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Marine fossils on the top of Mt. Everest indicate | (A) sea level was once higher than the top of Mt (B) the fossils are not actually marine fossils (C) but just look like them (D) c the rock at the top of Mt (E) d someone put them up there as a trick | C | Fossils give clues about major geological events. Fossils can also give clues about past climates. Fossils of ocean animals are found at the top of Mt. Everest. Mt. Everest is the highest mountain on Earth. These fossils show that the area was once at the bottom of a sea. The seabed was later uplifted to form the Himal... |
Preserved traces can include burrows. | (A) true (B) false | A | Fossils are preserved remains or traces of organisms that lived in the past. Most preserved remains are hard parts, such as teeth, bones, or shells. Examples of these kinds of fossils are pictured in Figure 11.1. Preserved traces can include footprints, burrows, or even wastes. Examples of trace fossils are also shown ... |
Scientists have discovered fossil footprints. | (A) true (B) false | A | Fossils are the preserved remains or traces of organisms that lived during earlier ages. Remains that become fossils are generally the hard parts of organismsmainly bones, teeth, or shells. Traces include any evidence of life, such as footprints like the dinosaur footprint in Figure 7.7. Fossils are like a window into ... |
Complete preservation occurs only when remains are preserved in rock. | (A) true (B) false | B | The process by which remains or traces of living things become fossils is called fossilization. Most fossils are preserved in sedimentary rocks. |
In the past, fossils inspired legends of monsters. | (A) true (B) false | A | It wasnt always known that fossils were parts of living organisms. In 1666, a young doctor named Nicholas Steno dissected the head of an enormous great white shark that had been caught by fisherman near Florence, Italy. Steno was struck by the resemblance of the sharks teeth to fossils found in inland mountains and hil... |
It is very likely that any given organism will become a fossil. | (A) true (B) false | B | Its very unlikely that any given organism will become a fossil. The remains of many organisms are consumed. Remains also may be broken down by other living things or by the elements. Hard parts, such as bones, are much more likely to become fossils. But even they rarely last long enough to become fossils. Organisms wit... |
Fossils in older rocks are more similar to animals that live today than fossils in younger rocks. | (A) true (B) false | B | That life on Earth has changed over time is well illustrated by the fossil record. Fossils in relatively young rocks resemble animals and plants that are living today. In general, fossils in older rocks are less similar to modern organisms. We would know very little about the organisms that came before us if there were... |
Fossils of ocean animals have been found at the top of Mt. Everest. | (A) true (B) false | A | Fossils give clues about major geological events. Fossils can also give clues about past climates. Fossils of ocean animals are found at the top of Mt. Everest. Mt. Everest is the highest mountain on Earth. These fossils show that the area was once at the bottom of a sea. The seabed was later uplifted to form the Himal... |
Fossils form when remains are replaced by minerals. | (A) true (B) false | A | Most fossils form when a dead organism is buried in sediment. Layers of sediment slowly build up. The sediment is buried and turns into sedimentary rock. The remains inside the rock also turn to rock. The remains are replaced by minerals. The remains literally turn to stone. Fossilization is illustrated in Figure 11.2.... |
Fossils show that Antarctica once had a much warmer climate. | (A) true (B) false | A | By knowing something about the climate a type of organism lives in now, geologists can use fossils to decipher the climate at the time the fossil was deposited. For example, coal beds form in tropical environments but ancient coal beds are found in Antarctica. Geologists know that at that time the climate on the Antarc... |
Index fossils are the first fossils ever discovered of an extinct species. | (A) true (B) false | B | Index fossils are commonly used to match rock layers in different places. You can see how this works in Figure |
Complete preservation is valuable because scientists can study the organisms DNA. | (A) true (B) false | A | Most uncommon is the preservation of soft-tissue original material. Insects have been preserved perfectly in amber, which is ancient tree sap. Mammoths and a Neanderthal hunter were frozen in glaciers, allowing scientists the rare opportunity to examine their skin, hair, and organs. Scientists collect DNA from these re... |
There are no plants in Antarctica so there are no plant fossils there. | (A) true (B) false | B | Fossils give clues about major geological events. Fossils can also give clues about past climates. Fossils of ocean animals are found at the top of Mt. Everest. Mt. Everest is the highest mountain on Earth. These fossils show that the area was once at the bottom of a sea. The seabed was later uplifted to form the Himal... |
