17.4. Monohybrid inheritance
A subsection of Biology, 0610, through 17. Inheritance
Listing 10 of 294 questions
For Examiner's Use A healthy kidney controls the excretion of urea and other waste products of metabolism from the blood. After kidney failure there are two possible treatments: dialysis or a kidney transplant. shows how blood and dialysis fluid move through a dialysis machine. bubble trap pump patient’s arm blood flow dialysis fluid blood A B Describe the changes that occur to the blood as it flows through the dialysis machine from A to B. For Examiner's Use Discuss the advantages of kidney transplants compared with dialysis. For Examiner's Use Two brothers have to make a difficult decision. One brother, with blood group AB, has kidney failure and is on dialysis. The healthy brother has agreed to donate one of his kidneys to his brother. He has to have a blood test. Their father has blood group A and their mother has blood group B. The brothers have a sister who has blood group O. Explain how this girl has blood group O when her parents have different blood groups. You must use the space below for a genetic diagram to help your answer. Use the symbols IA, IB and IO to represent the alleles involved in the inheritance of blood groups. parental phenotypes parental genotypes gametes girl’s genotype girl’s phenotype blood group A × × + blood group B The healthy brother can only donate the kidney to his brother if they both have the same blood group. What is the probability that the healthy brother also has blood group AB?
0610_s11_qp_31
THEORY
2011
Paper 3, Variant 1
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For Examiner's Use is an electron micrograph of some red blood cells and lymphocytes. Lymphocytes respond to infection by making and releasing special protein molecules called antibodies. Describe how antibodies provide protection from diseases caused by viruses and bacteria. For Examiner's Use Red blood cells have special molecules on their cell membranes. These are known as antigens and they stimulate the production of antibodies. These antigens also determine a person’s blood group. Before carrying out kidney transplants, it is important to check that the blood group of the donor matches the blood group of the recipient. This is called blood typing. It is necessary because blood group antigens are present on the inner lining of blood vessels in the kidney. Explain what would happen if a kidney from a person with blood group A was transferred into the body of a person with blood group O. Tissue typing is carried out before transplanting a kidney. This makes sure that there is a close match between the donated kidney and the recipient. However, it is possible to carry out transplants of the cornea without blood typing or tissue typing. Suggest why it is possible to transplant corneas successfully without carrying out any tissue typing or blood typing. For Examiner's Use The gene for the ABO blood group has three alleles, IA, IB and Io. A person with blood group O has parents who have blood groups A and B. Complete the genetic diagram to show how this is possible. Use the symbols, IA, IB and Io, for the blood group alleles. parental phenotypes parental genotypes gametes offspring genotype offspring phenotype blood group B blood group A × × + blood group O Use your answer to to give examples of the following. The first one has been completed for you. term example a dominant allele IA heterozygous genotype ……………………… codominant alleles ……………………… phenotype ………………………
0610_s12_qp_31
THEORY
2012
Paper 3, Variant 1
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For Examiner's Use Cystic fibrosis is an inherited disorder. People with this disorder produce mucus that is very thick and sticky. This mucus can block many passages in the body including the bronchi and bronchioles. Suggest why people with cystic fibrosis often have lung infections. Cystic fibrosis is controlled by a recessive allele. What is meant by the term recessive allele? Use F to represent the allele for normal mucus and f to represent the allele for very thick mucus, that causes cystic fibrosis. State the genotypes of a person with cystic fibrosis. Two parents with normal mucus have a child with cystic fibrosis. State the genotype of the parents. For Examiner's Use These parents have another child. Complete the genetic diagram to show the possibility that this child will also have cystic fibrosis. parental phenotypes parental genotypes gametes offspring genotypes offspring phenotypes possibility of a child having cystic fibrosis normal mucus normal mucus × × +
0610_s13_qp_22
THEORY
2013
Paper 2, Variant 2
