Advertisements
Advertisements
प्रश्न
Your mother always thought that fruit juices are very healthy for everyone. One day she read in the newspaper that some brands of fruit juices in the market have been found to contain certain level of pesticides in them. She got worried as pesticides are injurious to our health.
(a) How would you explain to your mother about fruit juices getting contaminated with pesticides?
(b) It is said that when these harmful pesticides enter our body as well as in the bodies of other organisms they get accumulated and beyond a limit cause harm and damage to our organs. Name the phenomenon and write about it.
Advertisements
उत्तर
(a) The pesticides are commonly used to kill the pests in crop fields. However, these pesticides contain several non-biodegradable chemicals, that can stick to the surface of the fruits, vegetables and other plant parts. If these fruits are not washed properly before use, these chemicals remain attached to them and thus can contaminate the fruit juices.
(b) A large number of pesticides and chemicals are used to protect our crops from pests and diseases. Some of these chemicals are washed down into the soil, while some enter into the water bodies. From the soil, they are absorbed by plants along with water and minerals, and from water bodies, they are taken up by aquatic plants and animals. This is how these chemicals enter the food chain. Because these chemicals cannot decompose, they accumulate progressively at each trophic level. As the food chain proceeds, the concentration of pesticides also increases. This increase in the concentration of harmful chemicals with each step of the food chain is called biomagnification.
APPEARS IN
संबंधित प्रश्न
Give reason to justify the following: The existence of decomposers is essential in a biosphere.
List two main components of ecosystem?
Give an example of a four step food chain operating in grassland. Name the secondary consumer in this food chain
What is a 'food web'? Show its formation.
A food chain occurring in the sea which provides food for many people can be written as :
phytoplankton → zooplankton → X → Y
Name two zooplanktons.
A food chain occurring in the sea which provides food for many people can be written as :
phytoplankton → zooplankton → X → Y
What could be X?
Most of the water surface of a lake is covered with algae. This algae is part of the food chain which also includes small fish, bird, larvae and big fish. Which of the following will obtain the maximum energy?
(a) big fish
(b) bird
(c) larvae
(d) small fish
Food chains are very important for the survival of most species.

Matter and energy are two fundamental inputs of an ecosystem. Movement of:
In the given food chain, suppose the amount of energy at the fourth trophic level is 5 kJ, what will be the energy available at the producer level?
Grass → Grasshopper → Frog → Snake → Hawk
In the following food chain, vertical arrows indicate the energy lost to the environment and horizontal arrows indicate energy transferred to the next trophic level. Which one of the three vertical arrows (A, C and E) and which one of the two horizontal arrows (B and D) will represent more energy transfer? Give reason for your answer.

A food chain in a forest ecosystem
