Solutions of Microorganisms: Friend and Foe, CH 2, CLASS 8

 1. a) Microscope

b) Nitrogen

c) Yeast

d) Bacteria- Vibrio cholera

2. a) (ii) alcohol

b) (ii) Streptomycin

c) (i) female Anopheles mosquito

d) (ii) housefly

e) (iii) growth of yeast cells

f) (iii) fermentation

3. 

A	B
(i) Bacteria	(e) Causing cholera
(ii) Rhizobium	(a) Fixing nitrogen
(iii) Lactobacillus	(b) Setting of curd
(iv) Yeast	(c) Baking of bread
(v) A protozoan	(d) Causing malaria
(vi) A virus	(f) Causing AIDS

4. Microorganisms cannot be seen by the naked eye because they are very small. They can be seen by using a microscope.

5. Major group of microorganisms are as follows

1. Bacteria
2. Fungi
3. Protozoans
4. Algae
5. Viruses

6. Rhizobium

7. Uses of microorganisms are listed below

• They are helpful in cleaning up of the environment. For example, the organic wastes (vegetable peels, remains of animals, faeces, etc.) are broken down into harmless and usable substances by bacteria.
• Curd contains several microorganisms. Of these, the bacterium, Lactobacillus promotes the formation of curd. It multiplies in milk and converts it into curd.
• Bacteria are also involved in the making of cheese, pickles and many other food items.
• Bacteria and yeast are also helpful for fermentation of rice idlis and dosa batter.
• Yeast reproduces rapidly and produces carbon dioxide during respiration. Bubbles of the gas fill the dough and increase its volume. This is the basis of the use of yeast in the baking industry for making breads, pastries and cakes.
• Microorganisms are used for the large scale production of alcohol, wine and acetic acid (vinegar).
• Antibiotics are being produced from bacteria and fungi.
• Microorganisms are helpful in producing vaccines against disease-causing agents.
• Some bacteria (Fig. 2.7) are able to fix nitrogen from the atmosphere to enrich the soil with nitrogen and increase its fertility.
• Microorganisms decompose dead organic waste of plants and animals to convert them into simple substances. These substances are again used by other plants and animals. Thus, microorganisms can be used to degrade the harmful and smelly substances and thereby clean up the environment.

8. Microorganisms cause diseases in plants and animals Ex; Cholera in humans is caused by bacteria called Vibrio cholera. In animals, the virus causes foot and mouth diseases. Microorganisms spoil the foods by decomposing the food material. Some microorganisms spoil leather and clothes. Microorganisms are responsible for food poisoning.

9. Chemical agents that kill or stop the growth of disease-causing microorganisms are called antibiotics. Antibiotics should be taken only on the advice of a qualified doctor. Also, one must complete the course prescribed by the doctor.

Solutions of Components of Food, CH 2, class 6

 1. The major Nutrients in our food are Carbohydrates, Proteins, Lipids, Vitamins and Minerals. In addition water and dietary fibers are also needed.

2. a) Carbohydrates

b) Proteins and minerals

c) Vitamin A

d) Calcium

3. a) Cream, Butter

b) Rice, Wheat

c) Whole grains, raw vegetables

d) Milk, Soya bean

4. (a) By eating rice alone, we can fulfill nutritional requirement of our body. ( F)

(b) Deficiency diseases can be prevented by eating a balanced diet. (√ )

(c) Balanced diet for the body should contain a variety of food items. (√ )

(d) Meat alone is sufficient to provide all nutrients to the body. (F )

5. (a) Rickets is caused by deficiency of Vitamin D.

(b) Deficiency of Vitamin B1 causes a disease known as beri-beri.

(c) Deficiency of Vitamin C causes a disease known as Scurvy.

(d) Night blindness is caused due to deficiency of Vitamin A in our food.

Solutions of Components of food NCERT Exemplar Class 6 Science

 1. (d): Milk.

Animal products like milk do not contain dietary fiber.

