Free Man and His Environment MCQs with Answers

131. Which of the following represents the 'niche' of a species?

• A. The habitat and specific functions of a species
• B. The specific place where an organism lives
• C. The specific specie's function and its competitive power
• D. none of these.

Explanation: Niche/ecological niche is the specific part of a habitat occupied by individuals of a species which is circumscribed by its range of tolerance, range of movement, microclimate, type of food and its availability, shelter, type of predator and timing of activity. A habitat has several ecological niches and supports a number of species. An ecological niche is used by a single species. Two or more species cannot use the same niche despite having a mutualistic association. Organisms or populations in competition have a niche overlap of a limited resource for which they compete. Both owls and cats feed on shrews and mice. They occupy the same niche because of being ecological equivalents though their habitats are different.

132. Which one of the following pairs is correctly matched?

• A. Parasitism ­- intraspecific relationship
• B. Uricotelism -­ aquatic habitat
• C. Excessive perspiration ­- xeric adaptation
• D. Streamlined body ­- aquatic adaptation

Explanation: A streamlined body is a secondary aquatic adaption. It is found in animals that live permanently in water but most of them are amphibious in nature. The streamlined body consists of compression of head, body and tail into a curved streamlined form. There is no protruberance over the body so that the animal can move easily through water. Parasitism is a relationship between two organisms of different species in which one organism called a parasite obtains its food directly from another living organism called the host. In xeric adaptations, perspiration is reduced to conserve water. Uricotelism is characteristic of terrestrial animals which excrete uric acid.

133. Study of inter­-relationships between organisms and their environment is

• A. ecology
• B. ecosystem
• C. phytogeography
• D. ethology.

Explanation: Ecology is the branch of science which deals with the study of inter-­relationship between organisms and their environment. The scope of ecology is very vast as it treats the organisms at the level of population, community and ecosystem.

134. The sum total of the populations of the same kind of organisms constitutes a

• A. colony
• B. genus
• C. community
• D. species.

Explanation: The sum total of the populations of the same kind of organisms constitutes a species. A species is a group of individuals of same kind of phenotypic characters that can interbreed.

135. The association of animals where both partners are benefitted is called _

• A. a colony
• B. mutualism
• C. commensalism
• D. ammensalism.

Explanation: In mutualism or symbiosis, both the organisms in association are mutually benefitted and further this association is obligatory, i.e., necessary for the existence of both organisms. Mycorrhiza is an example of symbiosis. It is the association between roots of higher plants and fungal hyphae. The fungal hyphae supply water and nutrients to the plant and in turn, get food from the plant. So both the organisms are mutually benefitted.

136. Fertility of soil is measured by its ability to

• A. Retain nutrients
• B. Hold organic materials
• C. hold water
• D. support life.

Explanation: Soil fertility is the characteristic of soil that supports abundant plant life. In particular the term is used to describe agricultural and garden soil.

137. Soil particles determine its

• A. texture
• B. field capacity
• C. water holding capacity
• D. flora.

Explanation: Soil particles determine its texture. The soil particles enclose living spaces in between them called a pore space. In coarse-textured soils, the pore space is wide but pore frequency is low. In fine-textured soil, the pore space is narrow but pore frequency is high.

138. Deep black soil is productive due to a high proportion of

• A. sand and zinc
• B. gravel and calcium
• C. clay and humus
• D. silt and earthworm.

Explanation: Deep black soil is productive due to a high proportion of clay and humus. The organic matter present in the soil is contributed by the death and decay of living organisms. These are the richest in nutrients and therefore these soils are the most fertile.

139. Which one is true?

• A. Commensalism is when none of the interacting populations affect each other
• B. Symbiosis is when the interaction is useful to both the populations
• C. Symbiosis is when neither populations affect each other
• D. Commensalism is when the interaction is useful to both the populations.

Explanation: In mutualism or symbiosis, both the organisms in association are mutually benefitted and further this association is obligatory, i.e., necessary for the existence of both organisms. Mycorrhiza is an example of symbiosis. It is the association between roots of higher plants and fungal hyphae. The fungal hyphae supply water and nutrients to the plant and in turn, get food from the plant. So both the organisms are mutually benefitted.

140. The relation between algae and fungi in a lichen is

• A. symbiosis
• B. parasitism
• C. commenalism
• D. protocooperation.

Explanation: Algae and fungi in a lichen show symbiotic relationship. Fungi give support to the algae, give protection and help in absorption of water while algae provide food to fungi which is achloro­ phyllous. No one is harmed but both are benefitted by each other.