24. History of Life on Earth

Why is the four-stage hypothesis for the abiotic origin of life useful?

The early atmosphere on Earth is thought to have lacked which of the following gases?

Currently scientists think the early atmosphere probably consisted of __________.

The Miller and Urey abiotic synthesis experiment (and subsequent, similar experiments) showed that __________.

The early atmosphere may not have been as reducing as originally postulated by Haldane, Oparin, Miller, and Urey. In light of current thinking about the composition of the early atmosphere, what is regarded as a likely place for the abiotic synthesis of organic molecules to have occurred?

Abiotically produced vesicles display which of the following rudimentary qualities necessary for life?

Many researchers now believe that the first self-replicating molecules were __________.

A radioactive isotope has a half-life of 1.2 billion years. As measured by the presence of the isotope and its stable decay product, a rock originally contained 10 grams of the radioactive isotope and now contains 1.25 grams. Approximately how many years old is the rock?

You are watching a movie in which one of the characters excitedly claims to have found human remains in Asia dated at 10 million years old. The date was obtained by carbon-14 dating. What is your reaction?

Single-celled prokaryotes had Earth to themselves for approximately __________.

The correct order of the geologic eras, from most ancient to most recent, is __________.

Ancient cyanobacteria were very important in the history of life because they __________.

What prokaryotic adaptation occurred during the oxygen revolution and opened up the possibility for energy-demanding multicellular life-forms?

What evidence supports the hypothesis that mitochondria and plastids evolved from prokaryotic endosymbionts?

Prior to the Cambrian explosion, most animals were small and soft-bodied. What development appears to have spurred adaptations such as sharp spines, claws, and body armor (shells)?

What evidence most strongly suggests that an impact by an asteroid or meteorite may have caused the extinction of the dinosaurs?

Adaptive radiations are often seen after __________.

What were the two major "problems" that had to be solved before plants, animals, and fungi could fully move into terrestrial habitats?

Plants colonized land in the company of __________; their symbiotic relationships still exist today.

Which of the following best describes how the breakup of Pangaea affected evolution?

Lake Malawi, in the African Rift Valley, is home to more than a hundred species of cichlid fishes, each with slightly different diets and habits. All these species probably evolved from a common ancestor, making them an example of __________.

The fauna and flora of Australia are very different from those of the rest of the world. Why might this be true?

Although they originated around 180 million years ago, mammals underwent an adaptive radiation starting approximately 65 million years ago. Why?

How does continental drift affect speciation?

Mutations in what class of genes have probably been responsible for many of the changes leading to the great diversity of life existing today?

If the feathers of extant flying birds originally arose as thermoregulatory devices in ancestral reptiles, then flight feathers could be accurately described as __________.

In the species selection model, __________ is to macroevolution as __________ is to microevolution.

Which of the listed examples is a current hypothesis regarding the Cambrian explosion?

Which of the following occurred during the Mesozoic era?

How many different species have been identified by science? How many are estimated to exist?

Fossilized stromatolites a. formed around deep-sea vents. b. resemble structures formed by bacterial communities that are found today in some shallow marine bays. c. provide evidence that plants moved onto land in the company of fungi around 500 million years ago. d. contain the first undisputed fossils of eukaryotes.

A cell is placed in a solution that is hypotonic to the cell. Which of the following best describes movement of water in this situation? a. Water will only flow into the cell. b. Water will only flow out of the cell. c. Water will flow into and out of the cell, but the overall net movement will be out of the cell. d. Water will flow into and out of the cell, but the overall net movement will be into the cell.

Choose the best definition of a fossil. a. a rock that contains information about an organism b. a bone, tooth, shell, or other hard part of an organism that has been preserved c. any trace of an organism that lived in the past d. any part of a dead organism

Which of the following results provided evidence of a discrete nuclear localization signal somewhere on the nucleoplasmin protein? a. The nucleoplasmin protein was small and easily slipped through the nuclear pore complex. b. After cleavage of the nucleoplasmin protein, only the tail segments appeared in the nucleus. c. Removing the tail from the nucleoplasmin protein allowed the core segment to enter the nucleus. d. The SRP bound only to the tail of the nucleoplasmin protein, not the core segment.

Add labels to the figure that follows, which illustrates the endosymbiotic hypothesis.

The oxygen revolution changed Earth's environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere? a. the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules b. the persistence of some animal groups in anaerobic habitats c. the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen d. the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria

Why does the presence of extinct forms and transitional features in the fossil record support the pattern component of the theory of evolution by natural selection? Select True or False for each statement. T/F It supports the hypothesis that individuals change over time. T/F It supports the hypothesis that weaker species are eliminated by natural selection. T/F It supports the hypothesis that species evolve to become more complex and better adapted over time. T/F It supports the hypothesis that species change over time.

Fill in the blanks in the following graph, which illustrates the decay curve of a radioactive element used to date fossil structures.

