Sastry CBSE

NCERT Solutions for Class 7 Science Chapter 1 Nutrition in Plants

Topics and Sub Topics in Class 7 Science Chapter 1 Nutrition in Plants:

Section Name	Topic Name
1	Nutrition in Plants
1.1	MODE OF NUTRITION IN PLANTS
1.2	PHOTOSYNTHESIS — FOOD MAKING PROCESS IN Plants
1.3	OTHER MODES OF NUTRITION IN PLANTS
1.4	SAPROTROPHS
1.5	How NUTRIENTS ARE REPLENISHED IN THE Soil

Q.1. Why do organisms need to take food?
Ans. Food is needed by all organisms for many purposes:
(a) The main function of food is to help in growth.
(b) Food provides energy for movements such as running, walking or raising our arm.
(c) Food is also needed for replacement and repairing damaged parts of body.
(d) Food gives us resistance to fight against diseases and protects us from infections

Q.3. How would you test the presence of starch in leaves?
Ans. The presence of starch in leaves can be tested by Iodine test. When we remove chlorophyll from leaf by boiling it in alcohol and then put 2 drops of iodine solution, its colour change to blue indicates the presence of starch.

Q.4. Give a brief description of the process of synthesis of food in green plants.
Ans. The green plants have chlorophyll in the leaves. The leaves use C02 and water to make food in presence of sunlight.

Q.5. Show with the help of a sketch that the plants are the ultimate source of food.

Q.6. Fill in the blanks:
(a) Green plants are called ________________ since they synthesise their own food.
(b) The food synthesised by the plants is stored as ________________ .
(c) In photosynthesis solar energy is captured by the pigment called ________________
(d) During photosynthesis plants take in ________________ and release ________________ .
Ans. (a) autotrophs (b) starch (c) chlorophyll (d) carbon dioxide, oxygen

Q.7. Name the following:
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode of nutrition.
(iii) The pores through which leaves exchange gases.
Ans. (i) cuscuta (ii) Insectivorous plant (iii) Stomata

Q.8. Tick the correct answer:
(a) Amarbel is an example of:
(i) Autotroph (ii) Parasite (iii) Saprotroph (iv) Host

(b) The plant which traps and feeds on insects is:
(a) Cuscuta (ii) China rose {iii) Pitcher plant (iu) Rose
Ans. (a) (ii) Parasite (b) (iii) Pitcher plant

Q.9. Match the items given in Column I with those in Column II:

Q.10. Mark T’ if the statement is true and ‘F’ if it is false:

(i) Carbon dioxide is released during photosynthesis. (T/F)
(ii) Plants which synthesise their food themselves are called saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
(iv) Solar energy is converted into chemical energy during photosynthesis. (T/F)
Ans. (a) F (ii) F (iii) T (iu) T

Q.11.Choose the correct option from the following.
Which part of the plant takes in carbon dioxide from the air for photosynthesis?
(i) Root hair (ii) Stomata (iii) Leaf veins (iv) Sepals
Ans. (ii) Stomata

Q.12. Choose the correct option from the following:
Plants take carbon dioxide from the atmosphere mainly through their:
(i) Roots (ii) Stem (iii) Flowers (iv) Leaves
Ans. (iv) Leaves

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NCERT Solutions Class 7 Science Chapter 9 Soil

Topics and Sub Topics in Class 7 Science Chapter 9 Soil:

Section Name	Topic Name
9	Soil
9.1	Soil teeming with life
9.2	Soil profile
9.3	Soil types
9.4	Properties of soil
9.5	Moisture in soil
9.6	Absorptions of water by soil
9.7	Soil and crops

Q1. Tick the most suitable answer in question 1 and 2.
In addition to the rock particles, the soil contains
(i) Air and water
(ii) Water and plants
(iii) Minerals, organic matter, air and water
(iv) Water, air and plants
Answer:
In addition to the rock particles, the soil contains
(iii) Minerals, organic matter, air and water.

Q2. The water holding capacity is the highest in
(i) Sandy soil
(ii) Clayey soil
(iii) Loamy soil
(iv) Mixture of sand and loam
Answer:
The water holding capacity is the highest in
(ii) Clayey soil

Q3. Match the items in Column I with those in Column II:

Column I	Column II
(i) A home for living organisms	(a) Large particles
(ii) Upper layer of the soil	(b) All kinds of soil
(iii) Sandy soil	(c) Dark in colour
(iv) Middle layer of the soil	(d) Small particles and packed tight
(v) Clayey soil	(e) Lesser amount of humus

Answer:

Column I	Column II
(i) A home for living organisms	(b) All kinds of soil
(ii) Upper layer of the soil	(c) Dark in colour
(iii) Sandy soil	(a) Large particles
(iv) Middle layer of the soil	(e) Lesser amount of humus
(v) Clayey soil	(d) Small particles and packed tight

Q4. Explain how soil is formed.
Answer:
Soil is formed through the process of weathering. Weathering is a process of physical breakdown and chemical decomposition of rocks and minerals near or at the surface of the earth. This physical and chemical decomposition is primarily done by wind, water, and climate. As a result of these processes, large rock pieces are converted into smaller pieces and eventually to soil.

