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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 (d) Plants convert solar energy into chemical energy

The answer is (b) Green plants get their food from organic compounds Explanation: Green plants produce their food by harnessing solar energy.... View Article

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 (d) Water

The answer is (a) a Decrease in energy at higher trophic levels Explanation: The available energy level at a particular trophic level is 10 times... View Article

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) (d) (ii) and (iv)

The answer is (d) (ii) and (iv) Explanation: Group i) has wood and leather which are biodegradable. Group iii) has grass that is biodegradable... View Article

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

The answer is (c) (i) and (iii) Ultraviolet is one of the electromagnetic radiation which is emitted by the Sun and is transmitted either in... View Article

Flow of energy in an ecosystem is always (a) unidirectional (b) bidirectional (c) multidirectional (d) no specific direction

The answer is (a) unidirectional Explanation: The flow of energy is from prey to predator and it cannot be in the reverse direction. In most... View Article

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 (d) food chain

The answer is (a) food web The Food web is a natural network of food chains. It interconnects at various trophic levels to form several feeding... View Article

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 (d) mechanical energy

The answer is (c) chemical energy Energy is available for transfer from one trophic level to the next in the form of food. Food is a chemical... View Article

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

The answer is (b) producers Producers use solar energy to synthesize food from water and carbon-di-oxide. Plants and few micro-organisms are... View Article

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

The answer is (a) chlorofluorocarbon compounds Chlorofluorocarbons (CFC) are gases used for various purposes including solvents, refrigerants... View Article

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 (d) accumulation

The answer is (c) biomagnification Biomagnification can be interpreted as the rise or increase in the contaminated substances caused by the... View Article

In the given food chain, suppose the amount of energy at the fourth trophic level is 5 kJ, what will be the energy available at the producer level? Grass → Grasshopper → Frog → Snake → Hawk (a) 5 k J (b) 50 k J (c) 500 k J (d) 5000 k J

The answer is (d) 5000 k J Explanation: The available energy level at a particular trophic level is 10 times the energy level at the next... View Article

An ecosystem includes (a) all living organisms (b) non-living objects (c) both living organisms and non-living objects (d) sometimes living organisms and sometimes non-living objects

The answer is (c) both living organisms and non-living objects An ecosystem is a complex of living and nonliving organisms and their... View Article

In a food chain, the third trophic level is always occupied by (a) carnivores (b) herbivores (c) decomposers (d) producers

The answer is (a) carnivores Trophic level In an ecosystem, a group of entities occupying the same level in a food chain is a trophic level. It... View Article

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Archives

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 (d) Plants convert solar energy into chemical energy

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 (d) Water

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) (d) (ii) and (iv)

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

Flow of energy in an ecosystem is always (a) unidirectional (b) bidirectional (c) multidirectional (d) no specific direction

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 (d) food chain

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 (d) mechanical energy

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

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

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 (d) accumulation

In the given food chain, suppose the amount of energy at the fourth trophic level is 5 kJ, what will be the energy available at the producer level? Grass → Grasshopper → Frog → Snake → Hawk (a) 5 k J (b) 50 k J (c) 500 k J (d) 5000 k J

An ecosystem includes (a) all living organisms (b) non-living objects (c) both living organisms and non-living objects (d) sometimes living organisms and sometimes non-living objects

In a food chain, the third trophic level is always occupied by (a) carnivores (b) herbivores (c) decomposers (d) producers

Draw an angle of 40⁰. Copy its supplementary angle.

Draw an angle of 70⁰. Make a copy of it using only a straight edge and compasses.

Draw an angle of measure 135⁰ and bisect it.

Draw an angle of measure 45⁰ and bisect it.

Construct with ruler and compasses, angles of following measures: (a) 60⁰ (b) 30⁰ (c) 90⁰ (d) 120⁰ (e) 45⁰ (f) 135⁰

Draw an angle of measure 153⁰ and divide it into four equal parts.

Draw a right angle and construct its bisector.

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