Biology for IGCSE & O level - Variation And Selection (Section 5)
1
Which of the following features are improved by breeders in cereal crops?
Answer
A
B
C
2
Which of the following processes does NOT directly contribute to genetic variation?
Answer
(C)
Selective breeding
3
What best describes the mechanism of natural selection?
Answer
(B)
Traits are passed on and individuals with advantageous traits reproduce at higher rates.
4
In the context of selective breeding, what is the goal?
Answer
(C)
To increase the value of the organism.
5
Which of the following are examples of adaptive features in desert plants?
Answer
A
B
C
6
Which of the following is NOT a characteristic of a population that undergoes natural selection?
Answer
(D)
All individuals are equally well-adapted.
7
What will happen if the sequence of DNA shown is mutated, resulting in: ACT GTT ACC TAG
Answer
(B)
The structure of the protein will change.
8
What is a potential consequence of inbreeding?
Answer
B
C
9
What is a characteristic of individuals that are 'better adapted' in a population?
Answer
(B)
They can reproduce more successfully.
10
What is the role of meiosis in the context of variation?
Answer
(A)
Meiosis reduces the number of chromosomes to create gametes, contributing to genetic variation through shuffling of genes.
11
In a population of insects, some individuals have a mutation that makes them resistant to a certain pesticide. What will happen to the proportion of pesticide-resistant insects over several generations if the area is sprayed with the pesticide?
Answer
(C)
The proportion of resistant insects will increase.
12
In artificial selection, who or what determines which traits are favored?
Answer
(C)
The breeder.
13
In plants adapted to aquatic environments, what is the main function of the extensive air spaces in their leaves?
Answer
(B)
To provide buoyancy and assist with gas exchange.
14
Which of the following is true regarding the relationship between genes and the environment regarding variation?
Answer
(C)
The environment can influence how genes are expressed, leading to different phenotypes.
15
What is the difference between continuous and discontinuous variation?
Answer
(A)
Continuous variation involves a range of values, and discontinuous variation is limited to distinct categories.
16
What is the role of the stigma?
Answer
(C)
To capture pollen.
17
What is the primary goal of breeders using artificial selection?
Answer
(C)
To select for desirable traits in offspring.
18
What is the advantage of continuous variation?
Answer
A
B
19
What is the definition of natural selection?
Answer
(B)
The process where organisms with advantageous traits are more likely to survive and reproduce, passing those traits to their offspring.
20
Merino sheep have much thicker wool than wild sheep. The results of Merino sheep are a result of:
Answer
(D)
selective breeding
21
Which of the following best describes the process of adaptation?
Answer
(B)
The process by which a population becomes better suited to its environment.
22
What is the most significant outcome when a gene is mutated?
Answer
(C)
A cell's protein may not function properly.
23
What is a key component that is necessary for natural selection to occur within a population?
Answer
(C)
Variation among individuals in heritable traits.
24
Which of the following statements are true about natural selection?
Answer
B
C
25
What is a potential risk associated with excessive inbreeding in animal or plant populations?
Answer
(B)
A higher chance of expressing harmful recessive genes.
26
What is the difference between the roles of the leaves and the roots of a hydrophytic plant?
Answer
(A)
Leaves absorb water and carbon dioxide; roots anchor the plant and provide nutrients.
27
Which of the following is an example of an environmental influence on variation?
Answer
(B)
The height of plants depending on the amount of sunlight they receive
28
What are the advantages of using outbreeding in the process of artificial selection?
Answer
(C)
Increasing hybrid vigour.
29
Bird pollination, as described, gives plants a selective advantage by:
Answer
(C)
Providing pollinators with a place to perch and feed.
30
What could be a potential drawback or risk associated with inbreeding?
Answer
(D)
Increased chance of expressing harmful recessive alleles.
31
In a population, what does competition for resources lead to?
Answer
(C)
A 'struggle for existence'.
32
In the context of evolution and adaptation, why is it crucial for an organism to have features that enhance its ability to reproduce?
Answer
(B)
To ensure the continuation of its genes within the gene pool.
33
What is the significance of the phrase 'struggle for existence' in the context of natural selection?
Answer
(A)
Organisms competing for resources like food, space, and mates.
34
An island was invaded by a species of bird that preyed on butterflies. In the population of butterflies, only those individuals that produced a toxic substance as a protection against predation survived. This is an example of:
Answer
(D)
natural selection
35
Which of the following scenarios best illustrates the concept of natural selection?
Answer
(B)
A population of moths changes color over time to blend in with a changing environment.
36
What are the factors that can lead to new alleles in a population?
Answer
(D)
Mutation
37
What type of variation is represented by human blood groups (A, B, AB, and O)?
Answer
(B)
Discontinuous
38
In a population, what is the role of competition for resources?
Answer
(C)
To drive natural selection by favoring certain traits.
39
In the context of mutations, what is a frameshift mutation?
Answer
(B)
A mutation that results in the insertion or deletion of a nucleotide, altering the reading frame.
40
What is an example of a behavioral adaptation?
Answer
(B)
The migration of birds.
41
A certain population of moths lives in a forest. Originally, the majority of the moths are light-colored, but over time, the proportion of dark-colored moths increases. Which of the following is most likely responsible for this shift?
Answer
(A)
Increased air pollution, leading to darker tree bark and better camouflage for dark moths.
42
Which of the following is an example of an acquired characteristic?
Answer
(B)
A scar from an injury
43
What role do humans play in the process of artificial selection?
Answer
(C)
They choose which individuals reproduce.
44
Which of the following scenarios is an example of an evolutionary adaptation?
Answer
(C)
The development of antibiotic resistance in bacteria.
45
In what way is the environment essential to natural selection?
Answer
(B)
It determines which traits are most advantageous.
46
What is the main goal of artificial selection?
Answer
(C)
To select for desirable traits.
47
Which of the following statements accurately describes the impact of environmental changes on a population?
Answer
(C)
Environmental changes select for existing variations.
48
What is an example of a discontinuous variation?
Answer
(C)
Eye color in humans
49
In which type of variation do individuals fall into distinct categories with no intermediates?
Answer
(B)
Discontinuous variation
50
Which of the following are examples of natural selection?
