Biology Questions
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Clinical correlates (neural tube malformations)
Founder effects and bottlenecks area. expected only in large populations.b. mechanisms that increase genetic variation in a population.c. two different modes of natural selection.d. forms of genetic drift.
Stabilizing selection differs from directional selection becausea. in the former, phenotypic variation is reduced but the average phenotype stays the same, whereas in the latter both the variation and the mean phenotype change.b. the former requires genetic variation, but the latter does not. c. intermediate phenotypes are favored in directional selection. d. None of the choices is correct.
For natural selection to result in evolutionary change,a. variation must exist in a population.b. reproductive success of different phenotypes must differ.c. variation must be inherited from one generation to the next.d. All of the choices are correct.
In a population of red (dominant allele) or white flowers in Hardy-Weinberg equilibrium, the frequency of red flowers is 91%. What is the frequency of the red allele?a. 9%b. 30% c. 91%d. 70%
The chloroplasts of brown algaea. have a chromosome with a very different DNA sequence than the chromosome of a red alga.b. are surrounded by four membranes.c. are surrounded by two membranes.d. have a chromosome with a DNA sequence that is similar to that in red algae, but very different from that in green algae.
During which times would you expect that geographic isolation would be particularly important in the evolution of life?a. The Cambrian periodb. The end of the Paleozoic erac. The beginning of the Cenozoic erad. Both a and c are correct.
Identify which of the following statements is false and correct the statement.a. Brown and red algae are not closely related phylogenetically.b. Chloroplasts in brown and red algae are monophyletic.c. Brown algae gained chloroplasts by engulfing green algae (endosymbiosis). d. None of the statements are false.
Although we do not know how early life arose, the following likely happened:a. All organic molecules were transported to Earth by meteors.b. High levels of oxygen were essential for glycolysis.c. Lipids organized to form cell membranes.d. Organic molecules formed once temperatures reached moderate levels, equivalent to those in today's environment.
Rapid rates of character change relative to the rate of speciation pose a problem for cladistics becausea. the frequency with which distantly related species evolve the same derived character state may be high. b. evolutionary reversals may occur frequently.c. homoplasy will be common.d. All of the choices are correct.
Fossil data indicate thata. life originated 4 BYA.b. life may have originated 3.5 BYA, but definitely did so by 3.2 BYA.c. the Cambrian explosion led to the origin of life.d. plants played an important role in causing glaciation.
The Miller-Urey experiment demonstrated thata. life originated on Earth.b. organic molecules could have originated in the early atmosphere.c. the early genetic material on the planet was DNA.d. the early atmosphere contained large amounts of oxygen.
In a paraphyletic groupa. all species are more closely related to each other than they are to a species outside the group.b. evolutionary reversal is common.c. polyphyly also usually occurs.d. some species are more closely related to species outside the group than to some species within the group.
A taxonomic group that contains species that have similar phenotypes due to convergent evolution is a. paraphyletic.b. monophyletic.c. polyphyletic.d. a good cladistic group.
Which of the following events occurred first in eukaryotic evolution?a. Endosymbiosis and mitochondria evolutionb. Endosymbiosis and chloroplast evolutionc. Compartmentalization and formation of the nucleusd. Formation of multicellular organisms
Which bits of evidence would convince you that life originated as early as 3.2 BYA?a. You look at a microfossil under a scanning electron microscope and it is the same shape as a cell.b. A high-quality transmission electron micrograph of a fossil cell reveals cellular compartments, including a possible nucleus.c. Potassium dating of a fossil containing a possible cell indicates that the fossil is 3.2 billion years old.d. Using transmission and scanning electron microscopy, you find evidence of a carbon-based material in what appears to be a cell wall of a fossil isotopically dated as 3.2 billion years old.
A global glaciation would be unlikely to occur ifa. a supercontinent formed near the equator and there was extensive rainfall.b. millions of acres of forest were cleared.c. vast amounts of phosphorus found its way into aquatic and oceanic environments.d. there was a rapid expansion of algal populations in the ocean.
Species recognized by the PSCa. sometimes also would be recognized as species by the BSC.b. are sometimes paraphyletic.c. are characterized by symplesiomorphies.d. are more frequent in plants than in animals.
A paraphyletic group includesa. an ancestor and all of its descendants.b. an ancestor and some of its descendants.c. descendants of more than one common ancestor.d. All of the choices are correct.
If reinforcement is weak and hybrids are not completely infertile,a. genetic divergence between populations may be overcome by gene flow. b. speciation will occur 100% of the time.c. gene flow between populations will be impossible.d. the speciation will be more likely than if hybrids were completely infertile.