questions stringlengths 37 1.22k | reasoning stringlengths 0 3.56k ⌀ | answers stringlengths 4 138 |
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Which inducer turns on the expression of the lac genes?
Here are the choices:
A. xerophyte
B. allolactose
C. glucose
D. galactose | When lactose is available, a lactose metabolite called allolactose binds to the allosteric site on the repressor. This interaction causes a conformational change in the repressor shape and the repressor falls off the operator, allowing RNA polymerase to bind to the promoter and initiate transcription. Allolactose is ca... | B: allolactose. |
What is the most common type of brain injury?
Here are the choices:
A. Anoxic Event
B. Contusion
C. concussion
D. Diffuse Axonal | The most common type of brain injury is a concussion. This is a bruise on the surface of the brain. It may cause temporary symptoms such as headache and confusion. Most concussions heal on their own in a few days or weeks. However, repeated concussions can lead to permanent changes in the brain. More serious brain inju... | C: concussion. |
Changing the shape of an elastic material gives it what type of energy?
Here are the choices:
A. initial
B. potential
C. thermal
D. practical | Changing the shape of an elastic material gives it potential energy. | B: potential. |
What type of traits are features that are passed from one generation to the next called?
Here are the choices:
A. familial traits
B. genetic traits
C. inherited traits
D. generational traits | The theory of evolution by natural selection means that the inherited traits of a population change over time. Inherited traits are features that are passed from one generation to the next. For example, your eye color is an inherited trait. You inherited your eye color from your parents. Inherited traits are different ... | C: inherited traits. |
What is your body made up of?
Here are the choices:
A. energy
B. skin
C. trillions of cells
D. millions of elements | According to the cell theory , all living things are made up of cells, which is the structural unit of living organisms, and living cells always come from other living cells. In fact, each living thing begins life as a single cell. Some living things, such as bacteria, remain single-celled. Other living things, includi... | C: trillions of cells. |
Hemoglobin is responsible for transporting what within our blood?
Here are the choices:
A. water
B. dioxide
C. oxygen
D. nitrogen | To predict the relative stabilities of metal complexes with different ligands. One of the most important properties of metallic elements is their ability to act as Lewis acids that form complexes with a variety of Lewis bases. A metal complex consists of a central metal atom or ion that is bonded to one or more ligands... | C: oxygen. |
How do bipedal creatures walk?
Here are the choices:
A. on four legs
B. on six legs
C. on two legs
D. on twelve legs | Birds are endothermic tetrapod vertebrates. They are bipedal, which means they walk on two legs. Birds also lay amniotic eggs with hard, calcium carbonate shells. Although birds are the most recent class of vertebrates to evolve, they are now the most numerous vertebrates on Earth. Why have birds been so successful? Wh... | C: on two legs. |
Any sample of matter that has the same physical and chemical properties throughout the sample is called what?
Here are the choices:
A. element
B. substance
C. molecule
D. type | Elements and Compounds Any sample of matter that has the same physical and chemical properties throughout the sample is called a substance. There are two types of substances. A substance that cannot be broken down into chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. A s... | B: substance. |
What is a measure of both speed and direction of motion?
Here are the choices:
A. distance
B. intensity
C. acceleration
D. velocity | Velocity is a measure of both speed and direction of motion. Velocity is a vector, which is a measurement that includes both size and direction. | D: velocity. |
What do fish eggs hatch to form?
Here are the choices:
A. fish eggs hatch to form larvae
B. unfertilized eggs
C. tadpoles
D. adolescent fish | Almost all fish have sexual reproduction, generally with separate sexes. Most fish are oviparous. Many species reproduce by spawning. Eggs hatch to form larvae, which undergo metamorphosis to become adults. | A: fish eggs hatch to form larvae. |
Commensalism, mutualism, and parasitism are known as what type of relationships?
Here are the choices:
A. various
B. simple
C. symbiotic
D. peculiar | 19.4 Community Ecology Communities include all the different species living in a given area. The variety of these species is referred to as biodiversity. Many organisms have developed defenses against predation and herbivory, including mechanical defenses, warning coloration, and mimicry. Two species cannot exist indef... | C: symbiotic. |
The modern model of the atom, which scientists call the quantum mechanical model, is based on what scientist's work on orbitals?
Here are the choices:
A. Bohr
B. schrödinger
C. Sagan
D. Newton | Schrödinger’s work on orbitals is the basis of the modern model of the atom, which scientists call the quantum mechanical model. The modern model is also commonly called the electron cloud model. That’s because each orbital around the nucleus of the atom resembles a fuzzy cloud around the nucleus, like the ones shown i... | B: schrödinger. |
Time, mass, length, and temperature are considered to be what kinds of units?
