Darwinism - Natural Selection and Fitness - Unsolved Practice Set
Chapter: Evolution | Topic: Darwinism Natural Selection and Fitness
DARWINISM - NATURAL SELECTION AND FITNESS - UNSOLVED PRACTICE SET
Topic: Darwinism Natural Selection and Fitness
Multiple Choice Questions
Q1. According to Darwin, "fitness" in an evolutionary sense primarily refers to an organism's:
- Physical strength alone
- Ability to survive and successfully reproduce, passing on genes to the next generation
- Intelligence level
- Body size
Q2. The type of natural selection that favours individuals with an average/intermediate phenotype, reducing variation, is called:
- Directional selection
- Disruptive selection
- Stabilising selection
- Sexual selection
Q3. The type of natural selection that favours individuals at both extremes of a phenotypic range, over the intermediate types, is called:
- Stabilising selection
- Disruptive selection
- Directional selection
- Genetic drift
Q4. The phenomenon of industrial melanism, seen in the peppered moth in England, is a classic real-world example of:
- Genetic drift
- Natural selection favouring a colour variant matching the environment
- Artificial selection
- Chemical evolution
Q5. According to Darwin, the "struggle for existence" arises mainly because:
- Resources are unlimited
- Organisms reproduce far more offspring than the environment can support with limited resources
- All individuals in a population are genetically identical
- Environmental conditions never change
Short Answer Questions
Q6. Define "biological fitness" as understood in the theory of natural selection.
Q7. Differentiate between stabilising selection and directional selection, giving a brief example of each if possible.
Q8. Why did Darwin propose that a "struggle for existence" occurs in natural populations?
Q9. Briefly explain what is meant by "differential reproduction" in the context of natural selection.
Long Answer Questions
Q10. Explain the key postulates of Darwin's theory of natural selection, describing how overproduction, variation, and struggle for existence lead to evolutionary change over time.
Q11. Describe the three types of natural selection (stabilising, directional, and disruptive), explaining how each affects the distribution of a trait in a population.
APPLICATION / ANALYSIS
Q12. During the industrial revolution in England, dark-coloured peppered moths became more common than light-coloured ones in polluted, soot-covered areas, while light-coloured moths remained more common in cleaner regions. Explain this observation using Darwin's theory of natural selection.
Q13. In a bird population, individuals with either very small or very large beak sizes are better able to access different food sources than those with medium-sized beaks, which struggle to compete for either resource. Identify the type of natural selection likely occurring here, and explain your reasoning.