Sex determination

Figure 9 shows a human egg cell viewed using a light microscope.

In Figure 9, the diameter of the image of the egg is 38 mm.

The magnification of Figure 9 is × 400

Calculate the real diameter of the egg cell in micrometres.

Use the equation:

1 millimetre = 1000 micrometres

Real diameter of egg cell = _____________________ micrometres

Draw a simple diagram of the egg cell shown in Figure 9.

On your drawing:

$l~bel two parts of the egg cell that are visible in Figure 9

$do not include other cells.

Some parts of a human egg cell are not visible in Figure 9.

Name one part of a human egg cell that is only visible using an electron microscope.

Name the process of cell division that produces egg cells.

How many chromosomes are in a human egg cell?

Describe how a chromosome in a sperm cell determines whether the offspring that forms is male or female.

Which hormone stimulates the release of an egg?

Tick () one box.

FSH

LH

Oestrogen

Oral contraceptive pills contain hormones that prevent the release of an egg.

Scientists studied the effectiveness of different types of contraception with perfect use and with use in real life.

‘Perfect use’ means following all the instructions.

‘Use in real life’ is what actually happens in the population. The instructions may not always be followed in real life.

Figure 10 shows the results.

Evaluate the effectiveness of the three types of contraception shown in Figure 10.

Use data from Figure 10.

Figure 1 shows a human egg cell viewed using a light microscope.

In Figure 1, the diameter of the image of the egg is 38 mm.

The magnification of Figure 1 is × 400

Calculate the real diameter of the egg cell in micrometres.

Use the equation:

1 millimetre = 1000 micrometres

Real diameter of egg cell = _____________________ micrometres

Draw a simple diagram of the egg cell shown in Figure 1.

On your drawing:

$l~bel two parts of the egg cell that are visible in Figure 1

$do not include other cells.

Some parts of a human egg cell are not visible in Figure 1.

Name one part of a human egg cell that is only visible using an electron microscope.

Name the process of cell division that produces egg cells.

How many chromosomes are in a human egg cell?

Describe how a chromosome in a sperm cell determines whether the offspring that forms is male or female.

Which hormone stimulates the release of an egg?

Tick () one box.

FSH

LH

Oestrogen

Oral contraceptive pills contain hormones that prevent the release of an egg.

Scientists studied the effectiveness of different types of contraception with perfect use and with use in real life.

‘Perfect use’ means following all the instructions.

‘Use in real life’ is what actually happens in the population. The instructions may not always be followed in real life.

Figure 2 shows the results.

Evaluate the effectiveness of the three types of contraception shown in Figure 2.

Use data from Figure 2.

This question is about genetics.

Draw one line from each term to the meaning of the term.

The inheritance of sex in humans is controlled by two chromosomes, X and Y.

Complete Figure 8 to show how sex is inherited.

In 2018 a scientist claimed to have genetically modified two human embryos.

Why is genetic modification of human embryos illegal in most countries?

Tick (✓) one box.

Genetic modification technology is too expensive.

Specialist equipment is needed for genetic modification.

The side effects of genetic modification are not known.

The scientist claimed the genetic modification was made to embryos immediately after fertilisation.

Why is genetic modification of embryos more of a concern than genetic modification of body tissues in an adult?

Tick (✓) one box.

Genetically modified body tissues are much larger than an embryo.

The genetic modification of an embryo would not affect all the body tissues.

The modified gene in an embryo could be passed on to future offspring.

The scientist claimed that the embryos were genetically modified to be resistant to HIV infection.

Why do some scientists think this use of genetic modification is not necessary?

Tick (✓) one box.

HIV infection can be treated with antiretroviral drugs.

Only adults are at risk of HIV infection.

Oral contraceptives reduce the risk of HIV infection.

This question is about genetics.

Explain why different genes are made from different lengths of DNA.

Describe why the human population produces approximately 50% female and 50% male babies.

In 2018, a scientist claimed to have genetically modified two human embryos.

Suggest why genetic modification of human embryos is illegal in most countries.

The scientist claimed that the embryos were genetically modified to have a faulty CCR5 gene.

The CCR5 gene codes for a protein that allows HIV to enter cells.

The genetic modification may have caused the embryos to be protected against AIDS.

Suggest how the embryos were genetically modified to make the CCR5 gene faulty.

Suggest what type of cell has the CCR5 protein in its cell membrane.

What type of drug is used to treat HIV?

Figure 8 shows a human sperm cell.

Cell part A contains DNA.

Name part A.

Describe the structure of DNA.

Sperm cells are male gametes.

What are female gametes called?

Figure 9 shows the chromosomes in a sperm cell.

Describe one difference between the chromosomes in a sperm cell and the chromosomes in a liver cell.

A sperm with the same chromosomes as those in Figure 9 fertilises a female gamete.

Explain what sex the offspring would be.

Use information from Figure 9 in your answer.

This question is about genetics.

Figure 3 shows the chromosomes of a man.

What evidence is there that the person is male?

Use Figure 3.

A combination of genes and the environment affect how tall a person is.

Give one other human characteristic that is affected by genes and the environment.

Do not refer to height in your answer.

Cystic fibrosis is an inherited disorder that affects the lungs.

Suggest one symptom caused by damaged lungs.

The allele for having cystic fibrosis is recessive, r.

The allele for not having cystic fibrosis is dominant, R.

What is the genotype of a person with cystic fibrosis?

Tick (✓) one box.

RR Rr rr

A man has the genotype RR.

Which word describes the genotype RR ?

Tick (✓) one box.

Characteristic

Homozygous

Phenotype

A woman has a child with a man.

Complete Figure 4 to show the possible genotypes of the child.

Figure 4

What is the chance of the child having cystic fibrosis?

Tick (✓) one box.

0% 25% 50% 75%

Drugs are being developed to treat cystic fibrosis in humans.

The drugs are tested before being used to treat patients.

Give two reasons why drugs are tested.

The drugs are tested on sheep that have been genetically modified (GM) to develop the symptoms of cystic fibrosis.

Give one ethical argument against the production of sheep with the symptoms of cystic fibrosis.

Do not refer to religion in your answer.

This question is about inheritance.

Complete Figure 8 to show why the probability of a child being a male is 0.5

Figure 8

Cystic fibrosis is an inherited disorder.

The allele for cystic fibrosis is recessive, r.

The dominant allele is R.

A man and a woman plan to have a child.

The man and the woman are both heterozygous for cystic fibrosis.

Determine the probability that the child will be a male with cystic fibrosis.

You should:

draw a Punnett square diagram identify which of the offspring genotypes will have cystic fibrosis.

Some sheep have been genetically modified to develop the symptoms of cystic fibrosis.

Give one ethical argument for the production of sheep with the symptoms of cystic fibrosis.

Do not refer to religion in your answer.

Give one ethical argument against the production of sheep with the symptoms of cystic fibrosis.

Do not refer to religion in your answer.

The sheep were genetically modified as embryos.

Describe the stages involved in producing a genetically modified sheep that shows symptoms of cystic fibrosis.