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

Accepted Answer

During metamorphosis, the tadpole's tail is no longer needed as the frog advances from water-dwelling to land-dwelling. Apoptosis, or programmed cell death, occurs in the cells of the tail, leading to its reduction in size and eventual disappearance.

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

Accepted Answer

Mitosis is fundamental for the growth and development of an embryo as it is the process of cell division that increases the number of cells from a single fertilized egg to a multicellular organism. All other processes listed depend on the increased cell number provided by mitosis.

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

Accepted Answer

Post-transcriptional control involves regulating gene expression after transcription has occurred. The removal of introns and alternative splicing of exons is an example of post-transcriptional control because it can produce different mRNA transcripts from the same gene, leading to different protein products. Choice A involves DNA methylation, which is a form of epigenetic control that occurs before transcription. Choice B involves transcriptional control, which occurs before RNA is produced. Choice D involves gene amplification, a form of DNA alteration, which is different from post-transcriptional control. Choice E involves chromatin structure, which also occurs before transcription.

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

Accepted Answer

Cell differentiation involves cells developing unique structures and functions in order to carry out specific roles within an organism. This differentiation is driven by the selective production of proteins that are specific to each cell type. Therefore, the production of tissue-specific proteins, such as muscle actin, is a key aspect of cell differentiation.

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

Accepted Answer

Gastrulation is the process by which the three embryonic cell layers (endoderm, mesoderm, and ectoderm) are formed and the embryo morphs into a gastrula. It also involves the movement and alignment of many embryonic cells. However, the formation of specialized adult tissues occurs later in development through processes such as differentiation and organogenesis.

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

Accepted Answer

Animal cells, but not plant cells, migrate extensively during morphogenesis. Plant cells have rigid cell walls that limit their mobility and prevent them from migrating during development. Animal cells, on the other hand, can move and migrate in response to various signals during embryonic development.

Question 7

During gastrulation, ________.
A) the neural tube forms
B) the blastula forms
C) somites form
D) three germ layers form

Accepted Answer

During gastrulation, the single-layered blastula develops into a gastrula with three germ layers - the endoderm, mesoderm, and ectoderm. The neural tube formation and somite formation occur later in the embryonic development.

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

Accepted Answer

Meristematic tissue cells in plants are similar to embryonic stem cells in animals. Both have the ability to differentiate into any cell type and are responsible for growth and development. Somite cells and mesodermal cells are already specialized cell types in animals, and ectodermal cells are not as closely related to the function of meristematic tissue cells in plants.

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

Accepted Answer

Hox genes often produce transcriptional factors that regulate the expression of other genes during development. While cell-surface molecules and maternal cytoplasmic signals are important in developmental regulation, they are not specifically produced by Hox genes. mRNA processing factors are also important, but are not typically associated with Hox gene action.

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.

Accepted Answer

C. elegans is an appropriate model organism for studying developmental processes because of its transparency and relatively small number of cells (about 1000), which makes it possible to follow the development of individual cells in vivo.

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.

Accepted Answer

Dolly the sheep was cloned by using a differentiated (somatic) cell, specifically a mammary cell, which was fused with an enucleated egg cell from another sheep of a different breed. This process involved transferring the nucleus from a somatic cell into an egg cell that had its nucleus removed, creating a new cell that could develop into an embryo and then into a living organism genetically identical to the somatic cell donor.

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

Accepted Answer

Regulatory transcription factors are proteins that bind to specific DNA sequences to activate or repress gene expression. They can modify chromatin structure, recruit other transcription factors or co-activators or co-repressors, and control the timing and level of gene expression during development and differentiation.

Answer: D
 Alternative splicing is a process by which different exons in a pre-mRNA can be spliced together to generate multiple mRNA isoforms that encode different proteins. This can result in tissue-specific patterns of gene expression, by allowing for different combinations of exons to be expressed in different cell types.

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

Accepted Answer

The correct sequence of early development is cleavage (rapid cell division), followed by gastrulation (formation of three germ layers), and then organogenesis (differentiation of organs and tissues). Option A is incorrect because organogenesis occurs after gastrulation. Option B is also incorrect because fertilization occurs before gastrulation. Option D is incorrect because blastulation (formation of blastula) occurs before gastrulation and neurulation (formation of neural tube) occurs after organogenesis. Option E is incorrect because preformation is not a recognized stage of early development.

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

Accepted Answer

Gastrulation is the process by which an embryo forms its three germ-tissue layers (endoderm, mesoderm, and ectoderm) through the movement of cells to new positions. This is different from determination, cleavage, fertilization, and induction, which are other stages or processes in embryonic development but do not involve the movement of cells to form the germ-tissue layers.

Question 15

Plant embryos do NOT undergo the process of ________.
A) gene expression
B) mitosis
C) embryogenesis
D) gastrulation

Accepted Answer

Plant embryos do undergo gene expression, mitosis, and embryogenesis, but they do not undergo gastrulation, which is a process of cell migration and differentiation that forms the three germ layers in animal embryos.

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

Accepted Answer

Enhancers are DNA sequences that regulate the transcription of nearby genes by increasing or decreasing the activity of RNA polymerase. This is an example of transcriptional control of gene expression.

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

Accepted Answer

Muscle cells and nerve cells are both types of specialized cells that have different functions and structures. However, the main difference between them is the genes they express. Muscle cells express genes that are required for muscle contraction and movement, while nerve cells express genes that are involved in transmitting electrical signals and communication between cells. The genetic code, ribosomes, and chromosomes are generally the same across different types of cells in an organism.

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

Accepted Answer

Cell-cell interactions are crucial for proper development, and disrupting a receptor involved in these interactions can lead to severe developmental defects and embryonic lethality.

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.

Accepted Answer

The DNA in all cells of an individual's body, including brain cells and heart cells, is essentially the same. The differences in cell function are due to different patterns of gene expression rather than differences in the DNA sequence itself.

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

Accepted Answer

The rate at which mRNA is degraded affects how much protein can be synthesized from that mRNA. If mRNA is quickly degraded, less protein will be made from it. Conversely, if it is stable and persists longer in the cell, more protein can be synthesized.

Quiz 21: Genes, Development, and Evolution

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

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

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

Cell differentiation always involves ________.

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

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

During gastrulation, ________.

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

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?

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

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

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

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

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

Plant embryos do NOT undergo the process of ________.

The functioning of enhancers is an example of ________.

Muscle cells differ from nerve cells mainly because they ________.

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

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