chapter 46 animal reproduction

Question 1

sexual reproduction

Answer 1

creation of offspring by fusion of male and female gamete

-forms zygote

Question 2

asexual reproduction

Answer 2

creation of offspring without the fusion of gametes

Question 3

fertilization depends on

Answer 3

mechanisms that bring together gametes of the same species

Question 4

Regulation of mammalian reproduction done by

Answer 4

interplay of tropic and sex hormones

Question 5

who produces and transports gametes

Answer 5

reproductive organs

Question 6

in placental mammals

Answer 6

embryo develops fully within mothers uterus

Question 7

asexual reproduction

Answer 7

• budding
• fragmentation (breaking of body into pieces)
• parthenogenesis (development of offspring from unfertilized egg–mostly invertebrates)
• most advantageous in stable, favourable environments

Question 8

sexual reproduction

Answer 8

• variance in phenotypes (recombination and gene shuffling)

- enhance reproductive success of parents when environmental factors change relatively rapidly

Question 9

Reproductive cycles

Answer 9

• most animals exhibit cycles related to changing seasons
• controlled by hormones and environmental cues
• ovulation
• some can reproduce both sexually and asexually

Question 10

ovulation

Answer 10

is the release of mature eggs at midpoint of a female reproductive cycle

Question 11

effects of global warming on reproduction

Answer 11

since seasonal temperature is important cue, climate change can decrease reproductive success

Question 12

variation in patterns of sexual reproduction

Answer 12

• finding a mate for sexual reproduction can be difficult
• solution: hermaphroditism (an individual has both sex organs)
• some animals, sex is environmentally determined and can change

Question 13

Fertilization (2 types)

Answer 13

1. External fertilization

2. Internal fertilization

Question 14

1. external fertilization

Answer 14

eggs shed by the female and are fertilized by sperm in external environment.

• Huge numbers of gametes
• low survival rate
• moist environment required
• spawning can occur (all cluster at same time and release gametes)

Question 15

2. Internal fertilization

Answer 15

• sperm deposited in/near female reproductive tract, where fertilization occurs
• requires behavioural interactions and compatible copulatory organs
• production of fewer gametes
• higher rate of survival
• parental care and protection of embryos

Question 16

all fertilization requires

Answer 16

• critical timing (often mediated by environmental cues)
• pheromones
• courtship and/or behaviour

Question 17

to reproduce sexually

Answer 17

• animals must produce gametes (most made by gonads)
• some simple systems don’t have gonads (gametes form from undifferentiated tissue)
• some have sets of accessory tubes/glands that carry, nourish and protect gametes+developing embryos

Question 18

most Insects have…

Answer 18

• separate sexes w/ complex reproductive systems

- in many, female has spermatheca

Question 19

spermatheca

Answer 19

in some insects, where sperm is stored during copulation

Question 20

gametogenesis

Answer 20

production of gametes, differs in male and female

-distinct structure and function of different sexes reflect the differences

Question 21

Endocrine glands responsible for human reproduction

Answer 21

• hypothalamus (GnRH) stimulates release of (FSH and LH) from anterior pituitary
• (FSH ann LH regulate processes in the gonads and production of sex hormones) gonads

Question 22

sex hormones

Answer 22

main sex hormones are steroid hormones

• testosterone (main androgen)
• estrogens (consist of mainly estradiol and progesterone)

Question 23

sex hormone functions

Answer 23

• gamete production
• promote sexual behaviour
• stimulate development of primary and secondary sex characteristics

Question 24

Menstrual cycles

Answer 24

characteristic of only humans and some primates

• endometrium is shed from uterus (menstruation)
• sexual receptivity not limited to a timeframe

Question 25

Estrous cycles

Answer 25

characteristic of most mammals - endometrium is reabsorbed by the uterus - sexual receptivity limited to a "heat" period (estrus) - length and frequency vary from species to species

Question 26

Embryonic development main steps (3)

Answer 26

1. Conception 2. Embryonic development 3. birth

Question 27

Embryonic development

Answer 27

1. Fertilization (sperm+egg=zygote) 2. Cleavage (blastula) 3. Gastrulation (gastrula) 4. Organogenesis (tail-bud embryo) * some: metamorphosis (larval stages)

Question 28

Fertilization (embryonic development)

Answer 28

the formation of a diploid zygote from haploid egg and sperm

Question 29

Fertilization (part 2)

Answer 29

- sperm penetrate the protective layer around the egg - receptors on the egg surface bind to molecules on the sperm surface - changes at the egg surface prevent polyspermy (entry of multiple sperm nuclei into egg)

Question 30

Acrosomal reaction

Answer 30

- triggered when sperm meets egg - acrosome (on tip of sperm) releases hydrolytic enzymes that digest material surrounding egg - gamete contact (and/or) fusion depolarizes the egg cell membrane, sets up a block to polyspermy

Question 31

cortical reaction

Answer 31

- fusion of egg and sperm also initiates this run - vesicles sebaceous in egg plasma membrane release contacts and form a fertilization envelope (acts as slow block to polyspermy) - requires a high [Ca2+] ions in the egg - rxn triggered by change in [Ca2+] - Ca2+ spread across the egg correlates with appearance of fertilization envelope.

Question 32

Egg activation

Answer 32

- rise in cytosolic Ca2+ increases rates of cellular respiration and protein synthesis by egg - with these rapid changes in metabolism, the egg is "activated" - proteins and mRNAs needed for activation already present in egg - sperm nucleus merges with the egg nucleus * cell division begins*

Question 33

Fertilization in mammals

Answer 33

- internal - zona pellucida (where sperm binds to a receptor) changes, ensure one sperm enters egg - first cell division occurs 12-36 hours after sperm binding - diploid nucleus forms after first division of zygote

Question 34

cleavage

Answer 34

(after fertilization) - period of rapid cell division, without growth - partitions the cytoplasm of one large cell into many smaller cells (blastomeres) - blastula forms

Question 35

blastula

Answer 35

- during cleavage | - ball of cells with a fluid-filled cavity (called blastocoel)

Question 36

Three germ layers

Answer 36

1. Endoderm 2. Mesoderm 3. Ectoderm

Question 37

1. Endoderm

Answer 37

epithelial lining of - digestive tract, liver and pancreas - respiratory tract - excretory - reproductive tracts and ducts - thymus, thyroid and parathyroid glands

Question 38

2. Mesoderm

Answer 38

- skeletal and muscular systems - circulatory and lymphatic systems - excretory and reproductive systems (except germ cells) - dermis of skin - adrenal cortex

Question 39

3. Ectoderm

Answer 39

- epidermis of skin, sweat glands and follicles - nervous systems - pituitary gland, adrenal medulla - jaws and teeth - germ cells