Selection Flashcards – Cambridge IGCSE (9–1) Biology 0970 (Extended) (2026–2028)

How can genetic variation affect adaptation within a population?

Some individuals carry alleles that make them better adapted to their environment than others.

What is the consequence of producing more offspring than can survive?

A struggle for survival, including competition for resources.

Why are better-adapted individuals more likely to pass their alleles to the next generation?

They are more likely to survive and reproduce.

How can natural selection affect the frequency of advantageous alleles over generations?

Alleles associated with advantageous inherited characteristics can become more common in the population.

How is selective breeding carried out?

Humans identify a desirable inherited feature, choose and cross parents showing it, then select offspring showing it as parents for the next generation. Selection and crossing are repeated over many generations.

What can repeated selective breeding achieve in crop plants and domesticated animals?

It can increase desirable features over many generations.

What type of selection is selective breeding?

Artificial selection.

What genetic variation can make some bacteria resistant to an antibiotic?

Some bacteria carry an allele that confers resistance to the antibiotic.

How does an antibiotic affect the survival and reproduction of susceptible and resistant bacteria?

Susceptible bacteria are more likely to die; resistant bacteria are more likely to survive and reproduce.

How is an antibiotic-resistance allele passed to the next bacterial generation?

Surviving bacteria pass the allele to their offspring.

How can an antibiotic-resistant bacterial strain arise over many generations?

Resistant bacteria can become more common in the population, producing a resistant strain.