Chapter 1 "Nutrition in Plants"
Q.1. Why do organisms need to take food?
Ans:- All organisms require energy for their life processes . Plants prepare their food and acquire nutrients from abiotic components like soil, air , water and sunlight. On the other hand animals need to get food from either plants or other animals to obtain nutrients. Hence animals need to take food to acquire nutrients and energy.
Q.2. Distinguish between a parasite and a saprotroph.
Ans:-
Parasite:- Organisms which live either in or on the host body is called parasite.
Example :- lice, liver fluke.
Saprotroph:- Organisms which take their nutrients from dead and decaying matter.
Example :- Fungi.
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.
Carbon dioxide + water (in the presence of sunlight and chlorophyll) ---> Glucose + Oxygen .
Q.5. Show with the help of a sketch that the plants are the ultimate source of food.
Chapter 2 Nutrition in animals
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.
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.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.
Chapter 3 :- Fibre to Fabric
Q.4. What is meant by the following terms?
(i) Rearing (ii) Shearing (iii) Sericulture
REELING:-The process of taking out threads from the cocoon fro use as silk is called reeling of silk.
SHEARING:-The fleece of sheep along with a thin layer of skin is removed from its body. This process is called shearing.
SERICULTURE:-Rearing of silkworms for obtaining silk is called sericulture.
Q.6 Make sketches of the two stages in the life history of the silk moth which are directly related to the production of silk
Ans.
Chap 4 " Heat"
1. State similarities and differences between the laboratory thermometer and the clinical thermometer.
Ans. Similarities:
(i) Both thermometers consist of long narrow uniform glass tubes.
(ii) Both have a bulb at one end.
(iii) Both contain mercury in bulb.
(iv) Both use Celsius scale on the glass tube.
Differences:
(i) A clinical thermometer reads temperature 35°C to 42°C while the range of laboratory thermometer is -10°C to 110°C.
(ii) Clinical thermometer has a kink near the bulb while there is no kink in the laboratory thermometer.
Due to kink mercury does not fall down on its own in clinical thermometer.
.2. Give two examples each of conductors and insulators of heat.
Ans. Conductors—aluminium, iron Insulators—plastic, wood.
Q.5. Discuss why wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing?
Ans.More layers of clothing keep us warm in winters as they have a lot of space between them. This space gets filled up with air. Air is a bad conductor, it does not allow the body heat to escape out.
Q.6. Look at figure 4.6. Mark where the heat is being transferred by conduction, by convection and by radiation
Q.7. In places of hot climate it is advised that the outer walls of houses be painted white. Explain.
Ans.In places of hot climate it is advised that the outer wall of houses be painted white because white colour reflects heat and the houses do not heat up too much
Chapter 5:- Acids , Bases and Salts
Q.1:- State differences between acids and bases.
Ans:-Properties of acids :-
- Produce hydrogen ions [H+] ions in water.
- Sour taste
- Turn blue litmus red
- Produce hydroxide ions [OH-] in water.
- Water soluble base are called alkalies.
- Bitter taste
.3.Name the source from which litmus solution is obtained. What is the use of this solution?
Ans.Litmus solution is extracted from lichens. It is used to determine whether the given solution is acidic or basic.
.4.Is the distilled water acidic/basic/neutral? How would you verify it?
Ans.Distilled water will be neutral. We can verify it by showing that neither blue nor red litmus paper changes its colour when dipped in it.
Q.5.Describe the process of neutralisation with the help of an example.
Ans.The reaction between an acid and a base is known as neutralisation. Salt and water are produced in this process with the evolution of heat.
Antacids like milk of magnesia (magnesium hydroxide), baking soda, etc. which contain a base are used for reducing acidity in stomach when excessive acid released by glands.
.7. Dorji has a few bottles of soft drink in his restaurant. But, unfortunately, these are
not labelled. He has to serve the drinks on the demand of customers. One customer
wants acidic drink, another wants basic and third one wants neutral drink. How
will Dorji decide which drink is to be served to whom?
Ans.Dorji can decide with the help of litmus paper:
(i) The drink which would turn a red litmus blue would be basic.
(ii) If the drink turns a blue litmus to red would be acidic.
(iii) The drink which would not affect both red and blue litmus would be neutral.
Q.8.Explain why:
(a) An antacid tablet is taken when you suffer from acidity.
(b) Calamine solution is applied on the skin when an ant bites.
(c) Factory waste is neutralised before disposing it into the water bodies.
