exam 3

Question 1

Segregation of homologous chromosomes occurs during what stage of cell division?

Answer 1

Meiosis I

Question 2

Based on the image above, the chromosomes in the circled region are what type of chromosomes?

Answer 2

These are very similar, homologous chromosomes, one from each parent.

Question 3

Recall the experiment discussed in class about guppy color patterns (spots) measured in populations exposed to varying risks of predation. From this experiment, it was concluded that:

Answer 3

Predators were more likely to catch and eat brightly-colored guppies.

Question 4

A certain species of butterfly varies in color from white to dark blue. The birds found in the same area feed on the white or lightly-colored butterflies, leaving butterflies that are dark in color. This pattern describes which mode of selection?

Answer 4

directional

Question 5

Galton’s study examined the relationship between height of parents and height of their offspring. The study found that offspring show a phenotype that is more similar to the population mean than their parental mean. Which of the following BEST explains the cause of this effect?

Answer 5

This effect is due to segregation and recombination breaking up genetic combinations that produce extreme phenotypes.

Question 6

Which of the following statements regarding the comparison of Mitosis and Meiosis is CORRECT?

Answer 6

Pairing of homologous chromosomes to form a bivalent, crossing over, and separation of homologous chromosomes occurs in Meiosis, but not Mitosis.

Question 7

what type of DNA damage is MOST LIKELY to have occurred?

Answer 7

chromosome breaks followed by translocations

Question 8

Which of the following is a characteristic of sympatric speciation?

Answer 8

Two populations diverge from each other with no geographic separation.

Question 9

There are two closely related species of squirrels living in the Grand Canyon area–one lives on the north rim and the other on the south rim. Speciation in these squirrels best fits which model?

Answer 9

allopatric

Question 10

Complex traits are influenced by which of the following?

Answer 10

by multiple genes, by the environment, and by lifestyle

Question 11

Use the data shown above to answer the following question regarding two genetically distinct strains of corn, strain 1 and strain 2.

Answer 11

This graph shows that the effect of environment on phenotype is different between the two corn strains.

Question 12

Genetic drift that results from a small number of individuals colonizing a new area is called:

Answer 12

founder effect

Question 13

Height, number of eggs laid per hen, and crop yield per acre are all examples of what?

Answer 13

complex traits

Question 14

Pluripotent stem cells are currently being tested in clinical trials for many diseases including blindness, diabetes, and spinal cord injuries. Why can pluripotent stem cells be used to treat these very different health problems?

Answer 14

Because pluripotent stem cells can differentiate to form every cell type in the body.

Question 15

When breeding pea plants heterozygous for two different traits Aa Bb (A is yellow versus a is green) and (B is round versus b is wrinkled), Mendel observed the following phenotypic ratios: 9 yellow and round: 3 yellow and wrinkled: 3 green and round: 1 green and wrinkled. How can the ratios of these traits be explained?

Answer 15

Traits for color and shape are encoded by genes on different chromosomes that independently assort during Meiosis.

Question 16

Scientists used genetic tools to overexpress a Death Receptor known to induce apoptosis in liver cells. Then, they added the signal that binds and activates the death receptor to the cells.

Answer 16

The gain-of-function mutation increased programmed cell death in the liver cells.

Question 17

Mutations occurring in which of the following cell types are inheritable by offspring?

Answer 17

oocyte

Question 18

Which of the following statements regarding alleles is CORRECT?

Answer 18

Alleles are different versions of the same gene having different nucleotide sequences.

Question 19

Which of the following mechanisms provides the greatest protection from incurring mutations?

Answer 19

Proofreading by DNA polymerase

Question 20

Which of the following has the greatest potency?

Answer 20

A totipotent zygote that can form the entire body and the placenta.

Question 21

Ancestors of the Galapagos finches had two different types of seeds to eat on some islands. Some seeds were very small, and required small beaks to handle, whereas other seeds were very large and required large strong beaks to crack. This led to __________ selection among the finches.

