17.4. Monohybrid inheritance
A subsection of Biology, 0610, through 17. Inheritance
Listing 10 of 294 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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Sickle cell anaemia is an inherited disease. The gene for haemoglobin exists in two forms, HbN and HbS. People who are HbSHbS have the disease and experience symptoms including fatigue and extreme pain in their joints. People who are HbNHbS are carriers of the disease and may have mild symptoms, if any at all. Table 2.1 shows four genetic terms. Complete Table 2.1 by stating a specific example, used in the paragraph above, of each genetic term. Table 2.1 genetic term example used in the passage an allele a heterozygous genotype a homozygous genotype phenotype Sickle cell anaemia is not found throughout the whole world. Most cases of the disease occur in sub-Saharan Africa and in parts of Asia. The distribution is similar to that for the infectious disease malaria. Explain why the distribution of sickle cell anaemia and malaria are similar. Down’s syndrome is an example of a characteristic that shows discontinuous variation. State the cause of Down’s syndrome. Explain how discontinuous variation differs from continuous variation, in its expression and cause.
0610_w14_qp_33
THEORY
2014
Paper 3, Variant 3
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The boxes on the left contain some genetic terms and the boxes on the right contain definitions of these genetic terms. Draw one straight line to join each term with its correct definition. Draw only six lines. term definition genotype having two different alleles of the same gene dominant the physical features of an organism heterozygous the genetic make-up of an organism phenotype an allele that is expressed in a heterozygote haploid a length of DNA which codes for a specific protein gene containing a single set of unpaired chromosomes Define the term mitosis. One role of mitosis is to repair damaged tissues. State two other examples of when mitosis occurs. The number of human male and female babies born is approximately equal. is an incomplete diagram to show the inheritance of the sex chromosomes in humans. Complete by filling in the sex chromosomes of the gametes and children. XX XY mother eggs father sperm parents gametes children The couple in are expecting another child. State the probability that it will be a boy. Write a letter M on to show where meiosis occurs.
0610_w15_qp_22
THEORY
2015
Paper 2, Variant 2
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Questions Discovered
294