Teeth are more likely than feathers to be preserved as fossils. | (A) true (B) false | A | Usually its only the hard parts that are fossilized. The fossil record consists almost entirely of the shells, bones, or other hard parts of animals. Mammal teeth are much more resistant than other bones, so a large portion of the mammal fossil record consists of teeth. The shells of marine creatures are common also. |
People first started discovering fossils about 150 years ago. | (A) true (B) false | B | Of all the organisms that ever lived, only a tiny number became fossils. Still, scientists learn a lot from fossils. Fossils are our best clues about the history of life on Earth. |
All fossils form when remains of dead organisms are covered with sediments. | (A) true (B) false | B | Most fossils form when a dead organism is buried in sediment. Layers of sediment slowly build up. The sediment is buried and turns into sedimentary rock. The remains inside the rock also turn to rock. The remains are replaced by minerals. The remains literally turn to stone. Fossilization is illustrated in Figure 11.2.... |
dark stain in rock left by the remains of an organism | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | G | Fossils may form in other ways. With complete preservation, the organism doesnt change much. As seen below, tree sap may cover an organism and then turn into amber. The original organism is preserved so that scientists might be able to study its DNA. Organisms can also be completely preserved in tar or ice. Molds and c... |
preserved tracks or other evidence of an organism that lived in the past | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | E | Fossils are preserved remains or traces of organisms that lived in the past. Most preserved remains are hard parts, such as teeth, bones, or shells. Examples of these kinds of fossils are pictured in Figure 11.1. Preserved traces can include footprints, burrows, or even wastes. Examples of trace fossils are also shown ... |
type of fossil that can be used to determine the age of rock layers | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | C | Fossils are used to determine the ages of rock layers. Index fossils are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in. Trilobite fossils, as shown in Figure... |
process by which remains or traces of living things become fossils | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | F | The process by which remains or traces of living things become fossils is called fossilization. Most fossils are preserved in sedimentary rocks. |
type of fossil that forms in a mold | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | D | Fossils may form in other ways. With complete preservation, the organism doesnt change much. As seen below, tree sap may cover an organism and then turn into amber. The original organism is preserved so that scientists might be able to study its DNA. Organisms can also be completely preserved in tar or ice. Molds and c... |
any preserved remains or traces of an organism that lived in the past | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | A | Fossils are preserved remains or traces of organisms that lived in the past. Most preserved remains are hard parts, such as teeth, bones, or shells. Examples of these kinds of fossils are pictured in Figure 11.1. Preserved traces can include footprints, burrows, or even wastes. Examples of trace fossils are also shown ... |
imprint of an organism left in rock | (A) fossil (B) mold (C) index fossil (D) cast (E) trace fossil (F) fossilization (G) compression | B | Fossils may form in other ways. With complete preservation, the organism doesnt change much. As seen below, tree sap may cover an organism and then turn into amber. The original organism is preserved so that scientists might be able to study its DNA. Organisms can also be completely preserved in tar or ice. Molds and c... |
Which of the following parts of organisms are most likely to be fossilized? | (A) skin (B) hair (C) shells (D) internal organs | C | Its very unlikely that any given organism will become a fossil. The remains of many organisms are consumed. Remains also may be broken down by other living things or by the elements. Hard parts, such as bones, are much more likely to become fossils. But even they rarely last long enough to become fossils. Organisms wit... |
Preserved traces of organisms might include | (A) casts (B) feces (C) molds (D) compressions | B | Fossils are preserved remains or traces of organisms that lived in the past. Most preserved remains are hard parts, such as teeth, bones, or shells. Examples of these kinds of fossils are pictured in Figure 11.1. Preserved traces can include footprints, burrows, or even wastes. Examples of trace fossils are also shown ... |
Preserved remains that have become fossils have turned to | (A) tar (B) rock (C) amber (D) none of the above | B | The process by which remains or traces of living things become fossils is called fossilization. Most fossils are preserved in sedimentary rocks. |
