7) Reproduction and Inheritance

Question 1

How many chromosomes does a human have?

Answer 1

46

Question 2

What is a gene?

Answer 2

A gene is a chemical instruction that codes for a particular protein. Genes control our inherited characteristics

Question 3

What are different versions of the same gene called?

Answer 3

Alleles

Question 4

What is DNA?

Answer 4

A DNA molecule has two strands in the shape of a double helix.

Question 5

What are the four different bases in DNA?

Answer 5

• (A) Adenine
• (C) Cytosine
• (G) Guanine
• (T) Thymine

Question 6

How are the four different bases joined up? And what is this called?

Answer 6

A=T
C=G
This is called complementary base-pairing

Question 7

What type of acid is DNA?

Answer 7

Nucleic

Question 8

What is asexual reproduction?

Answer 8

Asexual reproduction involves only one parent. The offspring have identical genes to the parent - so there’s no variation between parent and offspring

Question 9

What is mitosis?

Answer 9

Mitosis is when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes

Question 10

Apart from asexual reproduction, how else is mitosis useful?

Answer 10

Its how all plants and animals grow and repair dead tissue

Question 11

What is sexual reproduction?

Answer 11

It involves the fusion of male and female gametes, because there are two parents contain a mixture of their parents’ genes

Question 12

What is meiosis?

Answer 12

Meiosis produces four haploid cells whose chromosomes are not identical

Question 13

What is the male and female reproduction part of the flower?

Answer 13

Male part= The stamen

Female part= The carpel

Question 14

What does the stamen consist of and what do they do?

Answer 14

The anther= contains pollen grains

The filament= stalk that supports the anther

Question 15

What does the carpel contain and what do they do?

Answer 15

Stigma= the pollen grains attach to it
Style= the rod-like section that supports the stigma
Ovary= Contains the female gametes (eggs)

Question 16

What is pollination?

Answer 16

Is the transfer of pollen from anther to a stigma, so that the males gametes in sexual reproduction

Question 17

What is cross-pollination?

Answer 17

Cross pollination is a type of sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another

Question 18

What do plants that cross-pollinate rely on?

Answer 18

Things like insects or the wind

Question 19

What are the four things that plants can do to adapt for insect pollination?

Answer 19

1) Have brightly coloured petals to attract insects
2) Have scented flowers
3) They make big, sticky pollen grains, they stick to insects as they go from plant to plant
4) The stigma is also sticky so that any pollen picked up by insects on other plants will stick to the stigma

Question 20

Name five things that plants can do to adapt for wind pollination?

Answer 20

1) Small dull petals on flower
2) No strong scents
3) A lot of pollen grains (small and light)
4) Long filaments that hang the anthers outside the plant
5) A large feathery stigma to catch pollen

Question 21

What is fertilisation?

Answer 21

It is the fusion of gametes

Question 22

What is sperm?

Answer 22

Sperm are male gametes, they are made in the testes, all the time after puberty

Question 23

What is the urethra in a male?

Answer 23

A tube which carries sperm through ejaculation. Urine also passes through to exit the body

Question 24

What are the glands for in a male?

Answer 24

Produce the liquid that’s added to sperm to make semen.

Question 25

What is the erectile tissue?

Answer 25

Swells when filled with blood to make the penis erect

Question 26

What are the vas deferens (sperm duct)?

Answer 26

Muscular tube that carries sperm from the testis towards the urethra

Question 27

What are the testis for?

Answer 27

Where the sperm are made

Question 28

What is the scrotum for?

Answer 28

Hangs behind the penis and contains the testes

Question 29

What is the fallopian tube?

Answer 29

A muscular tube that carries the ovum from the ovary to the uterus

Question 30

What is the uterus (womb) ?

Answer 30

The organ where an embryo grows

Question 31

What is the ovary?

Answer 31

The organ that produces ova and sex hormones

Question 32

What is the endometrium (lining of the uterus) ?

Answer 32

Has a good blood supply for implantation of an emybro

Question 33

What is the cervix?

Answer 33

The neck of the uterus

Question 34

What is the vagina?

Answer 34

Where the sperm are deposited

Question 35

Explain the cycle of an egg

Answer 35

1) An ovum (egg) is produced every 28 days 2) It then passes into the fallopian tube 3) If it isn't fertilised by sperm the ovum will break up and pass out of the vagina

Question 36

What is the hormone that causes puberty in females?

Answer 36

Oestrogen

Question 37

What is the hormone that causes puberty in males?

Answer 37

Testosterone

Question 38

What happens to a female when she begins puberty?

Answer 38

- Extra hair on underarms and pubic hair - Hips widen - Development of breasts - Ovum release and start of periods

Question 39

What happens to a male when he begins puberty?

Answer 39

- Extra hair on face and body - Muscles to develop - Penis and testicles to enlarge - Sperm production - Deepening of voice

Question 40

Explain the four stages of the menstrual cycle

Answer 40

Stage 1= Day 1 when bleeding starts. The uterus lining breaks down for about four days Stage 2= The uterus lining builds up again from day 4 to day 14, into a thick layer of blood vessels, ready to receive a fertilised ovum Stage 3= An ovum develops and its released from the ovary at day 14 Stage 4= The wall is maintained till day 28, if no fertilised egg has been received then the whole cycle starts again

Question 41

What are the main effects of oestrogen?

Answer 41

- Causes the lining of the uterus to thicken and grow | - Stimulates the release of an ovum at day 14

Question 42

What is the main effect of progesterone?

Answer 42

Maintains the lining of the uterus. When the level of progesterone falls, the lining breaks down

Question 43

What is the main job of the placenta?

Answer 43

Once the embryo has implanted the placenta develops - this lets the blood of the embryo and the mother get very close to allow the exchange of food, oxygen and waste

Question 44

What is the theory of evolution?

Answer 44

Life began as simple organisms from which more complex organisms evolved

Question 45

What are mutations?

Answer 45

Mutations are changes to the genetic code. They are usually harmful