Ch 46 biol 1202

What role do germ cells play in gametogenesis?

They produce cells that divide by mitosis and then undergo meiosis to form gametes.

epididymis

coiled tubules where sperm passes into from seminiferous tubules

follicle

consists of one egg cell surrounded by one or more layers of follicle cells that nourish and protect the developing egg cell

True or false? The production of sperm begins at puberty when spermatogonia undergo meiosis I to form primary spermatocytes, which then undergo meiosis II to form secondary spermatocytes. These secondary spermatocytes go on to form spermatids, which mature into sperm cells.

false; Spermatogonia divide by mitosis and differentiate into primary spermatocytes. Starting at puberty, hormones stimulate the primary spermatocytes to undergo meiosis I to form secondary spermatocytes, which then undergo meiosis II to form spermatids.

scrotum

fold of body wall outside

In correct chronological order, the three phases of the human ovarian cycle are

follicular → ovulation → luteal.

ejaculatory duct

formed from joining of duct from seminal vesicle, opens to urethra

What products are formed when a diploid cell undergoes meiosis?

four haploid cells

endometrium

inner lining of uterus supplied with blood vessels

cervix

neck of uterus which opens into vagina

The secretion of androgens is regulated by a _____ feedback mechanism involving the _____ and _____.

negative ... hypothalamus ... pituitary gland

Increasing the temperature of the human scrotum by 2°C (i.e., near the normal body core temperature) and holding it there would

reduce the fertility of the man by impairing spermatogenesis.

vas deferens

two ducts that run from scrotum around and behind urinary bladder

Sperm exit a male's body via the _____.

urethra

describe the stages of the human female reproductive cycle

1.menstrual - thick lining of the uterus breaks down 2. follicular - ovary gets its internal system ready to release the egg. - the egg sits inside a follicle inside of the ovary - follicle develops and gets bigger 3. ovulation - the ovary could release the egg into the oviduct - ovary stimulated by LH from the pituitary gland, the follicle in the ovary bursts open and the egg is released into the oviduct 4. luteal - uterus wall thickens to prepare implantation of a zygote for fertilization - progesterone secreted by the burst ovarian follicle that released the egg, and is now called the corpus luteum

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

14

Which of the following characterizes parthenogenesis?

An egg develops without being fertilized.

How does spermatogenesis differ from oogenesis?

Diploid cells give rise to four functional gametes in spermatogenesis. Spermatogenesis results in the production of four sperm cells, whereas oogenesis only produces one ovum.

Which pituitary secretion stimulates sperm production?

FSH

Which pituitary secretion stimulates the testes to secrete androgens?

LH

Which male reproductive structures are responsible for the transport and delivery of sperm?

The vas deferens transports sperm from the epididymis to the ejaculatory duct, which empties into the urethra; the urethra carries sperm through the penis to the outside of the body and into the female reproductive tract.

In humans, the follicular cells that remain behind in the ovary following ovulation become

a steroid-hormone synthesizing structure called the corpus luteum.

Which hormone(s) is(are) directly responsible for triggering the development of the secondary sex characteristics of males, such as beard growth?

androgens

An advantage of asexual reproduction is that

asexual reproduction enables the species to rapidly colonize habitats that are favorable to that species.

beginning at puberty, a primary oocyte

completes its first meiotic division to form a secondary oocyte and a polar body approximately every month.

ovary

egg production. When the cell division takes place it happens unevenly cytokinesis. Ova are not continuously made.

Sperm become capable of movement while in the _____.

epididymis

Sperm cells are stored within human males in the

epididymis

After ovulation, high levels of _____ inhibit _____ secretion.

estrogen and progesterone ... FSH and LH

Developing ovarian follicles primarily secrete _____.

estrogens

Describe mechanisms that increase the probability that mature sperm will encounter fertile eggs of the same species in organisms that use external fertilization

external fertilized organisms do it in a moist habitat so that the sperm can swim to the eggs. eggs and sperm may be released at the same temperature or date. courtship behavior helps

Suppose you wanted to start an animal-breeding business. For most of the following animals, you could start out with just a single animal. Which of the animals below would require that you start with at least two individuals?

frogs; reproduce sexually and have separate sexes. Both a male and a female are needed to launch a breeding colony.

The hypothalamic hormone that triggers the secretion of FSH is

gonadotropin-releasing hormone (GnRH).

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

human chorionic gonadotropin; HCG, secreted by the early embryo, maintains the corpus luteum. The corpus luteum secretes estrogen and progesterone, which maintain the endometrium for implantation.

