Exam 1 review

Question 1

RNA molecules can both carry genetic information and be catalytic. This supports the proposal that

Answer 1

RNA was the first hereditary information.

Question 2

Which of the following is the correct sequence of these events in the origin of life?

I.formation of protocells

II.synthesis of organic monomers

III.synthesis of organic polymers

IV. formation of DNA-based genetic systems

Answer 2

II, III, I, IV

Question 3

In peas, a gene controls flower color such that R = purple is dominant to r= white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q(frequency of r) for this population?

Answer 3

0.8

Question 4

A defining characteristic of allopatric speciation is

Answer 4

geographic isolation.

Question 5

In bionomial nomenclature where humans are : Homo sapiens, sapiens is the:

Answer 5

species

Question 6

No two people are genetically identical, except for identical twins. The chief cause of genetic variation among human individuals is

Answer 6

he reshuffling of alleles in sexual reproduction.

Question 7

Which statement about natural selection is most correct?

Question options:

Well-adapted individuals leave more offspring, and thus contribute more to the next generation’s gene pool, than do poorly adapted individuals.

Adaptations beneficial at one time should generally be beneficial during all other times as well.

Different species that occupy the same habitat will adapt to that habitat by undergoing the same genetic changes.

Natural selection is the sole means by which populations can evolve.

Answer 7

Well-adapted individuals leave more offspring, and thus contribute more to the next generation’s gene pool, than do poorly adapted individuals.

Question 8

In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.7. What is the percentage of the population that is homozygous for this allele?

Answer 8

49

Question 9

Who was the naturalist who synthesized a concept of natural selection independently of Darwin?

Answer 9

Alfred Wallace

Question 10

Which of the following must exist in a population before natural selection can act upon that population?

Question options:

genetic variation among individuals

variation among individuals caused by environmental factors

sexual reproduction

A and C only

A, B, and C

Answer 10

genetic variation among individuals

Question 11

Which of these evolutionary agents is most consistent at causing populations to become better suited to their environments over the course of generations?

Answer 11

Natural selection

Question 12

“Improving the intelligence of an adult through education will result in that adult’s descendants being born with a greater native intelligence.” This statement is the idea of:

Answer 12

Lamarck

Question 13

In evolutionary terms, the more closely related two different organisms are, the

Answer 13

more recently they shared a common ancestor.

Question 14

If the half-life of carbon-14 is about 5,730 years, then a fossil that has one-eighth the normal proportion of carbon-14 to carbon-12 should be about how many years old?

Answer 14

17,190

Question 15

The theory of evolution is most accurately described as

Answer 15

a scientific explanation, supported by much evidence, for how populations change over time.

Question 16

Plant species A has a diploid number of 12. Plant species B has a diploid number of 16. A new species, C, arises as an allopolyploid from A and B. The diploid number for species C would probably be

Answer 16

28

Question 17

DDT was once considered a “silver bullet” that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. What would need to be true for pest eradication efforts to have been successful in the long run?

Answer 17

All individual insects should have possessed genomes that made them susceptible to DDT.

Question 18

In peas, a gene controls plant height such that T=tall and t=dwarf (T is completely dominant to t). In a isolated population, 91% of the population is tall while the rest are dwarf. Assume the population is in Hardy-Weinberg equilibrium. i. What is the allele frequency for this population ? ii. Calculate the proportion of each genotype.

Answer 18

p=0.7 q=0.3

TT=0.49

Tt=0.42

tt=0.09

Question 19

What would be the best technique for determining the evolutionary relationships among several closely related species, each of which still contains living members?

Answer 19

DNA or protein analysis

Question 20

What probably accounts for the switch to DNA-based genetic systems during the evolution of life on Earth?

Answer 20

DNA is chemically more stable and replicates with fewer errors (mutations) than RNA.

Question 21

List 2 lines of evidence supporting the endosymbiont theory!

Answer 21

1.Mitochondria and chloroplasts have their own DNA which is similar to the DNA in other prokaryotes

2. Mitochondria and chloroplasts replicate, translate, translate their DNA much like other prokaryotes

Question 22

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

Answer 22

All variation between individuals is due only to environmental factors.

Question 23

Fossil evidence indicates that horses have gradually increased in size over geologic time. Which of the following terms best describes this?

Answer 23

directional selection

Question 24

A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. What inferences might you make about this population?

The amount of available food may have increased.

The number of predators may have decreased.

The squirrels of subsequent generations should show greater levels of variation than previous generations because squirrels that would not have survived in the past will now survive.

A and B only

A, B, and C

Answer 24

A, B, and C

Question 25

A population is in Hardy-Weinberg equilibrium with two alleles, B and b at a frequency 0.8(B) and 0.2(b). Allele B results in blue colored flowers and is dominant to the allele b which results in white flowers.

i. Find the percentages for each genotype for the following generation.

ii. Calculate the percentage of each phenotype.

iii. Calculate the allele frequency in the new generation(show your calculations)

Answer 25

i) p=0.8 q=0.2

p2=0.8^2 =0.64 64% BB.

q2=0.2^2 =0.04 4% bb.

2pq=20.80.2=0.32 32% Bb.

64%+32%=96%

ii)

TT = 0.64 + 0.32 = 0.96 96 %
tt = 0.04 4%

iii)

T = 0.64 + 0.32/2 = 0.80
t = 0.04 + 0.32/2 = 0.20

Question 26

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth?

1. origin of mitochondria
2. origin of multicellular eukaryotes
3. origin of chloroplasts
4. origin of cyanobacteria
5. origin of fungal-plant symbioses

Answer 26

4,1,3,2,5

Question 27

How many half-lives should have elapsed if 3.125% of the parent isotope remains in a fossil at the time of analysis?

Answer 27

5

Question 28

The average birth weight for human babies is about 3 kg. While birth weights of much less than this or much more than this are rare. Which of the following terms best describes this?

Answer 28

stabilizing selection

Question 29

Which free-living cells were the earliest contributors to the formation of Earth’s oxidizing atmosphere?

Answer 29

cyanobacteria

Question 31

A fruit fly population has a gene with two alleles, A 1 and A 2 . T ests show that 70% of the gametes produced in the population contain the A1 allele. If the population is in Hardy-Weinberg equilibrium, what proportion of the flies carry both A1 andA2?

Answer 31

0.42

Question 32

If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?

Answer 32

D and F

Question 33

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?

Answer 33

More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.

Question 34

Charles Darwin was the first to propose

Answer 34

A mechanism of how evolution works supported by evidence

Question 35

Which gas was least abundant in Earth’s early atmosphere, prior to 2 billion years ago?

Answer 35

O2

Question 36

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

Answer 36

island forms and mainland forms descended from common ancestors.