02 Genetic testing FT

42 Some disorders are inherited.

One of these disorders is Huntington’s disease.

(a) Complete the sentences to show how Huntington’s disease is inherited.

Put a ring around the correct word to complete each sentence.

Huntington’s disease is caused by a change in one / two / multiple gene(s).

Only one faulty allele is required to cause the disease, because the allele is dominant /

recessive / powerful / weak. [2]

(b) Cystic fibrosis is another inherited condition.

Explain how the inheritance of cystic fibrosis is different from the inheritance of Huntington’sdisease.

.............................................................................................................................................. [2]

(c) Genetic testing can be used for screening adults, children and embryos.

Describe uses of genetic testing and the implications of these tests for these people.

The quality of written communication will be assessed in your answer.

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5(d) Genetic testing is viewed differently by different people.

Write down one argument for and one argument against genetic testing.

.............................................................................................................................................. [2]

[Total: 12]

© B1B2B3 Jan OCR 2012 Turn over

2Answer all the questions.

1 Body cells and sex cells have similarities and differences.

(a) Put ticks (✓) in the boxes next to the three correct statements.

A sex cell usually has two alleles of each gene.

Body cells contain pairs of chromosomes.

Sex cells contain alleles that can be dominant or recessive.

Body cells contain half the normal number of chromosomes.

A sex cell usually contains one allele of each gene.

Body cells in males have only Y sex chromosomes.

Sex cells in humans always have both X and Y chromosomes.[3]

(b) Body cells and sex cells both contain chromosomes.

Put ticks (✓) in the boxes next to the three correct statements.

Chromosomes are made from very long DNA molecules.

A person only has one allele for each gene.

Genes are sections of DNA molecules.

Genes are instructions for making fats and carbohydrates.

All DNA is found in the cytoplasm of cells.

All our characteristics are determined by genes.

Genes with a recessive allele always express that allele.

Many characteristics are produced by several different genes working together.

[3]

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3(c) Two parents each have a dominant allele (A) and a recessive allele (a) for the same gene.

Draw a genetic diagram to show how these alleles can be passed on to their children.

Explain your genetic diagram.

The quality of written communication will be assessed in your answer.

.............................................................................................................................................. [6]

B1B2B3 June 2012 OCR Turn over

4(d) Scientists are learning more about our genes.

This information can be used in many different ways.

Sheila, a student, gives a talk to her class about the use of this genetic information.

Knowledge of genetics will enable us to predictwhich diseases we will get and when we will getthem. This will allow doctors to produce medicinesthat will make all disease a thing of the past.

(i) Identify one mistake in Sheila’s talk.

Explain your answer.

...................................................................................................................................... [2]

(ii) Sheila continues her talk.

My father runs a business. By knowing all aboutthe DNA of people who apply for a job, he wouldbe able to select who to employ. He would knowwho would get ill and cost the company sick pay.I think making all the information about our DNAavailable to everyone can only be a good thing.

Do you agree with Sheila about making our DNA information available to everyone?

Explain your answer.

...................................................................................................................................... [2]

[Total: 16]

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42 Ali and Mary do not have cystic fibrosis, but their baby does.

(a) What does this tell us about Ali and Mary’s genes for this disorder?

.............................................................................................................................................. [1]

(b) Ali and Mary consider whether or not to have another child.These are some of the questions that they could consider before making their decision.

A How much will it cost to have another child with cystic fibrosis?

B What is the chance of another child of ours having cystic fibrosis?

C If we find that the foetus has cystic fibrosis should we have a termination?

D Do we want to have a boy or a girl?

E What will other people think?

F Should we discuss this with the grandparents?

(i) Which question, A, B, C, D, E or F, is an ethical issue?

question = [1]

(ii) Which question, A, B, C, D, E or F, can be answered by science?

question = [1]

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5(c) Another couple, Rajesh and Sangeeta, are thinking of having a baby.

They talk to a genetic counsellor.They are told that because of Sangeeta’s age they have a 1% chance of having a child withDown’s syndrome.This would mean that the child could have some physical and mental issues.

Look at the graph.

5

4%

chanceof having

a child withDown’s syndrome

(i) What is Sangeeta’s age?

3

2

1

020 25 30 35 40 45 50

age of mother in years

............................................................ years [1]

(ii) Describe the trend shown by the graph.

...................................................................................................................................... [2]

(iii) It is possible to increase confidence in the trend shown by the graph.Put ticks (✓) in the boxes next to the two best methods.

ask patients how they feel

use a larger sample size

collect data for other genetic conditions

collect data for other ages

use smaller graph paper

collect data from just one hospital

[2]

Turn overB1B2B3 June 2013 OCR

6(iv) Explain how the information supplied by the graph and the genetic counsellor could affect

any decision taken by Rajesh and Sangeeta about whether or not to have a baby.

...................................................................................................................................... [2]

(d) Rajesh and Sangeeta decide to have a baby.They decide that if Sangeeta becomes pregnant, the foetus will be tested for genetic disorders.

Describe the implications that need to be considered of having the foetus tested.

The quality of written communication will be assessed in your answer.

.............................................................................................................................................. [6]

[Total: 16]

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