Paper 1 - Inheritance

Question 1

What is the genome?

Answer 1

The entire DNA of an organism

Question 2

What is a gene?

Answer 2

A section of a molecule of DNA that codes for a specific protein

Question 3

What does the nucleus of a cell contain?

Answer 3

Chromosomes on which genes are
located

Question 4

In what alternative form do genes exist?

Answer 4

• As alleles
• Which give rise to differences in inherited characteristics

Question 5

What does dominant mean?

Answer 5

An allele that is always expressed even if there is only 1 of them (use a capital letter)

Question 6

What does recessive mean?

Answer 6

An allele that is only expressed when there are 2 of them

Question 7

What does homozygous mean?

Answer 7

Having either 2 dominant or 2 recessive alleles

Question 8

What does heterozygous mean?

Answer 8

Having 1 dominant and 1 recessive allele

Question 9

What does phenotype mean?

Answer 9

What you can visibly see expressed

Question 10

What does genotype mean?

Answer 10

All the alleles that make up an organism

Question 11

What are most phenotypic features a result of?

Answer 11

Polygenic inheritance rather than single genes

Question 12

How is the sex of offspring controlled by one pair of chromosomes?

Answer 12

• XX for female
• XY for male

Question 13

What does the division of a diploid cell by mitosis produce?

Answer 13

Two cells that contain identical sets of 46 chromosomes

Question 14

When does mitosis occur?

Answer 14

During :
- Growth
- Repair
- Cloning
- Asexual reproduction

Question 15

What does the division of a cell by meiosis produce?

Answer 15

4 daploid daughter cells, each with 23 chromosomes

Question 16

What does the division of a cell by meiosis result in?

Answer 16

The formation of genetically different
haploid gametes

Question 17

How does random fertilisation produce genetic variation in offspring?

Answer 17

• Random variation
• Different combinations of sperm and egg produce different zygotes
• Different zygotes create different phenotypes

Question 18

How many chromosomes does a gamete have?

Answer 18

23

Question 19

How many chromosomes does a haploid cell have?

Answer 19

23

Question 20

How many chromosomes does a diploid cell have?

Answer 20

46

Question 21

What causes variation within a species?

Answer 21

• Genetics
• Environment
• Or a combination of both

Question 22

What is mutation?

Answer 22

Mutation is a rare, random change in genetic material that can be inherited

Question 23

Explain Darwin’s theory of evolution by natural selection

Answer 23

• Variation in organisms is caused by mutation
• Selection pressure is put on organisms
• Food sources were different on each other Galapagos Island’s
• Depending on the food source type on the island, a certain characteristic would have been more advantageous because it gives the organism an advantage.
• These individuals are more likely to survive and reproduce
• Advantageous alleles are passed on to offspring

Question 24

How can resistance to antibiotics cause an increase in bacterial populations?

Answer 24

• Random mutation gives a bacteria immunity to an antibiotic so that bacteria survives and reproduces
• Passes on advantageous alleles to offspring so offspring are immune as well
• Non-immune bacteria die and then all bacteria are immune to antibiotics so bacterial population increases

Question 25

What can an increase in bacterial immunity to antibiotics cause?

Answer 25

It can lead to infections being difficult to control