EXTRA

Question 0

Explain what a ‘diploid cell’ is

Answer 0

A diploid cell has two pairs of each chromosome

Question 1

Where in the cell are chromosomes found?

Answer 1

The nucleus

Question 2

What is the diploid number for humans?

Answer 2

46 (23 pairs)

Question 3

Describe the structure of DNA

Answer 3

DNA has two strands that are coiled together in a double helix.

The two strands are linked by paired bases. The 4 bases are:

• adenine
• cytosine
• guanine
• thymine

The bases always pair up in the same way (adenine + thymine // cytosine + guanine)

Question 4

Explain the relationship between genes and the characteristics of an organism

Answer 4

Each gene codes for a specific protein, and proteins determine inherited characteristics

Question 5

What is an allele?

Answer 5

Alleles are different different versions of the same gene, that give different versions of a characteristic. (E.g. One cat can have short fur, and the other can have long fur - from the same litter)

Question 6

Describe what happens during pollination

Answer 6

Pollen grains from an anther are transferred to a stigma, so that male gametes can fertilise female gametes.

Question 7

Define the term ‘self-pollination’

Answer 7

It is sexual reproduction involving the transfer of pollen from an anther to a stigma on the same plant.

Question 8

Describe the process of fertilisation in plants

Answer 8

A pollen grain from one plant lands on the stigma of another plant. A pollen tube grows out of the pollen grain, down through the style to the ovary and into the ovule. A nucleus from the male gamete travels to the ovule to fertilise the female gamete, producing a zygote that divides to form an embryo. The fertilised female gamete forms a seed, while the ovary develops into a fruit.

Question 9

Name the female sex hormone

Answer 9

Oestrogen

Question 10

What is the function of the ovaries?

Answer 10

Producing ova (eggs) / sex hormones

Question 11

What is the function of the Fallopian tube?

Answer 11

To carry the ovum (egg) from the ovary to the uterus

Question 12

What is the function of the uterus?

Answer 12

To contain the growing embryo.

Question 13

Describe the role of the placenta

Answer 13

To allow food, oxygen and waste substances to be exchanged between mother and fetus

Question 14

Describe the role of the amniotic fluid

Answer 14

To protect the fetus against knocks/bumps

Question 15

Are birthmarks caused by genes?

Answer 15

No

Question 16

What is meant by the term ‘mutation’?

Answer 16

A rare, random change in an organism’s DNA that can be inherited

Question 17

Suggest how mutations may be beneficial

Answer 17

A mutation could cause a gene to produce a different protein that is an improvement on the one it usually produces, which gives an organism a survival advantage.

Question 18

Explain how carbon is released from dead organisms in the soil

Answer 18

Microorganisms decompose material from dead organisms and return carbon to the air as carbon dioxide through respiration.

Question 19

Explain why fossil fuels contain carbon

Answer 19

Fossil fuels are formed from dead animals/plants (which contain carbon)

Question 20

Explain why carbon monoxide is considered to be a pollutant

Answer 20

Carbon monoxide is taken in by red blood cells and prevents them from carrying oxygen, so is poisonous to humans/animals

Question 21

What is the role of restriction enzymes?

Answer 21

Restriction enzymes effectively cut through DNA strands so that a section of DNA can be taken from a cell.

Question 22

What can be used to join together different sections of DNA?

Answer 22

Ligase enzymes can be used to join together different sections of DNA.

Question 23

When does Mitosis cell division occur?

Answer 23

Mitosis cell division is the type that occurs in growth, repair cloning and asexual reproduction.