Explain the phenomenon of “biological magnification” How does it affect organisms belonging to different trophic levels particularly the tertiary consumers? [Delhi]
The process in which harmful chemicals enter a food chain and get accumulated progressively at each trophic level is called biological magnification.
Harmful and toxic chemicals enter our bodies when they are added to soil and water. Use of pesticides to protect the food crops from diseases and pests and chemical wastes of factories are dumped in open or disposed off into rivers. These chemicals are washed down into the soil and ultimately to water table or get absorbed or taken up from the soil by the plants along with water and minerals and in this way harmful chemicals enter the food chain. The quantity of these harmful chemicals increase with increase in trophic level of the food chain because these substances are not degradable. Man is at the top of the food chain, so concentration is maximum in human beings.
Thus, accumulation of DDT has been maximum in man as DDT is used to destroy pests. DDT is accumulated in the following way in this food chain:
This is the reason why our food grains such as wheat and rice, vegetables and fruits and even meat contain varying amounts of pesticides residues. So, the highest trophic level at the extreme right of food chain has the maximum concentration of harmful chemicals in a food chain.
Describe how decomposers facilitate recycling of matter in order to maintain balance in the ecosystem. [Foreign]
Write one or two words for each of the following statements/definitions :Write one or two words for each of the following statements/definitions :
(a) Each level of food chain where transfer of energy takes place
(b) The physical factors like temperature, rainfall, light, soil, air and water of an ecosystem
(c) Organisms which depend on the producers for food either directly or indirectly
(d) The physical and biological world where we live in
(e) Selfcontained unit of living things and their non-living environment needing only sunlight for its functioning
Which one of the following is not a terrestial ecosystem ?
Forest, Grassland, Aquarium, Desert
Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Consider the food chain :
Grass → Deer → Lion
What will happen if all the lions are removed from the above food chain ?
State two problems caused by the non- biodegradable waste that we generate in our daily life. [All India (C)]
Fill in the following blanks with suitable words :Fill in the following blanks with suitable words :
(a) Ultraviolet rays can cause skin…………………
(b) Pesticides enter the food chain at the…………………. level
(c) Grass →…………….→Human
(d) Lettuce →…………….→ Fox
(e) Plants→ Antelope→ …………….
Why is ozone layer getting depleted at the higher levels of the atmosphere? [Delhi (C)]
In a food chain consisting of grass, frog, bird and insects, where will the concentration of the harmful chemicals be maximum ?
Why did United Nations act to control the production of chlorofluorocarbons (CFCs) used in refrigerators? [Delhi]
In a food chain, 10,000 joules of energy is available to the producer. How much energy will be available to the secondary consumer to transfer it to the tertiary consumer? [All India ]
Which of the following belong to the first trophic level of a food chain? Grass, Grasshopper, Plants, Rat, Tiger [Foreign]
Name the organisms belonging to the second and the fourth trophic levels in the food chain comprising the following :
Frogs, Plants, Snakes, Hawk, Insects
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.
Can the organisms of any trophic level be removed without causing any damage to the ecosystem ? Will the impact of removing all the organisms in a trophic level be different for different trophic levels ?
Which of the following are biodegradable and which non-biodegradable ?
Glass bottle, Paper, Ball point pen refill, Hay, DDT, Wheat, Cake, Wood,
Polythene bag, Jute bag, Cotton cloth, Grass, Vegetable peels
A student went to study a local pond. In one part of the pond she noticed tadpoles scraping at some pond weed. In another part she saw a water beetle holding a tadpole in its jaws.A student went to study a local pond. In one part of the pond she noticed tadpoles scraping at some pond weed. In another part she saw a water beetle holding a tadpole in its jaws.
(a) Construct a food chain for the pond.
(b) How many links are there in this chain ?
Give a method for the disposal of household wastes such as left-over food, fruit and vegetable peels, and leaves of potted plants.
“Damage to the ozone layer is a cause for concern.” Justify this statement. Suggest any two steps to limit this damage. ‘ [Delhi]
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.
(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.