Chapter 9 Human Reproduction, Growth and Development

Question 1

the structure and function of..
ovary 
oviduct
uterus
cervix 
vagina

Answer 1

ovary - produces eggs and hormones
oviduct - cilia in the lining of the tube waft the egg from the ovary to the uterus
uterus - muscular wall protect the foetus, lining enables the exchange of materials
cervix - the neck of the uterus which dilates during labour
vagina - receives sperm and baby leaves the body here

Question 2

the structure and function of...
penis
urethra
testis
scrotal sac
sperm duct
prostate gland

Answer 2

penis - transfers semen (sperm plus seminal fluid) from male to female
urethra - tube in penis which carries the semen
testis - produces sperm and hormones
scrotal sac - holds testes outside the body to keep sperm 2 degrees below body temperature
sperm duct - carries sperm from testes to urethra
prostate gland - produces seminal fluid

Question 3

what is the structure and function of egg and sperm

Answer 3

egg - bigger, contains a nucleus, big as it has stored food

sperm - nucleus, small, tail to swim to the egg

Question 4

what is the number of chromosomes in the human body cells

Answer 4

46 chromosomes

Question 5

what does meiosis do

Answer 5

it halves the number of chromosomes during the formation of gametes

Question 6

describe the mechanism of transferring sperin in intercourse

Answer 6

the penis becomes erect due to blood entering the large blood spaces in the tissue this allows the male to place the penis into the vagina, semen travels through the urethra and is deposited close to the cervix

Question 7

where is the site of fertilisation

Answer 7

the upper part of the oviduct

Question 8

how does the zygote form a embryo

Answer 8

the zygote divides by mitosis to from ball of cells that is moved to the uterus where implantation occurs in the lining
the ball then divides to form the foetus, the amnion and the placenta

Question 9

what does the amniotic fluid do

Answer 9

it acts as a shock absorber to protect the foetus

Question 10

what is the placenta

Answer 10

the placenta is an exchange surface to allow materials to diffuse to and from the foetus

Question 11

what are the three stages of labour

Answer 11

the muscular walls of the uterus contract in order to dilate the cervix
the uterus walls squeeze to force the baby through the birth canal
following the birth the uterus contracts to push out the placenta

Question 12

why does the mother require a healthy diet, moderate exercise and sufficient rest

Answer 12

so the baby grows healthily and has lots of energy for growth

Question 13

what are the dangers of consuming alcohol or other drugs while being pregnant

Answer 13

alcohol - can cause learning difficulties by damaging the developing brain, this is because it can cross the placenta to harm the development of the brain

Question 14

what are the dangers of carbon monoxide to a baby

Answer 14

this reduces the amount of oxygen available for aerobic respiration therefore there is less energy for growth resulting in low birth weight
nicotine causes the blood vessels to go into spasm so the placenta receives less oxygen and nutrients

Question 15

what do gynaecologists and midwives do

Answer 15

they are involved in the care of the woman during pregnancy and birth

Question 16

why are viruses such as rubella and HIV are able to cross the placenta and infect the foetus

Answer 16

they are very small molecules that get across the placenta and can cause damage to the foetus

Question 17

how are identical twins and fraternal twins produced

Answer 17

if two eggs are released from the ovary and both are fertilised by separate sperm then twins are developed these are fraternal twins
the embryo splits into two groups of cells and these develop into separate foetus resulting in identical twins

Question 18

what are the benefits of breast feeding

Answer 18

this helps the delivery of the placenta and starts the suckling reflex in the baby - the milk contains a lot of antibodies which help protect the baby from infections, but after a few days the milk will provide protein, fat and sugar in correct proportions

Question 19

the need for parental care

Answer 19

human babies are completely dependent on parents to care for them

Question 20

what is the growth rate

Answer 20

the growth rate of the whole body changes during development this is called growth spurts and are in young children and adolescents

Question 21

when do many changes occur in people and what are they controlled by

Answer 21

adolescents and they are controlled by the sex hormones oestrogen and testosterone

Question 22

when does the menstrual cycle start and how long is it

Answer 22

in early adolescence and 28 days

Question 23

when is ovulation

Answer 23

mid way through 28 days

Question 24

what is the menstrual cycle controlled by

Answer 24

hormones

Question 25

what are hormones used for

Answer 25

as methods of contraception

Question 26

how does the menstruation cycle happen

Answer 26

FSH - causes the egg to mature, released by the piturity gland
oestrogen and progesterone - produced by the ovaries, cause the lining of the womb to thicken for implantation, inhibit FSH
LH - produced by the pituitary gland, causes the remains of the follicle to develop unto corpus luteum and produce progesterone, stimulates ovulation
if implantation does not occur the ovaries stop producing oestrogen and progesterone and the lining of the uterus breaks down leaving the body as menstrual flow
if the woman in pregnant the fertilized egg implants and the ovaries continue to produce oestrogen and progesterone to maintain the lining of the uterus
after 12 weeks the placenta produces hormones that maintain the lining of the uterus
if a fertilised egg is not implanted the corpus luteum breaks down

Question 27

what does the placenta do during pregnancy

Answer 27

the placenta secretes hormones some of which inhibit FSH preventing more eggs from maturing