Ch 46 Animal Reproduction

Question 1

Sexual reproduction

Answer 1

The creation of an offspring by fusion of a male gamete (sperm) and female gamete (egg) to form a zygote

Question 2

Asexual reproduction

Answer 2

The creation of offspring without the fusion of egg and sperm

Question 3

How do many invertebrates reproduce asexually?

Answer 3

Fission

Question 4

Fission

Answer 4

Separation of a parent into two or more individuals of about the same size

Form of asexual reproduction

Question 5

Budding

Answer 5

New individuals arise from outgrowths of existing ones

Form of asexual reproduction

Question 6

Fragmentation

Answer 6

Breaking of the body into pieces, some or all of which develop into adults

Form of asexual reproduction

Question 7

Parthenogenesis

Answer 7

The development of a new individual from an unfertilized egg

Question 8

In what organisms does parthenogenesis occur?

Answer 8

1) In many plants
2) Some invertebrates
3) Some vertebrates (amphibians and reptiles)

Question 9

What is one example of parthenogenesis occurring in vertebrate?

Answer 9

Aspidoscelis (whiptail lizards)

Question 10

In how many species of Aspidoscelis does parthenogenesis occur?

Answer 10

15

Question 11

How did the species of Aspidoscelis that reproduce by parthenogenesis arise?

Answer 11

From hybridization among sexual species

Question 12

What is the “twofold cost” of sexual reproduction?

Answer 12

Sexual females have half as many daughters as asexual females

Question 13

Do most eukaryotic species reproduce sexually or asexually?

Answer 13

Sexually

Question 14

Why does sexual reproduction provide potential advantages over asexual reproduction?

Answer 14

It results in genetic recombination

Question 15

Potential advantages of sexual reproduction

Answer 15

1) Increases the variation in offspring, providing an increase in the reproductive success in changing environments
2) Increases the rate of adaptation
3) Shuffles the genes and eliminates harmful genes from a population

Question 16

Most animals exhibit reproductive cycles related to what?

Answer 16

Changing seasons

Question 17

Most animals exhibit reproductive cycles controlled by what two things?

Answer 17

1) Hormones

2) Environmental cues

Question 18

Ovulation

Answer 18

The release of mature eggs at the midpoint of a female cycle

Question 19

Are reproductive cycles and mating behaviors retained in asexual whiptail lizards (Aspidoscelis)?

Answer 19

Yes

Question 20

Gonads

Answer 20

The organs that produce gametes

Question 21

In addition to gonads, many animals possess what?

Answer 21

Accessory organs

Involved in the transfer and reception of sperm

Question 22

Spermatheca

Answer 22

Organ in many female insects where sperm is stored during copulation

Question 23

Cloaca

Answer 23

A common opening for digestive, excretory, and reproductive systems

Typically found in nonmammalian vertebrates

Question 24

Female external reproductive structures of humans

Answer 24

1) Sensory clitoris

2) Two sets of labia

Question 25

Female internal reproductive structures of humans

Answer 25

1) Pair of gonads | 2) System of ducts and chambers that carry gametes and house the embryo and fetus

Question 26

Male external reproductive structures of humans

Answer 26

1) Penis | 2) Scrotum

Question 27

Male internal reproductive structures of humans

Answer 27

1) Gonads | 2) Accessory glands

Question 28

Vagina

Answer 28

Thin-walled chamber that is the repository for sperm during copulation Serves as birth canal

Question 29

Each ovary contains many what?

Answer 29

Follicles

Question 30

Follicle

Answer 30

Contains an oocyte

Question 31

Oocyte

Answer 31

A partially developed egg

Question 32

Ovum

Answer 32

A fully developed egg

Question 33

Oogenesis

Answer 33

Process where an oocyte develops into an ovum

Question 34

Oviduct (fallopian tube)

Answer 34

Tube through which the ovum cell travels from the ovary to the uterus

Question 35

Endometrium

Answer 35

Uterus lining

Question 36

How does the endometrium support egg development?

Answer 36

It has many blood vessels

Question 37

Seminiferous tubules

Answer 37

Site of sperm formation Found in the testes

Question 38

Leydig cells

Answer 38

Produce hormones Scattered between the tubules

Question 39

Sperm passes from the testes to what?

