HOMEWORK 1

1. (a) Complete the table below to show how many sets of chromosomes would be found in each cell in the human body.

Cell Number of sets of chromosomesSkin cellLiver cellEgg cell

(3)

(b) What term is used to describe a cell that has a double set of chromosomes? ________________________ (1) (c) Sex cells are described as being ‘haploid’. Describe what this means. ___________________________________________________ ___________________________________________________ (1)2. (a) Complete the table below to show the sex cells in animals and plants and their sites of production.

Organism Sex cell Male or Female Site of production

Animals EggMale

Plants OvaryPollen

(4) (b) What term is used to describe sex cells in plants and animals? ________________________ (1)

3. The diagram below shows the process of fertilisation.

Cell R is A a zygoteB a gameteC an ovuleD an embryo

Correct answer _________(1)

HOMEWORK 1 (continued)

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4. The table below shows information on the number of eggs fertilised and the survival of offspring for four different animals.

Animal Average number of eggs fertilised

at one time

Average number of surviving

offspring

Percentage survival rate

Dog 5 4Human 1 1 100

Bird 4 3 75Trout 1000 20 2

(a) Calculate the percentage survival for the dog and complete the table with the result.

(1)

(b) Draw a bar graph to show the percentage survival rates of the 4 animals on the grid below.

(3)HOMEWORK 2

1. (a) The diagram below shows a summary of events that occur during reproduction in a flowering plant.

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(i) Complete the diagram by entering the name of cell type R.(1)

(ii) Which process in the diagram represents fertilisation? ______________________ (1) (iii) Complete the following table by inserting a tick (√) in the correct boxes to show which of the cells in the diagram have a double or single set of chromosomes.

(2) (b) Explain the need to produce cells with a single set of chromosomes in reproduction.

_____________________________________________________ ____________________________________________ _________ (1)

HOMEWORK 2 (continued)

2. The diagram below shows a section through a flower.

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Name the sites of production of pollen grains and ovules in a flowe. Describe how these gametes are formed and describe the process of fertilisation.

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________

______________________________________________________ (5)

HOMEWORK 31. Sorghum is an important food crop in some parts of the world. The colour of the seed husk (coat) is controlled by a single gene. Purple husk colour (H) is dominant to tan husk colour (h).

(a) A true breeding purple husk plant is crossed with a true breeding tan husk plant. (i) What other term is used in genetics to indicate true breeding?

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(1) (ii) Complete the genotypes of the parental (P) generation below:

P purple X tan P genotypes _________ ___________

(1)

(iii) State the phenotype(s) of the F1 plants. F1 phenotype(s) __________________________________ (1) (b) An individual from the F1 generation is crossed with a true breeding tan husk plant. (i) Complete the Punnett square to show the expected results of this cross.

(2)

(ii) State the expected phenotype ratio for the offspring of this cross. ______________ purple husk : ____________ tan husk (1)

HOMEWORK 3 (continued)2. Match the following genetic terms with their correct definition by writing the correct number in the box beside each definition. Genetic term Definition

1. Gene Second filial generation in a monohybrid cross

2. Alleles Different forms of a gene

3. Genotype Allele which is masked by the dominant allele

4. Phenotype Genotype with the same alleles of a gene

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5. Dominant Genotype with different alleles of a gene

6. Recessive Another term for homozygous where the same alleles are present in the gene pair

7. Monohybrid cross Section of a chromosome which controls a characteristic

8. Homozygous Type of variation shows clear-cut, distinct values

9. True breeding Cross involving two true breeding parents who differ in the alleles of one gene

10. Heterozygous Combination of genes in a gene pair

11. P Physical appearance of a characteristic

12. F1 First filial generation in a monohybrid cross 13. F2 Allele which always shows in the phenotype

14. Continuous Parental generation in a monohybrid cross

15. Discrete Type of variation which occurs over a wide range

(15)HOMEWORK 4

1. Candytuft is a plant with white or pink flowers. The two forms of the gene responsible for the flower colour are:

P = pink flowers and p = white flowers (a) A plant breeder crossed two pink flowered plants as shown below.

Parents Pp x Pp (i) What is the expected ratio of pink to white flowered plants in the offspring?

