17 Reproduction in Humans

Question 1

Define fertilization

Answer 1

the fusion of the nuclei of a sperm cell and egg cell

Question 2

Adaptive features of a sperm cell

Answer 2

1. Acrosome - a vesicle containing enzymes to dissolve a way through the jelly coat surrounding the egg cell
2. Middle piece - contains mitochondria to release energy for swimming
3. Flagellum - allows sperm cell to swim quickly

Question 3

Adaptive features of an egg cell

Answer 3

1. cytoplasm containing yolk as an energy store
2. jelly coat is softened by the enzymes from the acrosome during fertilization

Question 4

What is an embryo?

Answer 4

a ball of cells that implants into the uterus lining

Question 5

Function of the placenta

Answer 5

1. placenta wall separates the mother’s blood and foetus’s blood
2. thin wall allows oxygen and food materials from the mother to diffuse across the placenta into the foetus’s blood

Question 5

Function of the umbilical cord

Answer 5

1. connects the placenta to the foetus
2. oxygen and food material in the mother’s blood diffuses across the placenta and carried to the foetus through the umbilical cord

Question 6

Function of amniotic fluid

Answer 6

1. supports and protects the foetus
2. allows the developing foetus to move about
3. maintains a constant temperature around the foetus

Question 7

Outline the menstrual cycle

Answer 7

1. FSH stimulates the development of a follicle in the ovary
2. The developing follicle secretes oestrogen which makes uterus lining thick and spongy
3. During this time, the pituitary gland secretes LH and FSH which stimulate the follicle to continue secreting oestrogen
4. When the follicle is fully developed there is a surge in LH causing ovulation to occur. The follicle releases an egg cell into the oviduct
5. The empty follicle stop secreting oestrogen and becomes a corpus luteum
6. The corpus luteum secretes progesterone causing levels of LH and FSH to fall
7. The progesterone maintains the thick and spongy uterus lining while supplying it with sufficient blood in case the egg cell gets fertlised
8. If fertilisation does not occur, the corpus luteum disintegrates. Progesterone is not secreted anymore hence the uterus lining breaks down
9. If fertilisation occurs, the corpus luteum continues to secrete progesterone until implantation occurs. The placenta will then take over the role of secreting progesterone throughout the pregnancy

Question 8

Birth control options

Answer 8

1. Condom
2. Diaphragm
3. Spermicides
4. Oral contraceptive
5. Vasectomy

Question 9

Similarities between AI and IVF

Answer 9

1. involve treatment with fertility drugs
2. intercourse does not occur
3. involves collection of sperms
4. implantation occurs

Question 10

Differences between AI and IVF

Answer 10

AI
1. fertilisation occurs in the body

IVF
1. fertilisation occurs outside the body on a petri dish
2. egg cells are removed from the ovaries