Genetics Populations Evolution and Ecosystems Practice Questions
A-Levels · A-Level Biology · 149 free MCQs with instant results and detailed explanations.
149
Total
51
Easy
78
Medium
20
Hard
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Sample Questions from Genetics Populations Evolution and Ecosystems
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Q1
Easy
What is the primary function of meiosis in sexually reproducing organisms?
A.
To produce diploid cells
B.
To create genetic diversity
C.
To maintain chromosome number
D.
To repair damaged DNA
Show Answer & Explanation
Correct Answer: B
Meiosis is crucial for sexual reproduction as it reduces the chromosome number by half and increases genetic diversity through processes like crossing over and independent assortment.
Q2
Easy
In a certain population of rabbits, brown fur (B) is dominant over white fur (b). If two heterozygous brown rabbits are bred, what is the probability of obtaining a white-furred rabbit?
A.
0%
B.
25%
C.
50%
D.
75%
Show Answer & Explanation
Correct Answer: B
When two heterozygous rabbits (Bb x Bb) are bred, the expected genotype ratio is 1 BB : 2 Bb : 1 bb. Thus, the probability of a white-furred rabbit (bb) is 25%.
Q3
Easy
Which of the following statements best describes a population in biological terms?
A.
A group of individuals of different species living together.
B.
A group of individuals of the same species in a given area.
C.
A collection of organisms that can interbreed in any environment.
D.
An assortment of organisms that do not share genetic material.
Show Answer & Explanation
Correct Answer: B
A population, in biological terms, refers to a group of individuals of the same species that inhabit a specific area and have the potential to interbreed, differentiating it from groups of different species.
Q4
Medium
In a population of rabbits, the allele for brown fur (B) is dominant over the allele for white fur (b). If 36% of the rabbits have white fur, what is the frequency of the brown fur allele in the population?
A.
0.6
B.
0.4
C.
0.8
D.
0.2
Show Answer & Explanation
Correct Answer: B
Using the Hardy-Weinberg principle, we know that q^2 (frequency of homozygous recessives) is 0.36, hence q (frequency of allele b) is 0.6. Therefore, p (frequency of allele B) is 0.4.
Q5
Medium
Which of the following scenarios is an example of stabilizing selection in a population of birds?
A.
Larger birds are favored over smaller birds.
B.
Smaller birds are more likely to survive than larger birds.
C.
Birds with an average wing size have higher survival rates than those with very small or very large wings.
D.
Birds that can fly longer distances are favored over those that cannot.
Show Answer & Explanation
Correct Answer: C
Stabilizing selection favors individuals with average traits, increasing their frequency in the population, hence birds with average wing size survive better.
Q6
Medium
In an experiment, two genetically different strains of bacteria are mixed and allowed to grow together. After a few generations, the bacteria show increased resistance to antibiotics. What is the mechanism responsible for this increased resistance?
A.
Natural selection
B.
Genetic drift
C.
Gene flow
D.
Mutualism
Show Answer & Explanation
Correct Answer: A
Natural selection favors bacteria with resistance traits in the presence of antibiotics, leading to a higher frequency of those traits in the population over generations.
Q7
Medium
A researcher studies a population of plants and finds that those with larger leaves have a higher rate of photosynthesis. However, larger leaves also lead to increased water loss. What type of evolutionary trade-off is exhibited in this scenario?
A.
Genetic drift
B.
Fitness trade-off
C.
Convergent evolution
D.
Adaptive radiation
Show Answer & Explanation
Correct Answer: B
This scenario demonstrates a fitness trade-off where larger leaves enhance photosynthesis but also increase water loss, affecting the overall fitness of the plants.
Q8
Hard
A forest ecosystem contains two species of trees, A and B. Species A has an average height of 20 meters with a height variance of 25 square meters. Species B has an average height of 15 meters with a height variance of 16 square meters. If a biologist wants to compare the height distributions of both species using a t-test, what does a higher variance indicate about the data of a species?
A.
Species has greater consistency in height.
B.
Species exhibits a wider range of heights.
C.
Species height is influenced by fewer environmental factors.
D.
Species has a lower average height.
Show Answer & Explanation
Correct Answer: B
A higher variance indicates that there is a greater spread of height values around the mean. Thus, species with higher variance, such as species A, will show a wider range of heights compared to species with lower variance, like species B.
Q9
Hard
In a population of rabbits, the allele for black fur (B) is dominant over the allele for white fur (b). If a cross between two heterozygous black-furred rabbits (Bb) results in 300 offspring, how many of these would you expect to have white fur?
A.
75
B.
150
C.
100
D.
50
Show Answer & Explanation
Correct Answer: A
In a Bb x Bb cross, the expected phenotypic ratio is 3:1 for black to white fur. Therefore, 1 out of 4 rabbits is expected to have white fur. For 300 offspring, 300/4 = 75 rabbits would have white fur.
Q10
Hard
In an ecosystem, the carrying capacity of a population is defined as what?
A.
The maximum population size that an environment can sustain indefinitely
B.
The average population size during the breeding season
C.
The minimum population size required for species survival
D.
The population size that occurs after a natural disaster
Show Answer & Explanation
Correct Answer: A
The carrying capacity refers to the maximum number of individuals of a particular species that an environment can support over time without degrading the habitat. It is crucial for understanding population dynamics.
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Practice All 149 Questions →Genetics Populations Evolution and Ecosystems — A-Levels A-Level Biology Practice Questions Online
This page contains 149 practice MCQs for the chapter Genetics Populations Evolution and Ecosystems in A-Levels A-Level Biology. The questions are organized by difficulty — 51 easy, 78 medium, 20 hard — so you can choose the right level for your preparation.
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