NEET Biology Organisms and Populations MCQs Set 16

Answer: (d) capillary water

Explanation:
1. Plants can absorb only capillary water, the film held in the small pores between soil particles. Gravitational water drains away and hygroscopic water is bound too tightly to particles.

Teacher's Note:
1. Capillary water is held by surface tension.
2. Roots absorb capillary water.

Answer: (b) tendency of biological systems to resist change

Explanation:
1. Homeostasis is the tendency of a biological system to resist change and keep a steady internal state despite changes in the surroundings.

Teacher's Note:
1. Regulators such as mammals show it best.
2. Homeostasis resists change.

Answer: (b) rich in organic matter

Explanation:
1. The surface layer of fertile soil is dark because it is rich in humus and other organic matter from decaying litter.

Teacher's Note:
1. Organic matter also holds water and nutrients.
2. Dark topsoil means organic matter.

Answer: (a) texture

Explanation:
1. Soil texture depends on the proportion of sand, silt and clay particles, so particle size and mix determine texture.

Teacher's Note:
1. Water holding capacity depends on texture but is not the direct property.
2. Particles determine texture.

Answer: (b) alluvial soil

Explanation:
1. Rivers carry silt and clay and deposit it on their plains, forming fertile alluvial soil.

Teacher's Note:
1. Laterite forms by leaching in heavy rain.
2. Rivers deposit alluvium.

Answer: (b) loamy

Explanation:
1. Loamy soil, a mix of sand, silt and clay with humus, drains well yet holds water and minerals, so it suits most plants.

Teacher's Note:
1. Clay holds too much water and sand too little.
2. Loam is best for plants.

Answer: (a) stenohaline

Explanation:
1. Stenohaline animals tolerate only a narrow range of salinity, while euryhaline animals tolerate a wide range.

Teacher's Note:
1. Salmon and eels are euryhaline.
2. Narrow salinity range means stenohaline.

Answer: (a) high altitude to low altitude and high latitude to low latitude

Explanation:
1. Species diversity is highest in the tropics and falls towards the poles. It also decreases with increasing altitude, so it rises from high to low altitude and from high to low latitude.

Teacher's Note:
1. Warm, stable climates support more species.
2. Diversity rises towards low altitude and latitude.

Answer: (b) oceans

Explanation:
1. Oceans cover about 70% of the Earth and their phytoplankton fix the largest share of carbon dioxide on the planet.

Teacher's Note:
1. Land forests fix less in total.
2. Oceans fix the most carbon.

Answer: (c) xerophyte

Explanation:
1. Xerophytes live in dry places and have sunken stomata in pits, which reduce water loss.

Teacher's Note:
1. Hydrophytes have stomata on the upper surface.
2. Sunken stomata are a xerophyte feature.

Answer: (d) Submerged hydrophytes

Explanation:
1. Submerged hydrophytes live wholly under water and have no stomata, taking gases and water directly through the surface.

Teacher's Note:
1. Floating leaves bear stomata on top.
2. Submerged plants have no stomata.

Answer: (d) Stream lined body — aquatic adaptation

Explanation:
1. A streamlined body reduces water resistance and is an adaptation of aquatic animals. Uricotelism suits dry habitats and parasitism is interspecific.

Teacher's Note:
1. Perspiration is not a xeric adaptation.
2. Streamlining is an aquatic adaptation.

Answer: (b) succulent

Explanation:
1. Desert plants such as Opuntia are succulent and store water in fleshy tissues, with thick cuticle and reduced leaves.

Teacher's Note:
1. Vivipary is seen in mangroves.
2. Desert plants are succulent.