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Biology for IGCSE & O level - Organisms And Their Environment (Section 2)

1
Which organisms are involved in the process of nitrification?
Answer
(B)
Bacteria only
2
What processes directly influence the amount of carbon dioxide in the atmosphere?
Answer
A
B
C
3
In a food chain, where does the energy transfer originate?
Answer
(C)
Producers
4
What is the role of lightning in the nitrogen cycle?
Answer
A
C
5
How does the amount of energy change as you move up the trophic levels in an ecosystem?
Answer
(C)
It decreases.
6
Which of the following would have the greatest biomass in a typical ecosystem?
Answer
(C)
Producers
7
What is the function of decomposers in an ecosystem?
Answer
(B)
To break down organic matter.
8
What is the primary purpose of the carbon cycle?
Answer
(B)
To recycle carbon in the ecosystem.
9
What are the two main products of photosynthesis?
Answer
(B)
Oxygen and glucose
10
What is the role of nitrogen-fixing bacteria?
Answer
(A)
To convert atmospheric nitrogen into a form plants can use.
11
What process is primarily responsible for returning carbon dioxide to the atmosphere?
Answer
(B)
Respiration
12
What is an example of a decomposer?
Answer
(C)
Mushroom
13
What is the role of bacteria and fungi in the carbon cycle?
Answer
(B)
They decompose dead organisms, releasing carbon.
14
What do the arrows in a food chain represent?
Answer
(B)
The direction of energy flow.
15
How does the energy transfer happen in an ecosystem?
Answer
(A)
Producers -> Consumers -> Decomposers
16
Which of these organisms is a primary consumer?
Answer
(C)
A cow
17
Which human activities directly contribute to the release of nitrogen into the environment?
Answer
A
B
18
What is the process that releases energy stored in glucose?
Answer
(B)
Respiration
19
What is the result of the burning of fossil fuels in relation to the carbon cycle?
Answer
(C)
It releases stored carbon into the atmosphere.
20
What are the key ingredients for photosynthesis?
Answer
(B)
Carbon dioxide and water
21
What is the role of the enzyme in decomposition?
Answer
(A)
To speed up chemical reactions in organic waste.
22
What is the process by which nitrogen is removed from the atmosphere and converted into a form usable by plants?
Answer
(C)
Nitrogen fixation
23
What would happen to the carbon cycle if there were no decomposers?
Answer
(B)
Carbon would be trapped in dead organisms.
24
Which of these processes are part of the carbon cycle?
Answer
A
B
D
25
How does energy flow through an ecosystem?
Answer
(C)
From producers to consumers to decomposers.
26
What is the primary function of decomposers in an ecosystem?
Answer
(B)
To break down dead organisms and recycle nutrients.
27
What is the main function of respiration in organisms?
Answer
(B)
To convert energy from food to a usable form.
28
What would happen if all the decomposers disappeared from an ecosystem?
Answer
(B)
Nutrients would not be recycled, and dead organisms would accumulate.
29
What organisms are responsible for breaking down dead plants and animals?
Answer
(C)
Decomposers
30
In the nitrogen cycle, what is the function of the bacteria in root nodules of plants?
Answer
(B)
To convert nitrogen gas into a form usable by plants.
31
What role does lightning play in the nitrogen cycle?
Answer
(A)
It converts nitrogen gas into usable forms for plants.
32
How is energy transferred between trophic levels?
Answer
(C)
Through feeding relationships
33
What is the difference between a food chain and a food web?
Answer
(B)
A food chain only shows one path of energy, while a food web shows multiple paths.
34
What is the main role of primary consumers in a food web?
Answer
(A)
To eat producers.
35
What type of consumer eats other consumers?
Answer
(B)
Secondary
36
What is the role of decomposers?
Answer
A
B
37
What do the arrows in a food web represent?
Answer
(B)
The direction of energy flow.
38
Which process releases the carbon that is stored in fossil fuels back into the atmosphere?
Answer
(C)
Combustion
39
What type of consumers eat other animals?
Answer
(B)
Carnivores
40
What are some of the ways in which nitrogen enters an ecosystem?
Answer
A
B
41
What type of organism gets energy by eating other organisms?
Answer
(C)
A consumer
42
In a food chain, which of the following best represents the flow of energy?
Answer
(C)
From producers to consumers, then to decomposers.
43
What is the process by which nitrates are converted back into nitrogen gas?
Answer
(D)
Denitrification
44
Which of these are the products of photosynthesis?
Answer
(C)
Glucose and oxygen
45
Which of the following is an example of a producer?
Answer
(B)
A tree
46
Which of the following is a human activity that impacts the carbon cycle?
Answer
A
B
47
Which of the following processes are key components of the carbon cycle?
Answer
A
B
D
48
Which of the following is a correct statement about the nitrogen cycle?
Answer
B
C
D
49
What is the role of nitrification in the nitrogen cycle?
Answer
A
B
50
In the carbon cycle, where does carbon dioxide go after it is released during respiration?
Answer
(C)
Into the atmosphere