AR2

Question 1

3 possible ways birth control pills can work?

Answer 1

1) No peak in oestrogen= no ovulation
2) Change in uterus mucus preventing sperm from finding egg
3) Make uterus inhospitable for sperm

Question 2

What are the stages in the 28 day cycle?

Answer 2

1) FSM + LH stimulate follicle to grow
2) Oestrogen secreted by growing follicle and then peaks causing LH surge
3) LH triggers ovulation
4) Corpus luteum secretes oestrogen + progesterone thickening uterus lining
5) If ovum is fertilised- embryos placental cells secrete chorionic gonadotropin maintaining corpus luteum so uterus lining stays intact

Question 3

What is the role of progesterone?

Answer 3

Grows and maintains endometrium

Question 4

What is the role of oestrogen?

Answer 4

Enhances growth of follicles and grows endometrium

Question 5

What is the role of FSH and LH in oogenesis?

Answer 5

FSH- Stimulates follicles and secretion of oestrogen

LH- stimulates maturation of follicles and release of ova at ovulation

Question 6

What is the role of FSH and LH in spermatogenesis?

Answer 6

FSH- Stimulates tubules where sperm form and acts with testosterone
LH- stimulates leydig cells to secrete testosterone which stimulates spermatogenesis

Question 7

What happens at puberty (hormones)?

Answer 7

• Hypothalamus secretes GnRH

- GnRH stimulates FSH and LH from anterior pituitary cells

Question 8

Describe the process of oogenesis

Answer 8

• Primary oocyte divides into 2 different sized daughter cells by meiosis
• Large cell becomes secondary oocyte
• Small cell = first polar body
• Volume of oocyte cytoplasm is conserved in a single large cell rather than split across 4

Question 9

What does a longer sperm mid-piece mean and why?

Answer 9

Means they can keep going for longer because they have more mitochondria in the midpiece to produce ATP

Question 10

Why do insects produce less sperm than humans?

Answer 10

Trade off- insects sperm is much longer than humans therefore they produce less

Question 11

Describe the process of spermatogenesis?

Answer 11

• Spermatogonial cells divide by mitosis initially producing diploid spermatocytes
• Meiosis 1 = homologous pair separate into 2 secondary spermatocytes
• Meiosis 2 = each secondary spermatocyte divides into 2 making 4 haploid spermatids