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QUESTION ONE: MITOSIS AND MEIOSIS
Below is a simplified diagram of mitosis.
(a)
State where mitosis occurs in a human.
In the regular body cells
(b)
Describe the purpose of mitosis and explain why it is necessary.
The purpose of mitosis to produce genetically identical cells. This allows for your regular
body functions to proceed without any changes. Mitosis is necessary as genetically identical
cells are required to keep all body functions consistent as to not change and harm the regular
body functions.
(c)
Discuss the differences between the mitosis and the meiosis processes.
In your answer you should include:

The purpose of meiosis

An outline of the key stages that occur in both mitosis and meiosis

The number of daughter cells produced in each

Which process provides variation and how it provides this variation
Mitosis in the duplication of human body cells that are genetically identical. Meiosis is the
production of sex cells (gametes) that are genetically different from one another. Mitosis
produces 2 daughter cells and meiosis produces 4 daughter cells. In meiosis, crossing over
occurs to produced genetic variation. Random assortment also occurs in meiosis, aiding in
genetic variation. The processes of meiosis occur twice where there’s only one in mitosis.
Meiosis provides genetic variation through crossing over of alleles and random assortment of
chromosomes.
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QUESTION TWO: VARIATION
Strawberry plants can reproduce both asexually and sexually. Explain how sexual
reproduction in strawberry plants will produce variation and how this benefits the plant.
Your answer you should include:

A definition of variation

How sexual reproduction provides variation

The benefits of this type of reproduction to the strawberry plants

An example of one type of benefit the strawberry plant may gain through
sexual reproduction
Genetic variation refers to the changes in DNA between individuals of a species. Sexual
reproduction will provide genetic variation by inheritance of different combinations of genes.
Sexual reproduction is beneficial to the plants as it allows for the individuals to be genetically
unique, allowing for the species to survive a larger range of diseases and environmental
changes. For example, sexual reproduction can allow for the strawberry to produce chemicals
to fight off infections, allowing for the surviving plants to be immune to the disease and
unaffected by future infections.
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QUESTION THREE: PUNNETT SQUARES
Unlike human males, male cockatiels have 2 of the same sex genes ZZ whilst the females
have 2 different sex genes ZW. During the spring and summer months females can lay
clutches of between 2 and 8 eggs.
(a)
Discuss the likelihood of a cockatiel pair to have a clutch with two males after they
previously had a clutch with two males.
In your answer you should:

Complete a Punnett square showing sex inheritance in cockatiels

Explain whether their previous clutch will have any relevance to their current
clutch
Female
Genotype
Male
Genotype
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(b)
A male cockatiel has the recessive yellow (g) colouring and a female is
heterozygous for grey (G) colouring. Discuss the probability that they will end up
with yellow offspring in their clutch.
In your answer you should:

Define the terms dominant and recessive alleles, providing an example of each
from the information above

Explain the probability of the two birds having yellow coloured offspring

Complete a labelled Punnett square to support your answer
Male
Genotype
Female
Genotype
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QUESTION FOUR: PEDIGREE CHARTS
Some people have the dominant trait (E) of being able to move their ears whilst others are
unable to move their ears at all (the recessive trait) (e).
The pedigree chart below shows the inheritance of being able to move ears in a family.
Pedigree Chart
Generation I
Generation II
Generation III
Male Female
Ear
mover (E)
Generation IV
Non-ear
mover (e)
(a)
Explain how you could work out the genotypes of the people from generation I.
In your answer you should:

Define the terms genotype and phenotype

State the genotypes and phenotypes of the two people from generation I

Complete a labelled Punnett square to support your answer

Explain how using the pedigree chart it is possible to work out the genotypes of
these 2 people
Male
Genotype
Female
Genotype
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(b)
Explain why the offspring in generation IV could be either heterozygous or
homozygous dominant for the ear moving trait.
In your answer you should:

Define the terms homozygous and heterozygous

State the possible genotypes and phenotypes of the offspring in generation IV

Explain why the offspring could be heterozygous or homozygous dominant
You may draw a Punnett square in order to illustrate your answer.
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A genetic mutation is a random change in the genes and or chromosomes of an
organism. A mutation the occurs in the regular body cells can not be passed down to
future offspring.
Variation in leaf size of species A can occur through either mutations to the plants
genetic code, or through genetic variation arising from sexual reproduction. Reducing
the light levels the species A has access to can cause the plants with smaller leaf sizes
to die off, but the plants with larger leaf sizes can survive.
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