IB Biology HL A4.1 Evolution and speciation questions

Exam-style multiple choice and written questions with full markschemes. Check multiple choice answers straight away, or type, photograph or draw a written answer and get it marked.

Type
Multiple choiceWritten
Difficulty
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Question 1

Paper 2Easy6 marks

Researchers record the percentage of beetles in a population with an inherited pale-colour characteristic.

GenerationBeetles with pale colour / %
132
547

One adult beetle develops greater leg-muscle mass through repeated exercise. This change is not passed to its offspring.

(a)

Calculate the increase in the percentage of beetles with pale colour from generation 1 to generation 5, in percentage points.

[2]
(b)

State what is meant by evolution.

[2]
(c)

Explain why the change in leg-muscle mass in the adult beetle does not count as evolution.

[2]

Question 2

Multiple choiceHard1 mark

Researchers recorded responses to courtship displays between and within two species, then recorded the outcomes of resulting matings. Evolution is a change in heritable characteristics of a population. Which interpretation is supported?

PairingCourtship displays accepted (%)Matings producing viable offspring (%)Viable offspring that were fertile (%)
P × P849296
Q × Q819095
P × Q8880
Show answer and explanation

Answer: C. Courtship displays were accepted less often between species than within either species, indicating a behavioural barrier to mating. Although some interspecific matings produced viable offspring, none of the viable hybrids were fertile, so they could not pass alleles to later generations. The results indicate barriers to allele flow but do not show a change in heritable characteristics of a population over time.

A: Confuses viability with fertility; the hybrids were viable but could not reproduce.
B: Reverses the barrier stages: courtship affects mating before fertilization, while sterility occurs in hybrids.
D: Treats a difference between pairings as evidence of heritable change over time; the data do not establish that change.

Remember: Viable offspring can still be sterile and unable to transmit alleles to another generation.

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