Dietary fiber is formed of cellulose and is obtained mainly from plant products.

Whole grains, whole pulses, fruits and vegetables are rich sources of dietary fiber.

2. (d): Cottage cheese (paneer)

Cottage cheese (paneer) is the source of animal protein whereas peas, gram and soya beans are the sources of plant proteins.

3. (b): Vitamin C

Vitamin C is present in a negligible amount in milk whereas protein, calcium and vitamin D are present in considerable amounts in milk.

4. (c): Wheat and Ghee.

Fats and carbohydrates are energy giving foods hence ghee is rich in fats whereas wheat is rich in carbohydrates. So, these are energy giving foods.

Iodized salt and spinach are protective foods because iodized salt contains minerals and spinach is rich in both minerals and vitamins.

5. (c): They are caused due to lack of nutrients in our diet. And they can be prevented by taking a balanced diet.

Deficiency diseases are the diseases which are caused by the deficiency of nutrients in the diet. These are non-infectious and do not spread from one to another person.

6. (b): ii, i, iv, iii

To test the presence of proteins in a food item, first, make a paste or powder of food to be tested (ii), then take a small quantity of the food item in a test tube, add 10 drops of water to it and shake it (i). After that add 2 drops of copper sulphate solution to it (iv), and finally, add 10 drops of caustic soda solution to the test tube and shake well (iii). Let the test tube stand for a few minutes and observe the colour of the solution in the test tube. The appearance of violet colour indicates the presence of proteins in the given food item.

7. (a) Protein

(b) Minerals

(c) Vitamin

(d) Carbohydrate

(e) Nutrients

(f) Fat

8. Water does not provide any nutrients to the human body, yet it is essential for life.

9. (a) fat, protein

(b) balanced diet

(c) obesity

(d) roughage

(e) vitamin C

10. 

Carbohydrate Rich food Item (A)	Protein Rich food Item (B)	Fat Rich food Item (C)
Sweet potato	Moong dal	Mustard oil
Rice	Fish	Cottage Cheese
Maize	Milk	Milk
White bread	Egg	Egg
	Beans	Butter
	Buttermilk	Fish
	Cottage cheese
	Peas

11. (a) (i) chapati

(b) (ii) phosphorus (iii) D

(c) (iv) Butter

(d) (v) protein (vi) calcium

(e) (vii) Papaya

(f) (viii) iron

(g) (ix) peas (x) proteins

Components of food NCERT Exemplar Class 6 Science

 1. Which one of the following food item does not provide dietary fiber?

(a) Wholegrain
(b) Whole pulses
(c) Fruits and vegetables
(d) Milk

2. Which of the following sources of protein is different from others?
(a) Peas
(b) Gram
(c) Soya beans
(d) Cottage cheese (paneer)

3. Which of the following nutrients is not present in milk?
(a) Protein
(b) Vitamin C
(c) Calcium
(d) Vitamin D

4. Read the food items given below.
(i) Wheat
(ii) Ghee
(iii) Iodized salt
(iv) Spinach (palak)
Which of the above food items are “energy-giving foods”?
(a) (i) and (iv)
(b) (ii) and (iv)
(c) (i) and (ii)
(d) (iii) and (iv)

5. Read the following statements about diseases.
(i) They are caused by germs.
(ii) They are caused due to lack of nutrients in our diet.
(iii) They can be passed on to another person through contact.
(iv) They can be prevented by taking a balanced diet.
Which pair of statements best describe a deficiency disease?
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (ii) and (iv)
(d) (i) and (iii)

6. 6. Given below are the steps to test the presence of proteins in a food item.

(i) Take a small quantity of the food item in a test tube, add 10 drops of water to it and shake it.
(ii) Make a paste or powder of food to be tested.
(iii) Add 10 drops of caustic soda solution to the test tube and shake well.
(iv) Add 2 drops of copper sulphate solution to it.
Which of the following is the correct sequence of the steps?
(a) i, ii, iv, iii
(b) ii, i, iv, iii
(c) ii, i, iii, iv
(d) iv, ii, i, iii

7. 7. Unscramble the following words related to components of food and write them in the space provided.

