17. Inheritance
A section of Biology, 0610
Listing 10 of 531 questions
For Examiner's Use Sickle cell anaemia is a genetic disorder that is found among people in certain parts of the world. A sample of blood was taken from a person with sickle cell anaemia and examined with an electron microscope. shows some of the red blood cells in the sample. Explain the problems that may occur as these cells circulate in the blood system. For Examiner's Use The gene for haemoglobin exists in two alternative forms: HA codes for the normal form of haemoglobin; HS codes for the abnormal form of haemoglobin. State the name for the alternative forms of a gene. A child has sickle cell anaemia. The parents do not have this disorder. Complete the genetic diagram to show how the child inherited the disorder. Use the symbols HA and HS in your answer. parental phenotypes parental genotypes gametes child’s genotype child’s phenotype normal HAHS normal HAHS × × + sickle cell anaemia The parents are about to have another child. What is the probability that this child will have sickle cell anaemia? For Examiner's Use The maps in show the distribution of sickle cell anaemia and malaria in some parts of the world. distribution of malaria distribution of sickle cell anaemia northern Australia Indonesia and the Philippines key malaria key sickle cell anaemia For Examiner's Use Explain why sickle cell anaemia is common in people who live in areas where malaria occurs. Suggest why sickle cell anaemia is very rare among people who live in Indonesia and northern Australia.
0610_w13_qp_31
THEORY
2013
Paper 3, Variant 1
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In tulip plants, the petals can have markings called flecks. There are two alleles for flecks in tulip plants: with flecks F; and without flecks f. Explain the meaning of the term dominant allele. A tulip grower crosses two tulip plants. He finds that 76 of the offspring have petals with flecks and 23 of the offspring have petals without flecks. Complete the genetic diagram to explain this result. parental genotypes ………………… X ………………… parental phenotypes ………………… X ………………… gametes X offspring genotypes …………………………… …………………………… offspring phenotypes petals with flecks present petals without flecks The tulip grower wants to produce a pure-breeding variety of tulips with petals without flecks. State the genotypes of the parent plants he should use to produce tulip plants without flecks. Explain your answer. parental genotypes ………………… X ………………… explanation
0610_w14_qp_31
THEORY
2014
Paper 3, Variant 1
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Questions Discovered
531