Q5. How is clayey soil useful for crops?
Answer:
Following are the properties of clayey soil:

1. It has very good water holding capacity.
2. It is rich in organic matter.

For growing crops such as wheat, gram, and paddy, the soil that is good at retaining water and rich in organic matter is suitable. Therefore, clayey soils having these characteristics are useful for such kind of crops.

Q6. List the differences between clayey soil and sandy soil.
Answer:

Clayey Soil	Loamy Soil
(i) It has much smaller particles.	(i) It has much larger particles.
(ii) It can hold good amount of water.	(ii) It cannot hold water.
(iii) It is fertile.	(iii) It is not fertile.
(iv) Air content is low.	(iv) Air get trapped between the particles.
(iv) Particles are tightly packed	(iv) Particles are loosely packed
(iv) Good for growing various crops.	(iv) Not suitable for growing crops.

Q7. Sketch the cross section of soil and label the various layers.
Answer:

Q8. Razia conducted an experiment in the field related to the rate of percolation. She observed that it took 40 min for 200 mL of water to percolate through the soil sample. Calculate the rate of percolation.
Answer:

9. Explain how soil pollution and soil erosion could be prevented.
Answer:
Prevention of soil pollution:
The persistent build-up of toxic compounds in the soil is defined as soil pollution. To prevent soil pollution, its causes must be controlled.

1. Reduce the use of plastics: Plastics and polythene bags destroy the fertility of soil. Hence, these should be disposed off properly and if possible, their use should be avoided.
2. Industrial pollutants: Some waste products from industries and homes pollute soil. These pollutants should be treated chemically to make them harmless before they are disposed off.
3. Insecticides: Other pollutants of soil include pesticides and insecticides. Therefore, excessive use of these substances should be avoided.

Prevention of soil erosion:
Removal of the upper fertile layer of the soil (top soil) by strong wind and flowing water is known as soil erosion. Following steps can be taken to reduce soil erosion:

1. Mass awareness to reduce deforestation for industrial purposes.
2. Helping local people to regenerate degrading forest.
3. Planting trees.

10. Solve the following crossword puzzle with the clues given:

Across
2. Plantation prevents it.
5. Use should be banned to avoid soil pollution.
6. Type of soil used for making pottery.
7. Living organism in the soil.

Down
1. In desert soil erosion occurs through.
3. Clay and loam are suitable for cereals like.
4. This type of soil can hold very little water.
5. Collective name for layers of soil.

Answer:

Across
2. Plantation prevents it. → Erosion
5. Use should be banned to avoid soil pollution. → Polythene
6. Type of soil used for making pottery. → Clay
7. Living organism in the soil. → Earthworm

Down
1. In desert soil erosion occurs through. → Wind
3. Clay and loam are suitable for cereals like. → Wheat
4. This type of soil can hold very little water. → Sandy
5. Collective name for layers of soil. → Profile

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NCERT Solutions Class 7 Science Chapter 8 Winds | Storms and Climate

Topics and Sub Topics in Class 7 Science Chapter 8 Winds | Storms and Climate:

Section Name	Topic Name
8	Winds, Storms and Cyclones
8.1	Air exerts pressure
8.2	High speed winds are accompanied by reduced air pressure
8.3	Air Expands on Heating
8.4	Wind currents are generated due to uneven heating on the earth
8.5	Thunderstorms and cyclones
8.6	Destruction Caused by Cyclones
8.7	Effective safety measures
8.8	Advanced technology has helped

Q.1.Fill the missing word in the blank spaces in the following statements:
(a) Wind is ___________air.
(b) Winds are generated due to _________ heating on the earth.
(c) Near the earth’s surface _________ air rises up whereas _________ air comes down.
(d) Air moves from a region _________of pressure to a region _________of pressure.
Ans.(a) moving (b) uneven
(c) warm, cooler (d) high, low

Q.2. Suggest two methods to find out wind direction at a given place.
Ans.(i) Take a piece of a paper in your hand. Allow it to fall from your hand. It will flow in the direction in which wind is blowing.
(ii) You can also use a wind-pane which helps us to know accurate wind direction.

Q.3.State two experiences that made you think that air exerts pressure.
Ans.(i) Balloons and balls can be used only when they are inflated with air. When balloon is overfilled with air it bursts due to excessive air pressure.
(ii) Compressed air is used in the brake system for stopping trains.