(a) reinpot ___________
(b) menliars __________
(c) tivanmi ___________
(d) bocatradhyer _______
(e) nitesturn__________
(f) tfa_______________

8. 8. Which of the following food items does not provide any nutrient

[Milk, Water, Orange juice, Tomato soup] Solution:

9. 9. Fill in the blanks from the list of words given below.

(carbohydrate, fat, protein, starch, sugar, vitamin A, vitamin C, roughage, balanced diet, obesity, goitre)

(a) Egg yolk is rich in_____and egg albumin is rich in___.
(b) Deficiency diseases can be prevented by taking a____.
(c) Eating too much of fat-rich foods may lead to a condition called____.
(d) The component of food that does not provide any nutrient to our body and yet is essential in our food is_____.
(e) The vitamin that gets easily destroyed by heating during cooking is ____.

10. 10. Read the items of food listed below. Classify them into carbohydrate-rich, protein-rich and fat-rich foods and fill them in the given table. Moong dal, fish, mustard oil, sweet potato, milk, rice, egg, beans, butter, buttermilk (chhachh), cottage cheese (paneer), peas, maize, white bread.

Carbohydrate Rich food Item (A)	Protein Rich food Item (B)	Fat Rich food Item (C)
……	…….	…….
……	…….	…….
……	…….	…….

11. Observe the items given in Fig. 2.2 carefully and answer the questions that follow.

(a) Food item rich in carbohydrates is (i)______
(b) Egg is a rich source of protein, the mineral (ii)__and vitamin (iii)______
(c) (iv)___is a rich source of fat.
(d) Milk provides __ (v)____ vitamin D and ___(vi)____(mineral).
(e) ___(vii)____(fruit) is a rich source of vitamin A.
(f) Spinach is a good source of the mineral__(viii)____
(g) Both eggs and ___(xi)____are rich in___(x)______

Solutions of Microorganisms Friend And Foe Chapter 2 NCERT Exemplar Class 8 Science

 1. The answer is (b) Virus

Explanation:

The virus is considered as intermediate between living and non-living. Outside a host-virus remains inactive. It can perform its life processes and reproduction only when it is inside a host cell.

2. The answer is (b) Influenza

Explanation:

Typhoid is caused by bacteria Salmonella typhoid.

Dysentry is caused by an amoeba which is a protozoan.

Cholera is caused by Vibrio cholera bacteria.

3. The answer is (b) Antibiotics

Explanation:

• Pain Killers gives relief from pain.
• Antibodies are produced by our immune system which acts and elicit a specific immune reaction.
• Antibiotics that inhibit or kill certain bacteria.
• Vaccines provide acquired immunity against a particular disease.

4. The answer is (d) Alga and Fungus

5. The answer is (b) Carbon dioxide

Explanation:

Carbon-di-oxide is released due to the fermentation process conducted by yeast. CO2 causes rising of the dough and make the bread fluffy.

6. The answer is (b) Malaria

Explanation:

Malaria is caused by protozoan named Plasmodium vivax which is transmitted by mosquitos. Other options are viral diseases hence they are wrong answers.

7. The answer is (b) Waste in pit B degraded faster than that in pit A.

Explanation:

Waste in pit B degrades faster than waste in pit A because Polythene in pit B is open and receives oxygen for composting whereas polythene in closed in pit A and organisms don’t receive oxygen to compost the waste material in the polythene bag.

8. a. Antibodies

b. Tuberculosis

c. Anthrax

d. Fermentation

9. a. Preservatives

b. Rhizobium

c. Carrier/ vector

d. Antibiotics

10. (a) Louis Pasteur – (iii) Fermentation

(b) Robert Koch – (ii) anthrax bacterium

(c) Edward Jenner – (iv) small pox vaccine

(d) Alexander Fleming – (i) Penicillin

11. Yeast is used in making bread and they are used in the fermentation of alcohol.

12. Fermentation is the process in yeast that converts sugars into alcohol.

13. Blue-green-algae enriches Nitrogen in the soil.

14. Tuberculosis can spread through the air when the infected person coughs. Hence we avoid standing close to a tuberculosis patient while he/she is coughing.

