NEET Biology Organisms and Populations MCQs Set 19

Answer: (d) Both

Explanation:
1. Two species in a community cannot occupy exactly the same niche for long, because of competitive exclusion.
2. But different species can live together permanently if their niches differ.
3. Statements B and C are true, so option d is correct.

Teacher's Note:
1. Niche is the functional role of a species.
2. Niche overlap causes competition.

Answer: (b) Has moderate water holding capacity

Explanation:
1. A good soil holds a moderate amount of water.
2. Too much water excludes air and too little causes drought.

Teacher's Note:
1. Loam is the best soil for crops.
2. It drains well and holds some water.

Answer: (b) Clay soil

Explanation:
1. Clay has very fine particles with abundant capillary pores, so it has the highest total pore space (porosity).
2. Sandy soil has large pores but fewer in total.

Teacher's Note:
1. Porosity is the pore space in soil.
2. Clay holds water but drains slowly.

Answer: (d) Both

Explanation:
1. A population is a group of individuals of one species living in a particular area at a given time.
2. A local population is also called a deme.
3. So the answer is Both.

Teacher's Note:
1. Demes are small interbreeding groups.
2. Population is the unit of study in population ecology.

Answer: (d) Mutualism

Explanation:
1. Mycorrhiza is an association between a fungus and plant roots in which both benefit.
2. The fungus absorbs phosphorus for the plant and gets sugars, so it is mutualism.

Teacher's Note:
1. Mutualism benefits both partners.
2. Lichens are another example.

Answer: (b) Organism

Explanation:
1. An organism is the basic unit of ecological study.
2. Populations, communities and ecosystems are built from organisms.

Teacher's Note:
1. Ecology studies organisms and their environment.
2. Level of organisation starts with the organism.

Answer: (b) Sea

Explanation:
1. The littoral zone is the shore region of a sea or lake.
2. It is exposed to wave action and is highly productive.

Teacher's Note:
1. Littoral means shore.
2. Marine zones also include neritic and oceanic.

Answer: (c) clay and humus

Explanation:
1. Deep black soil (regur) contains a high proportion of fine clay and humus, which hold water and nutrients.
2. This makes it very fertile for cotton.

Teacher's Note:
1. Black soil is good for cotton.
2. Clay and humus hold nutrients.

Answer: (b) alluvial soil

Explanation:
1. River water carries silt and deposits it on the plains as alluvial soil.
2. Alluvial soil is very fertile.

Teacher's Note:
1. Alluvial soil forms the Indo-Gangetic plain.
2. Laterite forms by leaching.

Answer: (b) loamy

Explanation:
1. Loam is a mixture of sand, silt and clay with humus.
2. It drains well but retains water and nutrients, so it suits plants best.

Teacher's Note:
1. Loam balances aeration and water holding.
2. Clay waterlogs and sand dries.

Answer: (b) succulent

Explanation:
1. Desert plants such as Opuntia are succulent and store water in their tissues.
2. They also have thick cuticle and reduced leaves.

Teacher's Note:
1. Xerophytes conserve water.
2. Opuntia has fleshy stems.

Answer: (b) water

Explanation:
1. Life needs liquid water.
2. The moon has no water on its surface, so life is absent there.

Teacher's Note:
1. Water is the basic need for life.
2. Temperature and light alone do not decide.

Answer: (b) Fresh water lakes

Explanation:
1. Eutrophication is nutrient enrichment, seen in fresh water lakes, which have limited water exchange.
2. The ocean is too large for this.

Teacher's Note:
1. Eutrophic lakes show algal bloom.
2. Sewage and fertilisers cause it.