Ch. 42 Animal Reproduction and Development Flashcards
the life cycle of animals is dominated by the ___ stage
diploid
haploid gametes are made by ___ in animals but made by ___ in plants and fungi
meiosis (animals)
mitosis (plants/fungi)
clones
genetically identical cells or individuals (result of asexual reproduction)
binary fission
type of asexual reproduction, genome replicates and cell divides (done by bacteria and archaea)
budding
type of asexual reproduction, new organism develops from an outgrowth or bud due to cell division at a particular site and separates when mature
-done by yeast
fragmentation
type of asexual reproduction, organism is split into fragments and each fragment becomes a mature organism
-done by molds, algae, sea stars, corals, worms
parthenogenesis
type of asexual reproduction, occurs when a female gamete develops a new individual without being fertilized by a male gamete
-done by many invertebrates and some special vertebrates
spermatozoa (sperm)
male gametes
ova (eggs)
female gametes
what results from the fusion of two gametes?
zygote
what happens to the zygote?
divides by mitosis and becomes an embryo
many asexually reproducing organisms can also reproduce sexually… true or false?
true!
environmental conditions are variable and being able to adapt to different conditions allows for greater reproductive success
what are some advantages to being asexual?
- no competition for mates
- no spending energy to attract a mate
what are some challenges to being asexual?
-everyone produces offspring, more competition and less survival of offspring
costs of external fertilization
- higher failure rate for fertilization
- need large amounts of gametes
- need to get the egg/sperm as close as possible
r-strategists
higher # of offspring, low energy investment, lower survival rates (fish)
k-strategists
lower # of offspring, high energy investment, higher survival rates (humans)
define oviparity
-producing young that hatch from eggs
yolk
provides all the nutrients that the developing embryo needs until it hatches
define viviparity
live birth
amnion
a membrane surrounding a fluid-filled cavity that allows the embryo to develop in a watery environment
-key development = freedom from water for reproduction
allantois
a second membrane that collects metabolic wastes
chorion
third membrane that surrounds the entire embryo along with its yolk and the allantoic sac
what are the extraembryonic membranes?
sheets of cells that extend out from the developing embryo
-includes the yolk sac, amnion, allantois, chorion
placenta
- chorion and allantis fuse to form this in mammals who give live birth
- this organ allows nutrients to be obtained directly from the mother
cleavage
early cell divisions of the zygote
blastula
a hollow ball following cleavage (forms after morula)
gastrula
multiple-layered embryonic stage of development
what are the 2 phases of the menstrual cycle?
- follicular phase
2. luteal phase
what happens during the follicular phase?
- FSH stimulates maturation of an oocyte
- granulosa cells secrete secret estradiol (causes uterine wall to thicken)
- high levels of progesterone maintain thickened wall
- surge in LH follows this
what does the surge in LH do?
causes ovulation (release of oocyte from the ovary)
ovulation marks the beginning of the ____ phase
luteal
what is the corpus luteum?
“yellow body”
formation of empty follicle cells post ovulation
secretes progesterone to maintain uterine lining
(if an embryo forms, the placenta takes over for progesterone production)
what happens to the oocyte after ovulation?
is it taken to the fallopian tube and travels to the uterus
- if fertilized, forms embryo
- if not fertilized, corpus luteum degenerates, progesterone and estrogen levels drop, uterine lining is shed (menstruation)
what is an estrus cycle?
uterine lining is reabsorbed instead of shed
-marked by the phases in which females are sexually receptive
gametogenesis
the formation of gametes
spermatogenesis (describe the process)
formation of sperm (occurs in the seminiferous tubules of the testes)
1. spermatogonia (2N) –> primary spermatocyte (N) –> secondary spermatocyte (N)
oogenesis
formation of of ova or eggs
primary oocytes –> secondary oocytes –> polar bodies and 1 mature egg
morula
solid ball of cells resulting form cleavage