Here are the choices:
A. unitary
B. base
C. support
D. measurement | Base units have independent scales and cannot be described by a combination of any other base units. Examples of base units used in chemistry are length, mass, temperature, and time. | B: base. |
What does the heat energy affect in the atmosphere?
Here are the choices:
A. gravity and precipitation
B. erosion and condensation
C. density and humidity
D. winds and weather | How do the differences in energy striking different latitudes affect Earth? The planet is much warmer at the equator than at the poles. In the atmosphere, the differences in heat energy cause winds and weather. On the surface, the differences cause ocean currents. Can you explain how?. | D: winds and weather. |
What are the taste receptors found as tiny bumps on the tongue called?
Here are the choices:
A. hard buds
B. ear buds
C. fat buds
D. taste buds | Taste receptors are found in tiny bumps on the tongue called taste buds (see Figure below ). There are separate taste receptors for sweet, salty, sour, bitter, and meaty tastes. The meaty taste is called umami . You can learn more about taste receptors and the sense of taste by watching the animation at the following l... | D: taste buds. |
What is the chemical formula for a glucose molecule?
Here are the choices:
A. a5 h12 o6
B. H2 C3 NA6
C. c6 h12 o6
D. d5 h12 o6 | The sugar glucose is a covalent compound. When sugar dissolves in water, it forms individual glucose molecules (C 6 H 12 O 6 ). You can see how this happens in the Figure below . Sugar is polar like water, so sugar molecules also have positive and negative ends. Forces of attraction between oppositely charged ends of w... | C: c6 h12 o6. |
In physics, the number of waves that pass a fixed point in a given amount time is referred to as what ?
Here are the choices:
A. wave frequency
B. creation frequency
C. wave count
D. combination frequency | Wave speed is related to both wavelength and wave frequency. Wavelength is the distance between two corresponding points on adjacent waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. This equation shows how the three factors are related:. | A: wave frequency. |
The reactions between alkali metals and water are particularly vigorous and include the rapid production of large quantities of what gas?
Here are the choices:
A. helium
B. carbon
C. oxygen
D. hydrogen | All alkali metals are very soft and can be cut easily with a knife. Due to their high reactivity, they must be stored under oil to prevent them from reacting with oxygen or water vapor in the air. The reactions between alkali metals and water are particularly vigorous and include the rapid production of large quantitie... | D: hydrogen. |
Batteries produce voltage through what type of reaction?
Here are the choices:
A. thermal
B. magnetic
C. radiation
D. chemical | Chemical cells are found in batteries. They produce voltage by means of chemical reactions. A chemical cell has two electrodes, which are strips made of different materials, such as zinc and carbon (see Figure below ). The electrodes are suspended in an electrolyte. An electrolyte is a substance containing free ions th... | D: chemical. |
The speed of a particle in what state is directly proportional to the temperature of the system?
Here are the choices:
A. liquid
B. solid
C. gas
D. frozen | The speed of a gas particle is directly proportional to the temperature of the system. | C: gas. |
Acne results from a blockage of sebaceous glands by what?
Here are the choices:
A. mucous
B. progesterone
C. fat
D. sebum | Chapter 5 1 The epidermis provides protection, the dermis provides support and flexibility, and the hypodermis (fat layer) provides insulation and padding. 3 Figure 5.6 These cells have desmosomes, which give the cells their spiny appearance. 5 D 7 C 9 C 11 D 13 B 15 A 17 C 19 C 21 C 23 B 25 The pigment melanin, produc... | D: sebum. |
Just as millions of different words are spelled with our 26-letter english alphabet, millions of different proteins are made with the 20 common what?
Here are the choices:
A. mutation acids
B. amino acids
C. enzymes
D. peptides | Just as millions of different words are spelled with our 26-letter English alphabet, millions of different proteins are made with the 20 common amino acids. However, just as the English alphabet can be used to write gibberish, amino acids can be put together in the wrong sequence to produce nonfunctional proteins. Alth... | B: amino acids. |
Anaerobic respiration takes place without what?
Here are the choices:
A. nitrogen
B. movement
C. oxygen
D. carbon | Aerobic respiration , which takes place in the presence of oxygen, evolved after oxygen was added to Earth’s atmosphere. This type of respiration is useful today because the atmosphere is now 21% oxygen. However, some anaerobic organisms that evolved before the atmosphere contained oxygen have survived to the present. ... | C: oxygen. |
Which other planet in the solar system is the easiest to observe from earth?