If a solution surrounding a cell is hypertonic relative to the inside of the cell, how will water move? a. It will move into the cell via osmosis. b. It will move out of the cell via osmosis. c. It will not move, because equilibrium exists. d. It will evaporate from the cell surface more rapidly.

The process of biological evolution                   . a. is not supported by scientific evidence; b. results in a change in the features of individuals in a population; c. takes place over the course of generations; d. B and C are correct; e. A, B, and C are correct

Which factor most likely caused animals and plants in India to differ greatly from species in nearby southeast Asia? a. The species became separated by convergent evolution. b. The climates of the two regions are similar. c. India is in the process of separating from the rest of Asia. d. India was a separate continent until 45 million years ago.

You set your time machine for 3 billion years ago and push the start button. When the dust clears, you look out the window. Which of the following describes what you would probably see? a. a cloud of gas and dust in space b. green scum in the water c. land and water sterile and devoid of life d. an endless expanse of red-hot molten rock

Which of the following best characterizes an adaptive radiation? a. Descendant species occupy a large geographic area. b. A single lineage diversifies rapidly, and descendant species occupy many habitats and ecological roles. c. Natural selection is particularly intense, because disruptive selection occurs. d. Species recover after a mass extinction.

What two conditions must be present for osmosis to occur?Integral membrane proteins are anchored in lipid bilayers.

How does the hydrolysis of ATP result in the movement of a motor protein along a cytoskeletal filament?

Large-scale, worldwide adaptive radiations have occurred in which of the following situations? (A)when there are no available ecological niches (B)after each of the big five mass extinctions (C)after colonization of an isolated island that contains suit-able habitat and few competitor species (D)whenever an evolutionary innovation was needed for or-ganisms to thrive

Adaptive radiations can be a direct consequence of three of the following four factors. Select the exception. a. vacant ecological niches b. genetic drift c. colonization of an isolated region that contains suitable habitat and few competitor species d. evolutionary innovation

Ancient photosynthetic prokaryotes were very important in the history of life because they a. produced the oxygen in the atmosphere. b. are the oldest-known archaea. c. were the first multicellular organisms. d. showed that life could evolve around deep-sea vents.

Which of the following groups of amino acid residues (see Ch. 3, Figure 3.2) would likely be found in the portion that crosses the lipid bilayer? a. acidic b. basic c. polar uncharged d. nonpolar

Scientists studying the origin of life have accomplished which of the following steps? (A)abiotic synthesis of protocells with self-replicating, catalytic RNA (B)formation of vesicles that use RNA as a template for DNA synthesis (C)formation of protocells that use DNA to direct the polymer-ization of amino acids (D)abiotic synthesis of RNA's bases (A, C, G, U)

Which of the following steps has not yet been accomplished by scientists studying the origin of life? a. synthesis of small RNA polymers by ribozymes b. formation of molecular aggregates with selectively permeable membranes c. formation of protocells that use DNA to direct the polymerization of amino acids d. abiotic synthesis of organic molecules

The animals and plants of India are very different from the species in nearby Southeast Asia. Why might this be true? a. India was once covered by oceans and Asia was not. b. India is in the process of separating from the rest of Asia. c. Life in India was wiped out by ancient volcanic eruptions. d. India was a separate continent until about 45 million years ago.

Adaptive radiations may be promoted by all of the following except one. Which one? a. mass extinctions that result in vacant ecological niches b. colonization of an isolated region with few competitors c. a gradual change in climate d. a novel adaptation

Consider the endosymbiosis theory for the origin of the mitochondrion. How did each endosymbiotic partner benefit from the relationship?

Draw and label the plasma membrane of a cell that is placed in a solution with concentrations of calcium ions and lactose that are greater than those on the inside of the cell. Use arrows to show the relevant gradients and the activity of the following membrane proteins: (1) a pump that exports protons; (2) a calcium channel; and (3) a lactose carrier.

Most of the proteins that enter the nucleus possess a nuclear localization signal (NLS), even if they are small enough to pass through the nuclear pore complex unhindered. Why would a small protein have an NLS, when it naturally diffuses across the nuclear pore complex without one?

Fossilization continues even today. If you wanted to increase the probability that your deceased favorite pet would become fossilized, what actions would you take? a. Place the corpse in an environment where decomposition is rapid (such as a forest). b. Place the corpse in an environment where decomposition is slow (such as a swamp or bog). c. Place the corpse in an environment where there are plenty of rocks (such as a boulder field). d. Place the corpse in an environment where plenty of oxygen is available (such as in a mountain stream).

Why was finding a close relationship between mitochondrial DNA and bacterial DNA considered particularly strong evidence in favor of the endosymbiosis theory?

In the late 1700s, machines that could blast through rock to build roads and railways were invented, exposing deep layers of rocks. How would you expect this development to aid the science of paleontology?

