Part 8 – Population Interactions: Mutualism & Commensalism
Part 8 – Population Interactions: Mutualism & Commensalism
Q1.
Mutualism is an interaction in which:
a) Both species are harmed
b) One benefits, other harmed
c) Both species benefit
d) One benefits, other unaffected
Answer: c) Both species benefit
Explanation:
- (a) Competition.
- (b) Predation/parasitism.
- (c) Correct → Mutualism = +/+ interaction.
- (d) Commensalism.
Q2.
Commensalism is an interaction in which:
a) Both benefit
b) One benefits, other unaffected
c) Both are harmed
d) One benefits, other harmed
Answer: b) One benefits, other unaffected
Explanation:
Classic +/0 relationship.
Q3.
Which of the following is an example of mutualism?
a) Lichen (algae + fungi)
b) Orchid on mango tree
c) Cuscuta on host plant
d) Koel laying eggs in crow nest
Answer: a) Lichen (algae + fungi)
Explanation:
- (a) Correct → Alga photosynthesizes, fungus absorbs water.
- (b) Orchid on tree = commensalism.
- (c) Cuscuta = parasitism.
- (d) Koel = brood parasitism.
Q4.
Which of the following shows commensalism?
a) Orchid on mango tree
b) Mycorrhiza
c) Lichen
d) Cuscuta
Answer: a) Orchid on mango tree
Explanation:
Orchid benefits by support, tree unaffected.
Q5.
Mycorrhiza is an example of:
a) Commensalism
b) Mutualism
c) Competition
d) Amensalism
Answer: b) Mutualism
Explanation:
Fungi absorb water/minerals, plant provides sugars.
Q6.
Rhizobium in root nodules of legumes represents:
a) Commensalism
b) Parasitism
c) Mutualism
d) Amensalism
Answer: c) Mutualism
Explanation:
Rhizobium fixes nitrogen, legume supplies food → both benefit.
Q7.
Clownfish living among sea anemone tentacles is an example of:
a) Commensalism
b) Mutualism
c) Amensalism
d) Predation
Answer: b) Mutualism
Explanation:
Clownfish gets protection, anemone gets cleaning & lure for prey.
Q8.
Which pollination system is a mutualism?
a) Bees pollinating flowers
b) Birds using trees for nesting
c) Cuckoo laying eggs in crow’s nest
d) Barnacles on whales
Answer: a) Bees pollinating flowers
Explanation:
Bees gain nectar, flowers get pollinated.
Q9.
The relationship between sea anemone and hermit crab is:
a) Commensalism
b) Mutualism
c) Parasitism
d) Competition
Answer: b) Mutualism
Explanation:
Hermit crab gets protection, anemone gets mobility and food scraps.
Q10.
An orchid growing on a mango tree without harming it represents:
a) Commensalism
b) Mutualism
c) Parasitism
d) Amensalism
Answer: a) Commensalism
Explanation:
Orchid benefits by support, mango tree unaffected.
Q11.
Barnacles on the body of a whale represent:
a) Commensalism
b) Parasitism
c) Mutualism
d) Amensalism
Answer: a) Commensalism
Explanation:
Barnacles get transport, whale unaffected.
Q12.
Lichen is a symbiotic association between:
a) Alga and fungus
b) Plant and bacteria
c) Fungus and root
d) Plant and plant
Answer: a) Alga and fungus
Explanation:
Classic textbook mutualism.
Q13.
Which of the following is NOT mutualism?
a) Mycorrhiza
b) Lichen
c) Orchid on mango tree
d) Rhizobium–legume
Answer: c) Orchid on mango tree
Explanation:
That’s commensalism, not mutualism.
Q14.
What type of interaction is seen between egret birds and grazing cattle?
a) Commensalism
b) Mutualism
c) Parasitism
d) Amensalism
Answer: a) Commensalism
Explanation:
Egrets eat insects flushed by cattle; cattle unaffected.
Q15.
Yucca plant and moth interaction is an example of:
a) Mutualism with co-evolution
b) Commensalism
c) Parasitism
d) Amensalism
Answer: a) Mutualism with co-evolution
Explanation:
Yucca pollinated by moth; moth lays eggs in flowers → both benefit.
Q16.
Which interaction helps invasive plants succeed by avoiding native competitors?
a) Commensalism
b) Mutualism
c) Escape from competition
d) Facilitation by mutualists
Answer: d) Facilitation by mutualists
Explanation:
Some invasives form strong mutualisms (e.g., with mycorrhizae).
Q17.
The relationship between cleaner fish and large fishes is:
a) Commensalism
b) Mutualism
c) Parasitism
d) Predation
Answer: b) Mutualism
Explanation:
Cleaner fish remove parasites → both benefit.
Q18.
The interaction between epiphytic ferns and mango tree is:
a) Mutualism
b) Commensalism
c) Parasitism
d) Competition
Answer: b) Commensalism
Explanation:
Fern uses tree only for support.
Q19.
The nitrogen-fixing cyanobacteria (Anabaena) in water fern (Azolla) show:
a) Commensalism
b) Mutualism
c) Amensalism
d) Parasitism
Answer: b) Mutualism
Explanation:
Cyanobacteria fix nitrogen, Azolla provides shelter.
Q20.
Which of the following is NOT a commensalistic association?
a) Barnacles on whales
b) Epiphytic orchids on trees
c) Egret and grazing cattle
d) Lichen
Answer: d) Lichen
Explanation:
Lichen is mutualism, not commensalism.
Q21.
What is the ecological significance of mutualism?
a) Helps in resource partitioning
b) Improves survival and reproduction of partners
c) Maintains balance in ecosystem
d) All of the above
Answer: d) All of the above
Explanation:
Mutualism stabilizes ecosystems and enhances adaptation.
Q22.
Which pollinator–plant interaction is species-specific?
a) Yucca–moth
b) Bee–sunflower
c) Bat–banana
d) Wind–grass
Answer: a) Yucca–moth
Explanation:
Obligate mutualism → moth only pollinates yucca.
Q23.
The cattle egret removing insects stirred by grazing cattle is:
a) Mutualism
b) Commensalism
c) Parasitism
d) Competition
Answer: b) Commensalism
Explanation:
Egret benefits, cattle unaffected.
Q24.
The relationship between man and intestinal bacteria producing vitamins is:
a) Commensalism
b) Mutualism
c) Amensalism
d) Parasitism
Answer: b) Mutualism
Explanation:
Bacteria get food and shelter; humans get vitamins.
Q25.
Which of the following is a +/0 interaction?
a) Commensalism
b) Mutualism
c) Parasitism
d) Competition
Answer: a) Commensalism
Explanation:
By definition, one benefits (+), other unaffected (0).
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