1. Genetics and Inheritance

Question 1

In humans what is the name of the female sex cell?

Answer 1

Egg cells

Question 2

In humans what is the name of the male sex cell?

Answer 2

Sperm cell

Question 3

When an egg cell and sperm cell fuse, this is called….

Answer 3

Fertilisation

Question 4

In a normal human body cell (e.g. skin cell) how many chromosomes are in the nucleus?

Answer 4

46 chromosomes

Question 5

How is DNA arranged in the nuclei of cells?

Answer 5

Into strands called chromosomes

Question 6

What is a gene?

Answer 6

A gene is a section of a chromosome that codes for a particular characteristic.

Question 7

How many forms of each gene do we inherit?

Answer 7

We inherit 2 forms of each gene. These are called alleles.

Question 8

What is the function of the cell membrane?

Answer 8

The cell membrane controls what enters and leaves the cell

Question 9

What is the function of the nucleus of a cell?

Answer 9

The nucleus contains the DNA (chromosomes)

Question 10

What do the letters DNA stand for?

Answer 10

Deoxyribonucleic acid (=DNA)

Question 11

What is an allele?

Answer 11

An allele is a different form of a gene. For example:

Gene is eye colour, the alleles could be brown, blue, green, etc.

Question 12

In terms of genetics what does the word homozygous alleles mean?

Answer 12

If an individual has 2 identical alleles (e.g. BB, tt) for a characteristic (e.g. two blue eyes alleles) they are said to be homozygous for this characteristic.

Question 13

In terms of genetics what does the word heterozygous alleles mean?

Answer 13

If an individual has 2 different alleles (e.g. Bb, Tt) for a characteristic (e.g. a blue allele and a brown allele) they are said to be heterozygous for this characteristic.

Question 14

What sex chromosomes has a male inherited?

Answer 14

XY

Question 15

What sex chromosomes has a female inherited?

Answer 15

XX

Question 16

In a human sex cell (e.g. sperm cell or egg cell) how many chromosomes are in the nucleus?

Answer 16

23 chromosomes

Question 17

Our phenotype (physical expression of our alleles) is due to 2 types of variation. What are these type of variation?

Answer 17

Genetic variation and environmental variation.

Question 18

Neil fell over when he was young and now has a scar on his arm. What type of variation is this?

Answer 18

Environmental variation

Question 19

Sajid’s blood group is AB. Was this genetically or environmentally inherited?

Answer 19

Genetically inherited

Question 20

What is a genetic disorder?

Answer 20

A genetic disorder is a disease caused by a faulty gene or chromosome.

Question 21

What is a recessive genetic disorder?

Answer 21

This is a genetic disorder where the individual has inherited 2 faulty alleles, one from Mum and one from Dad.

Question 22

What is a dominant genetic disorder

Answer 22

This is a genetic disorder where the individual has inherited one ONE faulty alleles. Either from Mum or Dad.

Question 23

What are the stages of selective breeding?

Answer 23

1. Choose two parents with the desired characteristic
2. Breed them together
3. Choose offspring that show the desired characteristic and breed them.
4. Repeat over many generations.

Question 24

What is selective breeding?

Answer 24

Selective breedingis when humans choose parents to breed together.
These parents have particular desirable characteristics toand are likely to produce offspring with the same desirable characteristics.

Question 25

Give two advantages of breeding crops or animals by selective breeding.

Answer 25

• Increased milk/meat yield from cattle (which may increase profits for farmers).
• Disease resistance in food crops or garden plants e.g. soya beans.
• Can produce domesticated animals with a gentle nature e.g. labradoodle.
• Decorative plants (e.g. with large or unusual/coloured flowers).
• New varieties of crops can be produced.

Question 26

Give two disadvantages of selective breeding.

Answer 26

• Selective breeding can lead to ‘inbreeding’.
• Because of the smaller genetic pool selective bred organisms are more likely to pass on harmful recessive alleles.
• There they are more likely to be susceptible to diseases.

Question 27

What does GMO stand for?

Answer 27

Genetically modified organism.

Question 28

What does the process of genetic engineering involve

Answer 28

It involves changing the genes of an organism

by introducing a gene from another organism to give a desired characteristic.

Question 29

What are the stages in genetic engineering?

Answer 29

1) Select the desired characteristic (e.g. insulin gene)
2) Isolate the gene responsible for the characteristic (using enzymes)
3) Insert this gene into another organism (e.g. a bacterium)
4) Replication of theorganism.

Question 30

Give 2 advantages of genetic engineering.

Answer 30

• Improving crop yield.
• Improving resistance to pesticides.
• Extend shelf-life of fruits/veg e.g. tomatoes.
• Manufacture a certain chemical (e.g. Insulin).

Question 31

Give 2 disadvantages of genetic engineering.

Answer 31

• Inserted genes may have unwanted side effects.
• Possible harm when GM crops are eaten by humans/other animals.
• Damage to food chains.
• GM animals/crops may breed with wild animals/plants thereby reducing biodiversity.

Question 32

What is cloning?

Answer 32

Cloning is making a genetically identical copy of an individual.

Question 33

What are the 2 types of clones that can be produced?

Answer 33

Natural cloning and artificial cloning.

Question 34

Give an example of natural cloning in animals.

Answer 34

Identical twins are natural clones of each other.

Question 35

Give 2 advantages of cloning.

Answer 35

• Can produce lots of identical offspring with desirable features.
• Study of clones could help treat/cure certain diseases.
• Could help/bring back endangered or extinct species.