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Quiz Chapter 12: Variation

10 questions ยท Form 5 Biology Bab 12: Variation

Question 1 of 10Score: 0

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

Full Question List & Answer Key

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

1. 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.

2. 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.

3. What occurs during nondisjunction in meiosis?

  1. Chromosomes replicate twice instead of once
  2. Homologous chromosomes or sister chromatids fail to separate properly
  3. DNA polymerase substitutes adenine with cytosine
  4. Centromeres divide prematurely during interphase
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Answer: B

Nondisjunction is the failure of chromosomes or chromatids to separate during cell division, leading to abnormal chromosome numbers.

4. Which event during sexual reproduction ensures that each zygote inherits a unique combination of paternal and maternal genes?

  1. Binary fission
  2. Random fertilization of an egg by a sperm cell
  3. Mitotic cell division
  4. Budding
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Answer: B

Random fertilization combines any one of millions of unique sperm with a unique egg cell.

5. 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.

6. Which medical condition is caused by an inherited autosomal recessive gene mutation affecting melanin synthesis?

  1. Albinism
  2. Down syndrome
  3. Haemophilia
  4. Color blindness
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Answer: A

Albinism is a gene mutation causing defect in the tyrosinase enzyme required for melanin pigment synthesis.

7. Which chromosomal structural mutation involves a segment of a chromosome breaking off and reattaching in reverse orientation?

  1. Deletion
  2. Duplication
  3. Inversion
  4. Translocation
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Answer: C

Inversion occurs when a chromosome segment breaks off, rotates 180 degrees, and reattaches.

8. Which human trait is controlled by polygenic inheritance?

  1. ABO blood group
  2. Fingerprint patterns
  3. Body mass
  4. Eye color in fruit flies
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Answer: C

Body mass is quantitative and governed by multiple genes acting additively alongside environmental factors.

9. 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.

10. 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.

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