(a) Describe an activity to show that while paper is biodegradable but plastic (say, polythene) is non-
biodegradable.
(b) Explain why, some materials are biodegradable but some are non-biodegradable.
(a) We take a piece of paper and a plastic bag (Polythene Bag). Now dig the ground to about 15 centimeters depth and place the piece of paper and plastic bag in the dug up ground separately. After a month, we dig up the buried material and observe them. We will find that the piece of paper has been partially eaten up but the plastic bag has been remained unaffected. This means that the paper have been decomposed by the micro-organisms present in the soil. So paper is biodegradable. On the other hand, the plastic bag has not been decomposed by the micro ?organisms present in the soil, therefore It is non-biodegradable.
(b) It is due to the property of decomposer organisms of being specific in their action that some waste materials are biodegradable and other are non- biodegradable.
(a) Define decomposers. Name one decomposer.
(b) What is the role of decomposers in the ecosystem ?
(a) What is meant by non-biodegradable waste materials ? Give two examples of non-biodegradable wastes.
(b) Which of the following materials are biodegradable ?Animal bones, Iron nails, Plastic mugs, Leather belts, Silver foil
‘If we excessively use pesticides to protect the crops from diseases, then it may cause long-term damage to mankind’. Justify this statement.
State whether the following statements are true or false :State whether the following statements are true or false :
(a) In biology, human beings are called producers.
(b) Secondary consumers and tertiary consumers, both are carnivores.
Give a method for the disposal of household wastes such as left-over food, fruit and vegetable peels, and leaves of potted plants.
Give an example to illustrate that indiscriminate use of pesticides may result-in the degradation of the environment. [All India]
Select two non-biodegradable substances from the following waste generated in a kitchen: spoilt food, paper bags, milk bags, vegetable peels, tin cans, used tea leaves. [Delhi]
Name the process in which a harmful chemical enters the food chain and gets concentrated at each trophic level.
If a harmful chemical enters a food chain comprising cat, mice and plants, which one of these organisms is likely to have the maximum concentration of the harmful chemical in its body ?
Explain how, harmful ultraviolet radiations of sunlight are prevented from reaching the earth’s surface.
Why did United Nations act to control the production of chlorofluorocarbons (CFCs) used in refrigerators? [Delhi]
Which of the following belong to the same trophic level ?
Tree ; Frog ; Snake ; Grass ; Lizard
Which one term in the following includes the others ?
air, flora, fauna, environment, water, sunlight, soil
(a) Describe an activity to show that while paper is biodegradable but plastic (say, polythene) is non-
biodegradable.
(b) Explain why, some materials are biodegradable but some are non-biodegradable.
Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Fill in the following blanks with suitable words : Fill in the following blanks with suitable words :
(a) Decomposer organisms are……………. in their action.
(b) In nature, all green plants are……………. whereas animals are consumers.
(c) A series of organisms, each of which feeds on the next organism, the beginning of which is a green plant, is called a…………….
(d) The science that deals with the inter-relationships of living things with one another and their environment is called …………….
(e) Plastic is a……………. material whereas paper is a……………. material.
What is the difference between the food habits of organisms belonging to the first and the third trophic levels ? Give one example each of the organisms belonging to these two trophic levels.
If 5 joules of energy is available at producer level (plants), then how much energy will be transferred to the lion in the following food chain ? If 5 joules of energy is available at producer level (plants), then how much energy will be transferred to the lion in the following food chain ?
Plants —> Goat —> Lion
State whether the following statement is true or false :
Only 10 per cent of the light energy given by the sun is available for transfer at each higher trophic level in a food chain.
Which disease is caused in human beings due to depletion of ozone layer in the atmosphere? [Foreign]
Name the phenomenon in which non-biodegradable chemicals get accumulated progressively at each trophic level of a food chain.