Part 7 – Population Interactions: Competition

Q1.

Competition is an interaction in which:
a) Both species benefit
b) One benefits, other harmed
c) Both are harmed
d) Neither benefits

Answer: c) Both are harmed

Explanation:

(a) Mutualism.
(b) Predation/parasitism.
(c) Correct → Competition wastes energy/resources, both harmed.
(d) Neutralism.

Q2.

Which principle states that two species competing for the same resource cannot coexist?
a) Hardy–Weinberg principle
b) Competitive exclusion principle
c) Coexistence principle
d) Carrying capacity principle

Answer: b) Competitive exclusion principle

Explanation:

(a) Hardy–Weinberg → Genetics.
(b) Correct → Gause’s law.
(c) Wrong.
(d) Related but not this.

Q3.

Who proposed the competitive exclusion principle?
a) Darwin
b) Gause
c) Malthus
d) Wallace

Answer: b) Gause

Explanation:
Based on experiments with Paramecium aurelia and P. caudatum.

Q4.

In Gause’s experiment, which Paramecium species survived when grown together?
a) P. caudatum
b) P. aurelia
c) Both
d) Neither

Answer: b) P. aurelia

Explanation:
P. aurelia outcompeted P. caudatum.

Q5.

Which of the following is an example of interspecific competition?
a) Two lions fighting
b) Crow and koel competing for nest
c) Two sparrows competing for food
d) Male deers fighting

Answer: b) Crow and koel competing for nest

Explanation:

(a, c, d) → Intraspecific (within species).
(b) Correct → Crow and koel are different species.

Q6.

Intraspecific competition is:
a) Between different species
b) Between members of same species
c) Always beneficial
d) Absent in nature

Answer: b) Between members of same species

Explanation:
Classic example → Plants competing for sunlight, water.

Q7.

Which is more severe: intra- or interspecific competition?
a) Interspecific
b) Intraspecific
c) Both equal
d) Neither

Answer: b) Intraspecific

Explanation:
Members of the same species require identical resources → competition stronger.

Q8.

Darwin described competition as:
a) Struggle for power
b) Struggle for existence
c) Struggle for dominance
d) Struggle for survival of predators

Answer: b) Struggle for existence

Explanation:
Competition is central to natural selection (“survival of the fittest”).

Q9.

Which of the following is an example of competition in plants?
a) Opuntia and cactus
b) Parthenium and native plants
c) Cuscuta and host plant
d) Algae and fungi in lichen

Answer: b) Parthenium and native plants

Explanation:
Parthenium (invasive) competes with indigenous vegetation.

Q10.

Resource partitioning reduces:
a) Predation
b) Competition
c) Mutualism
d) Commensalism

Answer: b) Competition

Explanation:
Species use different resources/niches to reduce overlap.

Q11.

An example of resource partitioning in lizards is:
a) Sharing same tree but different perching sites
b) Sharing same fruit equally
c) Competing until one goes extinct
d) Mimicry

Answer: a) Sharing same tree but different perching sites

Explanation:
Reduces direct competition → coexistence.

Q12.

Barnacles (Balanus and Chthamalus) on rocky coasts demonstrate:
a) Predation
b) Competition and niche differentiation
c) Mutualism
d) Commensalism

Answer: b) Competition and niche differentiation

Explanation:
Gause-like competition in nature → one occupies high tide, other low tide zone.

Q13.

The term “competitive release” means:
a) Increase in population size when competitor is removed
b) Decline in population due to competition
c) Predator removal
d) Migration to new habitat

Answer: a) Increase in population size when competitor is removed

Explanation:
Seen in barnacles and other field studies.

Q14.

Competition can lead to:
a) Competitive exclusion
b) Resource partitioning
c) Competitive release
d) All of the above

Answer: d) All of the above

Explanation:
Competition outcomes vary depending on ecological context.

Q15.

In which case can competition promote species coexistence?
a) When resources are completely overlapping
b) When resources are partially overlapping with partitioning
c) When predator is present
d) Never

Answer: b) When resources are partially overlapping with partitioning

Explanation:
Species can coexist by dividing resources.

Q16.

An example of intraspecific competition in animals is:
a) Deer and rabbit competing for grass
b) Two tigers fighting for territory
c) Sparrow and crow competing for food
d) Lion and hyena competing for prey

Answer: b) Two tigers fighting for territory

Explanation:
Same species → intraspecific.

Q17.

Which invasive plant is a strong competitor in India?
a) Cuscuta
b) Parthenium
c) Viscum
d) Loranthus

Answer: b) Parthenium

Explanation:
Exotic weed → competes strongly with native flora.

Q18.

Competition is a type of interaction where:
a) +/+
b) +/–
c) –/–
d) 0/0

Answer: c) –/–

Explanation:
Both suffer in terms of reduced availability of resources.

Q19.

Which is an example of interference competition?
a) Plants shading others
b) Bacteria secreting antibiotics
c) Tiger killing deer
d) Algae competing for light

Answer: b) Bacteria secreting antibiotics

Explanation:
Direct harm to competitor = interference. Others are exploitation competition.

Q20.

Which type of niche overlap increases competition the most?
a) No overlap
b) Partial overlap
c) Complete overlap
d) Random overlap

Answer: c) Complete overlap

Explanation:
According to Gause → complete overlap → exclusion.

Q21.

Which pair shows interspecific competition?
a) Tiger vs tiger
b) Crow vs koel
c) Parthenium vs native herbs
d) Both b and c

Answer: d) Both b and c

Explanation:
Crow–koel (nest), Parthenium–native herbs (space/resources).

Q22.

An example of competition between predator species is:
a) Lion vs zebra
b) Lion vs hyena
c) Cow vs goat
d) Deer vs rabbit

Answer: b) Lion vs hyena

Explanation:
Both compete for same prey (zebra, antelope).

Q23.

Competition can sometimes lead to:
a) Speciation
b) Extinction
c) Niche differentiation
d) All of the above

Answer: d) All of the above

Explanation:
Competition is a strong evolutionary force.

Q24.

What is the ecological outcome when two species completely compete for same resources?
a) Coexistence
b) One excluded (extinct locally)
c) Both flourish
d) Both migrate

Answer: b) One excluded (extinct locally)

Explanation:
Competitive exclusion principle.

Q25.

Which of the following is an example of amensalism (linked to competition)?
a) Penicillium secreting antibiotics killing bacteria
b) Cuscuta on host plant
c) Koel in crow’s nest
d) Deer grazing grass

Answer: a) Penicillium secreting antibiotics killing bacteria

Explanation:
Fungus not affected (0), bacteria harmed (–).

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Part 7 – Population Interactions: Competition