Free Man and His Environment MCQs with Answers

121. Mycorrhiza is an example of:

• A. A symbiotic relationship
• B. Ectoparasitism
• C. Endoparasitism
• D. Decomposers

Explanation: In mutualism or symbiosis, both the organisms in the 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. Mycorrhiza is a symbiotic association where fungal filaments grow in close contact with plant roots. Fungal filaments assist plant roots in nutrient absorption and in return get food

122. What is true for individuals of the same species?

• A. They live in the same niche.
• B. They live in the same habitat
• C. Interbreeding
• D. They live in different habitats

Explanation: Species may be defined as the uniform interbreeding population of individuals which freely interbreed among themselves. Niche represents the habitat and functions of a species. Habitat is a specific place where an organisms lives.

123. Which type of association is found between the entomophilous flower and pollinating agent?

• A. Mutualism
• B. Commensalism
• C. Cooperation
• D. Co­-evolution

Explanation: Co-­evolution can occur in any interspecific relationship like symbiosis or mutualism. The relation between an entomophilous flower and a pollinating insect shows co­-evolved mutualism. In this, the plant depends exclusively on the insect for pollination and the insect relies on the plant for food.

124. Two different species cannot live for long duration in the same niche or habitat. This law is

• A. Allen's law
• B. Gause's hypothesis
• C. Dollo's rule
• D. Weisman's theory.

Explanation: Interspecific competition is rivalry amongst members of different species. The severity of competition depends upon similarity in the requirement of food and shelter. Every type of organism has a particular niche, no two organisms can live in same niche. One of the two is eliminated. This phenomenon is called Gause hypothesis of competitive exclusion.

125. Which part of the world has a high density of organisms?

• A. Deciduous forests
• B. Tropical rain forests
• C. Grasslands
• D. Savannahs.

Explanation: Tropical forests are found in the tropical zones of the world and are characterized by very high temperatures with rainfall in abundance. The flora of tropical rainforests is very rich and highly diversified. The tropical forests have a very rich fauna both in density as well as in varieties. The reason for this high diversity and variety of flora and fauna is the occurrence of suitable conditions in these forests.

126. In desert grasslands, which type of animals are relatively more abundant?

• A. Aquatic
• B. Fossorial
• C. Diurnal
• D. Arboreal

Explanation: Desert animals prefer to live under the surface. The animal residing either permanently or for most of life inside the burrows or under the earth surface are known as burrowing or fossorial animals and their mode of existence is described as subterranean or underground.

127. Plants such as Prosopis, Acacia and Capparis are examples of tropical

• A. deciduous forests
• B. evergreen forests
• C. Grass lands
• D. Thorn forests.

Explanation: Tropical shrubs or thorn forests are found in places where moisture conditions are intermediate between desert and savanna on one hand and seasonal or rain forests on the other hand. Acacia and Prosopis are non­-succulent perennial plants and Capparis is a xerophytic shrub.

128. Which of the following communities is more vulnerable to invasion by outside animals and plants?

• A. Temperate forests
• B. Oceanic island communities
• C. Mangroves
• D. Tropical evergreen forests

Explanation: Tropical forests are found in the tropical zone of the world and are characterized by very high temperatures with rainfall in abundance. The flora of a tropical rainforest is very rich and highly diversified. The tropical forests have a very rich fauna both in density as well as in varieties. The reason for this high diversity and variety of flora and fauna is the occurrence of suitable conditions in these forests. So these are more vulnerable to invasion by outside plants and animals.

129. During harsh seasons, therophytes survive by

• A. rhizomes
• B. seeds
• C. bulbs
• D. corms.

Explanation: Therophytes are those plants that survive the winter as a seed and complete their life cycle between the spring and autumn.

130. Benthoic animals are those which

• A. are submerged in an area
• B. float on the sea surface
• C. are deep dwellers in the sea
• D. are floating (free) organisms.

Explanation: Benthoic organisms are attached to or rest on the bottom sediments. Benthoic animals may be divided into filter feeders, e.g., clams and deposit feeders e.g., snails.