Ecology Practice Questions
WAEC (West Africa) · WAEC Biology · 145 free MCQs with instant results and detailed explanations.
145
Total
41
Easy
78
Medium
26
Hard
Start Practicing Ecology
Take a timed quiz or customize your practice session
Sample Questions from Ecology
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
Which of the following terms describes the role of an organism in its environment, including its habitat and interactions with other organisms?
A.
Ecological niche
B.
Ecosystem
C.
Community
D.
Population
Show Answer & Explanation
Correct Answer: A
An ecological niche refers to the specific role and position a species has in its environment, which includes its habitat, resource use, and interactions with other species. This is why option A is the correct answer.
Q2
Easy
In an ecosystem, which of the following groups of organisms is primarily responsible for the decomposition of organic matter?
A.
Producers
B.
Consumers
C.
Decomposers
D.
Herbivores
Show Answer & Explanation
Correct Answer: C
Decomposers are organisms, such as fungi and bacteria, that break down dead organic matter, returning nutrients to the soil and making them available for producers. Thus, option C is correct.
Q3
Easy
Which of the following factors is a biotic component of an ecosystem?
A.
Soil pH
B.
Temperature
C.
Plants
D.
Water availability
Show Answer & Explanation
Correct Answer: C
Biotic components of an ecosystem refer to the living organisms that inhabit it, such as plants, animals, and microorganisms. Plants are living organisms, making option C the correct choice.
Q4
Medium
Which of the following factors is considered a biotic factor in an ecosystem?
A.
Soil type
B.
Temperature
C.
Predation
D.
pH level
Show Answer & Explanation
Correct Answer: C
Predation is a biotic factor because it involves living organisms interacting with each other. The other options are abiotic factors, which are non-living components.
Q5
Medium
In a food web, which of the following organisms typically occupies the second trophic level?
A.
Carnivores
B.
Producers
C.
Decomposers
D.
Herbivores
Show Answer & Explanation
Correct Answer: D
Herbivores occupy the second trophic level as they consume producers (plants), while carnivores are at higher levels, and decomposers break down organic matter.
Q6
Medium
If the population of a certain species doubles every year, and it started with 100 individuals, how many individuals will there be after 3 years?
A.
200
B.
400
C.
800
D.
1600
Show Answer & Explanation
Correct Answer: D
The population doubles each year: Year 1: 100, Year 2: 200, Year 3: 400, Year 4: 800 (end of Year 3). Thus, after 3 years, there will be 800 individuals.
Q7
Medium
What role do decomposers play in an ecosystem?
A.
They produce energy.
B.
They consume producers.
C.
They recycle nutrients.
D.
They compete with herbivores.
Show Answer & Explanation
Correct Answer: C
Decomposers break down dead organic matter and recycle nutrients back into the soil, supporting the growth of producers.
Q8
Hard
In a given ecosystem, if the primary producers are reduced by 50%, what is the most likely immediate effect on the primary consumers?
A.
They will thrive and increase in population.
B.
Their population will decrease due to food shortage.
C.
They will adapt to feed on secondary consumers.
D.
Their population will remain unchanged.
Show Answer & Explanation
Correct Answer: B
If primary producers are reduced by 50%, primary consumers lose a significant portion of their food source, leading to a decrease in their population.
Q9
Hard
A certain lake ecosystem has a nitrogen concentration of 1.5 mg/L. If the nitrogen cycle processes in this ecosystem are disrupted, what is the most probable ecological consequence?
A.
Increase in aquatic plant growth.
B.
Decrease in fish populations due to oxygen depletion.
C.
Enhanced biodiversity of aquatic species.
D.
Reduction in water clarity and quality.
Show Answer & Explanation
Correct Answer: B
A disruption in the nitrogen cycle can lead to excessive nutrient buildup, causing algal blooms which deplete oxygen in the water, negatively impacting fish populations.
Q10
Hard
In an ecological pyramid, which of the following statements is true regarding the energy flow from producers to apex predators?
A.
Energy is transferred efficiently with minimal losses.
B.
Energy flow decreases significantly at each trophic level.
C.
Producers receive energy directly from apex predators.
D.
Energy flow remains constant across all levels.
Show Answer & Explanation
Correct Answer: B
Energy flow decreases significantly at each trophic level due to energy loss through metabolic processes, heat, and waste. Thus, only a fraction of energy is transferred to the next level.
Showing 10 of 145 questions. Start a quiz to practice all questions with scoring and timer.
Practice All 145 Questions →Other WAEC (West Africa) Subjects
Ecology — WAEC (West Africa) WAEC Biology Practice Questions Online
This page contains 145 practice MCQs for the chapter Ecology in WAEC (West Africa) WAEC Biology. The questions are organized by difficulty — 41 easy, 78 medium, 26 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.