Natural Selection Probability Quiz

Name:

Date:

📚 Part 1: Probability Concepts

1. In a beetle population, 30% are green and 70% are brown. What is the probability a randomly chosen beetle is green?

0.30

0.003

0.70

3.0

2. Two heterozygous parents (Aa × Aa) mate. What is the probability an offspring is homozygous recessive (aa)?

0.25

0.50

0.75

0.125

3. A camouflaged insect has a 0.8 chance of surviving a predator encounter. What is the probability it survives two independent encounters?

0.64

0.16

0.40

1.60

4. Under Hardy-Weinberg assumptions, allele frequencies are p = 0.6 and q = 0.4. What proportion of the population is expected to be heterozygous (2pq)?

0.48

0.36

0.16

0.60

5. If each individual in a population has a 0.2 probability of displaying a slow-growth trait, how many individuals with the trait are expected in a random sample of 10?

0.2

🔬 Part 2: Natural Selection Scenarios

6. Green beetles survive at 0.90 and brown beetles at 0.60 per generation. If starting population is 50 green and 50 brown, what fraction of survivors will be green?

0.60

0.40

0.75

0.45

7. A beneficial allele increases survival by 10% each generation (multiplicative). If current survival is 0.50, what is expected survival after two generations?

0.605

0.600

0.550

0.500

8. A neutral allele has frequency 0.40 and experiences no selection. After many generations with random mating but no selection, the best expectation is:

The allele frequency will remain about 0.40

The allele will definitely be lost (0.0)

The allele will reach fixation (1.0)

The allele must drift to 0.5

9. In a population of 1,000, 200 individuals carry a beneficial allele. Carriers reproduce at 1.5× the rate of noncarriers. What fraction of the next generation's births would you expect to carry the allele (approx.)?

0.273

0.200

0.333

0.500

10. Which statement best uses probability to explain how natural selection changes trait frequencies?

An allele with higher survival or reproduction probability will tend to increase in frequency over generations.

Allele frequencies remain constant whenever any fitness difference exists.

Traits with lower survival probabilities are more likely to become common due to selection.

Random chance always prevents selection from changing trait frequencies.