D3 reproduction

Question 1

Explain how the acrosome reaction and cortical reaction prevent polyspermy during fertilization.

Answer 1

• acrosome reaction: release of digestive enzymes from the sperm which penetrate into the zona pellucida, prevents more sperm from entering the egg
• cortical reaction: release of cortical granules from the egg, modifies zona pellucida

Question 2

oxytocin during labour

Answer 2

stimulates contractions

Question 3

Which hormone controls metabolic rate?

Answer 3

thyroxin

Question 4

hCG in pregnancy

Answer 4

endometrial lining maintained by progesterone and oestradiol

• makes sure corpus luteum continues to secrete progesterone
• trophoblast secrete progesterone
• after, placenta takes the role

Question 5

where does fertilization occur

Answer 5

oviduct/ fallopian tube

Question 6

negative feedback mechanism in menstrual cycle

Answer 6

• increased oestradiol inhibits FSH to allow follicles to regress
• progesterone inhibits LH and FSH

Question 7

gametogenesis

Answer 7

Gametogenesis is the process by which gametes are produced in the male and female gonads.

Question 8

spermatogenesis vs oogenesis

Answer 8

spermatogenesis:
- in testes, forms sperm
- continuous process
- testosterone
- 4 sperm produced

oogenesis:
- in ovaries, ovum!
- long resting periods
- estrogen and progesterone
- one egg with polar bodies

Question 9

spermatogenesis:

Answer 9

• develops in the seminiferous tubules of the leydig cells (in testes)
  primary spermatocyte (2n) -> secondary spermatocyte (n) -> spermatid (n) -> sperm (secreted from sertoli cells)