Question 1

During which phase of the cell cycle are chromosomes replicated, and what is the ploidy of the cell immediately after this phase?

Accepted Answer

Chromosomes are replicated during the S phase, and the cell remains diploid.

Question 2

Which of the following best describes the role of microtubules during anaphase of mitosis?

Accepted Answer

Microtubules shorten by depolymerizing at the kinetochore, pulling sister chromatids toward opposite poles.

Question 3

A researcher observes a cell with a cell plate forming in the center during cytokinesis. Which type of cell is this, and what is the main difference in cytokinesis compared to animal cells?

Accepted Answer

It is a plant cell; plant cells form a cell plate from vesicles, while animal cells use a contractile ring of actin and myosin.

Question 4

Which protein complex is responsible for triggering the cell's entry into mitosis, and what experiment demonstrated its function?

Accepted Answer

Maturation-promoting factor (MPF); fusing a mitotic cell with an interphase cell caused the interphase nucleus to enter mitosis.

Question 5

A cell is observed to be in a non-dividing, quiescent state. Which phase is it in, and what is the significance of this phase?

Accepted Answer

G0 phase; the cell has exited the cell cycle and is not actively dividing.

Question 6

During meiosis, when do homologous chromosomes line up at the metaphase plate, and when are they separated?

Accepted Answer

They line up during metaphase I and are separated during anaphase I.

Question 7

Which of the following best explains the difference between mitosis and meiosis in terms of genetic diversity?

Accepted Answer

Mitosis produces genetically identical cells, while meiosis introduces genetic diversity through crossing over and independent assortment.

Question 8

A patient is diagnosed with a tumor caused by a mutation in a gene that normally halts the cell cycle if DNA is damaged. What type of gene is most likely mutated?

Accepted Answer

Tumor suppressor gene

Question 9

During which phase of meiosis does crossing over occur, and what is the biological significance of this process?

Accepted Answer

Crossing over occurs during prophase I, increasing genetic variation among gametes.

Question 10

Which of the following best describes the difference between phenotype and genotype?

Accepted Answer

Genotype is the genetic makeup, while phenotype is the observable physical or biochemical characteristics.

Question 11

A woman with PKU (phenylketonuria) marries a man who is a carrier for the PKU allele. PKU is a recessive disorder. What is the probability that their child will have PKU? Use $$P$$ for the normal allele and $$p$$ for the PKU allele.

Accepted Answer

50\%

Question 12

Which of the following is an example of incomplete dominance?

Accepted Answer

A red-flowered plant crossed with a white-flowered plant produces pink-flowered offspring.

Question 13

Which of the following best describes polygenic inheritance?

Accepted Answer

Multiple genes contribute to a single trait, resulting in continuous variation.

Question 14

In chickens, comb shape is determined by the interaction of two genes. This is an example of which genetic phenomenon?

Accepted Answer

Gene-by-gene interaction (epistasis)

Question 15

Which of the following statements about homologous chromosomes is correct?

Accepted Answer

They carry the same genes in the same order but may have different alleles.

Question 16

A scientist is using pea plants to study inheritance. Why were pea plants a particularly good model organism for Mendel's experiments?

Accepted Answer

Pea plants have easily observable traits, short generation times, and can self- or cross-pollinate.

Question 17

During which phase of meiosis do sister chromatids separate, and what is the result for the daughter cells?

Accepted Answer

Anaphase II; each daughter cell receives a single chromatid from each chromosome.

Question 18

Which of the following best describes the function of the mitotic spindle during cell division?

Accepted Answer

It organizes and separates chromosomes by attaching to kinetochores and pulling chromatids apart.

Question 19

Which of the following is true about the proteins involved in the cleavage furrow during animal cell cytokinesis?

Accepted Answer

Actin and myosin proteins interact to contract and pinch the cell in two.

Question 20

A diploid cell ($$2n) $$undergoes meiosis. How many chromosomes will each resulting gamete have, and what is the significance of this reduction?

Accepted Answer

Each gamete will have $$n$$ chromosomes; this ensures that fertilization restores the diploid number.

Comprehensive Study Guidance for Biology 1306 Exam (Chapters 12–14)

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