Which type of organisms remains are least likely to be preserved as fossils? | (A) jellyfish (B) salmon (C) shark (D) tuna | A | Its very unlikely that any given organism will become a fossil. The remains of many organisms are consumed. Remains also may be broken down by other living things or by the elements. Hard parts, such as bones, are much more likely to become fossils. But even they rarely last long enough to become fossils. Organisms wit... |
Fossils can show us | (A) how extinct organisms looked (B) what past environments were like (C) what geological processes occurred in the past (D) all of the above | D | Fossils are our best form of evidence about Earth history, including the history of life. Along with other geological evidence from rocks and structures, fossils even give us clues about past climates, the motions of plates, and other major geological events. Since the present is the key to the past, what we know about... |
To be used as index fossils, fossils must represent an organism that | (A) lived in the water (B) lived over a wide area (C) lived for a long period of time (D) lived less than 5 million years ago | B | An index fossil can be used to identify a specific period of time. Organisms that make good index fossils are distinctive, widespread, and lived briefly. Their presence in a rock layer can be used to identify rocks that were deposited at that period of time over a large area. |
Earths geologic processes have changed over time. | (A) true (B) false | B | Earths climate has changed many times through Earths history. Its been both hotter and colder than it is today. |
A rocks age compared to the ages of other rocks is called its | (A) absolute age (B) confirmed age (C) nominal age (D) none of the above | D | Early geologists had no way to determine the absolute age of a geological material. If they didnt see it form, they couldnt know if a rock was one hundred years or 100 million years old. What they could do was determine the ages of materials relative to each other. Using sensible principles they could say whether one r... |
Extinction occurs when a species completely dies out. | (A) true (B) false | A | Extinction is the complete dying out of a species. Once a species goes extinct, it can never return. More than 99 percent of all the species that ever lived on Earth have gone extinct. Five mass extinctions have occurred in Earths history. They were caused by major geologic and climatic events. The fifth mass extinctio... |
The Law of Superposition states that | (A) younger rocks are found below older rocks (B) older rocks are found below younger rocks (C) a rock that cuts across other rocks must be younger than the rock it cuts across (D) none of the above | B | Superposition refers to the position of rock layers and their relative ages. Relative age means age in comparison with other rocks, either younger or older. The relative ages of rocks are important for understanding Earths history. New rock layers are always deposited on top of existing rock layers. Therefore, deeper l... |
Layers of sedimentary rock are called strata. | (A) true (B) false | A | Sedimentary rocks are formed in horizontal layers. This is magnificently displayed around the southwestern United States. The arid climate allows rock layers to be well exposed (Figure 7.4). The lowest layers are the oldest and the higher layers are younger. Folds, joints and faults are caused by stresses. Figure 7.5 s... |
The rock layers at the Grand Canyon | (A) are the same on opposite sides of the river (B) were formed in different ways on each side of the river (C) are younger than the Colorado River in that region (D) none of these | A | The Grand Canyon provides an excellent illustration of the principles above. The many horizontal layers of sedi- mentary rock illustrate the principle of original horizontality (Figure 1.3). The youngest rock layers are at the top and the oldest are at the bottom, which is described by the law of superposition. Distinc... |
A good key bed must be | (A) found over a large area (B) similar to the rock units it is found with (C) a volcanic ash (D) all of these | A | 3. A key bed can be used like an index fossil since a key bed is a distinctive layer of rock that can be recognized across a large area. A volcanic ash unit could be a good key bed. One famous key bed is the clay layer at the boundary between the Cretaceous Period and the Tertiary Period, the time that the dinosaurs we... |
The relative age of a rock is its approximate age in years. | (A) true (B) false | B | Early geologists had no way to determine the absolute age of a geological material. If they didnt see it form, they couldnt know if a rock was one hundred years or 100 million years old. What they could do was determine the ages of materials relative to each other. Using sensible principles they could say whether one r... |
Rock layers on opposite sides of the Grand Canyon show lateral continuity. | (A) true (B) false | A | Rock layers extend laterally, or out to the sides. They may cover very broad areas, especially if they formed at the bottom of ancient seas. Erosion may have worn away some of the rock, but layers on either side of eroded areas will still match up. Look at the Grand Canyon in Figure 11.8. Its a good example of lateral ... |