15. If the children are suffering from diarrhoea oral polio drops will get excreted due to frequent motions. Hence children with diarrhoea are not given with polio drops.

16.Oils prevent the attack of bacteria which will help preserve the pickle for a long period of time.

17. Column A – Column B

(a) Lactobacillus – (iv) Bacteria

(b) Aspergillus – (iii) Fungi

(c) Spirogyra – (i) Algae

(d) Paramecium – (ii) Protozoa

18. 

Friendly	Harmful Microorganisms
Yeast	Malarial parasite
Lactobacillus	Bread mould
Rhizobium	Bacillus anthracis

 

19. The probable reason is that the chaat was contaminated by pathogenic microbes due to unhygienic conditions near the shop or the utensil used for serving could have contaminated.

The reason may be the contamination of food by pathogenic microbes. Contamination may be due to the unhygienic conditions near the shop or the utensil used to serve the chaat.

20. a. Polio, HIV

b. A virus can reproduce only when it is inside the host cell.

Microorganisms Friend And Foe Chapter 2 NCERT Exemplar Class 8 Science

 1. Which of the following reproduces only inside a host cell?

(a) Bacteria

(b) Virus

(c) Amoeba

(d) Fungus.

2. A disease in human beings caused by a virus is _______.

(a) Typhoid

(b) Influenza

(c) Dysentery

(d) Cholera

3. Pathogenic micro-organisms present in host cells are killed by medicines called

(a) Pain killer

(b) Antibodies

(c) Antibiotics

(d) Vaccines

4. The two micro-organisms which live in symbiotic association in lichens are

(a) Fungus and Protozoa

(b) Alga and Bacteria

(c) Bacteria and Protozoa

(d) Alga and Fungus

5. The gas released during the preparation of bread is

(a) Oxygen

(b) Carbon dioxide

(c) Nitrogen

(d) Sulphur dioxide

6. The disease caused by a protozoan and spread by an insect is _________.

(a) Dengue

(b) Malaria

(c) Polio

(d) Measles

7. Paheli dug two pits, A and B, in her garden. In-pit A, she put a polythene bag packed with some agricultural waste. In-pit B, she dumped the same kind of a waste but without packing it in a polythene bag. She then covered both the pits with soil. What did she observe after a month?

(a) Waste in pit A degraded faster than that in pit B.

(b) Waste in pit B degraded faster than that in pit A.

c) Waste in both pits degraded almost equally.

(d) Waste in both pits did not degrade at all.

8. Unscramble the jumbled words underlined in the following statements.

(a) Cells of our body produce santiidobe to fight pathogens.

(b) curbossulite is an air-borne disease caused by a bacterium.

(c) Xanrhat is a dangerous bacterial disease.

(d) Yeasts are used in the wine industry because of their property of meronettinaf.

9. Suggest a suitable word for each of the following statements.

(a) Chemicals added to food to prevent the growth of microorganisms.

(b) Nitrogen-fixing microorganism present in the root nodules of legumes.

(c) The agent spreads pathogens from one place to another.

(d) Chemicals which kill or stop the growth of pathogens.

10. Match the names of scientists given in Column A with the discovery made by them given in Column B.

Column A – Column B

(a) Louis Pasteur – (i) Penicillin

(b) Robert Koch – (ii) anthrax bacterium

(c) Edward Jenner – (iii) Fermentation

(d) Alexander Fleming – (iv) small pox vaccine

11. Name one commercial use of yeast

12. Name the process in yeast that converts sugars into alcohol.

13. In the soil, which nutrient is enriched by blue-green algae (cyanobacteria)?

14. Why should we avoid standing close to a tuberculosis patient while he/she is coughing?

15. Polio drops are not given to children suffering from diarrhoea. Why?

16. Paheli watched her grandmother making mango pickle. After she bottled the pickle, her grandmother poured oil on top of the pickle before closing the lid. Paheli wanted to know why oil was poured? Can you help her understand why?

