Vidaara.orgClass 12 · Mathematics
CodeVID-M12-WS
Organisms and Populations — Practice Worksheet
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Choose the correct option (A, B, C or D) for each question.
- The answer key is at the end — try the paper first!
Section A — Multiple Choice (1 mark each)
15 × 1 = 15 marks
1.
The study of organisms and their interactions with the environment is:
- A.Ecology
- B.Genetics
- C.Anatomy
- D.Cytology
2.
The place where an organism lives is its:
- A.Habitat
- B.Niche only
- C.Population
- D.Tissue
3.
Temperature, light and soil are ____ factors.
- A.Biotic
- B.Abiotic
- C.Living
- D.Animal
4.
Spines and a thick waxy stem in a cactus help it to:
- A.Reduce water loss
- B.Catch insects
- C.Float
- D.Make sound
5.
Winter sleep by which some animals escape the cold is:
- A.Aestivation
- B.Hibernation
- C.Migration only
- D.Predation
6.
A group of organisms of the same species in an area is a:
- A.Population
- B.Community
- C.Habitat
- D.Niche
7.
The number of individuals per unit area is the:
- A.Sex ratio
- B.Population density
- C.Age
- D.Habitat
8.
The proportion of young, adult and old individuals is the:
- A.Age structure
- B.Density
- C.Birth rate
- D.Sex ratio
9.
Unlimited resources produce a ____ growth curve.
- A.J-shaped (exponential)
- B.Flat
- C.Circular
- D.Negative
10.
The maximum population an environment can support is its:
- A.Carrying capacity (K)
- B.Sex ratio
- C.Density only
- D.Habitat
11.
A more realistic, S-shaped population curve is called:
- A.Logistic (sigmoid)
- B.Exponential
- C.Linear
- D.Random
12.
A lion eating a deer is an example of:
- A.Predation
- B.Mutualism
- C.Commensalism
- D.Competition
13.
Two plants struggling for the same sunlight show:
- A.Competition
- B.Mutualism
- C.Parasitism
- D.Commensalism
14.
Bees and flowers, where both benefit, show:
- A.Mutualism
- B.Predation
- C.Parasitism
- D.Competition
15.
An orchid growing on a tree for support (tree unaffected) is:
- A.Commensalism
- B.Parasitism
- C.Predation
- D.Mutualism
Section B — Challenge / Olympiad (2 marks each)
6 × 2 = 12 marks
16.
A J-shaped growth curve cannot continue forever in nature because:
- A.Resources are limited (carrying capacity)
- B.Animals stop breeding by choice
- C.Births are banned
- D.There is no death
17.
Removing all predators from an area can harm the ecosystem because the prey may:
- A.Overpopulate and exhaust resources
- B.Disappear at once
- C.Become predators
- D.Stop eating
18.
An age pyramid with a very broad base (many young) suggests the population will likely:
- A.Grow in the future
- B.Decline at once
- C.Stay forever fixed
- D.Vanish
19.
Lichens (alga + fungus) are mutualistic because the alga makes food while the fungus:
- A.Provides shelter, water and minerals
- B.Eats the alga
- C.Harms the alga
- D.Does nothing
20.
A desert kangaroo rat surviving with very little drinking water shows an adaptation to a key ____ factor.
- A.Abiotic (water scarcity)
- B.Biotic
- C.Predatory
- D.Social
21.
Both competition and parasitism harm at least one partner, but they differ because in competition:
- A.Both organisms are harmed by sharing a resource
- B.One lives inside the other
- C.Both benefit
- D.Neither is affected
Answer Key
Section A — Multiple Choice (1 mark each)
- (A) Ecology
- (A) Habitat
- (B) Abiotic
- (A) Reduce water loss
- (B) Hibernation
- (A) Population
- (B) Population density
- (A) Age structure
- (A) J-shaped (exponential)
- (A) Carrying capacity (K)
- (A) Logistic (sigmoid)
- (A) Predation
- (A) Competition
- (A) Mutualism
- (A) Commensalism
Section B — Challenge / Olympiad (2 marks each)
- (A) Resources are limited (carrying capacity)
- (A) Overpopulate and exhaust resources
- (A) Grow in the future
- (A) Provides shelter, water and minerals
- (A) Abiotic (water scarcity)
- (A) Both organisms are harmed by sharing a resource
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