Q.4.You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Ans.No, a house which has no ventilators is not a safe or healthy house to live in. The air circulation is not there in such a house. So, it has no fresh air. Because warm air rises up and goes out through ventilators and fresh air comes in through windows.

Q.5.Explain why holes are made in hanging banners and hoardings.
Ans.Air exerts pressure. Due to this pressure banners and hoarding flutter and torn when wind is blowing fast. Holes are made in banners and hoardings so that wind passes through the holes and they do not become loose and fall down.

Q.6.How will you help your neighbours in case cyclone approaches your village/town?
Ans. (i) I will make them aware of cyclone forecast and warning service.
(ii) Rapid communication of warning to the government agencies and all the important places.
(iii) Construction of cyclone shelters in the cyclone prone areas.
(iv) Helping them to shift essential goods, domestic animals etc. to safer places.

Q.7.What planning is required in advance to deal with the situation created by a cyclone?
Ans.To deal with cyclone, it is important to follow the following points :
(i) carefully listening the warnings transmitted on T.V. and radio.
(ii) moving to the safer places.
(iii) keeping an emergency kit ready.
(iv) store food in waterproof bags. .
(v) not venturing into sea.
(vi) keeping all the emergency numbers.

Q.8. Which one of the following places is unlikely to be affected by cyclone?
(i) Chennai (ii) Mangalore
(iii) Amritsar (iv) Puri
Ans.(iv) Amritsar

Q.9.Which of the statements given below is correct?
(i) In winter the winds flow from the land to the ocean.
(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.
Ans.(i) In winter the winds flow from the land to the ocean.

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NCERT Solutions Class 7 Science Chapter 7 Weather, Climate and Adaptations of Animals to Climate

Topics and Sub Topics in Class 7 Science Chapter 7 Weather, Climate and Adaptations of Animals to Climate:

Section Name	Topic Name
7	Weather, Climate and Adaptations of Animals to Climate
7.1	Weather
7.2	Climate
7.3	Climate and Adaptation

Q.1.Name the elements that determine the weather of a place.
Ans. The temperature, humidity, rainfall, wind-speed, etc. are called the elements that determine the weather of a place.

Q.2. When are the maximum and minimum temperature likely to occur during the day?
Ans.The maximum temperature of the day occurs generally in the afternoon and the minimum temperature occurs in the early morning.

Q.3.Fill in the blanks
(i) The average weather taken over a long time is called __________
(ii) A place receives very little rainfall and the temperature is high throughout the year, the climate of that place will be ________ and _________
(iii) The two regions of the earth with extreme climatic conditions are __________ and ____________
Ans. climate of the place (ii) hot, dry (iii) polar, tropical regions

Q.4.Indicate the type of climate of the following areas:
 (a) Jammu and Kashmir:
(b) Kerala:,
(c) Rajasthan:
(d) North-east India:
Ans.(a) Jammu and Kashmir—moderately hot and moderately wet climate.
(b) Kerala—very hot and wet climate.
(c) Rajasthan—hot and dry climate.
(d) North-east India—The north eastern India receives rain for a major part of the year, hence wet climate.

Q.5.Which of the two changes frequently, weather or climate?
Ans.Weather

Q.6.Followings are some of the characteristics of animals:
(i) Diets heavy on fruits , (ii) White fur (iii) Need to migrate (iv) Loud voice
(v) Sticky pads on feet (vi) Layer of fat under skin
(vii) Wide and large paws (viii) Bright colours
(ix) Strong tails (x) Long and large beak
For each characteristic indicate whether it is adaptation for tropical rainforests or polar regions. Do you think that some of these characteristics can be adapted for both regions?

Ans:
.-

Q.7. The tropical rainforests has a large population of animals. Explain why it is so.
Ans. Because of continuous warmth and rain, the tropical region supports an enormous number and a wide variety of animals

Q.8.Explain with examples, why we find animals of certain kind living in particular climatic conditions.
Ans. Animals are adapted to survive in the conditions in which they live. Features and habits which help them to adapt to their surroundings are the result of evolution. So, to survive in a particular type of climate the animals must have certain adapted features. This is the reason we find animals of certain kind living in particular climatic conditions. For example, animals in the polar region are adapted to the extremely cold climate. They have special characteristics, such as white fur, strong sense of smell, a layer of fat under the skin, wide and large paws for swimming and walking in snow etc

Q.9. How do elephants living in the tropical rainforests adapt themselves?
Ans. The elephant has adapted to the conditions of rainforest in many remarkable ways. It has a trunk that it uses as a nose because of this it has a strong sense of smell. The trunk is also used by it for picking up food. Its tusks are modified teeth. These can tear the bark of trees that an elephant loves to eat. So, the elephant is able to handle the competition for food very well. Large ears of the elephant help it to hear even very soft sounds. They also help the elephant to keep cool in the hot* humid climate of the rainforest.

