bio chapter 27

Which is NOT a potential advantage of asexual reproduction? a. It produces genetically diverse populations. b. It saves the time and energy required to produce gametes. c. It allows animals that do not move around to produce offspring without finding mates. d. It allows animals that are genetically well suited to a particular environment to quickly expand their populations.

a. It produces genetically diverse populations

The ___________ eventually develops into the sea urchin's digestive tract.

archenteron

During oogenesis, polar bodies:

are discarded

During gastrulation, invagination occurs at the _____.

blastopore

Several hours after fertilization, cleavage results results in the formation of a hollow ball of cells called a __________.

blastula

Which of the following is a similarity between spermatogenesis and oogenesis?

both involve meiosis and the production of haploid cells

Which statement regarding sexual reproduction is TRUE? a. Sexual reproduction creates an individual that is a genetic copy of one parent. b. Sexual reproduction allows animals to expand their populations faster than asexual reproduction. c. Sexual reproduction generates greater genetic variation than asexual reproduction. d. Populations of organisms that reproduce through sexual reproduce through sexual reproduction generally have more difficulty adapting to changing environments.

c. Sexual reproduction generates greater genetic variation than asexual reproduction.

During cleavage, cell division is accompanied by a(n) ______________.

decrease in cell size

Which is a direct result of cleavage?

division of cells

If there is no fertilization, degeneration of the corpus luteum results in a drop in _____, which results in the sloughing off of the uterus's endometrium.

estrogen and progesterone (both are responsible for maintaining the endometrium in the event that the egg has been fertilized)

After ovulation, high levels of _____ and _______ inhibit _____ and ________ secretion.

estrogen and progesterone ........ FSH and LH

Developing ovarian follicles primarily secrete _____.

estrogens

The completion of meiosis II during oogenesis occurs at:

fertilization

The three-layered embryo is the _________.

gastrula

Gametogenesis is to spermatogenesis and oogenesis as _____________________.

gonads are to testes and ovaries

In sea urchins, the process of fertilization produces a(n):

zygote

The sequence of stages in embryonic development in the correct order:

zygote, blastocyst, gastrula

The sequence in which most animals develop:

zygote, cleavage, blastula, gastrula, organ formation

Two important contributions that cleavage makes to development are to:

1. create a multicellular embryo 2. partition the embryo into developmental regions

Ovulation usually occurs on or about day _____ of a 28-day ovarian cycle.

14

What occurs during gastrulation?

A hollow blastula is changed into a hollow embryo that has three tissue layers

The anterior pituitary gland, under the control of the hypothalamus, produces __________, which stimulate _____________.

FSH and LH ... egg maturation and ovulation

___________ involves the development and migration of the three tissue layers - ectoderm, mesoderm, and endoderm.

Gastrulation

Fertilization in the female reproductive tract typically occurs in the:

Oviduct

What is the usual site of the fertilization of an egg cell?

Oviduct

Cell types in the correct order of their appearance during spermatogenesis:

Primary spermatocyte, secondary spermatocyte, spermatid, sperm

True or False: Meiosis in oogenesis produces one mature egg from one primary oocyte.

True

True or False: Men, but not women, can produce gametes throughout their adult lives.

True

True or False: Morning-after pills taken within 3 days protected intercourse prevent fertilization or implantation about 75% of the time.

True

How are the ovulation cycle and the menstruation cycle coordinated?

The processes regulate each other through a system that involves four major hormones

As cleavage continues, a zygote forms into a solid multicellular ball called a(n) _____.

morula

In vertebrates, the ectoderm gives rise to the _________.

outer layer of skin

Hermaphrodites are animals that:

possess both male and female reproductive systems

What is shed from the body in menstruation?

the thickened endometrium when fertilization has not occurred

The ovaries release increasing increasing levels of estrogen and progesterone immediately after ovulation. This results in __________.

thickening of the endometrium and reduced production of FSH and LH, which feeds back to prevent further ovulation

Sterilization, in which the sperm is surgically prevented from reaching the egg, is accomplished by:

tubal ligation or vasectomy

A fertilized egg usually implants itself and develops in the:

uterus

Which agent can cause infection that can ultimately develop into pelvic inflammatory disease in women?

Chlamydia

What is the function of the thickened endometrium?

It nourishes the early embryo during the process of implantation

A rapid increase in the _________ level stimulates ovulation.

LH

A surge in which hormones (s) immediately precedes ovulation?

LH and FSH

If there is fertilization, secretion of _____ by the early embryo maintains the corpus luteum.

human chronic gonadotropin (HCG)

From which part of a developing embryo are stem cells derived?

inner cell mass

Hypothetically speaking, if a diploid sperm fertilized a diploid ovum, the zygote would be _____________.

tetraploid

What is the cortical reaction?

the formation of a fertilization envelope that bars additional sperm from entry into the egg