Question 1

Which of the following best explains the role of homeotic (Hox) genes in animal development?

Accepted Answer

They are transcription factors that activate effector genes, specifying body part identity.

Question 2

A mutation in a Hox gene in Drosophila causes legs to grow in place of antennae. What type of mutation is this?

Accepted Answer

A homeotic mutation affecting segment identity.

Question 3

In Arabidopsis thaliana, a mutation in a MADS box gene causes petals and sepals to form in place of carpels and stamens. What does this demonstrate about MADS box genes?

Accepted Answer

They code for transcription factors that determine floral organ identity.

Question 4

Which statement about the organization of Hox genes in animals is correct?

Accepted Answer

Hox genes are arranged in clusters, and their order corresponds to their expression pattern in the embryo.

Question 5

What evidence supports the evolutionary conservation of Hox gene function?

Accepted Answer

Hox genes from mice can be expressed in fruit fly embryos and produce similar phenotypes.

Question 6

Which of the following is TRUE about stem cells used in therapies for blood disorders?

Accepted Answer

Hematopoietic stem cells from bone marrow, donor blood, or umbilical cord blood can be transplanted to treat blood disorders.

Question 7

Which property distinguishes human embryonic stem cells (hES cells) from adult stem cells?

Accepted Answer

hES cells are pluripotent and can differentiate into almost any cell type.

Question 8

What is a major ethical concern regarding the use of human embryonic stem cells in research and therapy?

Accepted Answer

Their source involves the destruction of human embryos.

Question 9

How are induced pluripotent stem (iPS) cells created from adult skin cells?

Accepted Answer

By inserting four genes active in pluripotent cells into skin cells using viral vectors.

Question 10

Researchers are working to treat diabetes by turning hES and iPS cells into pancreatic beta cells. Which process is essential for this therapy?

Accepted Answer

Differentiation of stem cells into insulin-producing cells using growth factors.

Question 11

Which change in gene expression led to limb loss in snakes?

Accepted Answer

A change in regulation causing Hoxc8 to be expressed where forelimbs should form, resulting in ribs instead of limbs.

Question 12

Loss of hindlimbs in whales is primarily due to which genetic change?

Accepted Answer

Failure to produce the signalling molecule sonic hedgehog in the pelvic region.

Question 13

Which of the following best summarizes the evo-devo (evolutionary developmental biology) perspective on evolutionary change?

Accepted Answer

Changes in the regulation of gene expression, rather than changes in gene number, drive evolutionary innovation.

Question 14

If a developmental process is disrupted in an embryo, what is the most likely outcome?

Accepted Answer

The embryo is likely to die.

Question 15

Which equation best represents the process by which stem cells can both self-renew and differentiate?

Accepted Answer

$$	ext{Stem cell} \xrightarrow{	ext{division}} 	ext{Stem cell} + 	ext{Specialized cell}$$

Question 16

Which of the following is a real-world application of stem cell therapy?

Accepted Answer

Using stem cells to treat blood disorders by transplanting hematopoietic stem cells.

Question 17

What is the significance of the homeobox sequence in Hox genes?

Accepted Answer

It encodes the DNA-binding domain of the transcription factor.

Question 18

Which process is illustrated by the following equation?
$$	ext{hES or iPS cell} \xrightarrow{	ext{growth factors}} 	ext{Pancreatic beta cell}$$

Accepted Answer

Differentiation of stem cells into insulin-producing cells for diabetes therapy.

Question 19

Why are Hox genes considered homologous across animal species?

Accepted Answer

They are descended from genes in a common ancestor and have conserved functions.

Genes, Development, and Evolution: Homeotic Genes, Stem Cells, and Evo-Devo

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