Form 5Chapter 15 Variation

Objective Questions

1 The difference between individuals from the same species is calledA alleleB variationC phenotypeD genotype

2 Which of the following genetic diseases is a result of mutation that causes changes in the gene that produces pigments?A AlbinismB HaemophiliaC Down’s syndromeD Colour blindness

3 Which of the following will not cause mutation in the cell undergoing meiosis?A Loss of one chromosomeB Part of the chromosome is invertedC Number of chromosomes reduces to half of the original numberD Both sex chromosomes are found in one daughter cell

4 Which of the following statements is true about mutation?Mutation is a process thatA occurs spontaneouslyB only occurs in animalsC can be slowed down by using X-raysD frequently kills organisms

5 Two identical twins that are raised in different environments may show differences in terms ofA ability to roll the tongueB skin colourC blood groupD attached earlobes

6 Which of the following statements about the types of attached earlobes is not true?A The number of humans with partially attached earlobes is very smallB It is a discontinuous variationC This characteristic is not influenced by environmental factorsD Can be inherited by the following generation

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7 In a study on variation, the following characteristics can be found.

The example of variation that was studied isA eye colourB skin colourC fingerprintD attached earlobe

8 Down’s syndrome may be caused by the fertilisation between gamete K and gamete L. What is the number of chromosomes that are found in gametes K and L?

Gamete K Gamete LA 23 23B 23 24C 22 23D 24 24

9 Farah has antigen A and antibody B, while Aini has antibody A and antibody B. What is the blood group of Farah and Aini?

Farah AiniA A blood group O blood groupB B blood group AB blood groupC A blood group AB blood groupD B blood group O blood group

10 Which of the following characteristics is/are influenced by environmental factors?I FingerprintsII Body weightIII Colour blindnessIV Ability to roll the tongueA II onlyB II and III onlyC II and IV onlyD I, II and IV only

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Has intermediate characteristics No visible differences Normal distribution graph

11 Which of the following processes will produce variation?I Sexual reproductionII Chromosomal mutationIII Asexual reproductionIV Gene mutationA II and IV onlyB I, II and IV onlyC II, III and IV onlyD I, II, III and IV

12 Which of the following is/are characteristic(s) of continuous variation?I Controlled by a lot of genesII Quantitative heredityIII Does not show clear and visible changesIV Can be fully passed on to the next generationA IV onlyB II and III onlyC I, II and III onlyD II, III and IV only

13 Discontinuous variation influenced by I the environmentII geneticsIII mutationIV crossing overA I onlyB I, II and III onlyC I, II and IV onlyD II, III and IV only

14 The sources of genetic variation areI food dietII X-raysIII chemical mutagenIV crossing over during meiosisA I and IV onlyB II and III onlyC I, II and III onlyD II, III and IV only

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Structured Questions

1 Figure 1 shows bar graphs that represent two types of variation among students in a class.

Figure 1

(a) Write the definition of variation.

(b) State two sources of variation.

(c) What is the type of variation shown in Figure 1(i) and 1(ii)?

(d) List three differences between the two types of variation that is shown in the figures above.

(e) Explain why the measurement obtained in Figure 1(i) cannot be grouped into two extreme groups that is tall and short.

2 (a) Write the definition for

(i) mutation(ii) mutagen(iii) mutant

(b) State three effects of mutation on humans.(c) Figure 2 shows various examples of mutation.

Figure 2

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(i) Name the type of mutation that is shown in Figure 2.(ii) Give the reason for your answer.(iii) When might the type of mutation stated in a(i) occur?(iv) Name processes R, S, T and U that is shown in Figure 2.(v) Write two differences between the change in characteristics that are caused

by genes and that are caused by the environment.(vi) Give the factor that causes mutation.(vii) How does mutation produce new hybrids?

Essay Question

(a) What is mutation? State the types of mutation.(b) What is the source that causes mutation?(c) By using examples, state three effects of mutation.

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AnswersObjective Questions1 B2 A3 C4 A5 B6 A7 B

8 C9 A10 A11 B12 C13 D14 D

Structured Questions1 (a) The difference in characteristics between individuals of the same species.

(b) Environmental factors and genetic factors.

(c) (i) Continuous variation(ii) Discontinuous variation

(d) (i) Continuous variation shows the differences in characteristics that are unclear and where intermediate characteristics exist. Discontinuous variation shows the differences in characteristics that are clear without intermediate characteristics.

(ii) Continuous variation is influenced by environmental and genetic factors. Discontinuous variation is only influenced by genetic factors only.

(iii) Continuous variation has a normal distribution, while discontinuous variation has discrete variation.

(e) Because there an intermediate value exists between the two extreme groups.

2 (a) (i) Spontaneous change on the genetic material that will be inherited by the following generation.

(ii) Substance that can cause mutation to occur.(iii) Organism that experiences mutation or inherits the characteristic that is

produced through the mutation.

(b) (i) Handicapped (ii) Genetic disease(iii) Death

(c) (i) Chromosomal mutation(ii) The mutation example shows the change in the gene/nitrogenous base sequences

on the chromosome(iii) During meiosis(iv) R: Inversion

S: TranslocationT: MultiplicationU: Elimination

(v) 1 The change in characteristics that is caused by the gene involves changes in the gene, while that caused by the environment does not involve

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2 The change in characteristics that is caused by genes can be inherited, while the changes in the genes that are caused by the environment cannot be inherited.

(vi) Radioactive rays, chemical substances such as benzene.(vii) Mutant with new characteristics may enable it to adapt itself in the environment.

In time, the mutant will replace other organisms that are weaker than it. So, the mutant is a new hybrid.

Essay Question (a) Mutation is the spontaneous change in the genetic material that can be inherited.

Mutation is divided into chromosomal mutation and gene mutation. Chromosomal mutation occurs due to a change in the number of chromosomes or a change in the gene/nitrogenous base sequences on the chromosome, while gene mutation occurs due to a change in the gene structure.

(b) The sources of mutation (mutagens) include: X-rays, radioactive rays, ultraviolet rays dangerous chemical substances such as asbestos, metanil yellow colouring,

insecticide, benzene algae poison, formaldehyde, and a few types of drug.

(c) Three effects of mutation are genetic diseases or heredity diseases, handicap, death. Heredity diseases or handicaps occur due to gene mutation, for example

haemophilia and colour blindness, or is caused by chromosomal mutation, for example Down’s syndrome.

This type of disease is inherited because any defects on the chromosome or gene is also copied and transferred to the gamete chromosome during meiosis.When fertilisation occurs, the gamete that carries the defective gene will produce a handicapped individual.The death gene due to gene mutation can cause death. An example of gene mutation is the change that occurs in nucleotide sequence of a DNA molecule. This condition will cause the production of other amino acids. Death can occur if the production of important proteins is hindered due to the changes.

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