Deck 21: Genes, Development, and Evolution

Question 1

During metamorphosis, a tadpole's tail is reduced in size by the process of ________.

A) regeneration
B) apoptosis
C) meiosis
D) oxidative phosphorylation
E) re-differentiation

Answer 1

B

Question 2

Which one of the following processes in a developing embryo is a prerequisite for all of the other processes?

A) organogenesis
B) cell differentiation
C) mitosis
D) germ layer formation

Answer 2

C

Question 3

Which of the following is an example of post-transcriptional control of gene expression?

A) the addition of methyl groups to cytosine bases of DNA
B) the binding of transcription factors to a promoter
C) the removal of introns and alternative splicing of exons
D) gene amplification contributing to cancer
E) the folding of DNA to form heterochromatin

Answer 3

C

Question 4

Cell differentiation always involves ________.

A) the production of tissue-specific proteins, such as muscle actin
B) the movement of cells
C) the transcription of the myoD gene
D) the selective loss of certain genes from the genome
E) the cell's sensitivity to environmental cues, such as light or heat

Question 5

Gastrulation is an important event in early embryonic development. Which of the following is NOT a result of gastrulation?

A) formation of three embryonic cell layers
B) movement and alignment of many embryonic cells
C) the formation of a gastrula
D) the formation of specialized adult tissues

Question 6

When we compare animal development to plant development, we find that ________.

A) plant cells, but not animal cells, migrate during morphogenesis
B) animal cells, but not plant cells, migrate during morphogenesis
C) plant cells and animal cells migrate extensively during morphogenesis
D) neither plant cells nor animal cells migrate during morphogenesis

Question 7

During gastrulation, ________.

A) the neural tube forms
B) the blastula forms
C) somites form
D) three germ layers form

Question 8

Meristematic tissue cells in plants are most similar to which kind of cells in animals?

A) somite cells
B) ectodermal cells
C) embryonic stem cells
D) mesodermal cells

Question 9

Gene expression in developing organisms is regulated on several different levels. In many developing animals, regulation of gene expression is influenced by the action of Hox genes. Which of the following regulatory elements is produced by many Hox genes?

A) transcriptional factors
B) cell-surface molecules for cell-cell interactions
C) signals from maternal cytoplasm, such as bicoid
D) mRNA processing factors

Question 10

Why is Caenorhabditis elegans an appropriate model organism for studying developmental processes?

A) C. elegans does not undergo programmed cell death.
B) C. elegans have meristems, regions that contain many stem cells.
C) C. elegans is transparent and has only about 1000 cells, allowing the cells to be followed during development.
D) C. elegans has millions of cells but can be easily mutated to have no gastrulation.
E) C. elegans has genes that are completely unique from mice and humans.

Question 11

Which of the following is TRUE of the cloning experiment that resulted in Dolly the sheep?

A) Dolly was genetically identical to the egg-cell donor.
B) Dolly was cloned by fusing an egg with an embryonic stem cell.
C) Dolly was infertile, which indicated incomplete nuclear reprogramming.
D) Dolly was cloned by using a differentiated cell fused to an egg from another breed of sheep.
E) Dolly was cloned by fusing the nuclei from two separate eggs harvested from the same individual.

Question 12

What is the primary mechanism by which eukaryotes control transcription during cellular differentiation?

A) regulatory transcription factors that influence chromatin structure and bind to regulatory regions
B) production of microRNAs to disable mRNAs that should not be expressed
C) post-translational control of proteins through ubiquitination and phosphorylation
D) alternative splicing of genes in different tissue types
E) inhibition of RNA polymerase through the expression of inhibitory enzymes

Question 13

From earliest to latest, the overall sequence of early development proceeds in which of the following sequences?

A) gastrulation → organogenesis → cleavage
B) ovulation → gastrulation → fertilization
C) cleavage → gastrulation → organogenesis
D) gastrulation → blastulation → neurulation
E) preformation → morphogenesis → neurulation

Question 14

Cells move to new positions as an embryo establishes its three germ-tissue layers during ________.

A) determination
B) cleavage
C) fertilization
D) induction
E) gastrulation

Question 15

Plant embryos do NOT undergo the process of ________.

A) gene expression
B) mitosis
C) embryogenesis
D) gastrulation

Question 16

The functioning of enhancers is an example of ________.

A) transcriptional control of gene expression
B) a post-transcriptional mechanism to regulate mRNA
C) the stimulation of translation by initiation factors
D) post-translational control that activates certain proteins
E) a eukaryotic equivalent of prokaryotic promoter functioning

Question 17

Muscle cells differ from nerve cells mainly because they ________.

A) express different genes
B) contain different genes
C) use different genetic codes
D) have unique ribosomes
E) have different chromosomes

Question 18

You are interested in studying a receptor and decide to make a knockout mouse. However, you notice severe developmental defects that result in embryonic lethality in this receptor knockout. Which developmental process is most likely affected when you disrupt a receptor on the cell surface, disrupting its ability to receive a signal and initiate a transduction pathway?

A) cell proliferation
B) cell-cell interactions
C) cell differentiation
D) cell movement
E) apoptosis

Question 19

Which of the following statements about the DNA in one of your brain cells is TRUE?

A) Most of the DNA codes for protein.
B) All of the genes of the genome are likely to be transcribed.
C) Each gene lies immediately adjacent to an enhancer.
D) Many genes are grouped into operon-like clusters.
E) It is the same as the DNA in one of your heart cells.

