Topic 1: Reproduction

Question 1

What are the 4 methods of asexual reproduction?

Answer 1

• Fragmentation/ regeneration
• Binary fission
• Budding
• Parthenogenesis

Question 2

Which type of animal cannot reproduce by parthenogenesis?

Answer 2

Mammals

Question 3

What is parthenogenesis?

Answer 3

Asexual production of offspring from unfertilised eggs

Question 4

When do aphids reproduce sexually?

Answer 4

High stress environments (introduce beneficial variation)

Question 5

When do aphids reproduce asexually?

Answer 5

Low stress environments

Question 6

What are the 3 fundamental processes of sexual reproduction?

Answer 6

• Gametogenesis
• Mating
• Fertilisation

Question 7

Which processes in sexual reproduction are evolutionarily conserved?

Answer 7

Gametogenesis and fertilisation

Question 8

Which process in sexual reproduction is highly diverse among different species?

Answer 8

Mating

Question 9

What are the 2 main processes in gametogenesis?

Answer 9

• Meiosis

- Spermatogenesis/oogenesis

Question 10

What are gonads?

Answer 10

Specialised reproductive organs (testes and ovaries)

Question 11

Where is sperm stored?

Answer 11

Epididymis

Question 12

Where is sperm produced?

Answer 12

Seminiferous tubules

Question 13

Where is sperm transferred to the penis?

Answer 13

Vas deferens

Question 14

How many sperm cells arise from a single primary spermatocyte?

Answer 14

4 sperm cells

Question 15

Explain the process of spermatogenesis.

Answer 15

• Spermatogonial stem cells divide by mitosis to produce primary spermatocytes (diploid)
• Meiosis 1: primary spermatocytes produce secondary spermatocytes (diploid)
• Meiosis 2: secondary spermatocytes produce spermatids (haploid) which become sperm cells

Question 16

What hormonal events occur at puberty in males and females?

Answer 16

• Hypothalamus secrets GnRH

- GnRH stimulates secretion of FSH and LH from anterior pituitary cells

Question 17

What does GnRH stand for?

Answer 17

Gonadotrophin releasing hormone

Question 18

What does LH stand for?

Answer 18

Luteinising hormone

Question 19

What does FSH stand for?

Answer 19

Follicle stimulating hormone

Question 20

What does FSH trigger in males?

Answer 20

• Activates Sertoli cells

- Development of seminiferous tubules

Question 21

What does LH trigger in males?

Answer 21

• Stimulates Leydig cells to produce testosterone

- Spermatogenesis

Question 22

Where are mitochondria located in sperm cells?

Answer 22

Midpiece

Question 23

What is the acrosome?

Answer 23

Covers sperm head and contains enzymes to penetrate the egg membrane to fertilise

Question 24

Where is the centriole located in sperm cells?

Answer 24

Neck

Question 25

What is sperm heteromorphism?

Answer 25

When one ejaculate contains sperm of different sizes

Question 26

Explain the process of oogenesis.

Answer 26

- Meiosis 1: Primary oocyte (diploid) divides to produce secondary oocyte (diploid) and 1st polar body - Meiosis 2: Secondary oocyte divides to form ovum (haploid) and polar body. 1st polar body divides into 2 polar bodies (now 3 polar bodies in total)

Question 27

How many egg cells arise from a single primary oocyte?

Answer 27

1 ovum

Question 28

What is the purpose of making polar bodies in oogenesis?

Answer 28

Conserves the cytoplasm (resources) in the production of a single ovum

Question 29

What is an oviparous animal?

Answer 29

Lays eggs

Question 30

What does FSH trigger in females?

Answer 30

- Development of follicles | - Stimulates oestrogen production

Question 31

What does LH trigger in females?

Answer 31

Maturation of follicles and release of egg at ovulation

Question 32

What does oestrogen do?

Answer 32

- Growth of follicles | - Growth of endometrium

Question 33

What does progesterone do?

Answer 33

- Grows and maintains endometrium | - Stimulates secretion of nutrients for embryo

Question 34

Which hormone is detected in pregnancy tests?

Answer 34

Human chorionic gonadotrophin (hCG)

Question 35

What are the 3 main structures in the testes?

Answer 35

- Epididymis - Seminiferous tubules - Vas deferens

Question 36

What are the 5 main structures of the mammalian ovum?

Answer 36

- Germinal vesicle - Ooplasm - Vitelline membrane - Zona pellucida - Corona radiata

Question 37

What is the germinal vesicle?

Answer 37

Nucleus containing DNA | Germinal spot = nucleolus

Question 38

What is the ooplasm?

Answer 38

Cytoplasm of ovum containing nutrients and control factors

Question 39

What is the vitelline membrane?

Answer 39

Ovum plasma membrane

Question 40

What is the zona pellucida?

Answer 40

Extracellular matrix containing glycoproteins | Protection

Question 41

What is the corona radiata?

Answer 41

Layers of follicle cells

Question 42

What is required for external fertilisation?

Answer 42

Water

Question 43

What are the problems associated with external fertilisation?

Answer 43

- Can't control delivery - Requires huge numbers of gametes - Predation of eggs

Question 44

What are the 2 methods of internal fertilisation?

Answer 44

- Indirect: male deposits spermatophore which is picked up by female - Direct: sperm transferred directly into female

Question 45

What is copulation?

Answer 45

Sexual intercourse

Question 46

What is an intromittent organ?

Answer 46

Specialised male external organ for delivering sperm

Question 47

How do hermaphrodites reproduce?

Answer 47

Partners exchange sperm and use it to fertilise their own eggs (Eggs are more costly to make than sperm)

Question 48

How do Bean Weevils reproduce?

Answer 48

Penis with spines internally wounds the female's reproductive tract which causes an early death. Female kicks to dislodge the male during copulation.

Question 49

How do Bed bugs reproduce?

Answer 49

Female lacks any genital openings so male pierces membranes and injects sperm into the haemocoel

Question 50

What is sexual cannibalism?

Answer 50

When the female eats the male during/ after copulation

Question 51

What is Wolbachia?

Answer 51

- Reproductive bacteria transferred in eggs of insects which kills males/ induces parthenogenesis - Feminises the population

Question 52

What is syngamy?

Answer 52

Fusion of haploid nuclei in fertilisation

Question 53

How do sperm penetrate ovum in mammals?

Answer 53

- Sperm penetrates cumulus cell layer via hyperactivated motility - Sperm undergoes acrosome reaction to penetrate zona pellucida - Sperm and oocyte plasma membranes fuse, mediated by ZP proteins - Sperm nucleus enters egg - Enzymes modify zona pellucida and membrane to block polyspermy

Question 54

How do sperm penetrate ovum in sea urchins?

Answer 54

- Sperm undergoes acrosome reaction to breakdown tough jelly coat - Bindin protein on acrosomal process binds to receptor on egg surface (species specific) - Sperm and egg plasma membrane fusion - Cortical reaction: electrical potential of egg plasma membrane changes to block polyspermy (faster block than in mammals)

Question 55

What is lysin?

Answer 55

Sperm protein in molluscs which is one of the fastest evolving metazoan proteins known