Organisms and Population Chapter-Wise Test 26

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following species interactions involves one species benefiting while the other is unaffected?

Mutualism
Commensalism
Parasitism
Competition
2

In commensalism, one species benefits while the other is neither harmed nor helped.

Which of the following species interactions is similar to predation?

Commensalism
Parasitism
Mutualism
Amensalism
2

Parasitism, like predation, benefits one species while harming the other, but parasites do not immediately kill their host.

Which of the following is a correct statement about ecological pyramids?

Pyramids of biomass are always upright.
Pyramids of energy can sometimes be inverted.
Pyramids of numbers can be inverted in some ecosystems.
Energy is not lost as heat at any trophic level.
3

In some ecosystems, such as forests, a few large trees support many herbivores, leading to an inverted pyramid of numbers.

Which of the following is an example of a keystone species?

Cattle grazing on grass
Tiger in a forest ecosystem
Rabbit in a grassland
Sparrow in an urban ecosystem
2

Tigers regulate prey populations and maintain ecosystem balance, making them keystone species.

Which factor is a major cause of population fluctuations in nature?

Genetic mutations
Climate variability
Individual adaptation
Internal organ development
2

Climate variability, such as droughts or temperature changes, can lead to fluctuations in population size.

What does the carrying capacity (K) of an environment represent?

Maximum number of individuals an environment can support
Total number of individuals born each year
Average lifespan of a species
Maximum number of species in an ecosystem
1

Carrying capacity (K) is the maximum population size that an environment can sustain over time.

Which population interaction involves one species benefiting while the other is harmed?

Mutualism
Commensalism
Parasitism
Amensalism
3

Parasitism benefits the parasite while harming the host by deriving nutrients or resources.

Which of the following factors is NOT density-dependent?

Competition for food
Spread of disease
Natural disasters
Predation
3

Natural disasters affect populations regardless of their density, making them density-independent factors.

Which of the following best describes the role of a keystone species in an ecosystem?

It is the most abundant species in the ecosystem
It has a disproportionately large impact on ecosystem stability
It is always at the top of the food chain
It contributes to primary productivity
2

A keystone species plays a critical role in maintaining ecosystem balance, even if it is not the most abundant.

Which of the following correctly defines immigration in population ecology?

Movement of individuals out of a population
Movement of individuals into a population
Birth rate increase
Death rate decrease
2

Immigration refers to the movement of individuals into a population, increasing its size.

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