Here are the choices:
A. mars
B. Pluto
C. Mercury
D. Jupiter | Mars is the easiest planet to observe. As a result, it has been studied more than any other planet besides Earth. People can stand on Earth and observe the planet through a telescope. We have also sent many space probes to Mars. In April 2011, there were three scientific satellites in orbit around Mars. The rover, Oppo... | A: mars. |
What is in the inside of your mouth and nose instead of skin?
Here are the choices:
A. scales
B. cuticle layer
C. gums
D. mucous membranes | The mouth and nose are not lined with skin. Instead, they are lined with mucous membranes . Other organs that are exposed to the outside world, including the lungs and stomach, are also lined with mucous membranes. Mucous membranes are not tough like skin, but they have other defenses. | D: mucous membranes. |
While matter is recycled, ecosystems need a constant input of what?
Here are the choices:
A. heating
B. food
C. energy
D. light | In all biomes, ecosystems need a constant input of energy. Matter, on the other hand, is constantly recycled in ecosystems. | C: energy. |
What is term for the smallest particle of an element that still has the properties of said element?
Here are the choices:
A. proton
B. nucleus
C. atom
D. molecule | Atoms are the building blocks of matter. They are the smallest particles of an element that still have the element’s properties. Elements, in turn, are pure substances—such as nickel, hydrogen, and helium—that make up all kinds of matter. All the atoms of a given element are identical in that they have the same number ... | C: atom. |
What is the protein that carries iron that binds with oxygen in red blood cells?
Here are the choices:
A. hemoglobin
B. potassium
C. insulin
D. keratin | The trillions of red blood cells in blood plasma carry oxygen. Red blood cells contain hemoglobin , a protein with iron that binds with oxygen. Red blood cells are made in the marrow of long bones, rib bones, the skull, and the vertebrae. These cells survive for about 120 days, and then they are destroyed. Mature red b... | A: hemoglobin. |
What branch of science is based on the modern atomic theory, which states that all matter is composed of atoms?
Here are the choices:
A. psychology
B. chemistry
C. biology
D. physics | Chemistry is based on the modern atomic theory, which states that all matter is composed of atoms. | B: chemistry. |
Why do sharks sense low levels of electricity?
Here are the choices:
A. to locate prey
B. to locate mates
C. to sleep
D. to reproduce | Fish also have a centralized nervous system with a brain. Fish brains are small compared with the brains of other vertebrates, but they are large and complex compared with the brains of invertebrates. Fish also have highly developed sense organs that allow them to see, hear, feel, smell, and taste. Sharks and some othe... | A: to locate prey. |
What membrane is populated by two types of photosystems that cooperate in the light reactions of photosynthesis?
Here are the choices:
A. thylakoid
B. choroid
C. chloroplasts
D. subcutaneous | A: thylakoid. | |
At what point can nutrients enter or exit an ecosystem?
Here are the choices:
A. Hottest Point
B. Largest Population Point
C. Longest Point
D. any point | Nutrients can enter or exit an ecosystem at any point and can cycle around the planet. | D: any point. |
B cells and t cells are examples of what type of cells?
Here are the choices:
A. skin cells
B. white blood cells
C. heart cells
D. cancer cells | There are two different types of specific immune responses. One type involves B cells. The other type involves T cells. Recall that B cells and T cells are types of white blood cells that are key in the immune response. Whereas the immune system's first and second line of defense are more generalized or non-specific, t... | B: white blood cells. |
There are three different types of rna. all three types are needed to make what?
Here are the choices:
A. proteins
B. Blood
C. lipids
D. acids | There are three different types of RNA. All three types are needed to make proteins. | A: proteins. |
Niche and habitat are concepts related to what broader term?
Here are the choices:
A. ecosystem
B. community
C. population
D. biome | 7. Compare and contrast the ecosystem concepts of niche and habitat. | A: ecosystem. |
What do opposite charges do to one another?
Here are the choices:
A. weaken
B. repel
C. strengthen
D. attract | Opposite charges attract, and like charges repel. | D: attract. |
What is the name for the sinking of the dense, salty seawater in cold climates?
Here are the choices:
A. downwelling
B. tidal activity
C. cyclones
D. jet stream | Water becomes more dense when it is colder and when it has more salt. In the North Atlantic Ocean, cold winds chill the water at the surface. Sea ice grows in this cold water, but ice is created from fresh water. The salt is left behind in the seawater. This cold, salty water is very dense, so it sinks to the bottom of... | A: downwelling. |
When gas particles heat up and gain energy, what do they do?
