Deck 16: Development, Stem Cells, and Cancer

Question 1

What is considered to be the first evidence of differentiation in the cells of an embryo?

A) cell division occurring after fertilization
B) the occurrence of mRNAs for the production of tissue-specific proteins
C) determination of specific cells for certain functions
D) changes in the size and shape of the cell
E) changes resulting from induction

Answer 1

B

Question 2

If a Drosophila female has a homozygous mutation for a maternal effect gene,

A) she will not develop past the early embryonic stage.
B) all of her offspring will show the mutant phenotype, regardless of their genotype.
C) only her male offspring will show the mutant phenotype.
D) her offspring will show the mutant phenotype only if they are also homozygous for the mutation.
E) only her female offspring will show the mutant phenotype.

Answer 2

B

Question 3

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

Answer 3

E

Question 4

The fact that plants can be cloned from somatic cells demonstrates that

A) differentiated cells retain all the genes of the zygote.
B) genes are lost during differentiation.
C) the differentiated state is normally very unstable.
D) differentiated cells contain masked mRNA.
E) differentiation does not occur in plants.

Question 5

Which of the following is true of embryonic stem cells but not of adult stem cells?

A) They normally differentiate into only eggs and sperm.
B) They can give rise to all cell types in the organism.
C) They can continue to reproduce for an indefinite period.
D) They can provide enormous amounts of information about the process of gene regulation.
E) One aim of using them is to provide cells for repair of diseased tissue.

Question 6

Let us suppose that someone is successful at producing induced pluripotent stem cells (iPS) for replacement of pancreatic insulin-producing cells for people with type 1 diabetes. Which of the following could still be problematic? I. the possibility that, once introduced into the patient, the iPS cells produce nonpancreatic cells
II) the failure of the iPS cells to take up residence in the pancreas
III) the inability of the iPS cells to respond to appropriate regulatory signals

A) I only
B) II only
C) III only
D) I and II
E) all of them

Question 7

Pax-6 is a gene that is involved in eye formation in many invertebrates, such as Drosophila. Pax-6 is found as well in vertebrates. A Pax-6 gene from a mouse can be expressed in a fly and the protein (PAX-6) leads to a compound fly eye. This information suggests which of the following?

A) Pax-6 genes are identical in nucleotide sequence.
B) PAX-6 proteins have identical amino acid sequences.
C) Pax-6 is highly conserved and shows shared evolutionary ancestry.
D) PAX-6 proteins are different for formation of different kinds of eyes.
E) PAX-6 from a mouse can function in a fly, but a fly's Pax-6 gene cannot function in a mouse.

Question 8

A researcher is using adult stem cells and comparing them to other adult cells from the same tissue. Which of the following is a likely finding?

A) The cells from the two sources exhibit different patterns of DNA methylation.
B) Adult stem cells have more DNA nucleotides than their counterparts.
C) The two kinds of cells have virtually identical gene expression patterns in microarrays.
D) The nonstem cells have fewer repressed genes.
E) The nonstem cells have lost the promoters for more genes.

Question 9

In animals, what is the difference between reproductive cloning and therapeutic cloning?

A) Reproductive cloning uses totipotent cells, whereas therapeutic cloning does not.
B) Reproductive cloning uses embryonic stem cells, whereas therapeutic cloning does not.
C) Therapeutic cloning uses nuclei of adult cells transplanted into enucleated nonfertilized eggs.
D) Therapeutic cloning supplies cells for repair of diseased or injured organs.

Question 10

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 11

In 1997, Dolly the sheep was cloned. Which of the following processes was used?

A) use of mitochondrial DNA from adult female cells of another ewe
B) replication and dedifferentiation of adult stem cells from sheep bone marrow
C) separation of an early-stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe
D) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate
E) isolation of stem cells from a lamb embryo and production of a zygote equivalent

Question 12

Which of the following genes map out the basic subdivisions along the anterior-posterior axis of the Drosophila embryo?

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

Question 13

In recent times, it has been shown that adult cells can be induced to become pluripotent stem cells (iPS). In order to make this conversion, what has been done to the adult cells?

A) A retrovirus is used to introduce four specific regulatory genes.
B) The adult stem cells must be fused with embryonic cells.
C) Cytoplasm from embryonic cells is injected into the adult cells.
D) An adenovirus vector is used to transfer embryonic gene products into adult cells.
E) The nucleus of an embryonic cell is used to replace the nucleus of an adult cell.

Question 14

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 sides of the embryo.
E) The embryo would develop normally.

Question 15

Reproductive cloning of human embryos is generally considered unethical. However, on the subject of therapeutic cloning there is a wider divergence of opinion. Which of the following is a likely explanation?

A) Use of adult stem cells is likely to produce more cell types than use of embryonic stem cells.
B) Cloning to produce embryonic stem cells may lead to great medical benefits for many.
C) Cloning to produce stem cells relies on a different initial procedure than reproductive cloning.
D) A clone that lives until the blastocyst stage does not yet have human DNA.
E) No embryos would be destroyed in the process of therapeutic cloning.

