Biology 2015

Only one sperm enters and fertilizes a human ovum because
a. sperm have an acrosome.
b. the corona radiata gets larger.
c. the zona pellucida lifts up.
d. a fertilization membrane forms.
e. All of these are correct.

Which of these stages is the first one out of sequence?
a. cleavage
b. blastula
c. morula
d. gastrula
e. neurula

Which of these stages is mismatched?
a. cleavage—cell division
b. blastula—gut formation
c. gastrula—three germ layers
d. neurula—nervous system
e. Both b and c are mismatched.

Developmental changes
a. require growth, differentiation, and morphogenesis.
b. stop occurring when one is grown.
c. are dependent on a parceling out of genes into daughter cells.
d. are dependent on activation of master genes in an orderly sequence.
e. Both a and d are correct.

The ability of one embryonic tissue to influence the growth and development of another tissue is termed
a. morphogenesis.
b. pattern formation.
c. apoptosis.
d. cellular differentiation.
e. induction.

Match the statement with the terms in the key.
Key:
a. apoptosis
b. homeotic genes
c. fate maps
d. morphogen gradients
e. segment-polarity genes

Have been developed that show the destiny of each cell that arises through cell division during the development of C. elegans

Match the statement with the terms in the key.
Key:
a. apoptosis
b. homeotic genes
c. fate maps
d. morphogen gradients
e. segment-polarity genes

Occurs when a cell-death cascade is activated

Match the statement with the terms in the key.
Key:
a. apoptosis
b. homeotic genes
c. fate maps
d. morphogen gradients
e. segment-polarity genes

Can have a range of effects, depending on its concentration in a particular portion of the embryo

Match the statement with the terms in the key.
Key:
a. apoptosis
b. homeotic genes
c. fate maps
d. morphogen gradients
e. segment-polarity genes

Genes that control pattern formation, the organization of differentiated cells into specific three-dimensional structures.

Label this diagram illustrating the placement of the extra embryonic membranes, and give a function for each membrane in humans.

Which developmental stage is mismatched?
a. second week—implantation
b. third week—heart development begins
c. fourth and fifth week—limb buds appear
d. sixth through eighth week—all organ systems present
e. None of these stages are mismatched.

Near the time of parturition, which hormone stimulates the fetal adrenal cortex to release androgens?
a. fetal ACTH
b. fetal estrogen
c. maternal ACTH
d. maternal estrogen

Which of the following is not an explanation for why the skin of older people tends to become wrinkled?
a. increased subcutaneous fat deposition
b. increased cross-linking of collagen fibers
c. decreased sebaceous gland activity
d. decreased number of elastic fibers

The onset of menopause is mainly due to
a. a lack of ovarian follicles that are able to ovulate.
b. an involution of the uterus that begins around age 45.
c. an unresponsiveness of the ovaries to FSH and LH from the pituitary.
d. an increased production of male hormones

Possible causes of the cellular damage that can accumulate and contribute to aging include
a. free radicals.
b. spontaneous DNA mutations.
c. cross-linked proteins.
d. UV radiation.
e. All of these are correct.