A good index fossil | (A) is found in a local area (B) is distinctive (C) existed for a long period of time (D) all of these | B | An index fossil can be used to identify a specific period of time. Organisms that make good index fossils are distinctive, widespread, and lived briefly. Their presence in a rock layer can be used to identify rocks that were deposited at that period of time over a large area. |
Key beds are rock layers that have unconformities. | (A) true (B) false | B | Geologists can learn a lot about Earths history by studying sedimentary rock layers. But in some places, theres a gap in time when no rock layers are present. A gap in the sequence of rock layers is called an unconformity. Look at the rock layers in Figure 11.10. They show a feature called Huttons unconformity. The unc... |
More than one type of index fossil provides stronger evidence that rock layers are the same age. | (A) true (B) false | A | Fossils are used to determine the ages of rock layers. Index fossils are the most useful for this. Index fossils are of organisms that lived over a wide area. They lived for a fairly short period of time. An index fossil allows a scientist to determine the age of the rock it is in. Trilobite fossils, as shown in Figure... |
The Cretaceous Period ended when the first dinosaurs appeared. | (A) true (B) false | B | During the Cretaceous Period, the dinosaurs reached their maximum size and distribution. For example, the well- known Tyrannosaurus rex weighed at least 7 tons! You can get an idea of how big it was from the T. rex skeleton in Figure 7.24. (Notice how small the person looks in the bottom left of the photo.) By the end ... |
The earliest geologic time scale showed how many years ago each era began. | (A) true (B) false | B | To create the geologic time scale, geologists correlated rock layers. Stenos laws were used to determine the relative ages of rocks. Older rocks are at the bottom and younger rocks are at the top. The early geologic time scale could only show the order of events. The discovery of radioactivity in the late 1800s changed... |
Fish were common organisms during the Paleozoic Era. | (A) true (B) false | A | Paleozoic life was most diverse in the oceans. Paleozoic seas were full of worms, snails, clams, trilobites, sponges, and brachiopods. Organisms with shells were common. The first fish were simple, armored, jawless fish. Fish have internal skeletons. Some, like sharks, skates, and rays, have skeletons of cartilage. Mor... |
Fossil B is younger than Fossil A, but the rock layer containing Fossil B is beneath the rock layer | (A) true (B) false | A | Other scientists observed rock layers and formulated other principles. Geologist William Smith (1769-1839) identified the principle of faunal succession, which recognizes that: Some fossil types are never found with certain other fossil types (e.g. human ancestors are never found with dinosaurs) meaning that fossils in... |
To help decipher the geologic history of a region, create a geologic time scale using the rock units you | (A) true (B) false | B | To be able to discuss Earth history, scientists needed some way to refer to the time periods in which events happened and organisms lived. With the information they collected from fossil evidence and using Stenos principles, they created a listing of rock layers from oldest to youngest. Then they divided Earths history... |
James Hutton thought Earth was old because he saw how slowly geological processes work now. | (A) true (B) false | A | James Hutton came up with this idea in the late 1700s. The present is the key to the past. He called this the principle of uniformitarianism. It is that if we can understand a geological process now and we find evidence of that same Checkerboard Mesa in Zion National Park, Utah. process in the past, then we can assume ... |
Cross-cutting relationships help geologists to determine the older and younger of two rock units. | (A) true (B) false | A | Rock layers may have another rock cutting across them, like the igneous rock in Figure 11.9. Which rock is older? To determine this, we use the law of cross-cutting relationships. The cut rock layers are older than the rock that cuts across them. |
In the process of relative dating, scientists determine the exact age of a fossil or rock. | (A) true (B) false | B | Fossils are useful for reconstructing the past only if they can be dated. Scientists need to determine when the organisms lived who left behind the fossils. Fossils can be dated in two different ways: absolute dating and relative dating. Absolute dating determines about how long ago a fossil organism lived. This gives ... |
whether a rock is older or younger than other rocks | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | C | Rock layers may have another rock cutting across them, like the igneous rock in Figure 11.9. Which rock is older? To determine this, we use the law of cross-cutting relationships. The cut rock layers are older than the rock that cuts across them. |
law stating that rock layers are deposited in horizontal layers | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | E | Sediments were deposited in ancient seas in horizontal, or flat, layers. If sedimentary rock layers are tilted, they must have moved after they were deposited. |