17. Match the microorganisms given in Column A to the group to which they belong in Column B.

Column A – Column B

(a) Lactobacillus – (i) Algae

(b) Aspergillus – (ii) Protozoa

(c) Spirogyra – (iii) Fungi

(d) Paramecium – (iv) Bacteria

18. Classify the following into friendly and harmful microorganisms.

Yeast, malarial parasite, Lactobacillus, bread mould, Rhizobium, Bacillus anthracis

19. While returning from the school, Boojho ate chaat from a street hawker. When he reached home, he felt ill and complained of stomach ache and fell ill. What could be the reason?

20. (a) Name two diseases that are caused by the virus.

(b) Write one important characteristic of the virus.

SOLUTIONS OF WORKSHEET 1 , CROP PRODUCTION AND MANAGEMENT CHAPTER 1, CLASS 8

 1. Weeds

2. Wild oat

3. Manual method, Chemical method, Biological method

4. Weedicides

5. Hoe

6. Tilling or ploughing

7. Manure and fertilisers

8. Irrigation

9. Wells, tubewells, ponds, lakes, etc.

10. Winnowing

11. Pea, gram

12. March/April

13. Soybean, groundnut

14. June/July

15. NPK, Diammonium phosphate

16. NPK, Diammonium phosphate

17. Agricultural practices are those practices which involve the necessary steps to be taken during production of crops.

18. Some of the crops are first grown in the nurseries and then transferred to the main field. This process is known as transplantation.

19. 

• It enhances water-holding capacity of soil.
• It improves soil quality.
• It promotes the growth of soil friendly microbes.
• It is renewable, biodegradable and eco-friendly.

20. 

• Storage: Storage of produce is an important task. If the crop grains are to be kept for longer time, they should be safe from moisture, insects, rats and microorganisms. Before storing, the grains are properly dried in the sun to reduce the moisture in them. This prevents the attack by insect pests, bacteria and fungi. Grains are stored by farmers in jute bags or metallic bins. However, large scale storage of grains is done in silos and granaries to protect them from pests like rats and insects.
• Harvesting: After maturation of crop, harvesting is an important task. In harvesting, crops are pulled out or cut close to the ground. It usually takes 3 to 4 months for a cereal crop to mature. Harvesting in our country is either done manually by sickle or by machine called harvester.

WORKSHEET 1 , CROP PRODUCTION AND MANAGEMENT CHAPTER 1, CLASS 8

 1. What is the name of the undesirable plants that grow among the crops?

2. Name one weed.

3. Name the methods applied for weeding.

4. Name the chemicals that are used to remove weeds.

5. Name a tool which is used for removing weeds and for loosening soil.

6. What is the process of loosening and turning of the soil called?

7. What are the substances which are added to the soil in the form of nutrients called?

8. What is the process of supplying water to crops at different intervals is called?

9. What are the sources of irrigation?

10. What is the process of separation of grain from chaff called?

11. Name two crops belonging to rabi crop.

12. Name the ideal months for the harvesting of rabi crops.

13. Name two kharif crops.

14. Name the ideal months for sowing kharif crops

15. Name any two fertilisers.

16. What is a crop?

17. What do you mean by the term agricultural practice?

18. Explain the term transplantation.

19. What are the advantages of manure?

20. Write short note on the terms:

• Storage
• Harvesting

CROP PRODUCTION AND MANAGEMENT(NCERT SOLUTIONS) CHAPTER 1, CLASS 8

 Exercise Questions

1. Select the correct word from the following list and fill in the blanks.

float, water, crop, nutrients, preparation

Sol. (a) The same kind of plants grown and cultivated on a large scale at a place is called the crop.