Ans.(a) We take an antacid such as milk of magnesia to neutralises the excessive acid released in stomach.
(b) Ant injects an acidic liquid (Formic acid) into the skin on biting which causes inflammation, to the skin. The effect of the acid can be neutralised by rubbing. Calamine solution which contains zinc carbonate which is very weak base and causes no harm to the skin.
(c) The wastes of factories contain acids. If acids are disposed off in the water body, the acids will harm the organisms. So factory wastes are neutralised by adding basic substances.
.9. Three liquids are given to you. One is hydrochloric acid, another is sodium hydroxide and third is a sugar solution. How will you identify them? You have only turmeric indicator.
Ans.Name of the substances Effect on turmeric indicator
1. Hydrochloric acid Yellow to blue
2. Sodium hydroxide Yellow to red
3. Sugar solution No change
Q.10. Blue litmus paper is dipped in a solution. It remains blue. What is the nature of the solution? Explain.
Ans. (i) It can be identified on the basis of the following observations : Bases change the colour of litmus paper to blue. As the colour of blue litmus paper is not affected, the solution must be basic.
(ii) If the solution is neutral, even then colour of litmus will not change.
Chapter 6
Q.4. When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Ans. The reaction between baking soda and lemon juice can be given as below:
Lemon juice + Baking soda ————-> C02 (bubbles) + Other substances
(Citric acid) + (Sodium hydrogen carbonate) --> (Carbon dioxide)
It is a chemical change
Q.5. When a candle burns, both physical and chemical changes take place. Identify these changes. Give another example of a familiar process in which both the chemical and physical changes take place.
Ans. When a candle burns, both physical and chemical changes occur:
(i) Physical change: melting of wax, vapourisation of melted wax.
(ii) Chemical change: Burning of vapours of wax to give carbon dioxide, heat and light.
LPG is another example in which physical change occurs when LPG comes out of cylinder and is converted from liquid to gaseous state and a chemical change occurs when gas burns in air.
Q.6. How would you show that setting of a curd is a chemical change?
Ans. We can say that setting of curd is a chemical change because we can not get the original substance, i.e., milk back and a new substance is formed with different taste, smell and other chemical properties
.7. Explain why burning of wood and cutting it into small pieces are considered as two different types of changes. ~
Ans. Burning of wood is a chemical change because in burning new substances are formed as
Wood + Oxygen ———–> Charcoal + Carbon dioxide + Heat + Light
But cutting it into small pieces is physical change because no new substance is formed. We can only reduce the size of wood.
Q.8. Describe how crystals of copper sulphate are prepared.
Ans. Take a cupful of water in a beaker and add a few drops of dilute sulphuric acid. Heat the water. When it starts boiling, add copper sulphate powder slowly. Continue to add copper sulphate powder till no more powder can be dissolved. .During this process continuously stir the solution. Filter the solution. Leave it for cooling. Look it after some time, you can see the crystals of copper sulphate
9. Explain how painting of an iron gate prevents it from rusting?
Ans. It is known that for rusting the presence of oxygen and moisture is essential. Painting prevents the iron gate from coming in contact with oxygen and moisture.
Q.10. Explain why rusting of iron objects is faster in coastal areas than in deserts.
Ans. As content of moisture in the air in coastal areas is higher than in the air in deserts. So, the process of rusting is faster in coastal areas.
Chapter 7
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.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 and humid climate of the rainforest.
Chap 8
.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.
.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.
Chapter 9 "Soil"
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:
It has very good water holding capacity.
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 -
(i) It has much smaller particles
(ii) It can hold good amount of water.
(iii) It is fertile
(iv) Air content is low.
(v) Particles are tightly packed
(vi) Good for growing various crops.
Loamy Soil:-
(i) It has much larger particles.
(ii) It cannot hold water
(iii) It is not fertile
(iv) Air get trapped between the particles.
(v) Particles are loosely packed
(vi) Not suitable for growing crops.
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.
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.
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.
Insecticides: Other pollutants of soil include pesticides and insecticides. Therefore, excessive use of these substances should be avoided.
Chapter 10 :- Respiration in organisms
Q1. Why does an athlete breathe faster and deeper than usual after finishing the race?
Answer:
During the run, the demand of energy is high but the supply of oxygen to produce energy is limited. Therefore, anaerobic respiration takes places in the muscle cells to fulfill the demand of energy. After finishing the race, an athlete breathe faster and deeper than usual so that more oxygen is supplied to the cells.
