an invertebrate. It does not have a backbone. It has an exoskeleton.

natural science


Question: Select the vertebrate.

Choices:
A. bald eagle
B. Christmas tree worm
C. mosquito
D. moon jellyfish

Hint: Mammals, birds, fish, reptiles, and amphibians are vertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A mosquito is an insect. Like other insects, a mosquito is an invertebrate. It does not have a backbone. It has an exoskeleton.
Like other jellyfishes, a moon jellyfish is an invertebrate. It does not have a backbone. It has a soft body.
A Christmas tree worm is a worm. Like other worms, a Christmas tree worm is an invertebrate. It does not have a backbone. It has a soft body.
A bald eagle is a bird. Like other birds, a bald eagle is a vertebrate. It has a backbone.

natural science


Question: How long is a sunflower seed?

Choices:
A. 15 millimeters
B. 15 centimeters
C. 15 meters
D. 15 kilometers

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using metric units, length can be written with units of millimeters, centimeters, meters, or kilometers. One meter contains 100 centimeters or 1,000 millimeters. So, 1 meter is larger than 1 centimeter, and 1 centimeter is larger than 1 millimeter.
The tip of the pencil shown here is only 1 millimeter wide, but the pencil is about 16 centimeters long.
A red fox is about 1 meter long. The Sydney Harbour Bridge in Australia is about 1,000 meters, or 1 kilometer, in length.

The best estimate for the length of a sunflower seed is 15 millimeters.
15 centimeters, 15 meters, and 15 kilometers are all too long.

natural science


Question:
What do these two changes have in common?
a penny tarnishing
a dinosaur bone turning into rock over millions of years

Choices:
A. Both are chemical changes.
B. Both are caused by cooling.
C. Both are caused by heating.
D. Both are only physical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Metal turning less shiny over time is called tarnishing. A penny tarnishing is a chemical change. When air touches the penny, the surface of the penny changes into a different type of matter. This matter makes the penny dull.
A dinosaur bone turning into rock is a chemical change. The matter that made up the bone when it was alive begins to break down. Over a long time, a different type of matter starts forming inside small gaps in the bone. The matter is made of minerals from the earth.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the amphibian.

Choices:
A. fruit bat
B. hippopotamus
C. bald eagle
D. California toad

Amphibians have moist skin and begin their lives in water.

A fruit bat is a mammal. It has hair and feeds its young milk.
Fruit bats eat fruit and drink nectar from flowers. They have special teeth to help them bite through fruit skins.
A bald eagle is a bird. It has feathers, two wings, and a beak.
Bald eagles live in trees near water. They build nests that can be up to 13 feet wide!
A hippopotamus is a mammal. It has hair and feeds its young milk.
Hippopotamuses keep cool by lying in mud or water.
A California toad is an amphibian. It has moist skin and begins its life in water.
Toads do not have teeth! They swallow their food whole.

natural science


Question: How long is a leather belt?

Choices:
A. 31 inches
B. 31 miles
C. 31 yards
D. 31 feet

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a leather belt is 31 inches.
31 feet, 31 yards, and 31 miles are all too long.

natural science


Question: Select the bird.

Choices:
A. anchovy
B. porcupinefish
C. flamingo
D. fruit bat

Birds have feathers, two wings, and a beak.

An anchovy is a fish. It lives underwater. It has fins, not limbs.
An anchovy is a small fish that lives in the ocean. Like some other types of fish, anchovies swim in large groups called schools.
A porcupinefish is a fish. It lives underwater. It has fins, not limbs.
Porcupinefish can puff up their bodies with air or water to scare off predators.
A flamingo is a bird. It has feathers, two wings, and a beak.
Flamingos live in large groups. These groups are called flocks.
A fruit bat is a mammal. It has hair and feeds its young milk.
Fruit bats eat fruit and drink nectar from flowers. They have special teeth to help them bite through fruit skins.

natural science


Question: What is the probability that a Syrian hamster produced by this cross will have wavy fur?

