AP Bio Ch 46

Sperm are produced within the seminiferous tubules. List the structures, in order, through which sperm will pass before ejaculation.

1) epididymis 2) vans defrans 3) seminal vesicle 4) urethra

If the first polar body divided, how many polar bodies could be formed in human female gametogenesis?___________How many eggs are formed?_________

3; 1

Some of the spermatogonia will differentiate to become the primary spermatocytes, which undergo meiosis. How many sperm cells are produced as a result of meiosis?

4

Human males produce hundreds of millions of sperm per day! Do a rough count of the number of secondary oocytes a typical human female might produce in her lifetime. (See the end of this Reading Guide for a solution.)

480 times

How long is the process of spermatogenesis in humans?

7 weeks

In females the hypothalamus secretes ________________________, which causes the anterior pituitary to produce two hormones, _____________________ and ______________________. These are trophic hormones. The target of FSH is the ovarian follicles, and as FSH levels increase, follicles grow and oocytes mature.

GnRH; FSH; LH

In males the hypothalamus secretes ________________________, which causes the anterior pituitary to produce two hormones, _____________________ and ______________________. These are trophic hormones, and their target tissues are in the ovaries and testes. They will regulate gametogenesis, as well as cause the production of ___________________________ in the testes and _________________________________________________ in the ovaries. (All blanks in this question should be filled with the name of a hormone.)

GnRH; FSH; LH; androgens; estrogens

An AP Review Question (not covered in this chapter; you will find the answer at the end of the Reading Guide): Life on land presents both plants and animals with problems related to moving sperm to egg. What plant groups have swimming sperm and require water for fertilization?

bryophytes

Hormone-based contraceptives typically have pregnancy rates of 1% or less. What are their negative side effects?

cardiovascular disease, blood clotting, high blood pressure, heart attack, and stroke

If fertilization does not occur, the corpus luteum disintegrates and the levels of both progesterone and estradiol drop. How do low levels of progesterone and estradiol affect the uterine lining?

causes it to disintegrate due to lack of circulation

How does progestin prevent pregnancy?

causes thickening of woman's cervical muscles so that it blocks sperm from entering the uterus

What is a follicle?

cavity lined with protective cells

Uterus

thick, muscular organ that expands during pregnancy

Epididymis

coiled duct where sperm passes through

Follicles

contains developing oocyte and secretes estrogen

Penis

contains urethra as well as three cylinders of erectile tissue

When ovulation occurs, into what does the ruptured follicle develop?

corpus luteum

What is menstruation?

cyclic shedding of endometrium from uterus

Zygote

diploid cell that results from the fusion of gametes

Parthenogenesis

egg develops without being fertilized

Both male and female gonads have the same function: to produce the gametes and to produce the sex hormones. With that in mind, what is produced by the ovaries?

eggs and estrogen

Labia majora

enclose and protect rest of vulva

Luteal phase

endocrine cells of the corpus luteum secrete female hormones

Secretory phase

endometrium continues to thicken, becomes more vascularized, and develops glands that secrete a fluid rich in glycogen

What is contained within the acrosome?

enzymes that help the sperm penetrate the egg

There are two ovarian hormones: estradiol and progesterone. What hormone does the maturing follicle produce?

estradiol

What hormone stimulates uterine contractions?

estradiol and oxytocin

Oviduct

fallopian tube; where egg travels to uterus

Ovary

female gonad; produces eggs

In populations that are stable in size, each mating pair of animals must produce a pair of offspring. The purpose of the preceding exercise was to lead you to making the following generalizations: Animals that have internal fertilization tend to produce _________________ (many/few) offspring. Animals that have greater parental care tend to produce _________________ (many/few) offspring. Animals that have external fertilization tend to produce _________________ (many/few) eggs.

few; many; many

Scrotum

fold of body wall

Follicular phase

follicles grow and oocytes mature

Vas defrens

forms part of ejaculatory duct

What advantage does sexual reproduction provide? In what type of an environment would it be favored?

genetic variation. favored environment in which factors rapidly change

Gametes

haploid reproductive cell such as a sperm or egg

For animals that are sessile (stationary), finding a mate presents a problem. What is one solution to this problem? Explain the origin of the term that describes this solution.

hermaphrodism in which each individual has both male and female reproductive systems. the term hermaphrodite merges the name hermes and aphrodite

Chicken protection of the embryo/parental care

high

Frogs # of eggs produced

high

Frogs # of offspring produced

high

Horse protection of the embryo/parental care

high

Oysters # of eggs produced

high

Salmon # of eggs produced

high

Salmon # of offspring produced

high

Endometrium

inner lining of uterus that is richly supplied with blood vessels

How does birth control pills/hormone skin patch or injection prevent pregnancy?

