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Quiz Chapter 12: Variation

10 questions ยท Form 5 Biology Bab 12: Variation

Question 1 of 10Score: 0

An individual with Klinefelter syndrome possesses which chromosomal constitution?

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. An individual with Klinefelter syndrome possesses which chromosomal constitution?

  1. 45, XO
  2. 47, XXY
  3. 47, XYY
  4. 46, XY
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Answer: B

Klinefelter syndrome is a genetic condition where a male inherits an extra X chromosome (47, XXY).

2. During which phase of meiosis does crossing over occur to generate genetic variation?

  1. Prophase I
  2. Metaphase I
  3. Anaphase II
  4. Telophase II
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Answer: A

Crossing over occurs during Prophase I between non-sister chromatids of homologous chromosomes.

3. What term describes agents such as X-rays, UV radiation, and formaldehyde that increase the rate of genetic mutations?

  1. Carcinogens
  2. Mutagens
  3. Teratogens
  4. Antigens
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Answer: B

Mutagens are physical or chemical agents that significantly elevate genetic mutation rates.

4. What is the total chromosome number and sex chromosome composition in an individual with Turner syndrome?

  1. 47, XXY
  2. 45, XO
  3. 47, Trisomy 21
  4. 46, XX
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Answer: B

Turner syndrome females have 45 total chromosomes with a single X chromosome (44 autosomes + XO).

5. Which characteristic represents discontinuous variation in humans?

  1. Body weight
  2. Intelligence Quotient (IQ)
  3. Presence of attached or free earlobes
  4. Skin tone
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Answer: C

Earlobe type is a discrete trait with distinct categories (free or attached) and no intermediate states.

6. Which condition is caused by a gene mutation resulting from a base substitution in the gene coding for hemoglobin?

  1. Down syndrome
  2. Sickle cell anemia
  3. Turner syndrome
  4. Klinefelter syndrome
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Answer: B

Sickle cell anemia is caused by a specific gene mutation (point substitution) in the beta-globin gene.

7. What type of graph is used to display data collected for discontinuous variation in a class?

  1. Line graph
  2. Histogram with touching bars
  3. Bar chart with separate bars
  4. Scatter plot
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Answer: C

Discontinuous data consists of distinct categories, represented visually using discrete bar charts with spaces between bars.

8. What is the key difference between a gene mutation and a chromosomal mutation?

  1. Gene mutations affect whole chromosomes; chromosomal mutations affect single bases
  2. Gene mutations alter the nucleotide sequence of a specific gene; chromosomal mutations alter structure or total number of chromosomes
  3. Gene mutations are inherited; chromosomal mutations are never inherited
  4. Gene mutations only occur in plants; chromosomal mutations only occur in animals
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Answer: B

Gene mutations affect nucleotide sequences within single genes, whereas chromosomal mutations involve structural or numerical changes in whole chromosomes.

9. Which human characteristic exhibits continuous variation?

  1. ABO blood group
  2. Ability to roll tongue
  3. Height
  4. Type of earlobe
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Answer: C

Height is controlled by multiple genes and environmental factors, displaying a continuous spectrum of intermediate values.

10. Why does discontinuous variation remain unaffected by environmental conditions?

  1. It is controlled entirely by polygenes
  2. It is determined purely by a single gene or very few alleles without environmental modification
  3. Environment only affects plants, not humans
  4. Discontinuous traits are acquired characteristics
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Answer: B

Discontinuous traits are monogenic and strictly governed by genotype, making them immune to environmental changes.

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