Development and Inheritance

Question 1

Fertilisation

Answer 1

Acrosomes of sperm release hyaluronidase and acrosin which allow them to penetrate the corona radiata and cona pellucida of the oocyte

Question 2

Oocyte activation

Answer 2

Oocyte completes meiosis II, becoming a mature ovum

Question 3

Block to polyspermy

Answer 3

Membrane depolarisation and cortical reaction act to ensure only 1 sperm fertilises an egg

Question 4

Amphimixis

Answer 4

Combining of male and female chromosomes

Question 5

First trimester

Answer 5

Cleavage subdivides the cytoplasm of the zygote in a series of mitotic divisions, the zygote becomes pre-embryo and then a blastocyst

Implantation
Placentation
Embryogenesis

Question 6

Implantation

Answer 6

Blastocyst becomes enclosed within the uterine endometrium

Occurs about 7 days after fetilisation as the blastocyst adheres to the uterine lining

Question 7

Placentation

Answer 7

Occurs as blood vessels form around the blastocyst and the placenta develops

Question 8

Blastocyst

Answer 8

Outer trophoblast

Inner cell mass

Question 9

Cytotrophoblast

Answer 9

Inner cellular layer

Question 10

Ectopic pregnancy

Answer 10

Implantation occurs somewhere other than within the uterus

Question 11

Gastrulation

Answer 11

Embryonic disc composed of:
Ectoderm
Mesoderm
Endoderm

Embyonic disc becomes a 3 layered sheet

Question 12

Induction

Answer 12

Chemical interplay among developing cells is induction

Question 13

Extra-embryonic membranes

Answer 13

Yolk sac, amnion, allantois, and chorion

Question 14

Yolk sac

Answer 14

Important site of blood cell formation

Question 15

Amnion

Answer 15

Encloses fluid that surrounds and cushions the developing embryo

Question 16

Allantois

Answer 16

Later gives rise to urinary bladder

Question 17

Chorion

Answer 17

Blood vessels here link emrbyo with trophoblast

Question 18

hCG

Answer 18

Maintains integrity of corpus luteum and promotes progesterone

Question 19

hPL

Answer 19

Prepares mammary glands for milk production

Question 20

Relaxin

Answer 20

Permits pelvis to expand, causes cervix to dilate

Question 21

Stages of labor

Answer 21

1. Dilation
2. Expulsion
3. Placental