Coral reefs are biodiverse ecosystems that provide food, income, coastal protection, and many other services to millions of people. Yet coral reefs are under threat from human impacts such as climate change—many corals cannot tolerate the warming ocean water and have suffered massive 'bleaching' events, which can be fatal. Researchers have discovered that some corals have the capacity to acclimatize to warmer water, while other corals do not. The researchers fear that because corals are long-lived colonial animals and thus evolve slowly, they may not be able to adapt to global warming fast enough to avoid extinction. Explain how the difference between acclimatize and adapt is important to the fate of corals.

In an experiment, you create two groups of liposomes in a solution containing 0.1 M NaCl—one made from red blood cell membranes and the other from frog egg cell membranes. When the liposomes are placed in water, those with red blood cell membranes burst more rapidly than those made from egg membranes. What could explain these results? Select True or False for each of the following statements. a. T/F The red blood cell liposomes are more hypertonic relative to water than the frog egg liposomes. b. T/F The red blood cell liposomes are more hypotonic relative to water than the frog egg liposomes. c. T/F The red blood cell liposomes contain more aquaporins than the frog egg liposomes. d. T/F The frog egg liposomes contain ion channels, which are not present in the red blood cell liposomes.

Major divisions in the geologic record are marked by a. radioactive dating. b. distinct changes in the types of fossilized life. c. regular time intervals measured in millions of years. d. the appearance, in order, of prokaryotes, eukaryotes, protists, animals, plants, and fungi.

Write a paragraph briefly describing the kinds of scientific evidence for evolution.

In the early 1800s, French naturalist Jean Baptiste Lamarck suggested that the best explanation for the relationship of fossils to current organisms is that life evolves. He proposed that by using or not using its body parts, an individual may change its traits and then pass those changes on to its offspring. He suggested, for instance, that the ancestors of the giraffe had lengthened their necks by stretching higher and higher into the trees to reach leaves. Evaluate Lamarck's hypotheses from the perspective of present-day scientific knowledge.

The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? Draw a horizontal axis to represent the number of species within phyla using a logarithmic scale (1, 10, 100, 1000 species, etc.). Then use Table 30.1 to map seven representative phyla from small to large at intervals of about an order of magnitude on this scale.

The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? Based on your reading of this chapter, propose at least five traits that you think might have been most important in triggering diversification within phyla (examples: origin of hearing, origin of internal fertilization).

The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? Jezkova and Wiens used a type of graph called a linear regression to find correlations between variables such as the proportion of species per phylum with legs (on the y-axis) and the diversification rate per phylum (on the x-axis). Sketch a graph to show what a strong positive correlation between these two variables would look like and what the absence of a correlation would look like.

SCIENTIFIC THINKING Cetaceans are fully aquatic mammals that evolved from terrestrial ancestors. Gather information about the respiratory system of cetaceans and describe how it illustrates the statement made in that 'Evolution is limited by historical constraints.'

The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? A sample of Jekova and Wiens' results is shown here. The R2 value represents the strength of the correlation (where 0.00 is lowest and 1.00 is highest). The P value represents the statistical significance. Which five traits look most important?

Which traits do not correlate strongly with diversification rate within phyla, but are likely to have been important in the original diversification of animal phyla during the Cambrian? Select True or False for each trait. T/F presence of a head T/F mobile lifestyle T/F terrestrial lifestyle T/F bilateral symmetry

Advocates of 'scientific creationism' and 'intelligent design' lobby school districts for such things as a ban on teaching evolution, equal time in science classes to teach alternative versions of the origin and history of life, or disclaimers in textbooks stating that evolution is 'just a theory.' They argue that it is only fair to let students evaluate both evolution and the idea that all species were created by God as the Bible relates or that, because organisms are so complex and well adapted, they must have been created by an intelligent designer. Do you think that alternative views of evolution should be taught in science courses? Why or why not?

Measurements indicate that a fossilized skull you unearthed has a carbon-14: carbon-12 ratio about 1/16th that of the skulls of present-day animals. What is the approximate age of the fossil? (The half-life of carbon-14 is 5,730 years.)

The vast majority of animals that ever existed are now extinct, but Tereza Jezkova and John Wiens wondered which variables were most important in driving the diversification of species that exist today. Why are there so many species in some phyla, such as Cnidaria (see photo), but so few in others, such as Ctenophora? The researchers know that correlation does not equal causation. However, can the absence of a correlation enable you to reject a hypothesis of causation? How would the R2 values be different in a scenario where a single trait was important to diversification in many phyla versus a scenario where different traits were important to diversification in different phyla?

SCIENTIFIC THINKING When Stanley Miller's experiment was published in 1953, his results made global headlines. The general public thought Miller had answered the question of how life on Earth began by creating life in a test tube. However, scientists understood that Miller's experiment was neither a final answer nor a recipe for life. Rather, it was the first test of a long-standing hypothesis about the origin of life. Write an essay describing how the process of science progresses over time toward understanding how nature works.