Here are the choices:
A. go up
B. move slower
C. stop
D. move faster | When gas particles heat up and gain energy, they move faster. This increases their collisions with each other and their container, causing greater pressure. | D: move faster. |
Ion pumps, the biological machines responsible for the selective transport of metal ions, are complex assemblies of what?
Here are the choices:
A. cells
B. minerals
C. acids
D. proteins | Ion Transport The Na+, K+, Mg2+, and Ca2+ ions are important components of intracellular and extracellular fluids. Both Na+ and Ca2+ are found primarily in extracellular fluids, such as blood plasma, whereas K + and Mg2+ are found primarily in intracellular fluids. Substantial inputs of energy are required to establish... | D: proteins. |
Lack of proper food over a period of time can lead to what condition, where the body is not getting enough nutrients to grow and stay healthy?
Here are the choices:
A. malnutrition
B. anemia
C. bulimia
D. mortality | Refusing one meal won't stunt your growth. But lack of proper food over a period of time can lead to malnutrition. That means, the body is not getting enough nutrients to grow and stay healthy. Kids who are malnourished may not grow as tall as they would otherwise. | A: malnutrition. |
Two water molecules contain 4 hydrogen atoms and how many oxygen atoms?
Here are the choices:
A. 2
B. 1
C. 6
D. 4 | Two water molecules contain 4 hydrogen atoms and 2 oxygen atoms. A mole of water molecules contains 2 moles of hydrogen atoms and 1 mole of oxygen atoms. | A: 2. |
The carrying angle is larger in females to accommodate their what?
Here are the choices:
A. cranium
B. wider pelvis
C. narrower pelvis
D. broader shoulders | the ulna and radius bones. The small, rounded area that forms the distal end is the head of the ulna. Projecting from the posterior side of the ulnar head is the styloid process of the ulna, a short bony projection. This serves as an attachment point for a connective tissue structure that unites the distal ends of the ... | B: wider pelvis. |
Examples of organ systems in a human include the skeletal, nervous, and what?
Here are the choices:
A. nervous systems
B. reproductive systems
C. affecting systems
D. immune systems | Organ system : Group of organs that work together to perform a certain function. Examples of organ systems in a human include the skeletal, nervous, and reproductive systems. | B: reproductive systems. |
Most hormones are controlled by what type of feedback, which causes the hormone to decrease its own production?
Here are the choices:
A. neutral
B. positive
C. negative
D. unusual | Most hormones are controlled by negative feedback in which the hormone feeds back to decrease its own production. This type of feedback brings things back to normal whenever they start to become too extreme. Positive feedback is much less common because it causes conditions to become increasingly extreme. | C: negative. |
What is the stage called for babies that are in the first year of life after birth?
Here are the choices:
A. original stage
B. infancy
C. primary stage
D. adolescence | Infancy is the first year of life after birth. Infants are born with a surprising range of abilities. For example, they have well-developed senses of touch, hearing, and smell. They can also communicate their needs by crying. During their first year, they develop many other abilities, including those described below. F... | B: infancy. |
What forms a barrier between the cytoplasm and the environment outside the cell?
Here are the choices:
A. cell wall
B. plasma membrane
C. epidermis
D. cuticle | The plasma membrane forms a barrier between the cytoplasm and the environment outside the cell. The plasma membrane has selective permeability. | B: plasma membrane. |
Over time, what changes solid rock into pieces?
Here are the choices:
A. metamorphosis
B. weathering
C. leaching
D. creep | Weathering changes solid rock into pieces. These pieces are called sediments. Sediments are described in the chapter Earth's Materials and Crust . Sediments are different sizes of rock particles. Boulders are sediments; so is gravel. At the other end, silt and clay are also sediments. Weathering may also cause the mine... | B: weathering. |
Eukaryotic cells undergo what kinds of divisions that more primitive cells do not?
Here are the choices:
A. budding
B. homologous
C. meiosis
D. mitosis | Mitosis , or division of the nucleus, occurs only in eukaryotic cells. By the time mitosis occurs, the cell’s DNA has already replicated. Mitosis occurs in four phases, called prophase, metaphase, anaphase, and telophase. You can see what happens in each phase in Figure below . The phases are described below. You can a... | D: mitosis. |
The orbicularis oris is a circular muscle that moves the lips, and the orbicularis oculi is a circular muscle that does what?
