Animal reproduction Flashcards

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1
Q

Fission

A

Asexual reproduction in some invertebrates

Separation of parent into 2 or more individuals of about the same size

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2
Q

Budding

A

New individuals arise from outgrowths of existing ones

Hydra and other cnidarians

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3
Q

Fragmentation

A

Breaking of body into pieces followed by regeneration of lost body parts
Pieces develop into adults
Segmented worms

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4
Q

Parthenogenesis

A

Development of new individual from unfertilized egg

Rotifers

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5
Q

“Twofold” cost of sexual reproduction

A

Sexual females have half as many daughters as asexual females

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6
Q

Why sexual reproduction is an evolutionary advantage

A

Genetic recombination: increased variation of offspring, increased rate of adaptation, shuffling of genes and elimination of harmful genes from population

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7
Q

Ovulation definition

A

Release of mature eggs at the midpoint of a female cycle

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8
Q

Control of reproductive cycles

A

Most animals exhibit reproductive cycles related to changing seasons
Reproductive cycles are controlled by hormones and environmental cues

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9
Q

Asexual whiptail lizards

A

Parthenogenesis

Females switch sexual roles (mounting triggers release of egg)

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10
Q

Hermaphroditic reproduction

A

2 hermaphrodites can mate

Some can self-fertilize

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11
Q

External fertilization

A

Eggs shed by female are fertilized by sperm in external environment
Example: female frog secretes eggs into pond, and male frog secretes sperm into pond to fertilize them

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12
Q

Internal fertilization

A

Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract
Requires behavioral interactions and compatible sexual organs
Critical timing: environmental cues, pheromones, and/or courtship behavior

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13
Q

Gonads

A

Organs that produce gametes via meiosis

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14
Q

Female external reproductive structures

A

Clitorus: arousal
Labia: protect opening into vagina

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15
Q

Ovaries

A
Female gonads
Contain follicles (partially developed egg, oocyte, surrounded by support cells; produce estradiol prior to ovulation)
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16
Q

Oogenesis

A

Development of oocyte into ovum (egg)

Prolonged process

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17
Q

Ovulation steps

A

Egg cell is expelled from follicle
Remaining follicular tissue forms into corpus luteum
Cilia in oviduct (fallopian tube) transport egg cell to uterus
Uterus lining (endometrium) contains many blood vessels

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18
Q

Corpus luteum

A

Follicule tissue minus egg cell
Secretes estradiol and progesterone that helps to maintain pregnancy
If egg isn’t fertilized, this degenerates

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19
Q

Female reproductive opening

A

Uterus narrows at cervix, then opens into vagina
Vagina opens to outside
Vagina serves as repository for sperm and the birth canal

20
Q

Male external and internal reproductive organs

A

External: scrotum and penis
Internal: gonads and accessory glands

21
Q

Testes

A

Male gonads

Consist of highly coiled tubes surrounded by connective tissue

22
Q

Seminiferous tubules

A

Coiled tubes in testes

Site of sperm formation

23
Q

Leydig cells

A

Produce hormones and are scattered between seminiferous tubules

24
Q

Scrotum

A

Outer covering of testes

Outside abdominal cavity: temperature is low enough to produce sperm

25
Q

Sperm flow in ejaculation

A

Seminiferous tubules -> epididymus (coiled tubules outside of testes) -> vas deferens (muscular tube) -> ejaculatory duct -> urethra

26
Q

Semen

A

Sperm + secretions from accessory glands

27
Q

Seminal vesicles

A

Contribute about 60% of total volume of semen

Male accessory gland

28
Q

Prostate gland

A

Secretes anticoagulant enzymes and sperm nutrients directly into urethra through several small ducts
Male accessory gland

29
Q

Penis

A

Composed of 3 cylinders of spongy erectile tissue

During arousal, erectile tissue fills with blood from arteries, causing erection

30
Q

Spermatogenesis

A

Development of sperm

Continuous and prolific (millions of sperm are produced each day, and each sperm takes about 7 weeks to develop)

31
Q

3 ways spermatogenesis differs from oogenesis

A
  1. All 4 products of meiosis develop into sperm, while only 1 of 4 develop into egg
  2. Spermatogenesis occurs throughout adolescence and adulthood
  3. Sperm are produced continuously without prolonged interruptions as in oogenesis
32
Q

Spermatogenesis steps

A
Primordial germ cell in embryo ->
Mitosis ->
Spermatogonial stem cell ->
Mitosis ->
Spermatogonium ->
Mitosis ->
Primary spermatocyte ->
Meiosis I ->
Secondary spermatocyte ->
Meiosis II ->
Early spermatid ->
Differentiation ->
Sperm cells
33
Q

Sertoli cells

A

Provide nutrients to developing sperm (spermatids) in spermatogenesis

34
Q

3 parts of sperm cell

A

Head: fertilizes egg
Midpiece
Tail

35
Q

Sperm head components

A

Acrosome: vacuole that contains enzymes to eat through egg
Nucleus: contains haploid genome

36
Q

Sperm midpiece

A

Contains many mitochondria: generate ATP to “swim”

37
Q

Oogenesis steps

A

Primordial germ cell in embryo ->
Mitosis ->
Oogonium ->
Mitosis ->
Primary oocyte (present at birth; arrested in prophase of meiosis I) ->
Completion of meiosis I and onset of meiosis II (occurs at puberty) ->
Secondary oocyte (arrested at metaphase of meiosis II) ->
Ovulation and sperm entry ->
Completion of meiosis II ->
Fertilized egg

38
Q

Gonadotropin-releasing hormone (GnRH)

A

Secreted by hypothalamus (part of brain that regulates reproduction): stimulated by high levels of estradiol in females and inhibited by high levels of testosterone in males
Directs release of follicle stimulating hormone (FSH) and lutenizing hormone (LH) by anterior pituitary gland

39
Q

Menstrual cycle

A
Menstrual flow phase (day 0 to day 5): FSH and LH stimulate follicle to grow, low estradiol and progesterone cause release of endometrium
Proliferative phase (day 6 to day 14): follicle matures, increase in estradiol causes spike in LH, LH triggers release of egg cell 
Secretory phase (day 15 to day 28): corpus luteum forms and secretes estradiol and progesterone, which cause thickening of endometrium
After day 28, cycle repeats
40
Q

Estrous cycles

A

Characteristic of most mammals (except primates and humans)
Endometrium is absorbed by uterus
Sexual receptivity is limited to a “heat” period

41
Q

Hormonal control of male reproductive system

A

Hypothalamus secretes GnRH
GnRH activates anterior pituitary gland, which releases FSH and LH
FSH stimulates sertoli cells, which stimulate inhibin (inhibit anterior pituitary from producing FSH) and spermatogenesis
LH stimulates Leydig cells, which stimulate testosterone (inhibits hypothalamus and anterior pituitary), which stimulates spermatogenesis
Hormone levels are steady, except for morning

42
Q

Vasectomy

A

Ties off vas deferens

43
Q

Birth control

A

Prevent oocyte development and ovulation

No sloughing of endometrial lining

44
Q

Condom or abstinence

A

Prevent entry of sperm into vagina

45
Q

Spermicides or diaphragm (inserted into vagina)

A

Prevent sperm movement through female reproductive tract

46
Q

Morning-after pill

A

Prevent union of sperm and egg and implantation of blastocyst in endometrium

47
Q

Tubal ligation

A

Ties off oviducts