Ecosystems Flashcards
Statement 1: Forest, grassland, wetland and desert are some examples of terrestrial ecosystems
Statement 2: pond, lake, river and estuary are some examples of aquatic ecosystems.
Statement 1 is incorrect
Wetlands are aquatic ecosystems
Vertical distribution of different species occupying different levels is called………..
stratification
Primary production is defined as……………. And the rate of this production of biomass is referred to as………
the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis
Productivity
………………. of an ecosystem is the rate of production of organic matter during photosynthesis.
Gross primary productivity
……………… is the available biomass for the consumption to heterotrophs
Net primary productivity
Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP)
………………. is defined as the rate of formation of new organic matter by consumers.3
Secondary productivity
The annual net primary productivity of the whole biosphere is approximately ……………… (dry weight) of organic matter.
170 billion tons
Despite occupying about…………. per cent of the surface, the productivity of the oceans are only……………
70
55 billion tons
Assertion: The earthworm is referred to as the farmer’s ‘friend’.
Reason: they help in the breakdown of complex organic matter as well as in loosening of the soil
The decomposers break down complex organic matter into inorganic substances like……./……/…… and the process is called………..
carbon dioxide, water and nutrients
decomposition
The important steps in the process of decomposition are
(5)
Fragmentation
Leaching
Catabolism
Humification
Mineralisation.
Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called……….
fragmentation
By the process of…………. water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.
leaching
Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as………
catabolism
Humification leads to accumulation of a dark coloured……….. substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely……… rate.
amorphous
slow
Being………….. in nature humus serves as a reservoir of nutrients
colloidal
The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as………….
mineralisation
The rate of decomposition is controlled by (2) factors
chemical composition of detritus
climatic factors
The decomposition rate is slower if detritus is rich in………./………. and quicker, if detritus is rich in………./………….. like sugars
lignin and chitin
nitrogen and water-soluble substances
………../……….. environment favour decomposition whereas…………./……….. inhibit decomposition
Warm and moist
low temperature and anaerobiosis
Except for the ………….. ecosystem, sun is the only source of energy for all ecosystems on Earth.
deep sea hydro-thermal
Of the incident solar radiation less than……….. per cent of it is photosynthetically active radiation (PAR).
50
Plants capture only ……….. per cent of the PAR and this small amount of energy sustains the entire living world.
2-10
Assertion: Ecosystems are not exempt from the Second Law of thermodynamics.
Reason:They need a constant supply of energy to synthesise the molecules they require, to counteract the universal tendency toward increasing disorderliness.
The producers in an aquatic ecosystem are various species like
Phytoplankton
Algae
Higher plants.
Assertion: No energy that is trapped into an organism remains in it for ever.
Reason: The energy trapped by the producer, hence, is either passed on to a consumer or the organism dies.
…………. of organism is the beginning of the detritus food chain/web.
Death
Statement 1: The detritus food chain (DFC) begins with dead organic matter.
Statement 2: It is made up of decomposers which are heterotrophic organisms, mainly fungi and bacteria
Both are correct
Decomposers secrete digestive enzymes that breakdown dead and waste materials into simple, inorganic materials, which are subsequently absorbed by them.
This mode is called as……
Saprophytic mode of nutrition
In an aquatic ecosystem……….. is the major conduit for energy flow.
GFC
Grazing food chain
In terrestrial ecosystem, a much larger fraction of energy flows through the…………. than through the…………
detritus food chain (DFC)
GFC
Assertion: Detritus food chain may be connected with the grazing food chain at some levels
Reason: Some organisms of DFC are prey to the GFC animals
Each trophic level has a certain mass of……….. material at a particular time called as the standing crop
living
The standing crop is measured as
the mass of living organisms (biomass)
the number in a unit area.
Assertion: The biomass of a species is expressed in terms of dry weight only
Reason: Measurement of biomass in terms of dry weight is more accurate.
Assertion is false and reason is true statement
The biomass of a species is expressed in terms of fresh or dry weight.
Measuring biomass in terms of dry weight is considered more accurate because it eliminates the variability introduced by water content, which can differ significantly between organisms and even within the same organism under different conditions.
Only……….. per cent of the energy is transferred to each trophic level from the lower trophic level
10%
Assertion: Any calculations of energy content, biomass or numbers, has to include all organisms at that trophic level.
Reason: No generalisations we make will be true if we take only a few individuals at any trophic level into account.
Statement 1: A given species may occupy more than one trophic level in the same ecosystem at the same time.
Statement 2: A sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary consumer when it eats insects and worms.
Both are correct and 2 explains the 1
Can you work out how many trophic levels human beings function at in a food chain?
3 trophic levels
2nd 3rd and potentially 4th
The pyramid of biomass in sea is generally………… because the biomass of fishes far exceeds that of phytoplankton
inverted
Tree ecosystem where insects feed on tree the pyramid of number is……….. whereas the pyramid of biomass and energy is………..
Inverted
Upright
Limitations of ecological pyramids
(4)
Not take into account the same species belonging to two or more trophic levels
It assumes a simple food chain, something that almost never exists in nature
It doesn’t accommodate food web
Saprophyte are not given any place in ecological pyramids even though they play vital role
