NEET Biology Ecosystem MCQs Set 08

Answer: (c) Pyramid of energy

Explanation:
1. Pyramid of number and of biomass can be inverted in some ecosystems.
2. The pyramid of energy is always upright and shows the rate of energy flow, so it best represents the functional features.

Teacher's Note:
1. Energy pyramids consider the rate of energy flow.
2. They never get inverted because energy is lost at each level.

Answer: (a) Inverted

Explanation:
1. One large tree supports many herbivores, and each herbivore carries many ectoparasites.
2. Number rises from producer to top level, so the pyramid of numbers is inverted.

Teacher's Note:
1. Parasitic food chains give inverted number pyramids.
2. Biomass pyramids in such a chain would still be upright.

Answer: (a) Are more diverse than pioneer communities

Explanation:
1. As succession proceeds, species diversity and biomass increase and the community becomes stable.
2. Hence the climax community is more diverse than the pioneer community.

Teacher's Note:
1. The climax is in near equilibrium with the environment.
2. Pioneer stages have few species and low stability.

Answer: (d) Ecesis

Explanation:
1. Ecesis is the successful establishment of a species in a new area.
2. It includes germination, growth and reproduction of the invaders.

Teacher's Note:
1. Steps of succession: nudation, invasion, competition, reaction, stabilisation.
2. Ecesis comes under invasion.

Answer: (a) Marsh-meadow stage

Explanation:
1. Hydrosere stages: phytoplankton, submerged, submerged floating, reed swamp, marsh-meadow, scrub, forest.
2. So the reed swamp is followed by the marsh-meadow stage.

Teacher's Note:
1. Hydrarch succession begins in water.
2. It ends in a mesic climax forest.

Answer: (d) Both (a) and (b)

Explanation:
1. Phosphate stays out of the cycle when it forms compounds with metals.
2. It is also held for a long time in bones and teeth.
3. So both (1) and (2) are right.

Teacher's Note:
1. Phosphorus cycling is slower than carbon cycling.
2. Excretion and decomposition return it to the soil.

Answer: (a) Inverted pyramid of biomass

Explanation:
1. The primary producer biomass (10 g) is less than the primary consumers (60 g), which is less than the secondary consumers (120 g).
2. A pyramid with a narrower base is inverted, as is seen in aquatic ecosystems.

Teacher's Note:
1. Energy pyramids can never be inverted.
2. Inverted biomass pyramids occur in ponds and seas because phytoplankton have a very short life and quick turnover.

Answer: (b) Tropical Rain Forest

Explanation:
1. Tropical rain forest shows five distinct layers: ground herbs, shrubs, short trees, tall canopy and emergent trees.

Teacher's Note:
1. Stratification is the vertical distribution of species in a community.
2. It is least marked in grasslands.

Answer: (b) Chemosynthetic bacteria

Explanation:
1. Deep-sea hydrothermal vents get no sunlight.
2. Their producers are chemosynthetic bacteria that oxidise sulphur compounds.

Teacher's Note:
1. No light means no photosynthesis.
2. Chemosynthesis is the energy source in such ecosystems.

Answer: (c) Least genetic diversity

Explanation:
1. A cropland is a managed system where a few crop varieties are grown.
2. This gives low genetic diversity.

Teacher's Note:
1. Weeds and soil organisms are present in cropland, and succession is stopped by farmers.
2. The system depends on human energy inputs.

Answer: (c) A.G. Tansley

Explanation:
1. The term ecosystem was introduced by A. G. Tansley in 1935.

Teacher's Note:
1. Odum is known as the father of ecology in the USA.
2. Haeckel coined the word ecology; Warming wrote early ecological plant geography.

Answer: (b) Gaseous cycle: carbon and nitrogen; sedimentary cycle: sulphur and phosphorus

Explanation:
1. Carbon and nitrogen have the atmosphere as their reservoir, so they are gaseous cycles.
2. Sulphur and phosphorus are held in rocks of the earth's crust, so they are sedimentary cycles.

Teacher's Note:
1. Gaseous: C, N, O.
2. Sedimentary: P, S, Ca.

Answer: (b) The gradual and predictable change in species composition occurs in a given area

Explanation:
1. Succession is a gradual and fairly predictable change in species composition.
2. The climax, not the pioneer, is in near equilibrium, and the animal types change along with the plants.

Teacher's Note:
1. The pioneer community is the first to occupy an area.
2. Succession is slow, and in primary succession it can take hundreds to thousands of years.

Answer: (c) Stratification

Explanation:
1. Vertical layering of species in a community is called stratification.

Teacher's Note:
1. Zonation is horizontal arrangement of communities, as on a mountain or shore.
2. Stratification gives stability.

Answer: (d) a(ii), b(i), c(iv), d(iii)

Explanation:
1. Earthworm is a detritivore.
2. Succession starts with pioneer species.
3. Pollination is an ecosystem service.
4. Natality is a measure of population growth.
5. So the match is a-ii, b-i, c-iv, d-iii.

Teacher's Note:
1. Ecosystem services include pollination, flood control and soil formation.
2. Natality is the birth rate.

Answer: (a) 0.02 J

Explanation:
1. Each step passes on 10 percent: producer 20 J, then mice 2 J, snake 0.2 J and peacock 0.02 J.

Teacher's Note:
1. Apply the 10 percent law once per link.
2. Four trophic levels means three transfers.

Answer: (b) Consumer

Explanation:
1. Secondary productivity is the rate at which consumers form new organic matter.

Teacher's Note:
1. Primary productivity is by producers.
2. Secondary productivity is by heterotrophs such as consumers.

Answer: (a) Cobra

Explanation:
1. In a food chain plant, insect, frog, snake and eagle, the missing link between a frog and an eagle is a snake.
2. Among the options only cobra is a snake that eats frogs and is eaten by an eagle.

Teacher's Note:
1. The sequence follows increasing trophic levels.
2. Eagle is the top carnivore.

Answer: (b) Secondary productivity

Explanation:
1. The rate of formation of new organic matter by a consumer such as a rabbit is secondary productivity.

Teacher's Note:
1. Primary productivity is by producers.
2. Secondary productivity is by consumers.

Answer: (d) Vallisneria

Explanation:
1. In the hydrosere the first stage is phytoplankton, and the second is submerged plants such as Vallisneria and Hydrilla.

Teacher's Note:
1. Azolla is a floating fern.
2. Typha is a reed swamp plant.