Choices:
A. 1/4
B. 0/4
C. 2/4
D. 4/4
E. 3/4

In a group of Syrian hamsters, some individuals have straight fur and others have wavy fur. In this group, the gene for the fur texture trait has two alleles. The allele for straight fur (F) is dominant over the allele for wavy fur (f).
This Punnett square shows a cross between two Syrian hamsters.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question: How long is a car?

Choices:
A. 4 feet
B. 4 inches
C. 4 yards
D. 4 miles

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a car is 4 yards.
4 inches and 4 feet are too short. 4 miles is too long.

natural science


Question: What is the probability that a koi fish produced by this cross will have Bekko patterning?

Choices:
A. 1/4
B. 2/4
C. 3/4
D. 4/4
E. 0/4

This passage describes the Bekko patterning trait in koi fish:
The Bekko pattern is a pattern of colors found on the bodies of some koi fish. A koi fish with Bekko patterning has black patches all over its body. A koi fish without Bekko patterning does not have these patches.
In a group of koi fish, some individuals have Bekko patterning and others do not. In this group, the gene for the Bekko patterning trait has two alleles. The allele for having Bekko patterning (B) is dominant over the allele for not having Bekko patterning (b).
This Punnett square shows a cross between two koi fish.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
In a Punnett square, each box represents a different outcome, or result. Each of the four outcomes is equally likely to happen. Each box represents one way the parents' alleles can combine to form an offspring's genotype. Because there are four boxes in the Punnett square, there are four possible outcomes.
An event is a set of one or more outcomes. The probability of an event is a measure of how likely the event is to happen. This probability is a number between 0 and 1, and it can be written as a fraction:
probability of an event = number of ways the event can happen / number of equally likely outcomes
You can use a Punnett square to calculate the probability that a cross will produce certain offspring. For example, the Punnett square below has two boxes with the genotype Ff. It has one box with the genotype FF and one box with the genotype ff. This means there are two ways the parents' alleles can combine to form Ff. There is one way they can combine to form FF and one way they can combine to form ff.
 | F | f
F | FF | Ff
f | Ff | ff
Consider an event in which this cross produces an offspring with the genotype ff. The probability of this event is given by the following fraction:
number of ways the event can happen / number of equally likely outcomes = number of boxes with the genotype ff / total number of boxes = 1 / 4.

natural science


Question: How long is a kitchen table?

Choices:
A. 7 inches
B. 7 miles
C. 7 feet
D. 7 yards

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a kitchen table is 7 feet.
7 inches is too short. 7 yards and 7 miles are too long.

natural science


Question:
What do these two changes have in common?
a piece of apple turning brown
compost rotting

Choices:
A. Both are caused by cooling.
B. Both are only physical changes.
C. Both are chemical changes.
D. Both are caused by heating.

Chemical changes and physical changes are two common ways matter can change.
In a chemical change, the type of matter changes. The types of matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. When paper gets hot enough, it reacts with oxygen in the air and burns. The paper and oxygen change into ash and smoke.
In a physical change, the type of matter stays the same. The types of matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, ice melting is a physical change that can be caused by heating. Ice and liquid water are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
A piece of apple turning brown is a chemical change. The apple reacts with oxygen in the air and turns into a different type of matter.
If you scrape off the brown layer of the apple, the inside is still white. The inside hasn't touched the air. So the chemical change didn't happen to that part of the apple.
Compost forms from the remains of plants and animals, such as vegetable scraps and egg shells. Compost rotting is a chemical change. As the compost rots, it breaks down and turns into a different type of matter.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: Select the invertebrate.

Choices:
A. domestic pig
B. magpie goose
C. leaf-tailed gecko
D. bess beetle

Hint: Insects, spiders, and worms are invertebrates.

Vertebrates and invertebrates are both groups of animals.
A vertebrate has a backbone. The backbone is made of many bones in an animal's back. A vertebrate's backbone helps connect the different parts of its body. In the drawings below, each vertebrate's backbone is colored orange.
An invertebrate does not have a backbone. In fact, invertebrates do not have any bones! Some invertebrates have an outer cover on their body called an exoskeleton. Other invertebrates have a soft body.

