Reproduction

Question 1

How does sexual reproduction occur in mammals?

Answer 1

Due to the production of sperm from the male and eggs from the female. This sperm and egg meet during intercourse - this is internal fertilisation

Question 2

How do fish reproduce ?

Answer 2

Using external fertilisation.

Question 3

Testes Definition

Answer 3

These are the structures responsible for the production of sperm

Question 4

Scrotum definition

Answer 4

The structure inside which the testes are held.

Question 5

Why are the testes held outside of the body?

Answer 5

The best temperature for the production of sperm is slightly lower than that of the rest of the body

Question 6

Sperm ducts

Answer 6

These are the tubes through which the sperm moves towards the prostate gland

Question 7

Prostate gland

Answer 7

This gland adds other substances to the sperm forming semen. These substances aid the sperms motility

Question 8

Urethra

Answer 8

This is the tube running through the penis. It carries both semen and urine out of the mans body

Question 9

Penis

Answer 9

This is made up of connective tissues with many cavities for blood. This is called erectile tissue

Question 10

Ovaries

Answer 10

These are the structures responsible for the production of eggs

Question 11

Oviducts

Answer 11

These are the tubes running from the ovaries towards the uterus, they are where fertilisation should take place

Question 12

Cervix

Answer 12

This is a ring of muscle found at the junction of the vagina and the uterus

Question 13

Uterus

Answer 13

Also known as the womb. This is the site in which the baby develops during pregnancy. Under normal circumstances the uterus is around 150 mm long

Question 14

Vagina

Answer 14

This is the muscular tube through which the baby passes during birth

Question 15

Vulva

Answer 15

The urethra from the bladder opens into the vulva which lies just in front of the vagina

Question 16

How are sperm cells adapted to their function? (3)

Answer 16

• They have a haploid nucleus
• mitochondria for energy production
• flagellum which makes them motile

Question 17

Describe egg cells

Answer 17

• much larger than sperm as they contain large food stores that will be used if fertilisation occurs

Question 18

How does fertilisation occur ? (3)

Answer 18

• when sperm are released during intercourse they swim through the uterus towards the oviducts of the female reproductive system
• if they encounter an egg in either oviduct, successful fertilisation may occur
• The haploid sperm and egg nuclei fuse to give a diploid zygote

Question 19

How is the embryo formed?

Answer 19

The zygote divides by mitosis many times to form a ball of cells (embryo) as it travels down the oviduct to the uterus

Question 20

What is implantation ?

Answer 20

When the embryo reaches the uterus and settles into the lining

Question 21

How is the placenta adapted for diffusion ? (3)

Answer 21

• having a large surface area between it and the uterus wall for exchanging dissolved nutrients, oxygen, carbon dioxide and urea
• Villi (finger like projections that extend into the uterus wall), which further increase the surface area of the placenta.
• A rich supply of maternal blood vessels in the maternal blood and foetal blood systems which are close together but not joined. They are separated by thin membranes that allow diffusion to occur.

Question 22

How are substances carried to or from the foetus in the blood vessels?

Answer 22

In the umbilical cord

Question 23

What is the amnion ?

Answer 23

The amnion is a membrane that forms around the embryo

Question 24

How is the foetus protected in the womb?

Answer 24

Amniotic fluid surrounds the embryo inside the amnion, cushioning and protecting the developing embryo.

Question 25

Describe a mechanical (physical) contraception, its method and the advantages and disadvantages

Answer 25

- Condoms - Acts As a Barrier to prevent the sperm entering the woman - Easily obtained and protects against STI’s e.g AIDS and chlamydia - However it is unreliable if not used properly

Question 26

Describe a chemical contraception, its method and the advantages and disadvantages

Answer 26

- contraceptive pill - taken regularly by the woman and prevents the ovaries from releasing eggs by changing hormone levels - very reliable - can cause some side effects such as weight gain and may increase the risk of blood clots

Question 27

Describe a male surgical contraception, its method and the advantages and disadvantages

Answer 27

Vasectomy - cutting of sperm tubes, preventing sperm entering the penis - virtually 100% reliable - very difficult or impossible to reverse

Question 28

Describe a female surgical contraception, its method and the advantages and disadvantages

Answer 28

Female sterilisation - cutting of oviducts preventing ova from moving through the oviduct and being fertilised - virtually 100% reliable - very difficult or impossible to reverse

Question 29

Describe the natural contraception

Answer 29

- it is known as the rhythm method - in this case the female monitors her menstrual cycle carefully and will only have intercourse on those days when there should be no egg present to be fertilised - it is extremely unreliable as the female’s cycle can change slightly from month to month

Question 30

Describe the secondary sexual characteristics in both males and females (10)

Answer 30

Males : - body hair and public hair develops - the sexual organs enlarge - the body becomes more muscular - the voice deepens - sexual awareness and drive increase Females: - hair grows in public region and in the armpits - sexual organs enlarge and the breasts develop - the pelvis and hips widen - Menstruation begins - sexual awareness and drive increase

Question 31

What is testosterone ?

Answer 31

Testosterone, produced by the testes, is a sex hormone that causes the secondary sexual characteristics in males

Question 32

What is oestrogen ?

Answer 32

Oestrogen, produced by the ovaries, is a sex hormone that causes the secondary sexual characteristics in women

Question 33

Describe the menstrual cycle (4)

Answer 33

- The start of the menstrual cycle is marked by menstruation, when the previous cycles uterus lining is lost (4-6 days) - the uterus will then begin to develop a brand new lining, and around 12 days the new lining will be complete - At around day 14 an egg will be released and at this stage intercourses is most likely to result in pregnancy - if no sperm are present or if the egg does not become fertilised then the uterus lining will begin to break down at day 28 (end of cycle)

Question 34

What is the role of oestrogen in the menstrual cycle ?

Answer 34

The whole process is controlled by fluctuations in the levels of various hormones including oestrogen.

Question 35

What happens when the production of oestrogen and other hormones stops?

Answer 35

The menstrual cycle stops. This is called the menopause at around age 45-55

Question 36

What is the hormone progesterone responsible for ?

Answer 36

Maintaining the lining of the uterus

Question 37

Explain some of the causes of infertility(3)

Answer 37

- Ovulatory disorders - Endometriosis - Tubal disorders

Question 38

Describe the process of IVF (4)

Answer 38

- IVF is used to inject hormones into the female to produce multiple ova in a single menstrual cycle. - These eggs are collected from her ovaries and the sperm sample donated by the male are introduced to the eggs in a Petri dish. - The resulting zygotes begin to divide. - 48 hours later the best embryos are selected by the embryologist and the female has the embryos implanted in her uterus.

Question 39

Treatment of infertility in humans (3)

Answer 39

- use of hormones to produce multiple ova - IVF - Transfer of several embryos into the uterus