law stating that rock layers closer to the surface are younger than deeper rock layers | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | B | Superposition refers to the position of rock layers and their relative ages. Relative age means age in comparison with other rocks, either younger or older. The relative ages of rocks are important for understanding Earths history. New rock layers are always deposited on top of existing rock layers. Therefore, deeper l... |
law stating that rock layers are older than any rocks that cut across them | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | F | Rock layers may have another rock cutting across them, like the igneous rock in Figure 11.9. Which rock is older? To determine this, we use the law of cross-cutting relationships. The cut rock layers are older than the rock that cuts across them. |
gap in a sequence of rock layers | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | G | Rock layers extend laterally, or out to the sides. They may cover very broad areas, especially if they formed at the bottom of ancient seas. Erosion may have worn away some of the rock, but layers on either side of eroded areas will still match up. Look at the Grand Canyon in Figure 11.8. Its a good example of lateral ... |
law stating that matching nearby rock layers are the same age | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | D | Superposition refers to the position of rock layers and their relative ages. Relative age means age in comparison with other rocks, either younger or older. The relative ages of rocks are important for understanding Earths history. New rock layers are always deposited on top of existing rock layers. Therefore, deeper l... |
study of rock layers | (A) stratigraphy (B) superposition (C) relative age (D) lateral continuity (E) original horizontality (F) cross-cutting relationships (G) unconformity | A | The study of rock strata is called stratigraphy. The laws of stratigraphy can help scientists understand Earths past. The laws of stratigraphy are usually credited to a geologist from Denmark named Nicolas Steno. He lived in the 1600s. The laws are illustrated in Figure 11.6. Refer to the figure as you read about the l... |
If sedimentary rock layers are tilted, they must have | (A) formed at an angle (B) moved after they formed (C) been cross-cut by igneous rock (D) formed from deposits on a mountainside | B | Sediments were deposited in ancient seas in horizontal, or flat, layers. If sedimentary rock layers are tilted, they must have moved after they were deposited. |
A key bed of clay from around the time the dinosaurs went extinct led to the hypothesis that the extinction was caused by a | (A) large flood (B) huge volcano (C) giant asteroid (D) none of the above | C | 3. A key bed can be used like an index fossil since a key bed is a distinctive layer of rock that can be recognized across a large area. A volcanic ash unit could be a good key bed. One famous key bed is the clay layer at the boundary between the Cretaceous Period and the Tertiary Period, the time that the dinosaurs we... |
Evidence shows that Earth is about | (A) 19 million years old (B) 28 million years old (C) 38 billion years old (D) 45 billion years old | D | How old is Earth? How was it formed? How did life begin on Earth? These questions have fascinated scientists for centuries. During the 1800s, geologists, paleontologists, and naturalists found several forms of physical evidence that confirmed that Earth is very old. The evidence includes: Fossils of ancient sea life on... |
Eons of the geologic time scale are divided first into | (A) years (B) periods (C) eras (D) epochs | C | The largest blocks of time on the geologic time scale are called eons. Eons are split into eras. Each era is divided into periods. Periods may be further divided into epochs. Geologists may just use early or late. An example is late Jurassic, or early Cretaceous. Figure 11.13 shows you what the geologic time scale look... |
The Cenozoic Era is called the age of | (A) dinosaurs (B) mammals (C) reptiles (D) life | B | We now live in the Phanerozoic Eon, the Cenozoic Era, the Quaternary Period, and the Holocene Epoch. Phanero- zoic means visible life. During this eon, rocks contain visible fossils. Before the Phanerozoic, life was microscopic. The Cenozoic Era means new life. It encompasses the most recent forms of life on Earth. The... |
What does the term paleozoic mean? | (A) fossil life (B) ancient rock (C) rock strata (D) old life | D | The Paleozoic is the furthest back era of the Phanerozoic and it lasted the longest. But the Paleozoic was relatively recent, beginning only 570 million years ago. Compared with the long expanse of the Precambrian, the Phanerozoic is recent history. Much more geological evidence is available for scientists to study so ... |
Many of the divisions of the geologic time scale mark major events in the history of | (A) life (B) science (C) astronomy (D) Earth science | A | Another tool for understanding the history of Earth and its life is the geologic time scale. You can see this time scale in Figure 7.18. It divides Earths history into eons, eras, and periods. These divisions are based on major changes in geology, climate, and the evolution of life. The geologic time scale organizes Ea... |