Here are the choices:
A. opens the eye
B. closes the eye
C. moisturizes the eye
D. pressure the eye | The orbicularis oris is a circular muscle that moves the lips, and the orbicularis oculi is a circular muscle that closes the eye. The occipitofrontalis muscle moves up the scalp and eyebrows. The muscle has a frontal belly and an occipital (near the occipital bone on the posterior part of the skull) belly. In other wo... | B: closes the eye. |
What may have developed to help our ancestors distinguish between ripe and unripe fruits?
Here are the choices:
A. night vision
B. color vision
C. acute hearing
D. fine motor skills | McKay Savage. Color vision may have developed to help our ancestors distinguish between ripe and unripe fruits . CC BY 2.0. | B: color vision. |
Which stage is specialized for dispersal & reproduction?
Here are the choices:
A. adult stage
B. fetal stage
C. larval stage
D. cocoon stage | A: adult stage. | |
What three parameters do seismographs measure?
Here are the choices:
A. trouble , length and distance
B. height, width and distance
C. aging , length and distance
D. strength, length and distance | Seismograms contain a lot of information about an earthquake: its strength, length and distance. Wave height used to determine the magnitude of the earthquake. The seismogram shows the different arrival times of the seismic waves ( Figure below ). The first waves are P-waves since they are the fastest. S-waves come in ... | D: strength, length and distance. |
What topographic feature does a circle with inward hatches represent on a contour map?
Here are the choices:
A. a mountain
B. a lake
C. a depression
D. vegetation | On a contour map, a circle with inward hatches indicates a depression. | C: a depression. |
Which temperatures cause particles of reactants to have more energy?
Here are the choices:
A. non-existant
B. reducing
C. lower
D. higher | When the temperature of reactants is higher, the rate of the reaction is faster. At higher temperatures, particles of reactants have more energy, so they move faster. They are more likely to bump into one another and to collide with greater force. For example, when you fry an egg, turning up the heat causes the egg to ... | D: higher. |
Not all cells of a leaf carry out photosynthesis. cells within the middle layer of a leaf have chloroplasts, which contain the photosynthetic what?
Here are the choices:
A. pipes
B. wires
C. apparatus
D. structure | Figure 5.7 Not all cells of a leaf carry out photosynthesis. Cells within the middle layer of a leaf have chloroplasts, which contain the photosynthetic apparatus. (credit "leaf": modification of work by Cory Zanker). | C: apparatus. |
What is the advantage of selecting for certain genetic traits for crops?
Here are the choices:
A. improves taste
B. promotes productivity
C. Faster growth
D. protection from pests | Improving crops by selecting for certain genetic traits. The desired traits promote productivity. Recently, genetically engineered crops have been introduced. | B: promotes productivity. |
What is given off from plants and taken in by animals?
Here are the choices:
A. sulfur
B. oxygen
C. nitrogen
D. methane | B: oxygen. | |
What is the simplest unit that has the fundamental chemical properties of an element?
Here are the choices:
A. neutron
B. nucleus
C. cell
D. atom | Covalent Molecules and Compounds Just as an atom is the simplest unit that has the fundamental chemical properties of an element, a molecule is the simplest unit that has the fundamental chemical properties of a covalent compound. Some pure elements exist as covalent molecules. Hydrogen, nitrogen, oxygen, and the halog... | D: atom. |
Bacteria are what kind of cell?
Here are the choices:
A. prokaryotes
B. eukaryotes
C. protists
D. blood | The rod-shaped organisms in Figure below are bacteria called Salmonella . Bacteria (bacterium, singular) are prokaryotes in the Bacteria Domain. The word Salmonella may sound familiar. That's because Salmonella is a common cause of food poisoning. Many other types of bacteria also cause human diseases. But not all bact... | A: prokaryotes. |
What is the first stage of cellular respiration?
Here are the choices:
A. glycolysis
B. gluconeogenesis
C. decarboxylation
D. Krebs cycle | The first stage of cellular respiration is glycolysis. It does not require oxygen. | A: glycolysis. |
Who study volcanoes to be able to predict when a volcano will erupt?
Here are the choices:
A. virologists
B. ornithologists
C. vocologists
D. volcanologists | Volcanic eruptions can be devastating, particularly to the people who live close to volcanoes. Volcanologists study volcanoes to be able to predict when a volcano will erupt. Many changes happen when a volcano is about to erupt. | D: volcanologists. |
What is the term for electric current that keeps reversing direction?
Here are the choices:
A. direct current
B. magnetic current
C. alternating current
D. AC/DC | The Figure below shows the direction of the current that is generated by a moving magnet. If the magnet is moved back and forth repeatedly, the current keeps changing direction. In other words, alternating current (AC) is produced. Alternating current is electric current that keeps reversing direction. | C: alternating current. |
How many alleles comes from each parent?
