Download Q1. The diagram shows the genetic inheritance of cystic fibrosis (CF

Q1.
The diagram shows the genetic inheritance of cystic fibrosis (CF) in a family.
Cystic fibrosis is a genetic disorder caused by the CF recessive allele.
(i) What is an allele?
Put a cross (
) in the box next to your answer.
(1)
A a change in a chromosome
B a characteristic caused by a gene
C an alternative form of a different gene
D an alternative form of the same gene
(ii) Both parents are carriers of the CF allele.
State the term used to describe an individual who is a carrier and has both a dominant and a
recessive allele.
(1)
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Q2.
The diagram shows the genetic inheritance of cystic fibrosis (CF) in a family.
Cystic fibrosis is a genetic disorder caused by the CF recessive allele.
Use words from the box to complete the following sentences.
(2)
Genes are found on structures called ............................................ .
These are found in the ........................................ of a cell.
Q3.
The diagram shows the genetic inheritance of cystic fibrosis (CF) in a family.
Cystic fibrosis is a genetic disorder caused by the CF recessive allele.
(i) Complete the Punnett square to show how cystic fibrosis is inherited if both parents are
carriers (Bb).
(2)
(ii) Give the percentage chance of a child being a carrier of CF when both parents are carriers
of CF.
(1)
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Q4.
Cystic fibrosis
About 8 000 people in the UK have the genetic condition called cystic fibrosis.
People with cystic fibrosis may take tablets daily and receive regular treatment.
(a) (i) The gene that controls cystic fibrosis is found on chromosome 7.
In which part of the cell is a chromosome found?
(1)
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(ii) Complete the sentence by putting a cross (
) in the box next to your answer.
Genes exist in alternative forms called
(1)
A alleles
B chromosomes
C daughter cells
D DNA
(iii) State two symptoms of cystic fibrosis.
(2)
1
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2
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(b) Cystic fibrosis is caused by two recessive alleles.
This table shows the genotypes of Susan and Paul.
Susan
Paul
Cc
CC
Genotype
C – normal allele
c – cystic fibrosis allele
(i) What word is used to describe Susan’s genotype (Cc)?
(1)
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The diagrams below are called pedigree charts.
These can show the inheritance of genetic disorders.
(ii) Susan and Paul have a baby.
Look at the pedigree charts above. Which chart shows Susan and Paul’s family tree?
(1)
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(iii) Explain why Susan and Paul’s baby does not have the genetic condition cystic fibrosis.
(2)
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Q5.
Sickle cell disease
Sickle cell disease is a genetic disorder caused by recessive alleles.
(a) (i) State the meaning of the word allele.
(1)
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(ii) Human characteristics are coded for by genes.
Describe where genes are found inside a human cell.
(2)
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(iii) Complete the sentence by putting a cross (
) in the box next to your answer.
Sickle cell disease causes a change in the shape of the
(1)
A lungs
B pancreas
C red blood cells
D white blood cells
(b) The diagram shows a family pedigree for the inheritance of sickle cell disease.
The recessive allele for sickle cell disease is (d) and the dominant allele is (D).
(i) Explain why David and Alexandra do not show the symptoms of sickle cell disease.
(2)
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(ii) Explain why there would be no children with sickle cell disease if one of the parents had the
genotype DD.
(2)
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