How much percent of the parent isotope remains after 2 half-lives? | (A) 100% (B) 50% (C) 25% (D) 75% | C | Radioactive materials decay at known rates, measured as a unit called half-life. The half-life of a radioactive substance is the amount of time it takes for half of the parent atoms to decay. This is how the material decays over time (see Table 1.2). No. of half lives passed 0 1 2 3 4 5 6 7 8 Percent parent remaining 1... |
The half-life of a radioactive element is | (A) half the estimated age of Earths crust (B) the time it takes for half a parent isotope to decay into the daughter isotope (C) half the weight of the original radioactive element (D) the time it takes for half of a daughter isotope to decay into a parent isotope | B | A radioactive isotope decays at a certain constant rate. The rate is measured in a unit called the half-life. This is the length of time it takes for half of a given amount of the isotope to decay. The concept of half-life is illustrated in Figure 11.9 for the beta decay of phosphorus-32 to sulfur-32. The half-life of ... |
Carbon dating is useful for | (A) igneous rocks (B) sedimentary rocks (C) organic materials (D) none of the above | C | Radiocarbon dating is used to find the age of once-living materials between 100 and 50,000 years old. This range is especially useful for determining ages of human fossils and habitation sites (Figure 1.1). The atmosphere contains three isotopes of carbon: carbon-12, carbon-13 and carbon-14. Only carbon-14 is radioac- ... |
Potassium-argon is better for dating igneous rocks than carbon-14 because | (A) the argon-39 half life is short (B) the potassium-40 half-life is long (C) igneous rocks do not contain carbon (D) all of these | B | The isotopes in Table 11.1 are used to date igneous rocks. These isotopes have much longer half-lives than carbon- 14. Because they decay more slowly, they can be used to date much older specimens. Which of these isotopes could be used to date a rock that formed half a million years ago? Unstable Isotope Decays to At a... |
For radiometric dating of Earths oldest rocks, it is best to use | (A) uranium-238 to lead-206 (B) potassium-argon (C) radiocarbon (D) none of these | A | Radioactivity turned out to be useful for dating Earth materials and for coming up with a quantitative age for Earth. Scientists not only date ancient rocks from Earths crust, they also date meteorites that formed at the same time Earth and the rest of the solar system were forming. Moon rocks also have been radiometri... |
The number of protons in atoms of the same element may vary. | (A) true (B) false | B | The number of protons per atom is always the same for a given element. However, the number of neutrons may vary, and the number of electrons can change. |
Almost all carbon atoms are atoms of carbon-14. | (A) true (B) false | B | Find carbon in the Figure 1.1, and youll see that its atomic number is 6. This means that all carbon atoms have 6 protons per nucleus. Almost all carbon atoms also have 6 neutrons per nucleus. These carbon atoms are called carbon-12, where 12 is the number of protons (6) plus neutrons (6). This gives carbon-12 nuclei a... |
When an atom of carbon-14 decays, it loses an electron. | (A) true (B) false | B | Like other unstable isotopes, carbon-14 breaks down, or decays. For carbon-14 decay, each carbon-14 atom loses an alpha particle. It changes to a stable atom of nitrogen-14. This is illustrated in Figure 11.17. The decay of an unstable isotope to a stable element occurs at a constant rate. This rate is different for ea... |
Using radioactivity scientists are able to measure the relative age of some rocks. | (A) true (B) false | B | Radioactivity turned out to be useful for dating Earth materials and for coming up with a quantitative age for Earth. Scientists not only date ancient rocks from Earths crust, they also date meteorites that formed at the same time Earth and the rest of the solar system were forming. Moon rocks also have been radiometri... |
Carbon-14 atoms decay to carbon-13 atoms. | (A) true (B) false | B | Carbon-14 forms naturally in Earths atmosphere when cosmic rays strike atoms of nitrogen-14. Living things take in and use carbon-14, just as they do carbon-12. The carbon-14 in living things gradually decays to nitrogen-14. However, it is constantly replaced because living things keep taking in carbon-14. As a result,... |
Radioactive isotopes gain or lose particles to become different elements. | (A) true (B) false | A | Radioactive elements and isotopes have unstable nuclei. To become more stable, the nuclei undergo radioactive decay. In radioactive decay, the nuclei give off, or emit, radiation in the form of energy and often particles as well. There are several types of radioactive decay, including alpha, beta, and gamma decay. Ener... |
The half-life of a radioactive isotope is constant. | (A) true (B) false | A | A radioactive isotope decays at a certain constant rate. The rate is measured in a unit called the half-life. This is the length of time it takes for half of a given amount of the isotope to decay. The concept of half-life is illustrated in Figure 11.9 for the beta decay of phosphorus-32 to sulfur-32. The half-life of ... |
