Extra Worksheet Inheritance

Heredity Biology 1 Name:__________________________________ Class:__________ Date:__________ Multiple-Choice Questions (10 marks) 1. Different forms of the same gene are known as ___________. A alleles B chromosomes C chromatids D genotypes ( ) 2. The physical appearance of an organism is known as its ___________. A genotype B phenotype C genome D alleles ( ) 3. When a normal fly with normal wings was mated with a fly with vestigial wings, all the offspring had normal wings. What conclusion can you draw from this? A Vestigial wing is dominant over normal wing. B Normal wing is dominant over vestigial wing. C Both alleles are codominant. D Insufficient information to draw a conclusion. ( ) Use the following information to answer questions 4 and 5. In humans, ‘curly hair’ is dominant over ‘straight hair’. 4. A heterozygous man marries a straight-haired woman. What is the expected ratio of their offspring? A 1 curly hair : 1 straight hair B 3 curly hair : 1 straight hair C all curly hair D all straight hair ( ) 5. A heterozygous couple would most likely have offspring that are ___________. A all homozygous for curly hair B all homozygous for straight hair C all heterozygous D a mixture of homozygous and heterozygous ( ) 25

Heredity Biology 2 Refer to the family tree to answer questions 6 to 8. The family tree below shows the inheritance of a disease caused by a dominant allele, R. 6. The genotype of J is ___________. A RR B Rr C rr D unknown ( ) 7. The genotype of K is ___________. A RR B Rr C rr D unknown ( ) 8. Which of the following statement is true about mutation? A Mutation is only affects discontinuous variation. B Mutation results from the accurate replication of hereditary materials. C Mutation will not occur in the absence of mutagens. D Mutation causes variations in a species. ( ) 9. Which of the following statements about the human ABO blood group is incorrect? A The allele IA is codominant with the allele IB. B The allele IO is recessive to the allele IB. C A person of blood group O has the genotype OO. D A person of blood group O is a homozygous. ( ) 10. The sex of a baby is determined by ___________. A the mother’s egg B the father’s sperm C the number of ova produced D the age of the mother ( ) Key to symbols: Male Female Affected male Affected female J K

Heredity Biology 3 Structured Questions (15 marks) 11. In pea plants, the flower colour is controlled by genes. The allele for purple flowers, F is dominant over the allele for white flowers, f. Indicate with a tick (√) in the table to show the possible phenotypes of offspring resulting from the various crosses listed below. [4] Phenotype of offspring Cross Genotype of parents Plants with purple flowers Plants with white flowers A FF × FF B Ff × ff C Ff × Ff D ff × ff 12. Normal peppered moths are pale coloured. Occasionally, dark moths are born as a result of a mutation. (a) (i) Why does the colour of the moths affect their chance of survival? [1] (ii) Which type of moth, pale or dark, would you expect to survive longest in a town that uses coal as the energy source? (Note: Burning of coal results in soot.) [1] (iii) Explain the reason for this. [1] (b) In a small town, pale moths have selective advantage over dark moths. Is this town most likely an agricultural or an industrialized town? Explain your answer. [2]

Heredity Biology 4 13. Most people have five toes on each foot. Occasionally a person is born with six toes. The number of toes is an inherited character, controlled by a pair of alleles. With reference to the two pedigrees given below, answer the questions that follow. (a) Based on Pedigree 1, which allele — five-toed or six-toed, is dominant? [1] (b) What is the possibility that individual 11 is six-toed? Using a genetic diagram, explain how you arrive at your conclusion. [3] Key to symbols: Male Female Affected male Affected female Pedigree I 2 1 3 4 5 6 8 7 9 10 11 Pedigree II ?

Heredity Biology 5 (c) In order to ensure their offspring will not have the six-toed characteristic, individual 5 undergoes a surgical operation to have her extra toe removed before marrying individual 10. Do you think this method is effective? Explain your answer. [2]

Heredity Biology 6 Answers Multiple-Choice Questions (10 marks) 12. Different forms of the same gene are known as ___________. A alleles B chromosomes C chromatids D genotypes ( A ) 13. The physical appearance of an organism is known as its ___________. A genotype B phenotype C genome D alleles ( B ) 14. When a normal fly with normal wings was mated with a fly with vestigial wings, all the offspring had normal wings. What conclusion can you draw from this? E Vestigial wing is dominant over normal wing. F Normal wing is dominant over vestigial wing. G Both alleles are codominant. H Insufficient information to draw a conclusion. ( B ) Use the following information to answer questions 4 and 5. In humans, ‘curly hair’ is dominant over ‘straight hair’. 15. A heterozygous man marries a straight-haired woman. What is the expected ratio of their offspring? A 1 curly hair : 1 straight hair B 3 curly hair : 1 straight hair C all curly hair D all straight hair ( A ) 16. A heterozygous couple would most likely have offspring that are ___________. E all homozygous for curly hair F all homozygous for straight hair G all heterozygous H a mixture of homozygous and heterozygous ( D )

Heredity Biology 7 Refer to the family tree to answer questions 6 to 8. The family tree below shows the inheritance of a disease caused by a dominant allele, R. 17. The genotype of J is ___________. A RR B Rr C rr D unknown ( B ) 18. The genotype of K is ___________. A RR B Rr C rr D unknown ( B ) 19. Which of the following statement is true about mutation? A Mutation is only affects discontinuous variation. B Mutation results from the accurate replication of hereditary materials. C Mutation will not occur in the absence of mutagens. D Mutation causes variations in a species. ( D ) 20. Which of the following statements about the human ABO blood group is incorrect? E The allele IA is codominant with the allele IB. F The allele IO is recessive to the allele IB. G A person of blood group O has the genotype OO. H A person of blood group O is a homozygous. ( C ) 21. The sex of a baby is determined by ___________. A the mother’s egg B the father’s sperm C the number of ova produced D the age of the mother ( B ) Key to symbols: Male Female Affected male Affected female J K

Heredity Biology 8 Structured Questions (15 marks) 22. In pea plants, the flower colour is controlled by genes. The allele for purple flowers, F is dominant over the allele for white flowers, f. Indicate with a tick (√) in the table to show the possible phenotypes of offspring resulting from the various crosses listed below. [4] Phenotype of offspring Cross Genotype of parents Plants with purple flowers Plants with white flowers A FF × FF √ B Ff × ff √ √ C Ff × Ff √ √ D ff × ff √ 13. Normal peppered moths are pale coloured. Occasionally, dark moths are born as a result