Our Environment
Subject: General Science
Sample Practice Questions
Question 1: Which of the following is biodegradable?
- Plastic bag
- Glass bottle
- Fruit peels
- Aluminium foil
Explanation: Fruit peels are biodegradable as they can be broken down by microorganisms. Plastic, glass, and aluminium are non-biodegradable and persist in the environment for a long time.
Question 2: Why are herbicides and pesticides harmful even if they are used to protect crops?
- They kill all plants
- They cause biological magnification in the food chain
- They increase soil fertility
- They have no harmful effects
Explanation: Pesticides and herbicides are non-biodegradable. They get accumulated progressively at each trophic level (biological magnification), causing the maximum concentration to accumulate in top consumers like humans.
Question 3: What is the primary source of energy in an ecosystem?
- Soil
- Water
- Sunlight
- Air
Explanation: Sunlight is the primary source of energy in most ecosystems. Producers (green plants) capture this energy through photosynthesis and convert it into chemical energy.
Question 4: Which of the following is a human-made (artificial) ecosystem?
- Forest
- Pond
- Aquarium
- Lake
Explanation: An aquarium is a human-made ecosystem. Forests, ponds, and lakes are natural ecosystems, while gardens and crop-fields are also artificial ecosystems.
Question 5: What is a trophic level?
- A type of ecosystem
- A step or level in a food chain
- A type of organism
- A type of energy
Explanation: Each step or level of the food chain forms a trophic level. Producers are at the first trophic level, primary consumers at the second, secondary consumers at the third, and tertiary consumers at the fourth.
Question 6: Which chemicals are responsible for the depletion of the ozone layer?
- Carbon dioxide
- Chlorofluorocarbons (CFCs)
- Methane
- Nitrogen oxides
Explanation: The decrease in the ozone layer has been linked to synthetic chemicals like chlorofluorocarbons (CFCs), which are used as refrigerants and in fire extinguishers.
Question 7: Which group contains only biodegradable items?
- Grass, flowers and leather
- Grass, wood and plastic
- Fruit-peels, cake and lime-juice
- Cake, wood and grass
Explanation: Grass, flowers, and leather are all biodegradable. Option C has fruit-peels, cake (biodegradable) and lime-juice (biodegradable). However, option A is also correct. Both A and D contain all biodegradable items.
Question 8: What happens to the energy available at each trophic level?
- It increases
- It remains the same
- It gets diminished progressively
- It gets converted to mass
Explanation: The energy available at each trophic level gets diminished progressively due to loss of energy at each level. Only about 10% of energy is transferred to the next level.
Question 9: What are organisms that can produce food by photosynthesis called?
- Consumers
- Decomposers
- Producers
- Herbivores
Explanation: Producers are organisms that can make organic compounds like sugar and starch from inorganic substances using sunlight energy in the presence of chlorophyll. All green plants and certain bacteria are producers.
Question 10: Which of the following is non-biodegradable?
- Wood
- Paper
- Plastic
- Cotton cloth
Explanation: Plastic is non-biodegradable and persists in the environment for a long time. Wood, paper, and cotton cloth are biodegradable.