Chapter 11 Biology Questions – Flashcards
Unlock all answers in this set
Unlock answersquestion
What controls the way in which a zygote differentiates?
answer
Selective genes are turned on and off, depending on the fate of the cell.
question
Anhidrotic ectodermal dysplasia is an X-linked disorder that results in the absence of sweat glands. How would this condition be manifested in a heterozygous female?
answer
She would have a random pattern of tissue with and without sweat glands.
question
When are DNA molecules the least tightly coiled?
answer
S phase of interphase
question
After translation is complete, the insulin polypeptide is activated by _____.
answer
the cutting of the initial translation product to yield two shorter chains joined together by sulfur linkages
question
In embryonic mice, a homeotic gene controls development of the neck, which includes the larynx and thymus. If this gene were deleted, a full-term mouse would show _____.
answer
lack of development of the larynx and thymus
question
Cloning experiments with differentiated root cells from carrots revealed that _____.
answer
an entire plant can grow from a differentiated cell
question
Since the first animal was produced using a fully differentiated cell, a number of observations have been made. Which of the following statements is true in regard to reproductive cloning?
answer
Cloned animals often develop chronic conditions that are usually only associated with old age.
question
Stem cells could be immensely important in the treatment of which of the following conditions?
answer
spinal cord injuries
question
Proto-oncogenes have the potential to become oncogenes. Which of the following is most likely to lead to cancer?
answer
a mutation that causes the proto-oncogene to become overactive
question
The Rb protein prevents mitosis by inhibiting cells from entering S phase. Human papillomavirus (HPV) is thought to inhibit the action of the Rb protein in cervical epithelial cells. What would be the effect of cervical cells being infected with HPV?
answer
The mitotic rate would increase.
question
In humans, the most common cancer is _____.
answer
lung cancer
question
In prokaryotes, a group of genes with related functions that are organized and regulated as a group is called ________
answer
an operon
question
Tryptophan is placed into a culture of E. coli cells. As a result, the bacterial cells switch off transcription of genes involved in the production of tryptophan because the amino acid binds to the __________.
answer
repressor
question
The gene for human growth factor is inserted into the E. coli lactose operon so that it replaces the structural genes with the gene for human growth factor. What substance must be added to the bacterial culture so that it produces human growth factor?
answer
lactose
question
Cells become specialized by a process known as ___
answer
differentiation
question
Anhydrotic dysplasia is a genetic disorder in humans that results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way. Women with this disorder typically have small patches of skin with sweat glands and other patches without sweat glands. This pattern of sweat-gland distribution can be explained by _____.
answer
X chromosome inactivation
question
Histones are _____.
answer
proteins around which DNA is coiled
question
In eukaryotes, gene expression is regulated mostly by _____.
answer
controlling the transcription of genes
question
MicroRNA (miRNA) functions by binding to _____ and blocking translation.
answer
complementary mRNA sequences
question
Gene expression can also be controlled after the mRNA molecule has left the nucleus. These mechanisms may include the _____.
answer
breakdown of RNA
question
It is possible for a cell to make proteins that last for months; for example, hemoglobin in red blood cells. However, many proteins are short-lived and may be degraded in days or even hours. Why do cells make proteins with such a short life?
answer
This enables cells to control the amount of protein present.
question
In fruit flies, there are molecules in the egg that determine the future head and tail ends of the animal. What occurs when mRNA from the head end of an embryo is injected into the tail end of an early embryo?
answer
Some head structures develop at the tail end; the head end develops normally.
question
A signal transduction pathway activates a transcription factor that responds by _____.
answer
initiating mRNA synthesis
question
Clones are derived _____.
answer
from a single ancestor cell
question
Experiments involving _____ have demonstrated that differentiated cells contain all of the genetic information found in undifferentiated cells.
answer
nuclear transplantation
question
In frogs, when the nucleus of an intestinal cell of a tadpole is transferred to an egg whose nucleus has been removed (nuclear transplantation), some of the eggs will develop into normal tadpoles. This demonstrates that _____.
answer
these cells have retained all of their genetic potential
question
Stem cells could be immensely important in the treatment of which of the following conditions in the near future?
answer
spinal cord injuries
question
Embryonic stem cells differ from adult stem cells because they _____.
answer
can differentiate into all cell types
question
A proto-oncogene is a normal gene that can change into an oncogene. Oncogenes are potentially lethal genes that can cause cancer. Why do cells continue to maintain proto-oncogenes?
answer
Proto-oncogenes are necessary for normal control of cell division
question
Which of the following statements best describes cancer cells?
answer
Normal controls over cell division have been altered.
question
Which of the following would be most likely to lead to cancer?
answer
generation of multiple copies of a proto-oncogene and inactivation of a tumor-suppressor gene
question
Most human cancers are _____.
answer
caused by the accumulation of mutations
question
Exposure to which of the following substances increases cancer risk?
answer
ultraviolet light exposure
question
In humans, the agent responsible for the greatest number of cancers is _____.
answer
tobacco