A living thing takes in carbon-14 only while it is alive. | (A) true (B) false | A | Carbon-14 forms naturally in Earths atmosphere when cosmic rays strike atoms of nitrogen-14. Living things take in and use carbon-14, just as they do carbon-12. The carbon-14 in living things gradually decays to nitrogen-14. However, it is constantly replaced because living things keep taking in carbon-14. As a result,... |
No one knows Earths age because no isotopes are good for substances that old. | (A) true (B) false | B | Radioactivity turned out to be useful for dating Earth materials and for coming up with a quantitative age for Earth. Scientists not only date ancient rocks from Earths crust, they also date meteorites that formed at the same time Earth and the rest of the solar system were forming. Moon rocks also have been radiometri... |
Carbon-14 dating can be used to determine the ages of rocks. | (A) true (B) false | B | Radioactive isotopes can be used to estimate the ages of fossils and rocks. The method is called radioactive dating. Carbon-14 dating is an example of radioactive dating. It is illustrated in the video at this URL: MEDIA Click image to the left or use the URL below. URL: |
Carbon-14 loses an alpha particle, which is two protons and two electrons. | (A) true (B) false | B | Alpha decay occurs when a nucleus is unstable because it has too many protons. The Figure 1.1 shows what happens during alpha decay. The nucleus emits an alpha particle and energy. An alpha particle consists of two protons and two neutrons, which is actually a helium nucleus. Losing the protons and neutrons makes the n... |
Plants take in carbon-14 during photosynthesis. | (A) true (B) false | A | Carbon-14 forms naturally in Earths atmosphere when cosmic rays strike atoms of nitrogen-14. Living things take in and use carbon-14, just as they do carbon-12. The carbon-14 in living things gradually decays to nitrogen-14. However, it is constantly replaced because living things keep taking in carbon-14. As a result,... |
The half-life of carbon-14 is 5730 years. | (A) true (B) false | A | Carbon-14 forms naturally in Earths atmosphere when cosmic rays strike atoms of nitrogen-14. Living things take in and use carbon-14, just as they do carbon-12. The carbon-14 in living things gradually decays to nitrogen-14. However, it is constantly replaced because living things keep taking in carbon-14. As a result,... |
All fossils can be dated with carbon-14 dating. | (A) true (B) false | B | Carbon-14 has a relatively short half-life (see Table 11.1). After about 50,000 years, too little carbon-14 is left in a fossil to be measured. Therefore, carbon-14 dating can only be used to date fossils that are less than 50,000 years old. Radioisotopes with a longer half-life, such as potassium-40, must be used to d... |
To date a rock that is as old as Earth, you could use potassium-40 dating. | (A) true (B) false | B | Potassium-40 decays to argon-40 with a half-life of 1.26 billion years. Argon is a gas so it can escape from molten magma, meaning that any argon that is found in an igneous crystal probably formed as a result of the decay of potassium-40. Measuring the ratio of potassium-40 to argon-40 yields a good estimate of the ag... |
Absolute ages are based on evidence from | (A) key beds (B) stratigraphy (C) index fossils (D) radiometric dating | D | Radioactivity turned out to be useful for dating Earth materials and for coming up with a quantitative age for Earth. Scientists not only date ancient rocks from Earths crust, they also date meteorites that formed at the same time Earth and the rest of the solar system were forming. Moon rocks also have been radiometri... |
Which of the following atomic particles may vary for atoms of a given element? | (A) protons (B) neutrons (C) electrons (D) all of the above | B | The number of protons per atom is always the same for a given element. However, the number of neutrons may vary, and the number of electrons can change. |
How many protons are found in each atom of carbon-14? | (A) 14 (B) 8 (C) 7 (D) 6 | D | Find carbon in the Figure 1.1, and youll see that its atomic number is 6. This means that all carbon atoms have 6 protons per nucleus. Almost all carbon atoms also have 6 neutrons per nucleus. These carbon atoms are called carbon-12, where 12 is the number of protons (6) plus neutrons (6). This gives carbon-12 nuclei a... |
If a carbon atom has 7 neutrons, it is the isotope named | (A) carbon-11 (B) carbon-12 (C) carbon-13 (D) carbon-14 | C | For most other elements, isotopes are named for their mass number. For example, carbon atoms with the usual 6 neutrons have a mass number of 12 (6 protons + 6 neutrons = 12), so they are called carbon-12. Carbon atoms with 7 neutrons have an atomic mass of 13 (6 protons + 7 neutrons = 13). These atoms are the isotope c... |
Plants use carbon dioxide for the process of | (A) respiration (B) germination (C) reproduction (D) photosynthesis | D | Producers such as plants or algae use carbon dioxide in the air to make food. The organisms combine carbon dioxide with water to make sugar. They store the sugar as starch. Both sugar and starch are carbohydrates. Consumers get carbon when they eat producers or other consumers. Carbon doesnt stop there. Living things g... |
