Chapter 46: Animal Reproduction Flashcards
Ovulation can best be described as
the release of mature eggs
Compare and contrast the outcomes of asexual and sexual
reproduction
The offspring of sexual reproduction are more genetically diverse. How-
ever, asexual reproduction can produce more offspring over multiple gen-
erations.
Parthenogenesis is the most common form of asexual reproduc-
tion in animals that at other times reproduce sexually. What
characteristic of parthenogenesis might explain this observation?
. Unlike other forms of asexual reproduction, parthenogenesis
involves gamete production. By controlling whether or not haploid eggs are fer-
tilized, species such as honeybees can readily switch between asexual and sexual
reproduction.
Compare external fertilization to internal fertilization
external: female releases eggs into the environment, male fertilizes
internal: sperm deposited in or near the female reproductive tract fertilize eggs within the tract
Among some species with external fertilization, individu-
als clustered in the same area release their gametes into the
water at the same time, a process known as ____
spawning
Gonads are organs that
produce gametes
Testes produce sperm in ____ ____.
semiferous tubules
From the semiferous tubules of a testis, the sperm pass into the
epididymis
During ejaculation, sperm are propelled from each epididymis through the____
vas deferens
Each vas deferens (one from each epididymis) extends around
and behind the____, where it joins a duct from
the seminal vesicle, forming a short ______
Each vas deferens (one from each epididymis) extends around
and behind the urinary bladder, where it joins a duct from
the seminal vesicle, forming a short ejaculatory duct
The ejaculatory ducts open into the ___
urethra
Three sets of accessory glands—_____, ______, and the _____—produce secretions
that combine with sperm to form semen
Three sets of accessory glands—the seminal vesicles, the pros-
tate gland, and the bulbourethral glands—produce secretions
that combine with sperm to form semen
The bulbourethral glands are
a pair of small glands along the urethra which secrete a clear mucus before ejaculation that neutralizes any acidic urine remaining in the urethra
During sexual arousal, the erectile
tissue ….
During sexual arousal, the erectile
tissue fills with blood from the arteries
The outer layer of each ovary is packed with ____, each consisting of an oocyte which is a…
follicles
oocyte, partially developed egg
upon ovulation, an oviduct, or fallopian tube,
cilia on the epithelial lining of the oviduct begin beat-
ing. This motion draws fluid from the body cavity into the
oviduct, bringing along the egg
TorF: the mammary glands are present in both males and females
true
Within the mammary glands, small sacs of ____ tissue secrete milk
epithelial
How does gametogenesis differ between males and females in terms of length of cycle?
spermatogenesis is continuous, oogenesis is prolonged
How does gametogenesis differ between males and females in terms of the products of meiosis?
sperm: four products of meiosis develop into mature gametes
in oogenes, cytokinesis durign meiosis is unequal, creating a single daughter cell
How does gametogenesis differ between males and females in terms of length of production?
spermatogenesis is continuous, in females oogenesis mitotic divisions complete before birth and the production of mature gametes ceases at about age 50
Describe the process of oogenesis
Begins in the female embryo with the production of
oogonia from primordial germ cells. Oogonia divide by mitosis
to form cells that begin meiosis, but stop the process at prophase I
before birth.
These developmentally arrested cells, which are
oocytes, each reside within a small follicle.
At birth, the ovaries together contain about
1–2 million primary oocytes, of which about 500 fully mature
between puberty and menopause.
Describe the process of spermatogenesis
Stem cells that give rise to sperm are situated near the outer edge
of the seminiferous tubules. Their progeny move inward as they
pass through the spermatocyte and spermatid stages, and sperm
are released into the lumen (fluid-filled cavity) of the tubule. The
sperm travel along the tubule into the epididymis, where they
become motile
The stem cells arise from division and differentiation of primor-
dial germ cells. In mature testes, the stem cells divide mitotically to form
spermatogonia, which in turn generate spermatocytes by mitosis.
Each spermatocyte gives rise to four spermatids through meiosis,
reducing the chromosome number from diploid (2n = 46 in humans)
to haploid (n = 23). Spermatids undergo extensive changes as they
differentiate into sperm