Question 16

Which of the following is most closely identical to the formation of twins?

A) cell cloning
B) therapeutic cloning
C) use of adult stem cells
D) embryo transfer
E) organismal cloning

Question 17

Embryonic lethal mutations result in

A) phenotypes that prevent fertilization.
B) failure to express maternal effect genes.
C) death during pupation.
D) phenotypes that are never born/hatched.
E) homeotic phenotype changes.

Question 18

Which of the following problems with animal cloning might result in premature death of the clones?

A) use of pluripotent instead of totipotent stem cells
B) use of nuclear DNA as well as mtDNA
C) abnormal gene regulation due to variant methylation
D) the indefinite replication of totipotent stem cells
E) abnormal immune function due to bone marrow dysfunction

Question 19

The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. Why?

A) The environment, as well as genetics, affects phenotypic variation.
B) Fur color genes in cats are influenced by differential acetylation patterns.
C) Cloned animals have been found to have a higher frequency of transposon activation.
D) X inactivation in the embryo is random and produces different patterns.
E) The telomeres of the parent's chromosomes were shorter than those of an embryo.

Question 20

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 21

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 22

Absence of bicoid mRNA from a Drosophila egg leads to the absence of anterior larval body parts and mirror-image duplication of posterior parts. This is evidence that the product of the bicoid gene

A) is transcribed in the early embryo.
B) normally leads to formation of tail structures.
C) normally leads to formation of head structures.
D) is a protein present in all head structures.
E) leads to programmed cell death.

Question 23

In colorectal cancer, several genes must be mutated in order to contribute to a cell developing into a cancer cell, supporting Knudsen's hypothesis. Which of the following kinds of genes would you expect to be mutated?

A) genes coding for enzymes that act in the colon
B) genes involved in control of the cell cycle
C) genes that are especially susceptible to mutation
D) the same genes that Knudsen identified as associated with retinoblastoma
E) the genes of the bacteria that are abundant in the colon

Question 24

The cancer-causing forms of the Ras protein are involved in which of the following processes?

A) relaying a signal from a growth factor receptor
B) DNA replication
C) DNA repair
D) cell-cell adhesion
E) cell division

Question 25

Which of the following is characteristic of the product of the p53 gene?

A) It is an activator for other genes.
B) It speeds up the cell cycle.
C) It causes cell death via apoptosis.
D) It allows cells to pass on mutations due to DNA damage.
E) It slows down the rate of DNA replication by interfering with the binding of DNA polymerase.

Question 26

Proto-oncogenes can change into oncogenes that cause cancer. Which of the following best explains the presence of these potential time bombs in eukaryotic cells?

A) Proto-oncogenes first arose from viral infections.
B) Proto-oncogenes normally help regulate cell division.
C) Proto-oncogenes are genetic "junk."
D) Proto-oncogenes are mutant versions of normal genes.
E) Cells produce proto-oncogenes as they age.

Question 27

In animals, embryonic stem cells differ from adult stem cells in that

A) embryonic stem cells can differentiate into more cell types than adult stem cells.
B) adult stem cells can differentiate into more cell types than embryonic stem cells.
C) embryonic stem cells have more genes than adult stem cells.
D) embryonic stem cells have fewer genes than adult stem cells.
E) embryonic stem cells are localized to specific sites within the embryo, whereas adult stem cells are spread throughout the body.

Question 28

Which of the following statements describes proto-oncogenes?

A) Their normal function is to suppress tumor growth.
B) They are introduced to a cell initially by retroviruses.
C) They are produced by somatic mutations induced by carcinogenic substances.
D) They can code for proteins associated with cell growth.
E) They are underexpressed in cancer cells.

Question 29

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 30

Apoptosis involves all but which of the following?

A) fragmentation of the DNA
B) cell-signaling pathways
C) activation of cellular enzymes
D) lysis of the cell
E) digestion of cellular contents by scavenger cells

Question 31

Tumor-suppressor genes

A) are frequently overexpressed in cancerous cells.
B) are cancer-causing genes introduced into cells by viruses.
C) can encode proteins that promote DNA repair or cell-cell adhesion.
D) often encode proteins that stimulate the cell cycle.
E) do all of the above.

Question 32

BRCA1 and BRCA2 are considered to be tumor-suppressor genes because

A) they prevent infection by tumor viruses that cause cancer.
B) their normal products participate in repair of DNA damage.
C) the mutant forms of either one of these prevent breast cancer.
D) the normal genes make estrogen receptors.
E) they block penetration of breast cells by chemical carcinogens.

Question 33

Forms of the Ras protein found in tumors usually cause which of the following?

A) DNA replication to stop
B) DNA replication to be hyperactive
C) cell-to-cell adhesion to be nonfunctional
D) cell division to cease
E) growth factor signaling to be hyperactive

Question 34

A genetic test to detect predisposition to cancer would likely examine the APC gene for involvement in which type(s) of cancer?

A) colorectal only
B) lung and breast
C) small intestinal and esophageal
D) lung only
E) lung and prostate