New atoms of carbon-14 form in the atmosphere because of | (A) pollution (B) cosmic rays (C) global warming (D) burning of fossil fuels | B | Carbon-14 forms naturally in Earths atmosphere when cosmic rays strike atoms of nitrogen-14. Living things take in and use carbon-14, just as they do carbon-12. The carbon-14 in living things gradually decays to nitrogen-14. However, it is constantly replaced because living things keep taking in carbon-14. As a result,... |
If you start with 1.00 g of carbon-14, the amount left after two half-lives will be | (A) 0 g (B) 025 g (C) 050 g (D) 075 g | B | Carbon-14 forms naturally in Earths atmosphere when cosmic rays strike atoms of nitrogen-14. Living things take in and use carbon-14, just as they do carbon-12. The carbon-14 in living things gradually decays to nitrogen-14. However, it is constantly replaced because living things keep taking in carbon-14. As a result,... |
using radioactive decay to estimate the age of a fossil or rock | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | G | The rate of decay of unstable isotopes can be used to estimate the absolute ages of fossils and rocks. This type of dating is called radiometric dating. |
radioactive element with a relatively long half-life | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | D | Radioactive materials decay at known rates, measured as a unit called half-life. The half-life of a radioactive substance is the amount of time it takes for half of the parent atoms to decay. This is how the material decays over time (see Table 1.2). No. of half lives passed 0 1 2 3 4 5 6 7 8 Percent parent remaining 1... |
rate of decay of a radioactive element | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | F | A radioactive isotope decays at a certain constant rate. The rate is measured in a unit called the half-life. This is the length of time it takes for half of a given amount of the isotope to decay. The concept of half-life is illustrated in Figure 11.9 for the beta decay of phosphorus-32 to sulfur-32. The half-life of ... |
atom of an element with a different number of neutrons | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | A | Some atoms of the same element may have different numbers of neutrons. For example, some carbon atoms have seven or eight neutrons instead of the usual six. Atoms of the same element that differ in number of neutrons are called isotopes. Many isotopes occur naturally. Usually one or two isotopes of an element are the m... |
stable isotope of carbon | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | C | Radiocarbon dating is used to find the age of once-living materials between 100 and 50,000 years old. This range is especially useful for determining ages of human fossils and habitation sites (Figure 1.1). The atmosphere contains three isotopes of carbon: carbon-12, carbon-13 and carbon-14. Only carbon-14 is radioac- ... |
radioactive element with a relatively short half-life | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | B | A radioactive isotope decays at a certain constant rate. The rate is measured in a unit called the half-life. This is the length of time it takes for half of a given amount of the isotope to decay. The concept of half-life is illustrated in Figure 11.9 for the beta decay of phosphorus-32 to sulfur-32. The half-life of ... |
breakdown of unstable elements into stable elements | (A) isotope (B) carbon-14 (C) carbon-12 (D) uranium-238 (E) radioactive decay (F) half-life (G) radiometric dating | E | Radioactive decay is the breakdown of unstable elements into stable elements. To understand this process, recall that the atoms of all elements contain the particles protons, neutrons, and electrons. |
ring of icy debris just beyond Neptune | (A) atmosphere (B) nuclear fusion (C) comet (D) solar nebula (E) water vapor (F) Kuiper belt (G) oxygen | F | Like the other outer planets, Neptune has rings of ice and dust. These rings are much thinner and fainter than Saturns. Neptunes rings may be unstable. They may change or disappear in a relatively short time. Neptune has 13 known moons. Only Triton, shown in Figure 25.30, has enough mass to be round. Triton orbits in t... |
Before the Sun formed | (A) temperature and pressure was extreme (B) radioactivity began (C) the planets formed (D) all of the above | A | The Sun and planets formed from a giant cloud of gas and dust. This was the solar nebula. The cloud contracted and began to spin. As it contracted, its temperature and pressure increased. The cloud spun faster, and formed into a disk. Scientists think the solar system at that time looked like these disk-shaped objects ... |
example of an object in the solar system | (A) atmosphere (B) nuclear fusion (C) comet (D) solar nebula (E) water vapor (F) Kuiper belt (G) oxygen | C | Since the time of Copernicus, Kepler, and Galileo, we have learned a lot more about our solar system. Astronomers have discovered two more planets (Uranus and Neptune), five dwarf planets (Ceres, Pluto, Makemake, Haumea, and Eris), more than 150 moons, and many, many asteroids and other small objects. Although the Sun ... |
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