interferes with oocyte development and ovulation

Now, how have animal species solved the problem of moving sperm to egg in a dry environment? And how have plants solved that same problem?

internal fertilization in animals; pollination in plants

How does a pregnancy test work?

levels of hCG are so high in maternal blood that some is secreted in urine which is an indicator in many pregnancy tests

Chicken # of eggs produced

low

Chicken # of offspring produced

low

Frogs protection of the embryo/parental care

low

Horse # of eggs produced

low

Horse # of offspring produced

low

Oysters # of offspring produced

low

Oysters protection of the embryo/parental care

low

Salmon protection of the embryo/parental care

low

Testes

male gonad

What conditions are always required for external fertilization?

moist or wet conditions for the sperm to travel in

Vagina

muscular but elastic chamber that is the site for insertion of penis and deposit of sperm

Cervix

neck of uterus that opens into vagina

Budding

new individuals arise from outgrowths of existing ones

By convention, what occurs on day 1 of the menstrual cycle?

new uterine and ovarian cycle

Mitosis

nuclear division in eukaryotic cells

What is gametogenesis in females called?

oogenesis

What are the gonads?

organs that produce gametes in animals

Urethra

outlet tube for reproductive and excretory tube

What does the LH surge trigger?

ovulation

Labia minora

pair of slender skin folds that surrounds the openings of the vagina and urethra.

The inner cell mass will become the embryo. What will the trophoblast form?

placenta

Menstrual flow phase

portion in which menstrual bleeding occurs

Proliferative phase

portion in which the endometrium regenerates and thickens

Urinary bladder

pouch where urine is stored prior to elimination

Now, study Figure 46.12, Oogenesis. First note that the process of meiosis begins during embryonic development but is halted before birth. At what stage are all the "eggs" when a female is born?

primary oocyte

The early embryo is called a blastocyst. What is the outer layer of the blastocyst called?

trophoblast

Study Figure 46.12, Spermatogenesis, carefully to answer the next group of questions. Which cells are constantly replenished by mitosis?

primordial germ cells

Seminal vesicle

produce secretions that combine with sperm to form semen

After ovulation, the follicle is transformed into a corpus luteum. What hormones does the corpus luteum produce?

progesterone and estradiol

FSH and LH get their names from events of the female reproductive cycle, but they also function in males. How are their functions in females and males similar?

regulate sex hormone production in humans; androgens in males and estrogens in females

In what ways are tubal ligation and vasectomy similar?

relatively safe and free from harmful effects

When a female ovulates, what is released?

secondary oocyte

Bulbourethral glands

secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra

Prostate gland

secretes products into urethra

Corpus luteum

secreting tissue in the ovary that forms from the collapsed follicle after ovulation

What three accessory glands produce the fluid part of semen?

seminal vesicles, prostate gland, and bulbourethral gland

Within the testes, where specifically are sperm formed?

seminiferous tubules

Which form of reproduction forms gametes?

sexual

Which form of reproduction produces a zygote?

sexual

Distinguish between sexual reproduction and asexual reproduction.

sexual reproduction is the fusion of two haploid gametes and two parents are involved, whereas asexual reproduction relies entirely on mitosis and offspring are identical to single parent

What is a polar body?

smaller cell that results from unequal cytokinesis of egg

What is gametogenesis in males called?

spermatogenesis

How do high levels of progesterone and estradiol affect the uterine lining (endometrium)?

stimulates continued development and maintenance of the uterine lining

The female gonads are the ovaries. What are the male gonads?

testes

What is produced in the Leydig cells?

testosterone and other androgens

Here's an interesting concept—in some animals, the sex is not fixed but can change during the life span of an individual. Males can become female, and females can become male! What is a possible trigger for these sex changes?

when their size is largest they switch to female to produce more gametes and therefore have more reproductive success

What is the role of HCG? Is it produced by the embryo or by the mother?

acts like pituitary LH in maintaining secretion of progesterone and estrogens in the corpus luteum. produced by embryo

What is the role of LH in males?

acts on leydig cells which produce androgens

What is the role of FSH in males?

acts on sertoli cells which nourish developing sperm

Your answer to question 30 should not have been the egg or an ovum! When is meiosis completed for the ovum?

after sperm enters

Which form of reproduction is seen in parthenogenesis?

asexual

Which form of reproduction occurs in budding?

asexual

Which form of reproduction relies entirely on mitosis?

asexual

Which form of reproduction results in offspring genetically identical to the parent?

asexual

What marks the transition from an embryo to a fetus? When does this occur?

at 8 weeks, all the major structures of the adult are present in rudimentary form and the embryo is called a fetus