BIOLOGY M.C.Q [1M]

2. Always upright.

4. Both b) and c).

1. Marine.

1. 170 billion tons (dry weight) of organic matter.

2. Climax community

Explanation:

The gradual change in the species structure of an ecological community is known as ecological succession. A climax community is the final community formed when the ecological succession becomes stable. It remains relatively unchanged until destroyed by an event such as fire or human interference. It is also known as a stable biological community.

1. Primary producers

Explanation:

Because primary producer first requires CO₂, for the process of photosynthesis by which they make their food.

3. Phytoplanktons.

4. Phosphorus and sulphur.

2. Phosphorous cycle

Explanation:

The term biogeochemical cycle is used for the exchange or circulation of biogenetic nutrients between living and nonliving components of the biosphere.

The nutrient cycle can be a gaseous cycle in which the materials involved in circulation between living and nonliving components are gases or vapors, e.g., carbon, hydrogen, oxygen.

In sedimentary cycles of matter; the materials involved in circulation between biotic and abiotic components of the biosphere are non-gaseous e.g., phosphorous, calcium, magnesium.

The reservoir of phosphorous is phosphates present in rocks.

3. Pioneer sere

Explanation:

Sere is a sequence of developmental stages from pioneer to climax communities. Plants that are first to invade a bare area are called as pioneer species.

2. Species that determine structure of biotic community

1. Mutualism.

2. Stratification.

4. Free-floating micro-algae, cyanobacteria and nanoplankton.

1. Phytoplankton

Explanation:

Primary production is the synthesis of food through the process of photosynthesis, which uses light as its source of energy. The primary production in the ocean is performed by free-living microscopic organisms called phytoplankton. Larger autotrophs, such as the sea grasses and seaweeds are generally confined within the photic zone. The majority of free-floating production takes place within microscopic organisms (phytoplankton)

2. Standing crop.

3. Upright.

2. Random mating.

3. Green food.

3. Functional unit of environment

Explanation:

The ecosystem is a segment of nature or biosphere consisting of a community of living beings and the abiotic or physical environment both interacting and exchanging materials between them. The ecosystem is defined as a functional unit of environment, which is independent and self-sustaining due to various interactions between abiotic and biotic components and different organisms among themselves.

3. Succession

Explanation:

The transition in the species composition of a given area is called ecological succession.

This takes place due to the change in the environmental conditions in a geographical area.

During succession, some species colonise an area and their populations become more numerous, whereas populations of other species decline and even disappear.

The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.

1. Species composition and stratification.

1. Non living, ecosystem

2. Equilibrium.

Climax community is in a state of equilibrium.

3. Biogeochemical cycle

Explanation:

A biogeochemical cycle or inorganic-organic cycle is a circulating or repeatable pathway by which either a chemical element or a molecule moves through both biotic (bio-) and abiotic (geo-) compartments of an ecosystem.

2. Moderate percentage of young individuals

1. Climate.

1. Aquarium.

2. Gause’s hypothesis.

1. Unidirectional.

1. Orderly and sequential.

2. Secondary productivity

Explanation:

The rate at which consumers like rabbit in a grassland convert the chemical energy of their food into their own biomass is called secondary productivity. The efficiency at which energy is transferred from one trophic level to another is called ecological efficiency.

2. Pyramid of standing crop aing crop.

2. 10%.

2. Desert.

3. Phytoplankton → Zooplankton → Fish.

4. Gene flow does not occur between the populations of a species.

3. Real basic units of classification.

3. Lichens

Explanation:

Lichens are considered as pioneer species in primary succession on rocks because they can easily grow on rocks where other plants cannot grow. They produce oxalic acid which induced the weathering of rocks and thus soil is formed. When these lichens die they increase the soil fertility so other plants can grow and start the chain reaction.

4. A tree should be planted in place of one to be cut.

3. Desert.

Desert ecosystem is expected in an area where evaporation exceeds precipitation, and means annual rainfall is below 100mm.

2. Climax community

Explanation:

Ecological succession is the process of change in the species structure of an ecological community over time. The community begins with relatively few pioneer plants and animals and gradually develops stable or self-perpetuating species as a climax community.

4. Fresh weight.

3. Rock

Explanation:

The natural reservoir of phosphate is the rock which contains phosphorus in the form of phosphates when rocks are weathered, minute amounts of these phosphate dissolve in soil solution and are absorbed by the roots of the plants. Herbivores and other animals obtain this element from plants.

1. Always upright

Explanation:

Pyramid of energy is always upright, can never be inverted, because the energy always flows from a particular trophic level to the next trophic level. The amount of available energy decreases during transfer from one trophic level to another. So, as we go from the first trophic level to the top trophic level, the amount of available energy becomes less and less.

3. Tropical rain forest.

1. Benthonic and brown algae.

2. Elton

Explanation:

An ecological pyramid is a graphical representation to describe the number of organisms, energy relationships, and biomass of an ecosystem. They are also called as Eltonian pyramids after Charles Elton, who developed the concept of ecological pyramids.