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A lot of dry leaves are collected in a school garden and are burnt every day. Do you think that it is right to do so? If not, what should be done to dispose off the dry leaves?

It is not right to burn dry leaves as it causes air pollution. The right way to dispose off the dry leaves is to convert them into compost. Leaf... View Article

Match the following A and B (A) – (B) (a) Smooth endoplasmic reticulum – (i) Amoeba (b) Lysosome – (ii) Nucleus (c) Nucleoid – (iii) Bacteria (d) Food vacuoles – (iv) Detoxification (e) Chromatin material – (v) Suicidal bag and nucleolus

Column-I Column-II A. Smooth endoplasmic 4. Detoxification B. Lysosome 5. Suicidal bag C. Nucleoid 3. Bacteria D. Food vacuoles 1.... View Article

Majority of cells cannot be seen directly with our naked eyes because: (a) organisms are generally unicellular (b) cells are microscopic (c) cells are present only inside the body (d) cells are grouped into tissues

b) Cells are microscopic. The majority of the cells cannot be seen directly with our naked eyes because cells are extremely small. Microscopes... View Article

If a person’s clothes catch fire, the best way to extinguish the fire is to: (a) throw water on the clothes. (b) use the fire extinguisher. (c) cover the person with a woollen blanket. (d) cover the person with a polythene sheet.

(c) cover the person with a woolen blanket. If a person's clothes catch fire, the best way to extinguish the fire is to cover the person with a... View Article

Select the incorrect sentence (a) Blood has matrix containing proteins, salts and hormones (b) Two bones are connected with ligament (c) Tendons are non-fibrous tissue and fragile (d) Cartilage is a form of connective tissue

(c) Tendons are non-fibrous tissue and fragile A tendon is a tough fibrous connective tissue that connects muscle to bone. Tendons have many... View Article

Select the correct statement (a) Heterotrophs do not synthesise their own food (b) Heterotrophs utilise solar energy for photosynthesis (c) Heterotrophs synthesise their own food (d) Heterotrophs are capable of converting carbon dioxide and water into carbohydrates

(a) Heterotrophs do not synthesize their own food Heterotrophs are those organisms which cannot make their own food from inorganic substances... View Article

A glass tumbler containing hot water is kept in the freezer compartment of a refrigerator (temperature < 0°C). If you could measure the temperature of the content of the tumbler, which of the following graphs (Fig.) would correctly represent the change in its temperature as a function of time.

Graph (a) is the right answer because water will cool initially until its temperature reaches 0 °C. After reaching the freezing point (0 °C)... View Article

While doing work and running, you move your organs like hands, legs etc. Which among the following is correct? (a) Smooth muscles contract and pull the ligament to move the bones (b) Smooth muscles contract and pull the tendons to move the bones (c) Skeletal muscles contract and pull the ligament to move the bones (d) Skeletal muscles contract and pull the tendon to move the bones

d) Skeletal muscles contract and pull the tendon to move the bones Skeletal muscles are striped, voluntary muscles, due to the presence of... View Article

The shape of guard cells changes due to change in the (a) protein composition of cells (b) temperature of cells (c) amount of water in cells (d) position of the nucleus in the cells

(c) amount of water in cells Guard cells are cells surrounding each stroma. They help to regulate the rate of transpiration by opening and... View Article

Beera wants to practice crop rotation in his field. Suggest a Rabi crop and a Kharif crop which will replenish his field with nitrogen. Which crop replenishes nitrogen and why?

Rabi crops are pea, wheat, mustard whereas kharif crops are paddy, maize, soybean. These crops require different climatic conditions and hence... View Article

An increase in carbon dioxide content in the atmosphere would not cause (a) more heat to be retained by the environment (b) increase in photosynthesis in plants (c) global warming (d) abundance of desert plants

d) Abundance of desert plants When the carbon dioxide is increasing it increases the earth temperature. The increase in carbon dioxide causes... View Article

Shyam was cooking potato curry on a chulha. To his surprise, he observed that the copper vessel was getting blackened from outside. It may be due to: (a) proper combustion of fuel. (b) improper cooking of potato curry. (c) improper combustion of the fuel. (d) burning of the copper vessel.

(c) improper combustion of the fuel. A reaction or process which entails only partial burning of a fuel. This may be due to a lack of oxygen or... View Article

Which of the following statements about the autotrophs is incorrect? (a) They synthesise carbohydrates from carbon dioxide and water in the presence of sunlight and chlorophyll (b) They store carbohydrates in the form of starch (c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight (d) They constitute the first trophic level in food chains

c) They convert carbon dioxide and water into carbohydrates in the absence of sunlight. Autotrophs can convert carbon dioxide and water into... View Article

When air is blown from the mouth into a test-tube containing lime water, the lime water turned milky due to the presence of (a) oxygen (b) carbon dioxide (c) nitrogen (d) water vapour

b) Carbon dioxide Carbon dioxide gas turns lime water milky. When air is blown from the mouth into a test-tube, the lime water turned milky... View Article

Many are responsible for causing pollution. Petroleum are a major source of pollutants like and . (sulphur dioxide, refineries, industries, nitrogen dioxide, gaseous, liquid, people, air).

Many Industries are responsible for causing air pollution. Petroleum refineries are a major source of gaseous pollutants like sulphur dioxide and... View Article

Boojho wants to separate the following materials as combustible and non-combustible. Can you help him? Charcoal, chalk, stone, iron rod, copper coin, straw, cardboard, glass, paper, wood.

(a) Combustible substances — charcoal, straw, card board, paper, candle wood, (b) Non-combustible substances — chalk, stone, iron... View Article

Plastic is used for making a large variety of articles of daily use and these articles are very attractive. But it is advised to avoid the use of plastic as far as possible. Why?

Most plastics are non - biodegradable, mainly because plastic is widely used because of its low cost, versatility and durability. This durability... View Article

Choose the incorrect statement from the following. A good fuel is one which: (a) is readily available. (b) produces a large amount of heat. (c) leaves behind many undesirable substances. (d) burns easily in the air at a moderate rate.

(c) leaves behind many undesirable substances. Any substance which upon combustion produces a usable amount of energy is known as fuel. For... View Article

Marked temperature changes in aquatic environment can affect (a) breeding of animals (b) more growth of aquatic plants (c) process of digestion in animals (d) availability of nutrients.

a) Breeding of animals Marine ecosystem covers the largest surface area of the earth. Two third of earth is covered by water and they... View Article

The process of nitrogen-fixation by bacteria does not take place in the presence of (a) molecular form of hydrogen (b) elemental form of oxygen (c) water (d) elemental form of nitrogen

b) Elemental form of oxygen Nitrogen fixation is the essential biological process and the initial stage of the nitrogen cycle . In this... View Article

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