Science M.C.Q

Plants occupy the first trophic level, herbivores constitute the second trophic level, carnivores constitute the third trophic level and higher carnivores occupy the fourth trophic level.

Depletion of ozone is mainly due to chlorofluorocarbons (CFCs).
All other substances except chlorofluorocarbon compounds do not contribute to the depletion of ozone.

 This ecosystem is created by humans.

Producers use solar energy to make carbohydrates from water and carbon dioxides. Water and carbon dioxide are inorganic compounds.

The microorganisms that break-down the complex organic substances into simple inorganic substances those goes into the soil and are used up once more by the plants.

In ecological pyramid, number of organisms at higher tropic level is always less than number of organisms at lower trophic level. An organism at higher trophic level usually feeds on more than one type of organisms. For example, consumers are always less than producers.

Producers use solar energy to make carbohydrates from water and carbon dioxides. Mainly the green leaves of the plant.

The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and convert it into food energy.

The flow of energy in the ecosystem is unidirectional. The energy enters the plants (from the sun) through photosynthesis during the making of food. This energy is then passed on from one organism to another in a food chain.
The energy given out by the organisms as heat is lost to the environment, it does not return to be used by the plants again. This makes the flow of energy in ecosystem 'unidirectional'.

​​​​​​​Grasshopper feeds on grass and hence is a primary consumer. Frogs feed on insects and hence are secondary consumers.

The 10% of energy available for transfer from one trophic level to the next in an ecosystem is in the form of chemical energy. The producers capture the energy present in sunlight and convert it into chemical energy which is passed into onto other trophic levels.

Both biotic and abiotic factors are present in an ecosystem.

Because of their non-biodegradable nature, plastic keeps on accumulating in the environment.

There is a loss of energy as we go from one trophic level to the next, this limits the number of trophic levels in a food-chain.

If deer is missing in the food chain then there will be no herbivore to consume grass, so population of grass will increase.

Tiger will start to die of hunger, so the population of tiger will decrease.

Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as bio-magnification.