BIO 160 Chapter 25 Practice Test

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

sedimentary rocks contain a layer of iridium, a mineral uncommon on earth

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

simple organic molecules can form spontaneously under conditions like those thought to prevail early in Earth's history

***Single-celled prokaryotes had the Earth to themselves for approximately _____.

1.5 billion years

What evidence supports the hypothesis that mitochondria and plastids evolved from prokaryotic endosymbionts? a) They have a single circular chromosome similar to bacterial chromosomes. b) They have flagella similar to bacterial flagella. c) Their ribosomes are more like prokaryotic ribosomes than eukaryotic ribosomes. d) They divide by a process similar to meiosis. e) The first and third responses are correct.

1st and 3rd responses correct They have a single circular chromosome similar to bacterial chromosomes. Their ribosomes are more like prokaryotic ribosomes than eukaryotic ribosomes.

***Adaptive radiations are often seen after _____. a) sexual selection takes place b) major new evolutionary adaptations, such as flight, occur c) mass extinctions d) bacteria and plants both have flagellated gametes e) The second and third responses are correct.

2nd and 3rd responses are correct - sexual selection takes place - mass extinctions

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?

3.6 billion years Three half-lives have elapsed since the sample was alive (10 grams to 5 grams, 5 grams to 2.5 grams, and 2.5 grams to 1.25 grams). Because half the isotope would be expected to decay by the end of each half-life, the sample is 3 × 1.2 billion years old.

What does the snowball Earth hypothesis propose?

Larger multicellular eukaryotes are scarce in the fossil record until the late Proterozoic because an ice age limited life to deep-sea vents and hot springs.

***Currently scientists think the early atmosphere probably consisted of _____.

N2, H2O, CO2, NH3, CH4, H2, and H2S Nitrogen gas, water, carbon dioxide, ammonia, methane, hydrogen gas, and hydrogen sulfid

If the wings of extant flying birds originally arose as thermoregulatory devices in ancestral reptiles, then the bird wings could be accurately described as _____.

exaptations

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

fungi

***The products of Hox genes _____.

provide positional information in animal embryos

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

reproduction and prevention of dehydration

***How does continental drift affect speciation? a) The closing of an ocean basin represents an enormous loss of habitat that can wipe out some species. b) Climate change associated with mountain building and plates moving to different latitudes creates new niches for some organisms and wipes out other organisms. c) The breaking apart of landmasses or the change in configuration of ocean basins promotes allopatric speciation. d) The joining of previously separated habitats may produce a hybrid zone or establish competition among previously isolated populations. e) All of the listed responses are correct.

All of the listed responses are correct.

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

Australia has been isolated for about 50 million years

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

Between 180 and 65 million years ago, mammals were outcompeted by the well-established dinosaurs.

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

It leads to predictions that can be tested

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

Paleozoic, Mesozoic and Cenozoic

Cech and Altman suggested that the first self-replicating molecules were _____.

RNA

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

produced atmospheric oxygen

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?

This can't possibly be true because carbon-14 dating can only be used back to about 75,000 years.

Which of the following organisms is most closely related to the ancestor of modern amphibians?

Tiktaalik

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 _____.

adaptive radiation

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

cellular respiration

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

developmental genes

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

differential speciation success... differential reproduction success

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?

near volcanoes

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

oxygen

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)?

predation

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

the ability to perform simple reproduction and metabolism

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

the geographic isolation of population that had previously coexisted led to speciation