Answer 39

The epididymis

Question 40

During ejaculation, sperm is propelled through what two structures?

Answer 40

1) Vas deferens | 2) Ejaculatory duct

Question 41

Urthera

Answer 41

Structure through which sperm exits the penis

Question 42

The human penis is composed of what?

Answer 42

Three cylinders of spongy erectile tissue

Question 43

What causes an erection?

Answer 43

During arousal, the erectile tissue fills with blood from the arteries

Question 44

Semen

Answer 44

Composed of sperm and secretions from three sets of accessory glands

Question 45

Three accessory glands that help form semen

Answer 45

1) Two seminal vesicles 2) Prostate gland 3) Bulbourethral glands

Question 46

Seminal vesicles

Answer 46

Contribute ~60% of the total volume of semen

Question 47

Prostate gland

Answer 47

Secrets its products directly into the urethra through several small ducts

Question 48

Bulbourethral glands

Answer 48

Secrete a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra

Question 49

Spermatogenesis

Answer 49

The development of sperm

Question 50

How many sperm are produced each day?

Answer 50

Millions

Question 51

How long does it take each sperm to develop?

Answer 51

7 weeks

Question 52

Oogenesis

Answer 52

The development of an egg

Question 53

Ovulation

Answer 53

The monthly release of a mature egg

Question 54

How many of the products of meiosis develop into sperm?

Answer 54

All four

Question 55

How many of the products of meiosis develop into an egg?

Answer 55

One of the four

Question 56

What are the two main male reproductive hormones?

Answer 56

1) Follicle stimulating hormone (FSH) | 2) Leutenizing hormone (LH)

Question 57

Follicle stimulating hormone (FSH)

Answer 57

Promotes the activity of Sertoli cells

Question 58

Sertoli cells

Answer 58

Nourish developing sperm

Question 59

Leutenizing hormone (LH)

Answer 59

Regulates Leydig cells

Question 60

Leydig cells

Answer 60

Secrete tetosterone and other androgens

Question 61

Testosterone and other androgens promote what?

Answer 61

Spermatogenesis

Question 62

What closely links the two cycles of female reproduction?

Answer 62

Hormones

Question 63

Ovarian cycle

Answer 63

Female reproductive cycle defined by changes in the ovaries

Question 64

Menstrual cycle (uterine cycle)

Answer 64

Female reproductive cycle defined by changes in the uterus

Question 65

What happens to the endometrium before ovulation?

Answer 65

It thickens in preparation for embryo implantation

Question 66

Menstruation

Answer 66

Shedding of the endometrium Occurs if an embryo does not implant into the endometrium

Question 67

What three hormones stimulate follicle growth?

Answer 67

1) Follicle stimulating hormone (LSH) 2) Leutenizing hormone (LH) 3) Gonadotropin releasing hormone (GnRH)

Question 68

Follicle growth and an increase in the hormone estradiol leads to what?

Answer 68

Ovulation and the release of a secondary oocyte (mature egg)

Question 69

Where do immature eggs form?

Answer 69

The female embryo

Question 70

When do eggs complete their development?

Answer 70

Many years after birth

Question 71

What does the follicle become after releasing an egg?

Answer 71

The corpus luteum

Question 72

The corpus luteum secretes what two hormones to maintain pregnancy?

Answer 72

1) Estradiol | 2) Progesterone

Question 73

Human chorionic gonadotropin (hCG)

Answer 73

Hormone released by the embryo to prevent menstruation

Question 74

How does the embryo obtain nutrients for the first 2 to 4 weeks?

Answer 74

Directly from the endometrium

Question 75

What forms the placenta?

Answer 75

Mingling between the trophoblast and endometrium

Question 76

What is one of the few examples of positive feedback loops in humans?

Answer 76

Hormonal controls in birth

Question 77

What replaces the menstrual cycle in most animals?

Answer 77

Estrous cycle

Question 78

Estrous cycle characteristics

Answer 78

1) Endometrium is reabsorbed by the uterus 2) Sexual receptivity is limited to a "heat" period 3) Length and frequency of the estrous cycles vary from species to species