Here are the choices:
A. three
B. two
C. one
D. none | When gametes unite during fertilization, the resulting zygote inherits two alleles for each gene. One allele comes from each parent. | C: one. |
How close a measurement is to the correct value for that measurement is known as what?
Here are the choices:
A. accuracy
B. frequency
C. temperature
D. rate | Accuracy and Precision of a Measurement Science is based on observation and experiment—that is, on measurements. Accuracy is how close a measurement is to the correct value for that measurement. For example, let us say that you are measuring the length of standard computer paper. The packaging in which you purchased th... | A: accuracy. |
What pigment is required for photosynthesis to occur?
Here are the choices:
A. chlorophyll
B. xanthophyll
C. chroma
D. carotene | A: chlorophyll. | |
What begins approximately six weeks after fertilization in an embryo?
Here are the choices:
A. incubation
B. calcification
C. elongation
D. ossification | Development of Bone Ossification, or osteogenesis, is the process of bone formation by osteoblasts. Ossification is distinct from the process of calcification; whereas calcification takes place during the ossification of bones, it can also occur in other tissues. Ossification begins approximately six weeks after fertil... | D: ossification. |
What do you call the energy that must be overcome in order for a chemical reaction to occur, or the minimum energy required to start a chemical reaction?
Here are the choices:
A. expression energy
B. kinetic energy
C. activation energy
D. phase energy | Regardless of whether reactions are exothermic reactions or endothermic reactions , they all need energy to get started. This energy is called activation energy . Activation energy is like the push you need to start moving down a slide. The push gives you enough energy to start moving. Once you start, you keep moving w... | C: activation energy. |
Frogs and toads, salamanders and newts, and caecilians are the three orders of what group of animals?
Here are the choices:
A. mammals
B. reptiles
C. amphibians
D. marsupials | There are about 6,200 known species of living amphibians. They are classified into three orders: frogs and toads, salamanders and newts, and caecilians. | C: amphibians. |
What are vesicles made of?
Here are the choices:
A. membranes
B. cells
C. filaments
D. phospholipids | A vesicle. Because vesicles are made of phospholipids, they can break off of and fuse with other membraneous material. This allows them to serve as small transport containers, moving substances around the cell and to the cell membrane. | D: phospholipids. |
Deoxyribonucleic acid (dna) is nucleotide that stores what type of information?
Here are the choices:
A. variation
B. genetic
C. mutation
D. mononucleus | Nucleic Acids The nucleic acids differ in their type of pentose sugar. Deoxyribonucleic acid (DNA) is nucleotide that stores genetic information. DNA contains deoxyribose (so-called because it has one less atom of oxygen than ribose) plus one phosphate group and one nitrogen-containing base. The “choices” of base for D... | B: genetic. |
What two basic types of feather does a bird have?
Here are the choices:
A. flight and landing
B. up and down
C. carrying and down
D. flight and down | Feathers help birds fly and also provide insulation and serve other purposes. Birds actually have two basic types of feathers: flight feathers and down feathers. Both are shown in Figure below . Flight feathers are long, stiff and waterproof. They provide lift and air resistance without adding weight. Down feathers are... | D: flight and down. |
Which fuels provide most of the world’s energy?
Here are the choices:
A. fossil fuels
B. coal fuels
C. pattern fuels
D. artificial fuels | Figure below shows the mix of energy resources used worldwide in 2006. Fossil fuels still provide most of the world’s energy, with oil being the single most commonly used energy resource. Natural gas is used less than the other two fossil fuels, but even natural gas is used more than all renewable energy resources comb... | A: fossil fuels. |
The cathode and anode collectively are the electrodes of what?
Here are the choices:
A. photo cell
B. circuit cell
C. switch cell
D. voltaic cell | One application of redox reactions requires that they be physically separated. Even though the two half reactions are physically separated, a spontaneous redox reaction still occurs. However, in this case, the electrons transfer through the wire connecting the two half reactions; that is, this setup becomes a source of... | D: voltaic cell. |
What part of the sweet potato store sugar from photosynthesis as starch?
Here are the choices:
A. shrubs
B. roots
C. skin
D. plants | Secondary growth of sweet potato roots provides more space to store food. Roots store sugar from photosynthesis as starch. What other starchy roots do people eat?. | B: roots. |
What is the ratio of charge on a capacitor to potential difference across it called?
