Question 1

Which statement best describes the principle of nuclear equivalence in multicellular organisms?

Accepted Answer

The nuclei of an adult's differentiated cells are genetically identical to one another and to the nucleus of the zygote from which they descended.

Question 2

During development, what is the primary difference between cell determination and cell differentiation?

Accepted Answer

Cell determination involves progressive restrictions of gene expression, committing cells to specific patterns of gene activity, while cell differentiation is the process by which cells become specialized in structure and function.

Question 3

Which of the following best explains why most cloned animals exhibit developmental defects?

Accepted Answer

Epigenetic changes in the donor nucleus must be reversed for proper gene expression during early development, and this process is often incomplete.

Question 4

Which type of stem cell has the potential to give rise to all tissues of the body and the placenta?

Accepted Answer

Totipotent stem cell

Question 5

A researcher introduces a mutation in a homeotic gene in Drosophila. What is the most likely result?

Accepted Answer

One body part will be replaced by another, such as a leg developing where an antenna should be.

Question 6

Which process is essential for normal nervous system development and morphogenesis of hands and feet in vertebrates?

Accepted Answer

Apoptosis

Question 7

What is the role of cytoplasmic determinants in early embryonic development?

Accepted Answer

They are maternal substances in the egg that influence early development by leading to differential gene expression in daughter cells.

Question 8

Which of the following is a correct sequence of events in pattern formation during animal development?

Accepted Answer

Maternal effect genes form morphogen gradients, which are then interpreted by segmentation genes to generate repeating body segments.

Question 9

Which of the following best describes the difference between embryonic stem cells (ES cells) and adult stem cells?

Accepted Answer

ES cells can form any type of body cell but cannot form cells of the placenta, while adult stem cells are more limited and can be harvested from umbilical cord tissue, infants, children, and adults.

Question 10

Researchers can reprogram mature cells to become induced pluripotent stem cells (iPSCs) by introducing:

Accepted Answer

A few key transcription factors that reactivate genes inactivated by DNA methylation, histone modification, and inhibitor microRNAs.

Question 11

Which of the following genetic changes can convert a proto-oncogene into an oncogene?

Accepted Answer

Movement of the proto-oncogene near an active promoter, amplification of the gene, or point mutations in the gene or its control elements.

Question 12

A mutation in the p53 gene is most likely to result in which of the following cellular outcomes?

Accepted Answer

Failure to suppress the cell cycle, leading to excessive cell division and reduced apoptosis.

Question 13

Which of the following is a function of tumor-suppressor proteins?

Accepted Answer

Repair damaged DNA, control cell adhesion, and inhibit the cell cycle.

Question 14

Why does the risk of cancer increase with age according to the multistep model of cancer development?

Accepted Answer

Multiple somatic mutations accumulate over time, and about half a dozen changes must occur at the DNA level for a cell to become fully cancerous.

Question 15

Which of the following best describes the role of the Ras protein in cancer development?

Accepted Answer

It activates a kinase cascade that leads to cell division; mutations can produce a hyperactive Ras protein, resulting in excessive cell division.

Question 16

A patient is found to have inherited mutations in the BRCA1 and BRCA2 genes. What is the most significant implication of this finding?

Accepted Answer

The patient is at increased risk for developing inherited breast cancer.

Question 17

Which of the following strategies can lower the risk of cancer by minimizing DNA damage?

Accepted Answer

Minimizing exposure to agents that damage DNA, such as ultraviolet radiation and chemicals found in cigarette smoke.

Question 18

In a scenario where a virus donates an oncogene to a human cell, which of the following is a possible outcome?

Accepted Answer

The cell may begin uncontrolled division, contributing to cancer development.

Question 19

Which equation best represents the relationship between the number of somatic mutations ($$n) $$and the probability of developing cancer ($$P) $$according to the multistep model?

Accepted Answer

$$P = 1 - e$$^{-kn}$$,\ where\ k\ is\ a\ constant$

Development, Stem Cells, and Cancer: Key Concepts in Developmental Genetics and Disease

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