sexual reproduction

Question 1

Spermatogenesis

Answer 1

The process of sperm production within the seminiferous tubules in the testes.

Question 2

where does spermatogenesis take place?

Answer 2

takes place in the seminiferous tubules

Question 3

how many seminiferous tubules are formed in each testis?

Answer 3

around 1000, where spermatozoa are formed

Question 4

where does the mobility of spermatozoa improve?

Answer 4

the epididymis where they are collected

Question 5

what do the seminal vesicles secrete?

Answer 5

mucus

Question 6

what fluids mix during ejaculation?

Answer 6

mucus and prostate fluid

Question 7

what is the purpose of the mucus and prostate fluids?

Answer 7

helps to maintain sperm mobility, provide nutrients e.g. fructose and are alkaline which neutralises acidity found in urine and the vagina

Question 8

what are the cells (in order of division and maturation) that are involved in spermatogensis?

Answer 8

germinal epithelial, spermatogonium, primary then secondary spermatocytes, spermatids and spermatozoon.

Question 9

how are spermatogonium produced?

Answer 9

diploid germinal epithelial cells divide by mitosis to produce diploid spermatogonium

Question 10

how do spermatocytes divide to form spermatids?

Answer 10

• primary spermatocytes divide by meiosis I to produce secondary spermatocytes.
• secondary spermatocytes undergo meiosis II forming spermatids

Question 11

how is spermatozoa formed?

Answer 11

when the spermatids differentiate, they mature into spermatozoa

Question 12

what is the purpose of Sertoli cells?

Answer 12

provide spermatozoa with nutrients and protect them from male’s immune system

Question 13

what do interstitial cells (cells of Leydig) secrete?

Answer 13

testosterone which is involved in stimulating the process of spermatogenesis

Question 14

what is an oocyte?

Answer 14

a developing egg

Question 15

what is the purpose of cilia in the oviduct?

Answer 15

wafts the secondary oocyte along the- oviduct

Question 16

how is polyspermy (entry of additional sperm) prevented to the secondary oocyte?

Answer 16

changes to the zona pellucida is made following the entry of a single spermatazoon

Question 17

what is capacitation?

Answer 17

glycoproteins are removed by enzymes from the surface of the sperm, making the plasma membrane more permeable to swim more rapidly

Question 18

what is the acrosome reaction?

Answer 18

hydrolytic enzymes in the

Question 19

what happens to the egg cell following fertilisation?

Answer 19

completion of the second meiotic division and formation of the ovum/ the cortical reaction.

Question 20

what is the cortical reaction?

Answer 20

occurs when the cortical granule membranes fuse with the oocyte cell membrane. The zona pellucida is converted into a fertilisation membrane

Question 21

what is the acrosome reaction?

Answer 21

when the acrosome releases enzymes which digest cells forming the corona radiate surrounding the oocyte allowing the sperm head to contact the zona pellucida. Now acrosin hydrolyses the zona pellucida, allowing the head to enter the oocyte.

Question 22

how is the diploid zygote formed?

Answer 22

when the sperm pronucleus fuses with the ovum pronucleus

Question 23

what happens to the Graafian follicle following fertilisation?

Answer 23

Becomes the corpus luteum and produces progesterone.
- if no fertilisation occurs, it regresses

Question 24

what happens if an embryo fails to emplant?

Answer 24

the endometrium layer that is filled with blood sheds each month during the menstrual cycle

Question 25

what is the function of the acrosome?

Answer 25

it contains proteases to digest the cells of the corona radiata and zona pellucida

Question 26

explanation of sexual intercourse

Answer 26

the erect penis is inserted into the vagina and semen is ejaculated by contractions of the smooth muscle in the walls of the epidiymis, vas deferns and penis.

Question 27

where is FSH produced?

Answer 27

anterior pituitary gland

Question 28

what is the effect of FSH?

Answer 28

stimulates the maturation of follicles and oocytes in the ovaries and to stimulate the follicles to produce oestrogen

Question 29

where is LH produced?

Answer 29

anterior pituitary gland

Question 30

what is the effect of LH?

Answer 30

stimulates the release of the secondary oocyte from the ovaries (for ovulation) and stimulates the empty follicle to produce progesterone

Question 31

where is oestrogen produced?

Answer 31

the ovaries

Question 32

what is the effect of oestrogen?

Answer 32

stimulates the repair of the endometrium and the release of LH but inhibits the release of FSH

Question 33

where is progesterone produced?

Answer 33

the ovaries

Question 34

what is the effect of progesterone?

Answer 34

stimulates further development of the endometrium and inhibits the release of LH and FSH

Question 35

why does the developing embryo secrete HCG just before and following implantation?

Answer 35

the release of HCG maintains the corpus luteum for the first 16 weeks of pregnancy

Question 36

what hormone does the placenta secrete?

Answer 36

progesterone and oestrogen which then increases to high levels in the blood plasma

Question 37

what hormones are inhibited during pregnancy?

Answer 37

FSH and LH

Question 38

what effect does progesterone have on the uterine wall?

Answer 38

supresses the uterine wall's ability to contract

Question 39

why is oestrogen important for the growth of the foetus?

Answer 39

it stimulates the growth of the uterus to accommodate the growing foetus and stimulates the growth and development of the mammary glands during pregnancy

Question 40

what is negative feedback?

Answer 40

when a disturbance to a system brings about a response that restores the system to its original state

Question 41

what is positive feedback?

Answer 41

when a disturbance to a system brings about a response that increases the disturbance even further

Question 42

where is the hormone HCG made?

Answer 42

the embryo

Question 43

where is excess HCG excreted?

Answer 43

in the urine, where its presence is used to test for pregnancy

Question 44

what happens to secretion of hormones just prior to birth?

Answer 44

progesterone levels decrease (for contractions to begin), whilst oestrogen levels increase

Question 45

what happens in the cervix just prior to birth?

Answer 45

contractions stimulate stretch receptors in the service, oxytocin to be released from pituitary glands which stimulates contraction

Question 46

what is the effect of prolactin?

Answer 46

stimulates milk production in the mammary glands

Question 47

What does suckling stimulate?

Answer 47

the nerves in the nippe and aerola that travels to the hypothalamus

Question 48

what hormones does the hypothalamus stimulate?

Answer 48

posterior pituitary oxytocin to release milk and anterior pituitary to release prolactin for additional milk production