Question 20

Within a cell, the amount of protein made using a given mRNA molecule depends partly on ________.

A) the degree of DNA methylation
B) the rate at which the mRNA is degraded
C) the presence of certain transcription factors
D) the number of introns present in the mRNA
E) the types of ribosomes present in the cytoplasm

Question 21

Gap genes, segment-polarity genes, and homeotic genes all ________.

A) act independently of one another
B) code for transcription regulatory factors
C) can be activated at any time during development
D) are unique to Drosophila embryos

Question 22

Suppose you found several Drosophila mutants that possessed additional legs growing out of their head segments. The probable mutation would be found in ________.

A) segment-polarity genes
B) gap genes
C) pair-rule genes
D) homeotic genes

Question 23

Which of the following likely has the most Hox genes?

A) jellyfish
B) slugs
C) dolphins
D) bees

Question 24

Which of the following are maternal effect genes that control the orientation of the egg and thus the Drosophila embryo?

A) homeotic genes
B) segmentation genes
C) egg-polarity genes
D) morphogens
E) inducers

Question 25

During Drosophila development, there is a regulatory cascade of gene activation. The proper sequence for this cascade is ________.

A) bicoid, gap genes, pair-rule genes, and segment-polarity genes
B) bicoid, pair-rule genes, gap genes, and segment-polarity genes
C) bicoid, segment-polarity genes, gap genes, and pair-rule genes
D) bicoid, gap genes, segment-polarity genes, and pair-rule genes

Question 26

Your brother has just purchased a new plastic model airplane. He places all the parts on the table in approximately the positions in which they will be located when the model is complete. His actions are analogous to which process in development?

A) morphogenesis
B) determination
C) induction
D) differentiation
E) pattern formation

Question 27

Suppose the protein specified by bicoid was injected into Drosophila embryos so that a high concentration was present everywhere in the embryo. What might be the result of such an experiment?

A) The embryos would grow larger than normal.
B) The embryos would show no development of posterior regions.
C) The embryos would show no development of anterior regions.
D) The embryos would halt their development.

Question 28

The protein of the bicoid gene in Drosophila determines the ________ of the embryo.

A) anterior-posterior axis
B) anterior-lateral axis
C) posterior-dorsal axis
D) posterior-ventral axis

Question 29

The product of the bicoid gene in Drosophila provides essential information about ________.

A) lethal genes
B) the dorsal-ventral axis
C) the left-right axis
D) segmentation
E) the anterior-posterior axis

Question 30

The duplication of homeotic (Hox) genes has been significant in the evolution of animals because it ________.

A) permitted the evolution of novel forms
B) caused the extinction of major groups
C) reduced morphological diversity into simpler forms of life
D) allowed animals to survive on significantly fewer calories

Question 31

Scientists have found that the lifetimes of mRNAs coding for pair-rule regulatory elements in Drosophila embryos may last only a few minutes. What does this suggest about the overall developmental plan of an animal body?

A) The role of mRNAs is less important than the position of genes in chromosomes.
B) Homeotic genes have greater impact in forming an embryo than mRNA from pair-rule genes.
C) Building an animal body requires a sequence of precisely timed steps.
D) Timing of pair-rule sequence determination is not as important as spatial signaling.

Question 32

Suppose there was a mutation in the segment-polarity genes of Drosophila. What do you suppose might be the outcome?

A) Several segments of the embryo will be missing.
B) Every other segment of the embryo will be missing.
C) Legs will appear in the place of antennae.
D) Antennae will appear in a different part of their usual segment.

Question 33

Suppose you have identified a type of lizard that seems to have acquired a mutation in which hindlimbs are absent. Which gene, also responsible for the loss of limbs in snakes, may be mutated in this animal?

A) bicoid
B) MONOPTEROS
C) PHANTASTICA
D) cytoplasmic determinants
E) Sonic hedgehog

Question 34

In combination, the products of gap genes, pair-rule genes, and segmentation-polarity genes ________.

A) trigger the reorganization of the larval body into an adult body
B) define the segmented body plan of the embryo
C) set up the back-to-belly axis of the larval body
D) direct cell movements during differentiation

Question 35

When the Bicoid protein is expressed in Drosophila, the embryo is still syncytial (divisions between cells are not yet fully developed). This information helps to explain which observation by Nüsslein-Volhard and Wieschaus?

A) mRNA from the egg is translated into the Bicoid protein.
B) Bicoid protein diffuses throughout the embryo in a concentration gradient.
C) Bicoid protein serves as a transcription regulator.
D) Bicoid protein determines the dorsoventral axis of the embryo.

Question 36

Suppose the pair-rule genes were inactivated in Drosophila embryos. What is the likely result of the experiment?

A) The embryos would develop normally.
B) The embryos would lack several segments.
C) The embryos would have impaired anterior-posterior polarity.
D) The embryos would have missing alternate segments.

Question 37

Mutations in which of the following genes lead to transformations in the identity of entire body parts?

A) morphogens
B) segmentation genes
C) egg-polarity genes
D) homeotic genes
E) inducers

Question 38

The bicoid gene product is normally localized to the anterior end of the embryo. If large amounts of the product were injected into the posterior end as well, which of the following would occur?

A) The embryo would grow to an unusually large size.
B) The embryo would grow extra wings and legs.
C) The embryo would probably show no anterior development and die.
D) Anterior structures would form in both ends of the embryo.
E) The embryo would develop normally.