This set of Class 12 Biology Chapter 13 Multiple Choice Questions & Answers (MCQs) focuses on “Population Interactions-1”.
1. What is the interaction between species in which the fitness of one overpowers the presence and fitness of another called?
a) Competition
b) Mutualism
c) Parasitism
d) Commensalism
View Answer
Explanation: In competition interaction, the fitness of one organism overpowers the presence and fitness of another. In these organisms of same or different species, living in the same or different community fights for the same resources.
2. Who gave the following sentence “Two closely related species competing for the same resources cannot co-exist indefinitely and the competitively inferior will be eliminated eventually”?
a) Gause’s competitive exclusion principle
b) Mutation Theory
c) Theory of Special Creation
d) Theory of Organic Evolution
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Explanation: The above sentence is given by Gause’s competitive exclusion principle. It states that two species having the same resources cannot live together at constant population values. The inferior species will be eliminated with time due to natural selection.
3. Where the interference competition does occur directly between individuals?
a) Two species have a common prey
b) One individual prevents the reproduction of others
c) Organism compete for space
d) Two separate species compete for the same resources and space
View Answer
Explanation: The interference competition is where one individual prevents the reproduction of others. Along with this, the survival of other species is also prevented. It can occur via aggression and is thought to stabilize consumer-resource systems.
4. Where exploitation competition does occur indirectly?
a) One individual prevents the survival and reproduction of others
b) Two species have common prey
c) Two separate species compete for different resources and space
d) Organisms compete for common space
View Answer
Explanation: The exploitation competition occurs indirectly when organisms compete for common resources like space or territory, food or prey. It results in depletion in the availability and amount of resources.
5. In which two species apparent competition occurs indirectly?
a) Compete for space
b) Fight for the same resources and mate
c) Have a common prey
d) Share the same resources in a territory
View Answer
Explanation: The apparent competition occurs indirectly between two species that fight for the same prey. In this, both the species may serve as prey for a common predator. It is an indirect negative interaction.
6. What is a competition between the individuals of two separate species for sharing the same resources in the same area known?
a) Apparent competition
b) Interspecific competition
c) Interference competition
d) Intraspecific competition
View Answer
Explanation: Interspecific competition is the competition between the individuals of two separate species for sharing the same resources in the same area. An example is tigers and lions living in the same area competing for the same prey.
7. What is a biological interaction between organisms of different species in which each individual receives benefit known?
a) Parasitism
b) Competition
c) Commensalism
d) Mutualism
View Answer
Explanation: Mutualism is a biological interaction between organisms of different species in which each individual receives a benefit. It is a positively directed relationship since both organisms are benefited.
8. What happens to two species in mutualism?
a) Only one is benefited
b) Both live differently
c) Both are benefited
d) Only one is harmed
View Answer
Explanation: Mutualism is a biological interaction between organisms of different species in which each individual receives a benefit. It is a positively directed relationship since both organisms are benefited.
9. What kind of interaction is mutualism?
a) Negative Interspecific
b) Positive Intraspecific
c) Negative Intraspecific
d) Positive Interspecific
View Answer
Explanation: Mutualism is a positively directed interspecific relationship. It is a biological interaction between organisms of different species in which each individual receives the benefit.
10. Who benefits the ungulates?
a) Sponges
b) Virus
c) Bacteria
d) Grass
View Answer
Explanation: Bacteria living in the intestine of ungulates benefit them. Since many of them are herbivores the gut-bacteria help in the digestion of cellulose. Most of the gut-bacteria are anaerobic in nature.
11. Who produces the cellulase in the intestine of ungulates?
a) Bacteria
b) Mosses
c) Lichens
d) Protozoa
View Answer
Explanation: Various bacterial species produce the cellulase in the intestine of ungulates. Since many of them are herbivores the gut-bacteria help in the digestion of cellulose. Most of the gut-bacteria are anaerobic in nature.
12. Which type of interaction does a mycorrhiza show?
a) Predation
b) Parasitism
c) Mutualism
d) Commensalism
View Answer
Explanation: Mycorrhiza is a mutualistic interaction between fungi and plants. About 80-90 percent of plants rely on mycorrhiza for the uptake of minerals (nitrogen, phosphorous, etc.) from the soil. While plants supply essential nutrients such as sugars to fungi for their proper growth.
13. What percent of land plants rely on mycorrhizal relationships?
a) 82%
b) 52%
c) 29%
d) 10%
View Answer
Explanation: Almost 80% of plants rely on the mycorrhizal relationship. Mycorrhiza is a mutualistic interaction between fungi and plants. Plants rely on mycorrhiza for the uptake of minerals (nitrogen, phosphorous, etc.) from the soil, while plants supply essential nutrients such as sugars to fungi for their proper growth.
14. Which relation does “sharing of food” describes?
a) Competition
b) Mutualism
c) Parasitism
d) Commensalism
View Answer
Explanation: The phrase “sharing of food” or “sharing of the table” describes commensalism. It is a long-term relationship between two species in which one species derives the benefit while other is neither harmed nor benefited.
15. Which relationship does an orchid growing as an epiphyte on a tree describe?
a) Commensalism
b) Mutualism
c) Parasitism
d) Amensalism
View Answer
Explanation: An orchid growing on epiphyte is an example of commensalism. Epiphytes grow on trees for air and sunlight while the tree is not harmed due to its presence. Another epiphyte growing on trees is a fern.
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