Variation

Free sample questions

Variation — sample Biology questions with answers

1. Question 1

   Variation among individuals of the same species can be divided into two main types: discrete variation and continuous variation. Which of the following is an example of discrete variation?

   • AHuman blood groups (A, B, AB, O)
   • BHuman height
   • CHuman weight
   • DHuman skin colour

   Answer: A. Human blood groups (A, B, AB, O)

   Human blood groups are discrete variation because they have clear, non-overlapping categories. Height, weight, and skin colour are continuous variation because their values are in a continuous range.

2. Question 2

   The graph below shows the frequency distribution of a trait in a population. Which graph shape indicates a continuous variation trait?

   • ABell-shaped (normal) graph
   • BBar graph with several categories
   • CGraph with several discrete peaks
   • DHorizontal straight line graph

   Answer: A. Bell-shaped (normal) graph

   Continuous variation produces a bell-shaped (normal) graph because most individuals are around the mean value. Other options represent discrete variation or non-normal distribution.

3. Question 3

   Which of the following factors does NOT cause genetic variation in a population?

   • ARandom fertilisation
   • BCrossing over during meiosis
   • CGene mutation
   • DEnvironmental temperature change

   Answer: D. Environmental temperature change

   Environmental temperature change is an environmental factor that causes phenotypic variation, not genetic variation. Random fertilisation, crossing over, and gene mutation are sources of genetic variation.

4. Question 4

   In an experiment, two pea plants with the same genotype are planted in different areas: one in fertile soil and one in barren soil. Both plants show a difference in height. What is the most suitable conclusion?

   • AVariation is caused by genetic factors only
   • BVariation is caused by environmental factors
   • CThere is no variation because the genotype is the same
   • DVariation is caused by mutation

   Answer: B. Variation is caused by environmental factors

   The difference in height is due to the difference in environmental conditions (fertile vs barren soil) even though the genotype is the same. This shows that environmental factors cause phenotypic variation.

5. Question 5

   A mutation that involves a change in a single nucleotide in the DNA sequence is known as?

   • AGene mutation (point mutation)
   • BChromosomal mutation
   • CFrameshift mutation
   • DInsertion mutation

   Answer: A. Gene mutation (point mutation)

   Point mutation is a change in one nucleotide. Frameshift and insertion mutations are types of gene mutation, but the general term for a single nucleotide change is point mutation (gene mutation). Chromosomal mutation involves changes in chromosome structure or number.