Human Reproduction

Question 1

Function of penis:

Answer 1

becomes erect when spaces in its structure fill with blood

Question 2

Function of testes:

Answer 2

made up of many coiled tubes which produce sperm and the cells between the tubes produce testosterone

Question 3

Function of urethra:

Answer 3

carries semen from the sperm duct to the tip of the penis

Question 4

Function of sperm ducts:

Answer 4

carry sperm from testes to urethra

Question 5

Function of prostate gland:

Answer 5

helps to produce the seminal fluid which makes up 99.5% of semen

Question 6

Function of scrotum:

Answer 6

holds the testes from outside the body, at the ideal temperature for the formation of sperm

Question 7

Function of oviduct:

Answer 7

carries ovum to uterus. Fertilization usually occurs in the first third of this.

Question 8

Function of ovary:

Answer 8

contains follicles which develop the ova - they poduce oestrogen and progesterone

Question 9

Function of uterus:

Answer 9

where the foetus develops. During pregnancy, it increases in volume.

Question 10

Function of the cervix:

Answer 10

a ring of muscle which, until birth, keeps the foetus in the uterus. Relaxes to allow birth.

Question 11

Function of the vagina:

Answer 11

receives the penis during intercourse and is the ‘way out’ for the baby during birth.

Question 12

Comparison of sperm and ovum size

Answer 12

10µm : 100µm

Question 13

Comparison of number of sperm and ovum

Answer 13

300 million per ejaculation : 1 per month

Question 14

Comparison of sperm and ovum mobility

Answer 14

Sperm: motile - can swim by beating flagellum
Ovum: stationary but contains large food source

Question 15

How often is a female gamete released?

Answer 15

About every 28 days (length of 1 menstrual cycle)

Question 16

What happens during the first stage of the menstrual cycle?

Answer 16

Menstruation! The uterus lining is shed and blood and fragments of tissue leave the body through the vagina. Menstruation is triggered by a decrease in the concentration of progesterone.

Question 17

What happens during the second stage of the menstrual cycle?

Answer 17

Repair phase! More blood vessels grow in the lining of the uterus, and the lining thickens and becomes more stable. These changes are triggered by an increase in oestrogen.

Question 18

What happens during the third stage of the menstrual cycle?

Answer 18

Receptive phase! The lining of the uterus and its blood vessels are now well developed. If fertilization has occurred, the embryo can become buried or implanted in the lining. The optimum set of conditions for implantation remains 6-7 days after ovulation, and is maintained by an increasing concentration of progesterone.

Question 19

What happens during the fourth stage of the menstrual cycle?

Answer 19

Premenstrual phase! The uterus lining degenerates as the progesterone concentration starts to decrease unless the embryo implantation has occurred, in which case progesterone keeps the lining intact to begin pregnancy.

Question 20

What is fertilisation in humans?

Answer 20

The joining together of the sperm and ovum.

Question 21

What happens after the first sperm penetrates the ovum’s membrane?

Answer 21

The ovum membrane alters to form a barrier to the entry of other sperm.
The head of the sperm (male nucleus) moves towards the nucleus of the ovum and the two fuse, forming a zygote.
The zygote now starts to divide - first into two, then into four, and so on - whilst continuing to move down the oviduct towards the uterus.
About 6 days after fertilization, the ball of cells, now called an embryo, becomes embedded in the thick lining of the uterus.
Once the embryo is attached to the lining of the uterus, some of its outer cells combine with some of its mother’s cells and a placenta begins to develop.

Question 22

Functions of placenta:

Answer 22

• exchange of soluble materials such as vitamins and minerals, wastes, and oxygen between mother and foetus
• physical attachment of the foetus to the wall of the uterus
• protection of foetus from mother’s immune system
• protection against dangerous fluctuations in mother’s blood pressure

Question 23

Function of umbilical cord:

Answer 23

connects foetus to placenta and contains blood vessels which carry materials for exchange between mother and foetus.

Question 24

Function of amniotic sac and fluid:

Answer 24

protect the foetus against mechanical shock, drying out and temperature fluctuations.

Question 25

What does AIDS stand for?

Answer 25

acquired immune deficiency syndrome

Question 26

What does HIV stand for?

Answer 26

human immunodeficiency virus

Question 27

What does AIDS do?

Answer 27

AIDS is a flu-like illness in the early stages. Many AIDS-related conditions may follow as the immune system begins to fail. The virus reduces the number of lymphocytes and decreases the ability to produce antibodies.

Question 28

Forms of transmission include:

Answer 28

• unprotected sex which an infected person
• contact with an infected person’s blood
• from infected mother to child during pregnancy or childbirth
• sharing syringes with an infected person while injecting drugs