Trophic levels are the feeding levels in a food chain. Example: grass → deer → lion. Grass is the producer and first trophic level, deer is the primary consumer and second trophic level, and lion is the secondary consumer and third trophic level.
Decomposers break down dead plants, animals and organic wastes into simpler substances. They recycle nutrients back into the soil and help maintain the flow of matter in the ecosystem.
Substances are biodegradable if decomposers such as bacteria and fungi can break them down using biological processes. Some substances are non-biodegradable because their chemical structure cannot be easily broken down by decomposers, or breaks down extremely slowly.
Biodegradable substances can release foul smell and provide breeding places for disease-causing organisms if they accumulate. During decomposition they may also release gases and organic matter that can pollute air or water if not managed properly.
Non-biodegradable substances persist for a long time and cause land and water pollution. They can enter food chains and undergo biological magnification, harming organisms at higher trophic levels.
Ozone is a molecule of three oxygen atoms, O₃. In the upper atmosphere it forms the ozone layer, which absorbs harmful ultraviolet radiation from the Sun and protects living organisms. If ozone is depleted, more UV radiation reaches earth and can damage organisms and ecosystems.
Two ways are: reduce the use of disposable items and reuse or recycle materials such as paper, glass, metals and plastics; and separate biodegradable waste from non-biodegradable waste so that composting and proper recycling/disposal are possible.
- a. Grass, flowers and leather
- b. Grass, wood and plastic
- c. Fruit-peels, cake and lime-juice
- d. Cake, wood and grass
Grass, flowers, leather, fruit-peels, cake, lime-juice and wood are biodegradable materials. The group with plastic is not entirely biodegradable.
(a), (c) and (d)
- a. Grass, wheat and mango
- b. Grass, goat and human
- c. Goat, cow and elephant
- d. Grass, fish and goat
Grass is eaten by goat, and goat products/meat may be consumed by humans, forming a food chain.
(b) Grass, goat and human
- a. Carrying cloth-bags to put purchases in while shopping
- b. Switching off unnecessary lights and fans
- c. Walking to school instead of getting your mother to drop you on her scooter
- d. All of the above
All three practices reduce waste or energy/fuel use, so they are environment-friendly.
(d) All of the above
If all organisms in one trophic level are killed, food chains are disturbed. Organisms at higher trophic levels may lose their food and decline, while organisms at lower trophic levels may increase excessively, upsetting the ecosystem balance.
Yes, the impact will differ depending on the trophic level removed. Removing producers would collapse the whole food chain because energy enters through them. Removing herbivores would affect both plants and carnivores. Removing top carnivores may increase herbivore numbers and disturb vegetation. No trophic level can be removed completely without damaging the ecosystem, because all levels are interdependent.
Biological magnification is the increase in concentration of non-biodegradable toxic substances at successive trophic levels of a food chain. Yes, levels are different; the concentration is lowest in producers and becomes higher at each higher trophic level, usually maximum in top consumers.
Non-biodegradable wastes persist in the environment, pollute soil and water, harm animals through ingestion or entanglement, and may enter food chains. Toxic non-biodegradable chemicals can accumulate and biomagnify, causing health problems in organisms.
No. Even biodegradable waste can harm the environment if produced in large amounts. Its decomposition can create foul smell, attract pests, spread disease, consume oxygen in water bodies and release gases. Proper disposal and composting are still necessary.
Damage to the ozone layer is a concern because ozone shields the earth from harmful UV radiation. More UV radiation can cause skin cancer, cataracts, reduced immunity and damage to plants and plankton. To limit this damage, the use of chlorofluorocarbons (CFCs) and other ozone-depleting substances has been reduced or banned through international agreements, and safer substitutes are used.