Answer 21

disruptive

Question 22

Given the changes shown above, what type of mutation has MOST LIKELY occurred?

Answer 22

Deletion mutation that causes a frameshift.

Question 23

It is estimated that humans accumulate 30 mutations per generation per haploid genome, so 60 mutations per diploid genome. Why are we okay?

Answer 23

Because most the changes occur in regions that do not encode proteins.

Question 24

In the Hardy-Weinberg equation, the frequencies of two alleles in a population can be designated as:

Answer 24

p and q

Question 25

Which of the following statements regarding gametes and somatic cells is CORRECT?

Answer 25

Gametes have one copy of every chromosome and somatic cells have two copies of every chromosome.

Question 26

Which of the following is a consequence of nondisjunction during meiosis?

Answer 26

Gametes may have an extra chromosome or may be missing a chromosome.

Question 27

DNA damage occurred that caused the deamination of cytosine to form uracil. Which of the following repair mechanisms will be used to repair the DNA?

Answer 27

Base excision repair by uracil glycosylase to detect and remove the uracil.

Question 28

Darwin proposed that natural selection occurs in an environment by:

Answer 28

Favoring heritable features that make organisms better suited to survive and reproduce

Question 29

Based on the image above, how many chromosomes are present in this individual.

Answer 29

47

Question 30

Which of the following would not be considered different species under the biological species concept?

Answer 30

Two snake populations that look different but often form fertile hybrids

Question 31

Which of the following events occurs by the end of Meiosis I?

Answer 31

The number of chromosomes is reduced by half.

Question 32

If an individual is a heterozygote, it means which of the following?

Answer 32

The individual has two different copies of the same allele.

Question 33

For a gene with two alternative alleles, A and a, the term in the algebraic form of the Hardy-Weinberg equilibrium that represents the homozygous recessive genotype is:

Answer 33

q2

Question 34

If species are competing for the same resource and live in the same area, natural selection may lead to:

Answer 34

character displacement

Question 35

Studies of monozygotic twin showing both twins develop the same diseases suggest which of the following?

Answer 35

This finding suggests that shared genetic changes are responsible for disease development.

Question 36

Which of the following statements regarding polymorphisms is CORRECT?

Answer 36

Polymorphisms are any difference in nucleotides in a population.

Question 37

ALL of the following are disorders that result from nondisjunction EXCEPT:

Answer 37

huntington’s syndrome

Question 38

There are two versions of a gene that specifies hair texture. Mating of people with curly hair to people with straight hair results in the phenotypic ratios of 1 curly haired person to 2 wavy haired persons to one straight haired person (1:2:1). Based on these phenotypic outcomes, you predict that the gene controlling hair is inherited in which of the following ways?

Answer 38

incomplete dominance

Question 39

Which of the following represents post-zygotic reproductive isolation?

Answer 39

Hybrid sterility in crosses between horses and donkeys

Question 40

Which of the following statements about the cartoon and light microscope image above is CORRECT?

Answer 40

The image shows a preimplantation blastocyst consisting of two cell types.

Question 41

Based on the segregation of sex chromosomes during meiosis, which of the following should occur?

Answer 41

Random fertilization should result in a 1:1 ratio of XX and XY progeny.

Question 42

The several hundred species of fruit flies of the Hawaiian islands are genetically different from each other, yet can all trace their evolutionary ancestry to a fruit fly population in Asia. This pattern is likely a result of:

Answer 42

adaptive radiation

Question 43

The transcription factor Oct4 is highly conserved at the DNA sequence and amino acid sequence levels in mice and humans. Oct4 induces the expression of genes that maintain the pluripotent state. What would happen if you caused the loss-of-function of Oct4 in mice and would it have the same effect or a different effect in humans?

Answer 43

Loss of Oct4 would result in the failure to form cell types of the body in mice and humans.