A bess beetle is an insect. Like other insects, a bess beetle is an invertebrate. It does not have a backbone. It has an exoskeleton.
A domestic pig is a mammal. Like other mammals, a domestic pig is a vertebrate. It has a backbone.
A magpie goose is a bird. Like other birds, a magpie goose is a vertebrate. It has a backbone.
A leaf-tailed gecko is a reptile. Like other reptiles, a leaf-tailed gecko is a vertebrate. It has a backbone.

natural science


Question:
What do these two changes have in common?
using polish to remove tarnish from a silver spoon
a dinosaur bone turning into rock over millions of years

Choices:
A. Both are chemical changes.
B. Both are caused by cooling.
C. Both are caused by heating.
D. Both are only physical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
A tarnished silver spoon is one that has become less shiny over time. Polishing the spoon makes it look shiny again.
The polish changes the tarnish into a different type of matter that can be easily wiped away. So, using polish to remove tarnish from silver is a chemical change.
A dinosaur bone turning into rock is a chemical change. The matter that made up the bone when it was alive begins to break down. Over a long time, a different type of matter starts forming inside small gaps in the bone. The matter is made of minerals from the earth.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are chemical changes. They are not physical changes.
Both are chemical changes.
Both changes are chemical changes. The type of matter before and after each change is different.
Both are caused by heating.
Neither change is caused by heating.
Both are caused by cooling.
Neither change is caused by cooling.

natural science


Question: What is the expected ratio of offspring with climbing growth to offspring with bush growth? Choose the most likely ratio.

Choices:
A. 4:0
B. 3:1
C. 0:4
D. 2:2
E. 1:3

This passage describes the growth pattern trait in rose plants:
Climbing growth and bush growth are different growth patterns in rose plants. Rose plants with climbing growth have long, bendable stems that act like vines. These plants may grow upward to cover fences or walls. Rose plants with bush growth stay near the ground. These plants form low bushes or shrubs.
In a group of rose plants, some individuals have climbing growth and others have bush growth. In this group, the gene for the growth pattern trait has two alleles. The allele for bush growth (g) is recessive to the allele for climbing growth (G).
This Punnett square shows a cross between two rose plants.

Offspring phenotypes: dominant or recessive?
How do you determine an organism's phenotype for a trait? Look at the combination of alleles in the organism's genotype for the gene that affects that trait. Some alleles have types called dominant and recessive. These two types can cause different versions of the trait to appear as the organism's phenotype.
If an organism's genotype has at least one dominant allele for a gene, the organism's phenotype will be the dominant allele's version of the gene's trait.
If an organism's genotype has only recessive alleles for a gene, the organism's phenotype will be the recessive allele's version of the gene's trait.
A Punnett square shows what types of offspring a cross can produce. The expected ratio of offspring types compares how often the cross produces each type of offspring, on average. To write this ratio, count the number of boxes in the Punnett square representing each type.
For example, consider the Punnett square below.
 | F | f
F | FF | Ff
f | Ff | ff
There is 1 box with the genotype FF and 2 boxes with the genotype Ff. So, the expected ratio of offspring with the genotype FF to those with Ff is 1:2.

To determine how many boxes in the Punnett square represent offspring with climbing growth or bush growth, consider whether each phenotype is the dominant or recessive allele's version of the growth pattern trait. The question tells you that the g allele, which is for bush growth, is recessive to the G allele, which is for climbing growth.
Climbing growth is the dominant allele's version of the growth pattern trait. A rose plant with the dominant version of the growth pattern trait must have at least one dominant allele for the growth pattern gene. So, offspring with climbing growth must have the genotype GG or Gg.
There are 2 boxes in the Punnett square with the genotype GG or Gg. These boxes are highlighted below.
Bush growth is the recessive allele's version of the growth pattern trait. A rose plant with the recessive version of the growth pattern trait must have only recessive alleles for the growth pattern gene. So, offspring with bush growth must have the genotype gg.
There are 2 boxes in the Punnett square with the genotype gg. These boxes are highlighted below.
So, the expected ratio of offspring with climbing growth to offspring with bush growth is 2:2. This means that, on average, this cross will produce 2 offspring with climbing growth for every 2 offspring with bush growth.

natural science


Question: Which organ pulls on bones to move the body?

