Question 1

What are homeotic genes and what do they do?

Accepted Answer

The answer of What are homeotic genes and what do...

Question 2

What are the role and relationship of egg-polarity genes, segmentation genes, pair-rule genes, gap genes, and homeotic genes in Drosophila development?

Accepted Answer

The answer of What are the role and relationship of...

Question 3

Describe the epigenetic changes that occur in cells during development and the role they play in differentiation of cell types within a multicellular organism.

Accepted Answer

The answer of Describe the epigenetic changes that occur in...

Question 4

The loss of a tadpole's tail during amphibian metamorphosis and the separation of the digits in human hands during embryonic development are caused by:

Accepted Answer

Apoptosis is a programmed cell death process that is responsible for the removal of unnecessary or unwanted cells, such as the tadpole's tail during metamorphosis and the separation of digits in human embryonic development.

Question 5

Regulation of apoptosis involves initial activation of the enzymes called _____, which act as proteases that can trigger a cascade of cellular protein degradation, bringing about eventual DNA fragmentation.

Accepted Answer

Caspases are a family of protease enzymes that play essential roles in programmed cell death (apoptosis) by initiating a cascade that leads to cellular protein degradation and DNA fragmentation.

Question 6

Use the following to answer questions 
The diagram below illustrates the normal expression of three different groups of genes (A, B, and C) within four different whorls of a developing flower. Normally, whorl 1 produces sepals, whorl 2 produces petals, whorl 3 produces stamens, and whorl 4 produces carpels. Furthermore, expression of class A genes inhibits class C genes, and expression of class C inhibits class A. 
-What kind of mutation would produce sepals in all four whorls?

Accepted Answer

The answer of Use the following to answer questions 
The...

Question 7

What is apoptosis?

Accepted Answer

Apoptosis is the process of programmed cell death, which is a controlled and regulated mechanism that allows cells to die without causing harm to the organism.

Question 8

In wild-type flowering plants, carpel development is determined by what class of gene products?

Accepted Answer

Carpel development in flowering plants is determined by C gene products according to the ABC model of flower development.

Question 9

Use the following to answer questions 
The diagram below illustrates the normal expression of three different groups of genes (A, B, and C) within four different whorls of a developing flower. Normally, whorl 1 produces sepals, whorl 2 produces petals, whorl 3 produces stamens, and whorl 4 produces carpels. Furthermore, expression of class A genes inhibits class C genes, and expression of class C inhibits class A. 
-What would be the identity of the four whorls if gene B was ectopically expressed in whorls 1 and 2?

Accepted Answer

Gene B is responsible for the development of petals and stamens. Ectopic expression in whorls 1 and 2 would convert sepals to petals and petals to stamens.

Question 10

Use the following to answer questions 
The diagram below illustrates the normal expression of three different groups of genes (A, B, and C) within four different whorls of a developing flower. Normally, whorl 1 produces sepals, whorl 2 produces petals, whorl 3 produces stamens, and whorl 4 produces carpels. Furthermore, expression of class A genes inhibits class C genes, and expression of class C inhibits class A. 
-What kind of mutation would produce sepals in whorls 1 and 4 and petals in whorls 2 and 3?

Accepted Answer

A mutation defective in C would lead to the production of sepals in whorls 1 and 4 and petals in whorls 2 and 3, as C function is responsible for the development of stamens and carpels in whorls 3 and 4.

Question 11

The insect hormone ecdysone is known to trigger apoptosis during metamorphosis that turns larva into adult structures. Which of the following experiments would confirm the activation of apoptosis by ecdysone?

Accepted Answer

Inhibition of rpg and hid genes, which are pro-apoptotic, should result in excess cells that would normally be eliminated through apoptosis, confirming that ecdysone triggers apoptosis.

Question 12

A flower is made up of four concentric rings of modified leaves called whorls. Which of the following lists the individual whorls in CORRECT order going from the outside toward the inside of the flower?

Accepted Answer

The correct order of the whorls from the outside to the inside of a flower is sepals, petals, stamens, and carpels.

Question 13

The following diagram describes the genetic regulation of flower development in angiosperms. In each box, write the class of gene, and below write the flower structures determined by those gene(s).

Accepted Answer

The answer of The following diagram describes the genetic regulation...

Question 14

Use the following to answer questions 
The diagram below illustrates the normal expression of three different groups of genes (A, B, and C) within four different whorls of a developing flower. Normally, whorl 1 produces sepals, whorl 2 produces petals, whorl 3 produces stamens, and whorl 4 produces carpels. Furthermore, expression of class A genes inhibits class C genes, and expression of class C inhibits class A. 
-What kind of mutation would produce carpels in whorls 1 and 4 and stamens in whorls 2 and 3?

Accepted Answer

A mutation defective in A would lead to the transformation of sepals (whorl 1) into carpels and petals (whorl 2) into stamens, while whorls 3 and 4 remain as stamens and carpels, respectively.

Question 15

What are morphogens, and what do they do?

Accepted Answer

The answer of What are morphogens, and what do they...

Question 16

Use the following to answer questions 
The diagram below illustrates the normal expression of three different groups of genes (A, B, and C) within four different whorls of a developing flower. Normally, whorl 1 produces sepals, whorl 2 produces petals, whorl 3 produces stamens, and whorl 4 produces carpels. Furthermore, expression of class A genes inhibits class C genes, and expression of class C inhibits class A. 
-What kind of mutation would produce sepals in whorls 1 and 2 and carpels in whorls 3 and 4?

Accepted Answer

A mutation defective in B would result in sepals in whorls 1 and 2 and carpels in whorls 3 and 4, as B function is required for petal and stamen development in whorls 2 and 3.

Question 17

The genes that determine flower development were divided into three classes by Meyerowitz and his colleagues: class A, class B, and class C. What would the flowers produced by a plant with a mutation in a class B gene look like?

Accepted Answer

The answer of The genes that determine flower development were...

Question 18

What is the function of segmentation genes and homeotic genes in Drosophila?

Accepted Answer

The answer of What is the function of segmentation genes...

Question 19

(a) Explain briefly the roles of Bicoid and Nanos proteins in determining the anterior-posterior axis of the fruit-fly embryo. (b) Explain how the Bicoid and Nanos protein gradients are established in the fruit-fly embryo. (c) Bicoid mutant embryos lack head structures and instead have structures at the anterior end of the embryo that are characteristic of the posterior end. Propose an explanation of this phenotype.

Accepted Answer

The answer of (a) Explain briefly the roles of Bicoid...

Question 20

During development, cells can respond to the presence of hormones and other signals with changes in gene expression that can bring about cell differentiation. In most cases, the differentiated state needs to be maintained through subsequent cell divisions and long after the inducing signal has disappeared. Describe a mechanism that can maintain the differentiated state after the inducing signal has disappeared.

Accepted Answer

The answer of During development, cells can respond to the...

Quiz 22: Developmental Genetics and Immunogenetics