BIOLOGY 1 Marks Question

Stratification.

The amount of energy or biomass remaining in a producer after meeting the cost of its respiration is called the net primary productivity.

Phytoplanktons are the dominant producers in aquatic ecosystem. Primary consumers are also known as herbivores.

The grazing food chain starts with producers while the detritus food chain starts with decomposers.

Natural and artificial ecosystem.

Some of the gross primary productivity gets lost in the form of respiration, that is why all primary productivity is not available for herbivores.

An ecosystem is a functional unit of nature, where biotic components (living organisms) interact among themselves and also with the abiotic environmental or physical factors.

Because when energy flows from a particular trophic level to the next trophic level, some energy is always lost as heat at each step.

The pyramid of biomass is inverted in a pond ecosystem because the biomass of fish (top consumer) is far larger than the producers (phytoplanktons).

Forest is the climax community for both successions.

Differences:

S.No.	Standing State	Strndirg Crop
(i)	Standing state refers to the amount of nutrients such as nitrogen, phosphorus, calcium, etc. present in the soil of an ecosystem at a given time.	Standing crop refers to the amount of biomass or organic matter available at a given rophic level/ ecosystem at a given time.
(ii)	It is in the abiotic comPonents.	It is in the biotic components.

Secondary consumers.

Fragmentation, leaching, catabolism, humification and mineralisation.

It states that only 10% energy of a trophic level is transferred to the next higher trophic level.

The rate of succession is much faster in secondary succession as the substratum (soil) is already present as compared to primary succession where the process starts from a bare area (rock).

Two factors that determine the vegetation and soil type of an ecosystem are:

1. Precipitation.
2. Temperature.

A considerable amount of gross primary productivity is used by the plants in respiration; so not all primary productivity is available for consumers.

Detritus.

He occupies third tropic level, i.e. he is a secondary consumer.

In a tree ecosystem.

Sunlight (solar radiation).

Grass (floor of forest) → Amaranthus → Shrubby plants → Teak (tree).

Shark.

Some of the organisms of DFC are prey to the animal of GFC, hence they are interlinked.

Green algae are autotrophic organisms, i.e. they synthesise their own food with the help of photosynthesis. At deepest layers of ocean, light is absent. So, photosynthesis does not take place there and hence, green algae are not found in deep strata

Natural or human induced disturbances like fire, deforestation, etc.

Population, community, ecosystem, biosphere.

The process of degradation of humus by microbial action and release of inorganic nutrients.

Man and sparrow.

It is the amount of living material or organic matter present in an organism, community or biome.

Oceans contribute about 55 billion tons organic matter.

The vertical distribution of different species occupying different levels in an ecosystem is called stratification. Trees occupy the topmost vertical layer of a forest, shrubs occupy the second layer and herbs and grasses occupy the bottom most or base layers.

Primary productivity is determined as the amount of biomass or organic matter produced per unit area over a time period by the plants during photosynthesis.

Net Primary Productivity (NPP) is the weight of the organic matter stored by the producers which is available to heterotrophs for consumption. It is equal to the rate of organic matter produced during photosynthesis GPP minus respiratory losses (R), i.e. NPP = GPP - R

Net primary productivity.

Measurement of biomass in terms of dry weight is more accurate because it avoids variations in weights due to seasonal moisture differences.

The entire sequence of communities that change in a given area.

Photosynthetically Active Radiation.

Photosynthetic Active Radiation.

The standing crop is measured as the mass of living organisms or the number in a unit area. The biomass of a species is expressed in terms of fresh or dry weight.

Atmosphere and oceans.

Many organisms occupy positions in different food chains and several food chains become interconnected to form a food web.

X and Z- Respiration and Y- Photosynthesis.

Energy exchange and flow of nutrient cycling

Two ways of measuring the standing crop of a trophic level are:

1. Biomass of living organisms.
2. Number in an unit area.

Standing crop represents total amount of living matter or organic matter present in an ecosystem in an unit area and at a specific time.