Choices:
A. skeleton
B. skin
C. large intestines
D. muscles

natural science


Question:
What do these two changes have in common?
melting wax
rain forming in a cloud

Choices:
A. Both are only physical changes.
B. Both are caused by cooling.
C. Both are caused by heating.
D. Both are chemical changes.

Matter is made of very small particles called atoms. Atoms can be linked together by chemical bonds. When two or more atoms link together, they form a molecule.
In a chemical change, the chemical bonds in the molecules break. The atoms then link together to form different molecules. The types of molecules in matter before and after a chemical change are always different.
Some chemical changes are caused by heating or cooling. For example, burning a piece of paper is a chemical change caused by heating. As paper burns, paper molecules react with oxygen molecules in the air. This reaction breaks the chemical bonds in the molecules. The atoms then link together in a different way to form different molecules. For example, carbon dioxide molecules are formed when paper burns.
In a physical change, chemical bonds do not break. The types of molecules in matter before and after a physical change are always the same.
A change of state is a type of physical change. Changes of state can be caused by heating or cooling. For example, water vaporizing is a physical change that can be caused by heating. Liquid water and water vapor are made of the same type of matter: water.
The law of conservation of mass says that all physical and chemical changes conserve mass. Conserve means to keep the same. So, the total mass before a physical or chemical change is equal to the total mass after the change.

Step 1: Think about each change.
Melting wax is a change of state. So, it is a physical change. The wax changes from solid to liquid. But it is still made of the same type of matter.
Rain forming in a cloud is a change of state. So, it is a physical change. Water vapor in the air condenses into tiny droplets of liquid water. These droplets make up a cloud. When there is enough water in the air, the droplets will fall as rain.
Step 2: Look at each answer choice.
Both are only physical changes.
Both changes are physical changes. No new matter is created.
Both are chemical changes.
Both changes are physical changes. They are not chemical changes.
Both are caused by heating.
Wax melting is caused by heating. But rain forming in a cloud is not.
Both are caused by cooling.
Rain begins to form when water vapor in the air becomes liquid water. This is caused by cooling. But melting wax is not.

natural science


Question: How long is a car key?

Choices:
A. 3 yards
B. 3 inches
C. 3 miles
D. 3 feet

Select the best estimate.

Measurements are written with both a number and a unit. The unit comes after the number. The unit shows what the number means.
When you are using customary units, length may be written with units of inches, feet, yards, or miles.
There are 12 inches in 1 foot, and 3 feet in 1 yard. There are 5,280 feet in 1 mile.
A football is about 1 foot long. A football field is 100 yards long.

The best estimate for the length of a car key is 3 inches.
3 feet, 3 yards, and 3 miles are all too long.

natural science


Question: Select the bird.

Choices:
A. seahorse
B. loon
C. salmon
D. Hermann's tortoise

Birds have feathers, two wings, and a beak.

A seahorse is a fish. It lives underwater. It has fins, not limbs.
Seahorses live in shallow, warm water. They can use their tails to hold on to plants.
A loon is a bird. It has feathers, two wings, and a beak.
Loons usually live near lakes. They dive in the water to hunt for food.
A salmon is a fish. It lives underwater. It has fins, not limbs.
Unlike most other fish, salmon can live in both fresh water and salt water.
A Hermann's tortoise is a reptile. It has scaly, waterproof skin.
A tortoise's shell protects it from predators. When a tortoise feels threatened, it can pull its head and legs inside its shell.

natural science