Our Environment Test - 26

In a food chain, plants are the producers. Herbivores are organisms that eat plants. So, they are the primary consumers.

In given food web, rosebush is producer and aphid feed on the rosebush, so, it is a herbivore and primary consumer. Ladybug and spider feed on aphid and serve as a carnivore and secondary consumers. Sparrow is the top consumer of the food web. Decomposers, the organisms that feed on debris left behind by scavengers, are not shown on the web. Thus, the correct answer is E.

Decomposers recycle the nutrients in an ecosystem. Bacteria and fungi act as major decomposers feed on organic matter present in the dead bodies of animals and plants. Decomposers in turn break down the organic matter present in the dead animals to simple nutrients in the soil. This organic matter is used by plants to grow.

Thus, the correct answer is option D.

Solar energy is the ultimate source of energy. The light energy is given by the sun is converted to chemical energy by plants. This energy is taken up by consumers further, in the form of food.

Microorganisms are the decomposers as they break-down the complex organic substances into simple inorganic substances that go into the soil and are used up once more by the plants.

In African plains, grasses are producers which are grazed upon by wild beasts, zebras and other herbivores. Lion and hyenas hunt these grazers (primary consumers) and thus occupy the position of secondary consumers. Five kinds of vultures feed on dead animals and serve as the scavenger. Since lions hunt on primary consumers there and occupy the rank of secondary consumers.

All the organisms in nature are interconnected by the food chains and food webs. Even if one of the organism groups is less, there will be a disturbance in the food webs and thereby imbalance is created in nature. For example, if wild animals are killed then herbivores increase their population thereby more consumption of plants takes place which leads to a decrease in the plant's population. Like this, an imbalance is created in nature. 

• The organisms which cannot produce food by themselves and depend on producers are known as consumers. 
• With the increase in the trophic levels, the energy goes on decreasing as there is a loss of energy during the transfer at each step. This is the reason that the lower trophic levels have more energy when compared to the higher trophic levels. 
• Many food chains are interconnected in the food web and so one organism may be associated with more than one food chain. The same organism may feed or be eaten by one or more organisms. 
• The producers capture the radiant energy of the sun and prepare their food. This food is consumed by consumers. When a plant or an animal dies, its dead remains are broken down into simpler inorganic compounds by decomposers. Decomposers derive nutrition from the dead decaying matter.