Here are the choices:
A. velocity
B. capacitance
C. electromagnetism
D. resonance | When a capacitor is placed in a circuit, current does not actually travel across it. Rather, equal and opposite charge begins to build up on opposite sides of the capacitor --- mimicking a current --- until the electric field in the capacitor creates a potential difference across it that balances the voltage drop acros... | B: capacitance. |
What substances that primarily comprise plasma membranes form a bilayer?
Here are the choices:
A. enzymes
B. steroids
C. phospholipids
D. amino acids | Plasma membranes are primarily made up of phospholipids (orange). The hydrophilic ("water-loving") head and two hydrophobic ("water-hating") tails are shown. The phospholipids form a bilayer (two layers). The middle of the bilayer is an area without water. There can be water on either side of the bilayer. There are man... | C: phospholipids. |
What type of friction is friction that acts on objects when they are sliding over a surface?
Here are the choices:
A. rolling friction
B. spreading friction
C. sliding friction
D. static friction | Sliding friction is friction that acts on objects when they are sliding over a surface. Sliding friction is weaker than static friction. That’s why it’s easier to slide a piece of furniture over the floor after you start it moving than it is to get it moving in the first place. Sliding friction can be useful. For examp... | C: sliding friction. |
Billions of what inside the human digestive tract help us digest food, make vitamins and play other important roles?
Here are the choices:
A. bacteria
B. red blood cells
C. viruses
D. neurons | There are billions of bacteria inside the human digestive tract. They help us digest food. They also make vitamins and play other important roles. We use bacteria in many other ways as well. For example, we use them to:. | A: bacteria. |
In a controlled scientific study, what do you call a factor that can take on different values?
Here are the choices:
A. output
B. input
C. vector
D. variable | An experiment is a controlled scientific study of specific variables. A variable is a factor that can take on different values. For example, the speed of an object down a ramp might be one variable, and the steepness of the ramp might be another. | D: variable. |
What is a group of similar ecosystems with the same general abiotic factors and primary producers called?
Here are the choices:
A. ecological environment
B. biome
C. population
D. ecoculture | Sahara Desert in northern Africa (left). Rainforest in northeastern Australia (right). Two very different biomes are pictured here. A biome is a group of similar ecosystems with the same general abiotic factors and primary producers. Both are found at roughly the same distance from the equator. | B: biome. |
Since 1900, four of the five earthquakes of the greatest magnitude occurred near what appropriately nicknamed pacific location?
Here are the choices:
A. shower of fire
B. seismic zone
C. quake epicenter
D. ring of fire | Earthquakes with a magnitude in the 9 range are rare. The United States Geological Survey lists five such earthquakes on the moment magnitude scale since 1900 (see Figure below ). All but one, the Great Indian Ocean Earthquake of 2004, occurred somewhere around the Pacific Ring of Fire. | D: ring of fire. |
All chemical changes involve a transfer of what?
Here are the choices:
A. energy
B. fuel
C. pressure
D. oxygen | Describe ways protists are important to humans. | A: energy. |
What is the most common type of capillary?
Here are the choices:
A. large
B. continuous
C. channels
D. ending | Continuous Capillaries The most common type of capillary, the continuous capillary, is found in almost all vascularized tissues. Continuous capillaries are characterized by a complete endothelial lining with tight junctions between endothelial cells. Although a tight junction is usually impermeable and only allows for ... | B: continuous. |
What is the bending of waves around a corner called?
Here are the choices:
A. reflection
B. diffraction
C. propulsion
D. absorption | Diffraction is the bending of waves around a corner. | B: diffraction. |
In what kind of bond does one atom contribute both of the electrons in the shared pair?
Here are the choices:
A. a metallic bond
B. a covalent bond
C. an ionic bond
D. a valence bond | The carbon monoxide molecule is correctly represented by a triple covalent bond between the carbon and oxygen atoms. One of the bonds is a coordinate covalent bond , a covalent bond in which one of the atoms contributes both of the electrons in the shared pair. | B: a covalent bond. |
Mirrors and lenses are used in optical instruments to reflect and refract what?
Here are the choices:
A. gravity
B. electricity
C. light
D. mass | Mirrors and lenses are used in optical instruments to reflect and refract light. Optical instruments include microscopes, telescopes, cameras, and lasers. | C: light. |
The zygote undergoes many cell divisions before it implants in the lining of what?
Here are the choices:
A. pelvis
B. vagina
C. ovaries
D. uterus | The zygote undergoes many cell divisions before it implants in the lining of the uterus. | D: uterus. |
What are carbonated beverages pressurized with?
