Home / IB DP Biology- D1.3 Mutations and gene editing- IB Style Questions For SL Paper 2

IB DP Biology- D1.3 Mutations and gene editing- IB Style Questions For SL Paper 2 - FA 2025

IBDP Biology Paper 2 - All Chapters

Question

Over generations, populations change through natural selection as they interact with their physical environment and with other species in the community.
(a) State one factor that can introduce genetic variation into a population.
(b) Describe how shifts in environmental conditions can affect the process of natural selection.
(c) Describe how removing a keystone species can impact the structure and stability of an ecosystem.

Most-appropriate topic codes:

• TOPIC D1.3: Mutation and gene editing — part (a)
• TOPIC D2.1: Cell and nuclear division — part (a)
• TOPIC D4.1: Natural selection — part (b)
• TOPIC D4.2: Stability and change — part (c)
▶️ Answer/Explanation
Detailed solution

(a)
One example is mutation. (Other valid answers include sexual reproduction / meiosis / crossing over / independent assortment / random fertilization.)

(b)
When the environment changes, it creates new selection pressures. Individuals whose characteristics are best suited to the new conditions are more likely to survive, reproduce and pass on their advantageous alleles to the next generation. Over time, these favorable traits become more common in the population.

(c)
A keystone species exerts a disproportionately large influence on its ecosystem. If it is removed, there can be a major reduction in biodiversity, substantial shifts in population sizes of other species, and serious disruption to food webs. This can lead to loss of ecosystem stability and, in extreme cases, ecosystem collapse.

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