A rapid increase in the _____ level stimulates ovulation.

luteinizing hormone

testes

male gonads consisting of many coiled tubes surrounded by layers of connective tissue

fragmentation

mechanism of asexual reproduction; A single parent breaks into parts that regenerate into whole new individuals

budding

mechanism of asexual reproduction; Outward growths from the parent form and pinch off to live independently or remain attached and form extensive colonies

fission

mechanism of asexual reproduction; The separation of the parent into two or more individuals of roughly the same size

parthenogenesis

mechanism of asexual reproduction; Type of reproduction in which females produce offspring from unfertilized eggs. Very common in rotifers and aphids; also some vertebrates (fish, amphibians, lizards)

In humans, oogenesis in comparison to spermatogenesis is different in that _____.

oogenesis does not complete meiosis until after fertilization, but spermatogenesis is complete before the sperm leave the body

Fertilization of human eggs usually takes place in the

oviduct

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

oviduct

Which characteristic of the male reproductive system is not variable among animal species that reproduce sexually?

presence of genitalia

oogenesis

process by which the female gametes, or ova, are created. The female gamete is called an ovum.

bulbourethral gland

produces fluid that neutralizes any acidic urine in the urethra

corpus luteum

secretes additional estrogens and progesterone, hormone that helps uterine lining maintinence during pregnancy; disintegrates if egg cell is not fertilized

Sperm develop in the _____.

seminiferous tubules

Human sperm cells first arise in the

seminiferous tubules.

Peaks of LH and FSH production occur during

the period just before ovulation

In male mammals, excretory and reproductive systems share

the urethra

vagina

thin-walled chamber that is repository for sperm during copulation

True or false? The basic functions of the human female reproductive system are to produce eggs, develop offspring, and make hormones.

true

True or false? Humans form gametes by a process called gametogenesis.

true; Humans form gametes by gametogenesis.

A fertilized egg usually implants itself and develops in the _____.

uterus

where does the human fetus develop?

uterus

Explain how hermaphroditism may be advantageous in sessile or burrowing animals that have difficulty encountering a member of the opposite sex.

when an organism contains both male and female reproductive organs - if isolated organisms that don't see organisms of the opposite sex are hermaphroditic, they can sometimes fertilize themselves, making reproduction much easier than if they were to wait for an organism of the opposite sex to come their way

uterus

womb; thick, mucular organ that expands during pregnancy

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 are responsible for maintaining the endometrium in the event that the egg has been fertilized.

Testosterone is synthesized primarily by the

Leydig cells

Which hormone spikes midway through the menstrual cycle and triggers ovulation?

Luteinizing hormone (LH) secreted by the pituitary gland causes the mature ovarian follicle to rupture, a process called ovulation.

Describe three major differences between oogenesis and spermatogenesis

Meiotic divisions of oogenesis: cytokinesis is unequal with almost all cytoplasm monopolized by single daughter cell Though cells from which sperm develop continue to divide by mitosis in male's life, oogenesis only occurs sometimes Oogenesis has long "resting" periods

Which function is not performed by the male reproductive system?

Production and storage of oogonia; Oogonia are produced bythe female reproductive system.

asexual reproduction

Reproduction involving one parent that produces genetically identical offspring

sexual reproduction

Reproduction involving two parents that give rise to offspring with unique combinations of genes inherited from both parents

Which diploid cells are produced by an embryonic germ cell?

Spermatogonia; are male diploid cells that are produced by embryonic germ cells

Which of the following events occurs at the onset of the luteal phase of the menstrual cycle?

The corpus luteum develops from the ruptured follicle during the luteal phase after ovulation.

Explain how the uterine cycle and ovarian cycle are synchronized in female mammals. Note in detail the functions of the hormones involved

The uterine cycle is the thickening of the uterus in preparation for an embryo to be implanted; the ovarian cycle oversees the releasing of coyotes. Both these cycles are synchronized as the ovarian cycle cues the thickening of the uterine lining, which is the uterine cycle. Hormones involved are FSH and LH; FSH triggers the uterine thickening and LH triggers the process of ovulation. Also, The uterine cycle consists of the proliferative phase, secretory phase, and the menstrual phase while the ovarian cycle consists of the follicular phase, ovulation, and the luteal phase

prostate gland

anticoagulant enzymes and citrate

Animals utilizing external fertilization are typically _____.

aquatic animals

oviduct

fallopian tube; has funnel-like opening that has cilia which collects egg cell by drawing fluid from body cavity into duct

Regeneration, the regrowth of lost body parts, normally follows

fragmentation