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Worksheet Biology Topic :Genetics/ inheritanceName:____________ Calss:- II-OQ1. (a) State where DNA is found and describe its importance in living organisms. .........................................................................................................................................................
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........................................................................................................................................................................... [3] (b) Describe the causes of (i) sickle cell anaemia,
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................................................................................................................................................................................ (ii) Down’s syndrome.
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(c) Explain, with the use of a genetic diagram, how a child may be born with a blood group different from that of either parent.
[4] [Total: 10]Q2. (a) Define the term mitosis.
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............................................................................................................................................................................ [2](b) Describe the role of mitosis in organisms.
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(c) Explain how the cells of offspring have the same number of chromosomes as the cells of
their parents.
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Q3. (a) (i) Name a hormone that is commonly produced using genetic engineering.
........................................................................................................................................................................... [1] (ii) Name the organ that produces this hormone in the human body, and state two functions of the hormone in the body.
organ .................................................functions of the hormone
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Fig. 3.1 shows how genetic engineering can be used to manufacture an enzyme (chymosin) that clots milk in the stomachs of young mammals.
Fig 3.1
(b) (i) Name the thread-like structure of which the DNA strand is a part.
....................................................................................................................................................................... [1] (ii) Name the part of the strand labelled A in Fig. 3.1.
...................................................................................................................................................................... [1](c) Suggest (i) how the yeast could be cultured during stage B, .........................................................................................................................................................
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.......................................................................................................................................................................... [3] (ii) the identity of the waste products that may be formed during this process.
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Q4. Fig. 4.1 shows the blood groups of the members of two families.
Fig. 4.1
The alleles responsible for blood groups are IA.IB and Io
(a) State the term used to describe the relationship between alleles IA and IB
......................................................................... [1] (b) Identify, by number, which one of the children had been adopted by their family and could not be the genetic offspring of the parents. Explain your answer. child number ................................
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(c) When children 4 and 5 grow up, they have a child of their own, child 8, as shown in Fig. 4.1. Using a genetic diagram, explain the possible genotypes and phenotypes of child 8.
[4] [Total: 7]Q5. (a) Explain why there are approximately equal numbers of babies born of each sex.
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.........................................................................................................................................................................[3] (b) With the aid of a genetic diagram, describe the possible genotypes and phenotypes of the
offspring of two parents who both have codominant alleles for a named character.
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Q6. (a) (i) Name the structures within the nucleus that are responsible for inheritance.
............................................................................................................................................................................[1] (ii) Name the chemical in these structures that makes inheritance possible.
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A fly was homozygous dominant for each of two different characters. It was crossed with a fly showing the recessive phenotypes for both characters. Two of the offspring were then crossed. The result of this cross is shown in Fig. 6.1.
Fig. 6.1
(b) State the two pairs of contrasting characters shown by these flies.
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2. .........................................................................................................................................................................[2] (c) (i) State the recessive phenotype of one of the pairs of characters you have identified in (b). Give a reason for your answer.
recessive phenotype ..............................................
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(ii) Draw fully-labelled genetic diagrams to show the possible outcomes of crossing a fly showing the recessive phenotype, that you have identified in c(i), with one showing the dominant phenotype.
[6] [Total: 12]Q7. Fig. 7.1 shows the chromosomes present in the nucleus of a human cell.
Fig. 7.1 (a) Name the chemical contained within a chromosome that is responsible for inheritance.
............................................................................................................................................................................[1] (b) (i) Name the type of cell division that occurs only in the sex organs to produce gametes.
............................................................................................................................................................................[1] (ii) State how many chromosomes would be present in a gamete from this person.
........................................ [1]Fig. 7.2 shows the chromosomes present in the nucleus of a cell from a different person.
Fig. 7.2 (c) State the sex of this person and explain your answer.
sex ...........................................
explanation .......................................................................................................................................................[2] (d) Suggest a condition which the person whose chromosomes are shown in Fig. 7.2 has and
explain your answer.
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...........................................................................................................................................................................[3] (e) Suggest why offspring that are produced by crossing two different species are usually
infertile.
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............................................................................................................................................................................[2] [Total: 10]Q8.Cystic fibrosis is a genetic condition in humans that results from a failure to inherit a particulardominant allele of a gene. (a) State where genes are found in a cell........................................... [1] (b) (i) Use a fully labelled genetic diagram to show how cystic fibrosis is inherited by the children of two heterozygous parents. Use the letter D to represent the dominant allele and d to represent the recessive allele.
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(ii) State the expected ratio of phenotypes in the children.
........................................................................................................................................................................... [1] Fig. 8.1 shows some of the main regions of the alimentary canal in a person.
Fig. 8.1
(c) State the name of region C.
.......................................... [1] (d) One effect of cystic fibrosis is that the bile and pancreatic duct becomes blocked with
mucus. Suggest why a person whose bile and pancreatic duct is blocked may find it difficult to
gain weight despite eating a balanced diet.
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......................................................................................................................................................................... . [4] [Total: 10]Q9. (a) Explain the differences between mitosis and meiosis. Your explanation should include references to where the processes occur and why they occur.
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.......................................................................................................................................................................... [5].(b) Explain how it is possible that parents with different blood groups are able to produce only children with blood groups different from themselves.
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Q10. Species D lives in a forest. Fig. 10.1 shows what can happen, over the same period of time, if some members of species D migrate from the forest to a desert region.
Fig. 10.1 (a) Name the two main causes of variation in organisms.
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2. ................................................................ [2] (b) Name the process involving variation and natural selection that has led to the development
of species E.
.................................................................... [1](c) Suggest how the processes of variation and natural selection may have acted to produce the
new species E in the desert.
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........................................................................................................................................................................... [4](d) Members of species D are no longer able to breed successfully with members of new
species E. Suggest reasons for this.
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........................................................................................................................................................................... [2] [Total: 9]Q11. (a) Define the term gene. .........................................................................................................................................................
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(b) A gene mutation occurs when part of the DNA on a single chromosome is changed. State
two factors that may increase the rate of gene mutation.
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2. ............................................................................................................................................................................. [2](c) Sickle cell anaemia is caused by a gene mutation. Fig. 11.1 shows red blood cells from a healthy person and from a person with sickle cell anaemia.
Fig. 11.1 Fig. 11.2 shows the flow of red blood cells through a blood vessel in a healthy person and in a person with sickle cell anaemia.
Fig 11.2 Use information from Fig. 11.1 and Fig. 11.2 to suggest why the transport of oxygen to tissues
is reduced in a person with sickle cell anaemia.
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