___________ : __________ (1) pink white

(ii) If 48 offspring had been produced, how many white flowered plants would have been expected?

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Space for calculation

_______________ white flowered plants(1)

(iii) The offspring actually consisted of 24 pink flowered and 16 white flowered plants. What is the simplest whole number ratio of pink to white flowered plants in the offspring? Space for calculation

__________ : ___________ (1) pink white (iv) Suggest a reason for the difference between the expected ratio and the observed ratio.

____________________________________________________

____________________________________________________ (1)

HOMEWORK 4 (continued)Question 1 (continued) (b) What name is given to two forms of a gene?

________________________________ (1)

(c) Some plant characteristics show discrete variation.

(ii) What is meant by ‘discrete variation’?

__________________________________________________

__________________________________________________ (1)

(ii) State two human characteristics which show discrete variation.

1. ___________________________

2. ___________________________ (2)

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HOMEWORK 51. Polydactyly is a condition which results in extra toes in mice. It is controlled by the dominant form of a gene (N). The normal phenotype is controlled by the recessive form (n). The diagram below shows a cross between two mice of different genotypes.

(a) (i) Complete the diagram above to show the possible genotypes of the F2 generation.

(1) (ii) Give the phenotypes of each of the following mice:

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Parent 1 _____________________ Parent 2 _____________________ F1 _____________________ (2) (iii) What term is used to describe the type of variation shown by these phenotypes? ___________________________ (1) (b) Why are the actual phenotype ratios in the F2 generation often different from the predicted ones? ___________________________________________________

___________________________________________________ (1)HOMEWORK 5 (continued)

2. In fowl, the dominant form (R) of one gene determines rose comb shape; single comb shape results from the recessive form (r) of the gene. The diagram below shows the results of two crosses.

(a) (i) Which offspring contains only one phenotype? __________________________ (1) (ii) Complete the Punnett square below to show the genotypes of the gametes of the Cross 2 single comb parent and the genotypes of the offspring produced.

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(2)

(b) Decide if each of the following statements is True or False, and tick (√) the appropriate box. If the statement is False, write the correct word in the Correction box to replace the word underlined in the statement.

(3)HOMEWORK 6

1. Tongue-rolling is an inherited characteristic. The diagram below shows the pattern of its inheritance in one family.

(a) (i) Using R for the dominant form of the gene and r for the recessive form, state the genotypes of: 1 Maureen ___________ 2 Jim ___________ 3 Kevin ___________

(2) (ii) If Rab and Fiona have a child, what are the chances of the child being able to roll its tongue? Space for calculation

_______________ (1)

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(iii) Which of the original parents could be described as true breeding? Tick (√) the correct box.

(1)

(iv) Name a tongue roller from the F1 generation.

__________________________________ (1)HOMEWORK 6 (continued)

2. In humans, the allele for free ear lobes (E) is dominant to the allele for fixed earlobes (e). The diagram below shows the inheritcance of this characteristic.

Which line in the table identifies correctly the genotypes of persons P and Q?

Correct answer ________

(1)

3. A hairy stemmed pea plant is crossed with a smooth stemmed pea plant. All the F1 plants had hairy stems. The genotype of the F1 plants was

A heterzygous B homozygous C dominant D recessive

Correct answer ______________(1)

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4. Differences in the mass of sunflower seeds are due to the interaction of the alleles of several genes. This type of inheritance is called A dominant B monohybrid C polygenic D co-dominant

Correct answer ______________(1)

HOMEWORK 6 (continued)5. In gerbils, agouti coat colour is dominant to white. Some heterozygous gerbils were allowed to interbreed and 56 offspring were produced. What would be the expected number of aguoti gerbils?

A 14 B 28 C 42 D 56

Correct answer ___________ (1)

6. A hairy stemmed pea plant was crossed with a smooth stemmed pea plant and all of the F1 had hairy stems. The genotype of the hairy stemmed parent plant is

A heterozygous dominant B heterozygous recessive C homozygous recessive D homozygous dominant

Correct answer ______________(1)

7. Skin colour in humans is an example of

A discrete variation B co-dominance C polygenic inheritance D single gene inheritance

Correct answer ______________(1)

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