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ScienceClass 10CBSE

1. Suggest one word for each of the following statements/ definitions (a) The physical and biological world where we live in (b) Each level of food chain where transfer of energy takes place (c) The physical factors like temperature, rainfall, wind and soil of an ecosystem Organisms which depend on the producers either directly or indirectly for food

Soln: Environment Trophic level Abiotic factors Consumers or heterotrophs

ScienceClass 10CBSE

1. Differentiate between biodegradable and non-biodegradable substances. Cite examples.

Soln: Substances which can be broken into pieces by biological process are known as biodegradable substance. Substances which cannot be broken into pieces by biological process are known as non-biodegradable substance.

ScienceClass 10CBSE

1. Why are crop fields known as artificial ecosystems?

Soln: Crops field are known as artificial ecosystems because they are manmade where certain biotic and abiotic components are manipulated.

ScienceClass 10CBSE

1. What are the advantages of cloth bags over plastic bags during shopping?

Soln: Advantages of cloth bags over plastic bags during shopping are as follows They can carry more weight than plastic bags They are bio-degradable They can be reused. They donot cause environment pollution.

ScienceClass 10CBSE

1. Why is improper disposal of waste a curse to environment?

Soln: Wastes pollute our environment, air, soil and water, and cause harmful effects on all living organisms.

ScienceClass 10CBSE

1. Disposable plastic plates should not be used because (a) they are made of materials with light weight (b) they are made of toxic materials (c) they are made of biodegradable materials they are made of non-biodegradable materials

Soln: Answer is (d) they are made of non-biodegradable materials Explanation: Plastics are non-biodegradable hence they start accumulating in nature harming living organisms.

ScienceClass 10CBSE

1. The decomposers in an ecosystem (a) convert inorganic material, to simpler forms (b) convert organic material to inorganic forms (c) convert inorganic materials into organic compounds do not breakdown organic compounds

Soln: Answer is (b) convert organic material to inorganic forms

ScienceClass 10CBSE

1. What will happen if deer is missing in the food chain given below? Grass → Deer → Tiger (a) The population of tiger increases (b) The population of grass decreases (c) Tiger will start eating grass The population of tiger decreases and the population of grass increases

Soln: Answer is (d) The population of tiger decreases and the population of grass increases. Explanation: Lack of predators will increase population of grass. Population of tiger will reduce due to lack of food.

ScienceClass 10CBSE

1. The percentage of solar radiation absorbed by all the green plants for the process of photosynthesis is about (a) 1 % (b) 5 % (c) 8 % (d) 10 %

Answer is (a) 1 % Explanation: Green plants utilize 1% of radiation absorbed by leaf and use it for photosynthesis.

ScienceClass 10CBSE

1. Which group of organisms are not constituents of a food chain? (i) Grass, lion, rabbit, wolf (ii) Plankton, man, fish, grasshopper (iii) Wolf, grass, snake, tiger (iv) Frog, snake, eagle, grass, grasshopper (a) (i) and (iii) (b) (iii) and (iv) (c) (ii) and (iii) (i) and (iv)

Soln: Answer is (c) (ii) and (iii) Explanation: In option ii) plankton does not eat grass. In option iii) none of them eat grass hence option c) is the right answer.

ScienceClass 10CBSE

1. Which of the statement is incorrect? (a) All green plants and blue green algae are producers (b) Green plants get their food from organic compounds (c) Producers prepare their own food from inorganic compounds Plants convert solar energy into chemical energy

Soln: Answer is (b) Green plants get their food from organic compounds Explanation: Green plants produce their food by harnessing solar energy. Solar energy is used to prepare carbohydrate with the help of CO2 and water which are in-organic substances.

ScienceClass 10CBSE

1. Which of the following limits the number of trophic levels in a food chain? (a) Decrease in energy at higher trophic levels (b) Sufficient food supply (c) Polluted air Water

Soln: Answer is (a) Decrease in energy at higher trophic levels Explanation: Available energy level at a particular trophic level is 10 times the energy level at next tropic level. When we reach fourth trophic level; a minute portion of energy from producer is available.

ScienceClass 10CBSE

1. In the following groups of materials, which group (s) contains only non-biodegradable items? (i) Wood, paper, leather (ii) Polythene, detergent, PVC (iii) Plastic, detergent, grass (iv) Plastic, bakelite, DDT (a) (iii) (b) (iv) (c) (i) and (iii) (ii) and (iv)

Soln: Answer is (d) (ii) and (iv) Explanation: Group i) has wood and leather which are biodegradable. Group iii) has grass which is biodegradable hence the answer is d) (ii) and (iv)

ScienceClass 10CBSE

1. Excessive exposure of humans to U V-rays results in (i) damage to immune system (ii) damage to lungs (iii) skin cancer (iv) peptic ulcers (a) (i) and (ii) (b) (ii) and (iv) (c) (i) and (iii) (iii) and (iv)

Soln: Answer is (c) (i) and (iii) Explanation: UV rays affect upper surface our body. UV rays lead to skin cancer and effect on skin will affect our immune system as skin is considered as primary level of immune barrier.

ScienceClass 10CBSE

1. Flow of energy in an ecosystem is always (a) unidirectional (b) bidirectional (c) multi directional no specific direction

Soln: Answer is (a) unidirectional Explanation: Flow of energy is from prey to predator and it cannot be in reverse direction . Hence flow of enrgy is uni- directional.

ScienceClass 10CBSE

1. Organisms of a higher trophic level which feed on several types of organisms belonging to a lower trophic level constitute the (a) food web (b) ecological pyramid (c) ecosystem food chain

Soln: Answer is (a) Food Web

ScienceClass 10CBSE

1. In an ecosystem, the 10% of energy available for transfer from one trophic level to the next is in the form of (a) heat energy (b) light energy (c) chemical energy mechanical energy

Soln: Answer is (c) chemical energy Explanation: Energy is available for transfer from one trophic level to the next in the form of food. Food is a chemical form of energy.

ScienceClass 10CBSE

1. Organisms which synthesise carbohydrates from inorganic compounds using radiant energy are called (a) decomposers (b) producers (c) herbivores carnivores

Soln: Answer is (b) producers Explanation: Producers use solar energy to synthesize food from water and carbon-di-oxide. Plants and few micro-organisms are the producers. Organisms that decompose organic material are called decomposers. Herbivores are the organisms that feed on plant and its products. Carnivore are the ones which feed on other organisms.

ScienceClass 10CBSE

1. Depletion of ozone is mainly due to (a) chlorofluorocarbon compounds (b) carbon monoxide (c) methane pesticides

Soln: Answer is (a) chlorofluorocarbon compounds

ScienceClass 10CBSE

1. Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as (a) eutrophication (b) pollution (c) biomagnification accumulation

Soln: Answer is (c) biomagnification Explanation: Eutrophication is richness of nutrient beyond optimum Eutrophication occurs due to run off from land. Introduction of an undesired substance into Pollution leads to harmful effects on living organisms.

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