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Name the type of cell division that forms gametes (sperm cells and egg cells). State the difference between the number of chromosomes in gametes and the number of chromosomes in other body cells. The sex of a human is determined by the sex chromosomes, X and Y. State which sex chromosomes are present in a male and in a female. male female Define the term allele. The fur colour in a species of mouse can be black or white. The allele for black fur is dominant to the allele for white fur. shows the cross between a mouse that is homozygous for black fur and a mouse that is homozygous for white fur. parental phenotype: parental genotype: black fur BB white fur bb × × × All the offspring are black and have the genotype Bb. Two of these offspring were mated together. Complete to show the results of this cross. parental phenotype: parental genotype: gametes: offspring genotype: offspring phenotype: black fur black : white × × × + + × ratio: black fur In an investigation, a mouse with black fur and a mouse with white fur were mated several times. A total of 40 offspring were produced. There were 19 offspring with black fur and 21 with white fur. Deduce the genotype of the parent that had black fur. genotype
0610_s14_qp_21
THEORY
2014
Paper 2, Variant 1
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Some students used beetles to investigate inheritance. One group of students decided to breed a beetle which had long antennae with a beetle which had short antennae. shows the beetles they used. short antennae long antennae All of the offspring from this first breeding experiment had long antennae. The students decided that the beetles they had used must have been pure-breeding for the lengths of their antennae. Explain the term pure-breeding. The students used the results of their breeding experiment to make conclusions about the alleles for long and short antennae. State what is meant by an allele. What conclusions can be made about the alleles for long and short antennae? long antennae short antennae The students decided to breed two of the offspring (with long antennae) from their first breeding experiment with each other. There were 20 offspring from this second breeding experiment. 15 of these beetles have long antennae. State the number of beetles which have short antennae. Calculate the ratio of long antennae to short antennae. shows part of the genetic diagram for the second breeding experiment. Complete . • Use A to represent the allele for long antennae. • Use a to represent the allele for short antennae. Aa gametes offspring genotype offspring phenotype parental phenotype parental genotype In another investigation, a beetle with long antennae and a beetle with short antennae were bred together several times. A total of 60 offspring were produced. There were 31 with long antennae and 29 with short antennae. Deduce the genotype of the parent that had long antennae.
0610_s14_qp_23
THEORY
2014
Paper 2, Variant 3
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Define the following genetic terms. mutation heterozygous recessive allele People use sun-cream to protect their skin. Ultra-violet light from the sun is a type of ionising radiation. shows sun-cream being applied. Suggest how using sun-cream reduces the damaging effect of the Sun’s rays. shows the hand of a person who suffers from a mutation that results in people having more than five digits on each hand . The mutation that results in this condition is dominant. shows how the condition is inherited in a family. Q R P male female Key normal affected by polydactyly State the genotype of the individuals shown in . Use AA, Aa or aa. Write your answers in Table 5.1. Table 5.1 numbered person on genotype of person Using evidence from , state which of the couples, P, Q or R, provides proof that the mutation is not recessive. couple Explain the reason for your answer.
0610_s15_qp_21
THEORY
2015
Paper 2, Variant 1
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Cystic fibrosis is an inherited disease. A person with cystic fibrosis produces mucus which is very sticky. The mucus affects the function of the cilia in the air passages. Suggest what effects this will have on the person with this condition. The sticky mucus can also block the tube from the pancreas to the small intestine. Explain why this affects the digestion of fats in a person with cystic fibrosis. Cystic fibrosis is caused by a recessive allele. State what is meant by the term allele. shows a family tree where one child has cystic fibrosis. father mother unaffected male unaffected female affected male Key Using the symbols N for the dominant allele and n for the recessive allele: state the genotypes of the parents father ………………………………… mother ………………………………… state the genotype of child 2 ………………………………… state the possible genotypes of child 1 and child 3. child 1 ………………………………… child 3 ………………………………… The parents have another child. What is the probability that the child will have cystic fibrosis?
0610_s15_qp_22
THEORY
2015
Paper 2, Variant 2
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Questions Discovered
294