Q2. List the similarities and differences between aerobic and anaerobic respiration.
Answer:
Similarity:
(i) In both aerobic and anaerobic respiration, food is broken down to release energy.
(ii) Both takes place inside cells.
(iii) Both produces byproducts.
Differences:
Aerobic Respiration
(i) It takes place in the presence of oxygen.
(ii) Energy is released in higher amount.
(iii) Carbon dioxide and water are produced as byproducts.
(iv) It is a slow process.
(v) Examples: Animals and plants cells.
Anaerobic Respiration
(i) It takes place in the absence of oxygen.
(ii) Energy is released in lesser amount
(iii) Carbon dioxide and water are produced as byproducts.
(iv) It is a fast process.
(v) Examples: Human cells, yeast, Bacteria etc.
Q3. Why do we often sneeze when we inhale a lot of dust-laden air?
Answer:
We often sneeze when we inhale a lot of dust-laden air to expel out these foreign particles. These particles get past the hair in the nasal cavity and irritate the lining of the cavity which results in sneezing.
Q4. Take three test-tubes. Fill each of them with water. Label them A, B and C. Keep a snail in test-tube A, a water plant in test-tube B and in C, keep snail and plant both. Which test-tube would have the highest concentration of CO2 ?
Answer:
Test-tube A will have the highest concentration of CO2 because snail will take in oxygen and gives out CO2.
In test-tubes B and C, the CO2 will be utilized by the water plant for synthesizing food and hence there will be less concentration of CO2 in these.
Chapter 11 " Transportation in animals and plants"
Q.4.Why is transport of materials necessary in a plant or an animal? Explain.
Ans.Transport of materials is necessary for plants or animals because due to it the nutrients and oxygen are made available to all the parts of the body. If the transport of necessary nutrients and oxygen does not take place in the body, the body will not be able to survive.
Q.5.What will happen if there are no platelets in the blood?
Ans.The blood platelets are responsible for the clotting of the blood. When some injury occurs blood starts flowing. But it clots on its own. If there are no platelets, the blood will not be able to clot and keep on flowing. Huge loss of blood ultimately causes death.
Q.6.What are stomata? Give two junctions of stomata.
Ans.There are small openings on the lower surface of the leaves. These pores are called stomata. These openings are surrounded with guard cells.
Functions of stomata:
1. It helps in the transpiration of water, i.e., the loss of excess water from the plant.
2. Loss of water from the stomata creates an upward pull, i.e., suction pull which helps in absorption of water from the roots.
3. They help in exchange of gases.
Q.7.Does transpiration serve any useful function in plants? Explain.
Ans.(i) It helps to enhance the absorption of water and dissolved minerals by creation of a suction pull.
(ii) It helps in getting rid of the excess water.
(iii) It helps in transport of water and minerals to leaves and leaves use the water for photosynthesis. ‘
(iv)It produces a cooling effect on the plant
Q.8.What are the components of blood?
Ans.There are four components of blood:
(i) Plasma is a liquid part of blood which is yellowish in colour and contain 90% water. It contains food, enzymes, wastes and proteins etc
(ii) Red blood cells are disc shaped cells containing red coloured pigment called haemoglobin in it. Haemoglobin helps in transportation of oxygen.
(iii) White blood cells are the fighting cells which protect us against bacteria and foreign materials causing infections.
(iv) Platelets help in clotting of the blood
Q.9.Why is blood needed by all the parts of a body?
Ans. Blood is needed by all the parts because it contains the digested food and oxygen in it. It supplies the oxygen and digested food to various parts of the body to provide essential energy to them which helps the body to perform various functions
Q.10.What makes the blood look red?
Ans. A red pigment called haemoglobin gives the blood its red colour. This pigment helps in carrying oxygen to various parts of the body by blood
Q.11.Describe the function of the heart.
Ans. The right auricle and ventricle receive blood with carbon dioxide from all parts of the body. The collected blood is then pumped to the lungs for the purification. In lungs, the exchange of gases takes place and purified blood is sent back to left auricle. It pumps it to the left ventricle, which in turn pumps off the purified blood to all parts of body through arteries
Q.12.Why is it necessary to excrete waste products?
Ans. Certain waste and toxic products are formed during functioning of body cells. The waste products like urea etc. are toxic. When these toxic materials are not removed from the body, they get mixed with blood and can damage the cells of body. It is necessary to remove such poisonous waste materials from our body.
Q.13.Draw a diagram of the human excretory system and label the various parts.
Ans.