Q.10.Choose the correct option which answers the following question:
A carnivore with stripes on its body moves very fast while catching its prey. It is likely to be found in:
(i) polar regions (ii) deserts
(iii) oceans (iv) tropical rainforests
Ans. (iv) tropical rainforests

Q.11.Which features adapt polar bears to live in extremely cold climate?
(i) A white fur, fat below skin, keen sense of smell.
(ii) Thin skin, large eyes, a white fur.
(iii) A long tail, strong claws, white large paws.
(iv) White body, paws for swimming, gills for respiration.
Ans.(iv) A white fur, fat below skin, keen sense of smell.

Q.12.Which option best describes a tropical region?
(i) hot and humid
(ii) moderate temperature, heavy rainfall (iii) cold and humid (iv) hot and dry
Ans.(i) Hot and humid

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NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals 

Topics and Sub Topics in Class 7 Science Chapter 2 Nutrition in Animals:

Section Name	Topic Name
2	Nutrition in Animals
2.1	Different Ways of Taking Food
2.2	Digestion in Humans
2.3	Digestion in Gross Eating Animals
2.4	Feeding and Digestion System of Amoeba

Q.1.Fill in the blanks:
(a) The main steps of nutrition in humans are ___________, ___________, ___________ , ___________ and ___________
(b) The largest gland in the human body is ___________.
(c) The stomach releases hydrochloric acid and ___________ juices which act on food.
(d) The inner wall of the small intestine has many finger-like outgrowths called ___________
(e) Amoeba digests its food in the ___________ .
Ans.(a) ingestion, digestion, absorption, assimilation, egestion
(b) liver (c) digestive (d) villi (e) food vacuole.

Q.2. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(a) Digestion of starch starts in the stomach. (T/F)
(b) The tongue helps in mixing food with saliva. (T/F)
(c) The gall bladder temporarily stores bile. (T/F)
(d) The ruminants bring back swallowed grass into their mouth and chew it for sometime. (T/F)
Ans. a) F (b) T (c) T (d) T

Q.3.Tick (S) mark the correct answer in each of the following:
(a) Fat is completely digested in the
(i) stomach (ii) mouth (in) small intestine (iv) large intestine

(b) Water from the undigested food is absorbed mainly in the:
(i) Stomach (ii) Food pipe (iii) Small intestine (iv) Large intestine

Ans.(a) (iii) Small intestine (b) (iv) Large intestine

Q.4.Match the items of column I with those given in column II:

Q.5. What are villi? What is their location and function?
Ans. The finger like projections in the inner walls of the small intestine is called villi. These are found in small intestine.
Function: The villi increase the surface area for absorption of the digested food

Q.6. Where is the bile produced? Which component of the food does it help to digest?
Ans. Bile is produced in liver. The bile juice stored in sac called the gall bladder. It helps in the digestion of fats.

Q.7. Name the type of carbohydrate that can be digested by ruminants but not by humans. Give the reason also.
Ans. Cellulose is the carbohydrate that can be digested by ruminants. Ruminants have large sac like structure between the small intestine and large intestine. The cellulose of the food is digested by the action of certain bacteria which are not present in humans.

Q.8. Why do we get instant energy from glucose?
Ans. Because it easily breaks down in the cell with the help of oxygen which provides instant energy to the organism. Glucose does not need digestion, it is directly absorbed into the blood.

Q.9. Which part of the digestive canal is involved in:
(i) Absorption of food ________ .
(ii) Chewing of food ________ .
(iii) Killing of bacteria ________ .
(iv) Complete digestion of food ________ .
(v) Formation of faeces ________ .
Ans. (i) Small intestine (ii) Mouth (iii) Stomach (iv) Small intestine (v) Large intestine

Q. 10. Write one similarity and one difference between the nutrition in amoeba and human beings.
Ans. Similarity: The digestive juices in amoeba are secreted into food vacuole and in human beings the digestive juices are secreted in stomach and small intestine. Then the juices convert complex food into simpler soluble and absorbable substances. ‘
Difference: Amoeba captures the food with help of pseudopodia and engulf it. In human beings food is taken by the mouth.

Q.11. Match the items of Column I with suitable items in Column II.

Ans.

Q.12.Label Fig. 2.11 of the digestive system (as given in the NCERT Textbook Exercise)

Ans.

Q.13. Can we survive only on raw, leafy vegetables/grass? Discuss.
Ans. We know that the animals, fungi, bacteria, non-green plants and human being do not have the ability to make their own food. They depend upon autotrophs for their food directly or indirectly. The green plant (leafy vegetables/grass) trap solar energy and make their own food in the form of glucose. So, we can say that leafy vegetables and grass can provide sufficient energy to help us survive.

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