Organisms and Populations Practice Questions
Class 12 · Biology · 2842 free MCQs with instant results and detailed explanations.
2842
Total
877
Easy
1404
Medium
561
Hard
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Topics in Organisms and Populations
Populations
935
Population Interactions
936
Organism and Environment
971
Sample Questions from Organisms and Populations
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
Which of the following terms refers to the role an organism plays in its environment?
A.
Niche
B.
Habitat
C.
Biome
D.
Ecosystem
Show Answer & Explanation
Correct Answer: A
A niche encompasses how an organism interacts with its environment, including its role in the ecosystem.
Q2
Easy
What is the primary factor affecting the distribution of organisms?
A.
Soil pH
B.
Temperature
C.
Precipitation
D.
All of the above
Show Answer & Explanation
Correct Answer: D
All listed factors, including soil pH, temperature, and precipitation, significantly affect organism distribution.
Q3
Easy
The number of individuals of a species per unit area is referred to as what?
A.
Biomass
B.
Population density
C.
Carrying capacity
D.
Biodiversity
Show Answer & Explanation
Correct Answer: B
Population density refers to the number of individuals of a species living in a specific area.
Q4
Medium
Which of the following factors is considered abiotic in an ecosystem?
A.
Temperature
B.
Fungi
C.
Plants
D.
Animals
Show Answer & Explanation
Correct Answer: A
Temperature is an abiotic factor that influences the living organisms in an ecosystem.
Q5
Medium
In a given habitat, if the temperature increases, which of the following changes is likely to occur in species distribution?
A.
Decrease in species diversity
B.
Increase in species diversity
C.
No change in species diversity
D.
Random distribution of species
Show Answer & Explanation
Correct Answer: A
Higher temperatures can stress certain species, leading to a decrease in diversity as some species may not survive.
Q6
Medium
What term describes the role of an organism in its ecosystem, including its habitat and interactions with other organisms?
A.
Niche
B.
Habitat
C.
Community
D.
Population
Show Answer & Explanation
Correct Answer: A
A niche encompasses everything about an organism’s role and interactions within its environment.
Q7
Medium
Which of the following is a density-dependent factor affecting population growth?
A.
Natural disasters
B.
Competition for resources
C.
Climate change
D.
Habitat destruction
Show Answer & Explanation
Correct Answer: B
Competition for resources increases as population density rises, affecting growth rates.
Q8
Hard
Which of the following statements correctly describes the concept of ecological niche?
A.
An ecological niche is the role and position a species has in its environment.
B.
An ecological niche refers only to the habitat of a species.
C.
An ecological niche is the physical space occupied by an organism.
D.
An ecological niche is the sum of biotic and abiotic factors affecting a species.
Show Answer & Explanation
Correct Answer: A
The ecological niche encompasses the role and position a species holds within its ecosystem, including its interactions with other organisms and its environment.
Q9
Hard
Which of the following factors is NOT a density-dependent factor affecting population growth?
A.
Disease
B.
Competition
C.
Natural disasters
D.
Predation
Show Answer & Explanation
Correct Answer: C
Natural disasters are density-independent factors because they affect populations regardless of their density, unlike disease, competition, and predation.
Q10
Hard
In a layered forest ecosystem, which layer is primarily responsible for photosynthesis?
A.
Understory layer
B.
Forest floor
C.
Canopy layer
D.
Emergent layer
Show Answer & Explanation
Correct Answer: C
The canopy layer receives the most sunlight and is thus primarily responsible for photosynthesis in a forest ecosystem.
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Organisms and Populations — Class 12 Biology Practice Questions Online
This page contains 2842 practice MCQs for the chapter Organisms and Populations in Class 12 Biology. The questions are organized by difficulty — 877 easy, 1404 medium, 561 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. This chapter covers 3 topics, giving you comprehensive coverage of the entire chapter.