Question
Niche is [NEET 2018]
(a) the range of temperature that the organism needs to live
(b) the physical space where an organism lives
(c) all the biological factors in the organism’s environment
(d) the functional role played by an organism where it lives
Answer/Explanation
Ans. (d)
Niche is an ecological component of habitat which is delimited by functioning of an organism. A species may live in more than one niche in diferent stages of its life cycle.
Question
Which one of the following pairs is mismatched? [CBSE AIPMT 2005]
(a) Savanna $\quad-$ Acaciatrees
(b)Prairie – Epiphytes
(c) Tundra – Permafrost
(d) Coniferous forest – Evergreen trees
Answer/Explanation
Ans. (b)
Prairies contain tall grasses and shrubs
(a) Savanna -Acacia trees
(b) Tundra -Permafrost
(c) Coniferous forest-Evergreen trees
Question
Keystone species in an ecosystem are those which [CBSE AIPMT 1997]
(a) are present in maximum number
(b) are most frequent
(c) attain a large biomass
(d) contribute to ecosystem properties
Answer/Explanation
Ans. (d)
Keystone species of an ecosystem is a species that exerts an important regulatory effect on other species in the community, i.e. contributes to ecosystems properties. It maintains higher species diversity in a community by reducing the densities of strong competitors.
Question
Niche of a species in an ecosystem refers to its [CBSE AIPMT 1996]
(a) function at its place of occurrence
(b) place of its occurrence
(c) competitive ability
(d) centre of origin
Answer/Explanation
Ans. (a)
Niche word is used for the functional role of species or population that it plays in its ecosystem.
Question
Tropical forests occur in India [CBSE AIPMT 1994]
(a) Jammu and Kashmir
(b) Rajasthan
(c) Kerala and Assam
(d) The forests do not occur in India
Answer/Explanation
Ans. (c)
Tropical forest occur in India in Assam, Western Ghats and Western Himalayas. Major vegetation made of sal (Shorea robusta), shrubs, grasslands and desert community in the regions of decreasing rainfall.
Question
Xeric environment is characterised by [CBSE AIPMT 1994]
(a) precipitation
(b) low atmospheric humidity
(c) extreme of temperature
(d) high rate of vapourisation
Answer/Explanation
Ans. (b)
Xeric environment is characterised by low atmospheric humidity. This environment is found in deserts.
Question
Study of inter-relationships between living organisms and their environment is [CBSE AIPMT 1993]
(a) Ecology
(b) Ecosystem
(c) Phytogeography
(d) Ethology
Answer/Explanation
Ans. (a)
Study of inter relationship between living organisms and their environment is called as Ecology. Ecology may be called environmental biology.
Question
The sum total of the population of the same kind of organisms constitute [CBSE AIPMT 1993]
(a) colony
(b) genus
(c) community
(d) species
Answer/Explanation
Ans. (d)
Species is a group of organisms similar in structure, function and behaviour.
Question
What is true for individuals of same species? [CBSE AIPMT 2002]
(a) Live in same niche
(b) Live in same habitat
(c) Interbreeding
(d) Live in different habitats
Answer/Explanation
Ans. (c)
According to the biological concept of species. Species is a group of organisms which can interbreed freely in nature and produce fertile offsprings.
Question
Which part of the world has high density of organisms? [CBSE AIPMT 1999]
(a) Deciduous forests
(b) Grasslands
(c) Savannas
(d) Tropical rain forests
Answer/Explanation
Ans. (d)
The tropical rain forests are most diverse and highly dense with maximum productivity (approximately $12000 \mathrm{kcal}$ ) $\left.\mathrm{m}^2 / \mathrm{yr}\right)$.
Question
An association of individuals of different species living in the same habitat and having functional interactions is [CBSE AIPMT 2015]
(a) ecological niche
(b) biotic community
(c) ecosystem
(d) population
Answer/Explanation
Ans. (b)
An association of individuals of different species living in the same habitat and having functional interaction is called biotic community (biocoenosis). The biotic community is dominated by one of the character. It determines the nature of community. It can be biotic or abiotic.
Question
Competition for light, nutrients and space is most severe between [CBSE AIPMT 1988]
(a) closely related organisms growing in different niches
(b) closely related organisms growing in the same area/niche
(c) distantly related organisms growing in the same habitat
(d) distantly related organisms growing in different niches
Answer/Explanation
Ans. (b)
Niche word was used for the first time by Joseph Grinnel (1917). Niche means functional role of an organism in an ecosystem. Competition becomes most severe between the closely related organisms which share same niche.