Here are the choices:
A. co2
B. helium
C. dioxide
D. hydrogen | NaN3 is 1.847 g/cm . What is the volume of the gas produced compared to the solid reactant? Suggest a plausible reason to explain why skin burns can result from the inflation of an airbag during an automobile accident. Under basic conditions, the reaction of hydrogen peroxide (H 2O2) and potassium permanganate (KMnO4) ... | A: co2. |
Which principle states that two species cannot occupy the same niche in a habitat?
Here are the choices:
A. produce exclusion
B. tough exclusion
C. competitive exclusion
D. complete exclusion | Competitive Exclusion Principle Resources are often limited within a habitat and multiple species may compete to obtain them. All species have an ecological niche in the ecosystem, which describes how they acquire the resources they need and how they interact with other species in the community. The competitive exclusi... | C: competitive exclusion. |
What happens to the rate of chemical reactions in higher temperatures?
Here are the choices:
A. they become erratic
B. they increase
C. they stop
D. they decrease | The temperature of a region is the other important part of climate. The rate of chemical reactions increases with higher temperatures. The rate doubles for every 10°C increase in temperature. Plants and bacteria grow and multiply faster in warmer areas. | B: they increase. |
An alternative to inclusive fitness is group selection, a type of what scenario where small groups of organisms of the same species are effectively acting as single (perhaps colonial) organisms?
Here are the choices:
A. evolutionary
B. combination
C. introductory
D. molecular | Group selection A proposed alternative to inclusive fitness (sometimes known as kin selection) is the concept of group selection. In this type of evolutionary scenario, small groups of organisms of the same species are effectively acting as single (perhaps colonial) organisms. It is the reproductive success of the grou... | A: evolutionary. |
The complement system is a series of proteins constitutively found in the what?
Here are the choices:
A. nucleus
B. blood plasma
C. organs
D. platelets | Complement System The complement system is a series of proteins constitutively found in the blood plasma. As such, these proteins are not considered part of the early induced immune response, even though they share features with some of the antibacterial proteins of this class. Made in the liver, they have a variety of... | B: blood plasma. |
What are cations simply named after?
Here are the choices:
A. the parent element
B. the scientist
C. the body part
D. the cell structure | The cations are simply named as the parent element. The sodium cation is still called “sodium. ” Often, the charge would be attached for clarity, so the sodium cation might be referred to as “sodium one plus. ”. | A: the parent element. |
Inorganic chemistry refers to the study of materials *not* containing which element?
Here are the choices:
A. oxygen
B. hydrogen
C. helium
D. carbon | Inorganic chemistry is the study of chemicals that do not, in general, contain carbon. Inorganic chemicals are commonly found in rocks and minerals. One current important area of inorganic chemistry deals with the design and properties of materials involved in energy and information technology. | D: carbon. |
How many chambers does an amphibian heart have?
Here are the choices:
A. three
B. one
C. four
D. two | Amphibians have a relatively complex circulatory system with a three-chambered heart. Their nervous system is also rather complex, allowing them to interact with each other and their environment. Amphibians have sense organs to smell and taste chemicals. Other sense organs include eyes and ears. Of all amphibians, frog... | A: three. |
Electrons in the "outer shell" are also known as what kind of electrons?
Here are the choices:
A. intermediate
B. charged
C. static
D. valence | Determine the total number of valence (outer shell) electrons. For cations, subtract one electron for each. | D: valence. |
What is created when energy turns a turbine?
Here are the choices:
A. light
B. force
C. torque
D. electricity | 4. Electricity is made when some type of energy turns a turbine. Explain how this happens and give two examples. | D: electricity. |
Where in the periodic table of elements are the nonmetals located?
Here are the choices:
A. top left
B. top right
C. bottom left
D. bottom right | As described in Section 1.7 "Introduction to the Periodic Table", the metals are on the bottom left in the periodic table, and the nonmetals are at the top right. The semimetals lie along a diagonal line separating the metals and nonmetals. In most cases, the symbols for the elements are derived directly from each elem... | B: top right. |
How many different main types of diabetes are there?
Here are the choices:
A. two
B. ten
C. three
D. four | A: two. | |
Where do most amphibians live, salt water or fresh water?
Here are the choices:
A. aquariums
B. saltwater
C. deserts
D. fresh water | Most amphibians live in fresh water, not salt water. Their habitats can include areas close to springs, streams, rivers, lakes, swamps and ponds. They can be found in moist areas in forests, meadows and marshes. Amphibians can be found almost anywhere there is a source of fresh water. Although there are no true saltwat... | D: fresh water. |
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