Humans

Question 1

what is fertilisation

Answer 1

fusion of the nuclei
from a male gamete (sperm) and a female
gamete (egg cell)

Question 2

Function of the testes

Answer 2

production of sperm cells (by meiosis) and testosterone

Question 3

What is testosterone?

Answer 3

male hormone involved in primary: sperm production- and secondary: penis enlargement, deep voice, body hair, shoulder enlargement, “aggressiveness” (sexual male characteristics)

Question 4

What is the function of the scrotum?

Answer 4

sac enclosing testes outside of the body - protection and to ensure a proper temperature in testicles (35-33 deg.C)

Question 5

What is the function of the sperm duct?

Answer 5

sperm passes to urethra

Question 6

What is the function of the prostate gland?

Answer 6

lubricating secretion for semen: releases fluid rich in sucrose, which sperm cells will use as a source of energy in aerobic respiration)

Question 7

What is the function of the urethra?

Answer 7

releases urine from urinary bladder for excretion and during ejaculation releases semen

Question 8

What is the function of the penis?

Answer 8

penis becomes erect and can be inserted inside the vagina

Question 9

What is the function of the ovaries?

Answer 9

production of egg/follicle cells by meiosis and oestrogen + progesterone

Question 10

What is progesterone?

Answer 10

female hormone involved in primary - follicle production - and secondary - breast development, hips enlargement, body hair and fat deposits develop (sexual female characteristics)

Question 11

What is the function of the oviducts?

Answer 11

tube that moves follicle cells from the ovary towards the uterus using peristalsis and ciliated cells, usual site for fertilisation

Question 12

What is the function of the uterus?

Answer 12

muscular organ where embryo implants, foetus grows and further contracts during birth/labour so baby is delivered

Question 13

What is the function of the cervix?

Answer 13

muscular opening for uterus: dilates for birth, acts as a barrier against sperm cells, opens when a woman is ovulation so it increases chance of fertilisation

Question 14

What is the function of the vagina?

Answer 14

muscular tube where blood is released out of the body during menstruation, semen is deposited during sexual intercourse, passageway of natural child birth

Question 15

How are sperm adapted to their function?

Answer 15

flagellum: important for movement
mitochondria: important for aerobic respiration to keep flagellum moving
enzymes in acrosome: break down jelly coat present in the egg

Question 16

How is an egg cell adapted to its function?

Answer 16

• jelly coat: changes stiffness when sperm cell penetrates, avoiding penetration of other sperm cells, avoiding polyspermy
• energy stores in cytoplasm: allows egg to survive for several days + nourishes zygote if fertilisation occurs until it can implant in the wall of the uterus

Question 17

Compare male and female gametes in terms of: size, mobility and numbers

Answer 17

Female: large cell size, doesn’t move (is moved), one per menstrual cycle
Male: small cell size, moves using flagellum, millions per ejaculation (live for up to 5 days)

Question 18

What happens to the zygote in early development?

Answer 18

the zygote forms an embryo which is a ball of cells that implants into the lining of the uterus

Question 19

State the functions of the umbilical cord

Answer 19

• connects the foetus to the placenta
• contains arteries that deliver deoxygenated blood from foetus to placenta for exchange
• contains one vein, delivering oxygenated blood from placenta to foetus

Question 20

State the functions of the placenta

Answer 20

• respiration
• excretion
• nutrition
• immunity
• hormonal

Question 21

What is the placenta?

Answer 21

a very thin membrane that allows diffusion to take place: there is very close contact between maternal and baby blood, but they don’t mix to avoid coagulation of different blood types

Question 22

Placenta: respiration

Answer 22

allows diffusion of oxygen from mother to foetus and CO2 from foetus to mother

Question 23

Placenta: excretion

Answer 23

allows diffusion of waste products produced by the baby such as lactic acid, urea, and bicarbonates into mother’s blood

Question 24

Placenta: nutrition

Answer 24

allows diffusion of glucose, vitamins, and minerals from mother to foetus

Question 25

Placenta: immunity

Answer 25

mother’s antibodies pass to baby

Question 26

Placenta: hormonal

Answer 26

placenta releases 3 hormones to maintain pregnancy (HCG, oestrogen and progesterone)

Question 27

What is the maternal artery?

Answer 27

artery carrying oxygenated blood, sending O2 and nutrients towards baby

Question 28

What is the maternal vein?

Answer 28

vein carrying deoxygenated blood, removed carbon dioxide and waste products away from the baby

Question 29

What is the umbilical artery?

Answer 29

carries CO2 away from baby to mother

Question 30

What is the umbilical vein?

Answer 30

carries oxygenated blood from mother’s blood towards baby

Question 31

What is the intervillous space?

Answer 31

part of the placenta that surround the villi and contains maternal blood, has low pressure so exchange of materials is constantly done

Question 32

Describe the thickening phase

Answer 32

corpus luteum releases progesterone causing endometrium to thicken for implantation

Question 33

Describe the menstruation phase

Answer 33

endometrium sheds, FSH is released, stimulating growth and maturation of 1 egg

Question 34

Describe the follicular phase

Answer 34

follicles grow and mature, oestrogen releases as response to FSH stimulus (positive feedback) causing endometrium to rebuild

Question 35

Describe the ovulation phase

Answer 35

oestrogen stimulates release of LH from pituitary gland, causing release of eg into oviduct: empty follicle, without egg, is called corpus luteum

Question 36

Where are oestrogen and progesterone released from and what do they target?

Answer 36

released by ovary, targets the uterus lining

Question 37

What is the role of FSH?

Answer 37

stimulates ovulation and development of the corpus luteum

Question 38

What is the role of oestrogen?

Answer 38

builds up endometrium after menstruation

Question 39

What is the role of progesterone?

Answer 39

thickens endometrium after ovulation

Question 40

What happens to the corpus luteum if the egg IS NOT fertilised?

Answer 40

corpus luteum is degenerated therefore levels of progesterone fall, leading to menstruation

Question 41

What happens to the corpus luteum if the egg IS fertilised?

Answer 41

blastocysts releases a hormone that stimulates maintenance of corpus luteum: therefore levels of progesterone are kept high during all pregnancy so endometrium doesn’t shed

Question 42

What is an STI (sexually transmitted infection)?

Answer 42

an infection that is transmitted through sexual contact

Question 43

What is HIV?

Answer 43

human immunodeficiency virus- a pathogen that causes an STI

Question 44

What may HIV infection lead to?

Answer 44

AIDS

Question 45

Describe the methods of transmission of HIV

Answer 45

- transmitted by direct contact with certain body fluids from an infected person: like blood, semen and vaginal fluid. - can happen through: - unprotected sex, - cuts and sores, - using contaminated needles for injecting drugs, - receiving blood transfusions, - mother to child during childbirth/pregnancy/breast-feeding

Question 46

How is the spread of STIs controlled?

Answer 46

using condoms