Our Environment - 2

Rainfall is not a living organism

Plastic bags are synthetic materials. These are not degraded by bacteria.

The organisms in an ecosystem are related through food requirements. This relationship is called food chain. In option (i) grass is eaten by rabbit, rabbit is consumed by wolf and lion eats wolf. In option (iv) grasshopper eats grass, frog eats grasshopper, snake eats frog and eagle consumes snake. In option (ii) grasshopper is found in terrestrial ecosystems not aquatic ecosystems. In option (iii) there is no herbivore animal to consume grass. Thus, the correct answer is option C.

As per standard 10% rule.

UV rays or ultraviolet rays can affect human health in many ways like causing skin cancer or weakening immune system. Excessive exposure to UV rays can lead to skin cancer because the UV rays cause damage to the DNA in skin cells. 

Concentration of chemicals like insecticides in living system is called biological magnification.

An ecosystem includes both living and non-living organisms.

Crop field is an artificial ecosystem.

The third trophic level in a food chain is always occupied by carnivores.

According to 10% rule, energy available at producer level will be 5 x 10 x 10 x 10 = 5000 kJ.

There are many food chains which are interconnected to form the food web and so one organism can feed at different trophic levels in the different food chain. There is a 0gradual decrease in the energy of the increasing trophic levels due to the loss of energy with each transfer. The producers are the organisms which can synthesize food and the organisms which feed on the other sources are known as consumers. The detrivores are the organisms which feed on the dead matter of the organisms which belong to all the trophic levels. 

Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the food web.

Depletion of ozone layer is mainly due to chlorofluorocarbon compounds.

• A food chain comprising birds, green plants, fish and man.
• Food chain in ecology, the sequence of transfers of matter and energy in the form of food from one organism to another organism.
• Food chains intervined locally into a food web because most organisms consume more than one type of animal or plant.
• Each level of a food chain represents a different trophic level.
• Humans are to be present at the top of the food chain because they eat all kinds of plants and animals.
• The human food chain starts with plants.
• Humans are dominant consumers.
• They affect food webs through energy production and agriculture, pollution, habitat destruction, overfishing and hunting it affect both soil and aquatic ecosystem.

All green plants and few blue-green algae which can produce food by photosynthesis are called the producers.