(b) The first step before growing crops is the preparation of the soil.

(c) Damaged seeds would float on top of the water.

(d) For growing a crop, sufficient sunlight and water and nutrients from the soil are essential.

2. Match items in column A with those in column B.

sol:-

(i) Kharif crops.	(e) Paddy and maize.
(ii) Rabi crops.	(d) Wheat, gram, pea.
(iii) Chemical fertilisers.	(b) Urea and superphosphate.
(iv) Organic manure.	(c) Animal excreta, cow dung urine and plant wastes.

3. Give two examples of each.

(a) Kharif crop

(b) Rabi crop

Soln:

Kharif crops- Paddy and maize

Rabi crops- Wheat and Pea

4. Write a paragraph in your own words on each of the following.

(a) Preparation of soil

(b) Sowing

(c) Weeding

(d) Threshing

Soln:

a) Preparation of the soil is the first step in agriculture. Preparation of the soil is done to loosen the soil, which is essential for the root penetration into the soil. This allows the roots to breathe easily. Loosening of the soil allows the growth of earthworms and microorganisms, which will help to keep the soil fertile by adding humus to the soil. Loosening of soil also brings nutrient-rich soil to the top layer, which is essential for the growth of plants.

b) Sowing is an important process in crop production. First, healthy seeds are selected before sowing. After selecting healthy seeds sowing is done by either traditional methods or by using equipment’s seed drill.

c) Removal of unnecessary plants from the field is called weeding. Weeds compete with crop plants for nutrients and water. This will reduce the yield of the desired crops. Weeds also interfere while harvesting and gets mixed with crops. Some weeds are poisonous to animals and humans. Tilling is a common method which helps removal of weeds before sowing crops, manual methods like physical removal of plants are used to remove weeds. Weedicides are sprayed to get rid of weeds, but this method may affect the health of farmers because of chemicals used as weedicides.

d) Process of separating the chaff from the crop is known as threshing. Threshing is carried by a machine called ‘combine’ which is a harvester as well as a thresher. Threshing is also done by winnowing where to blow of wind is used to separate the chaff from crops.

5. Explain how fertilisers are different from manure.

Soln:

Fertilizers	Manure
Fertilizer is an inorganic substance.	Manure is an organic substance.
Fertilizers are prepared artificially.	Manure is obtained by decomposition of animal, plant and human waste.
Prepared in factories.	Prepared in fields.
Does not provide Humus to the soil.	Provide humus to the soil.
Rich in plant nutrients.	Relatively less plant nutrients.
Long term usage has adverse effects on soil.	Long term usage improves soil fertility.

6. What is irrigation? Describe two methods of irrigation which conserve water.

Soln:

The supply of water to crops at regular intervals is called irrigation. Methods of irrigation which conserve water are

a) Drip Irrigation: Here the water goes drop by drop directly into the roots this method is very useful as it conserves the water and also helps in avoiding weeds.

DRAW DIAGRAM HERE

b) Sprinkler system: This method is in use in mainly uneven land where sufficient water is not available. The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline at regular intervals. When water is allowed to flow through the main pipe under pressure with the help of a pump, it escapes from the rotating nozzles. It gets sprinkled on the crop as if it is raining.

DRAW DIAGRAM HERE

7. If wheat is sown in the Kharif season, what would happen? Discuss.

Soln:

Wheat crops may get destroyed if sown in Kharif season because of unfavourable temperature, pests and adaptable conditions for the plants to grow. Kharif come during the rainy season, hence it is not a wise idea to grow wheat in Kharif season.

8. Explain how soil gets affected by the continuous plantation of crops in a field.

Soln:

Plants require nutrients for their growth. Without optimum nutrients plants will die. Continuous plantation of crops results in depletion of certain nutrients like Nitrogen, Phosphorus, Potassium etc. This results in the decrease of yield due to loss of nutrients hence there should be a gap between crops in order to get a good yield.

9. What are weeds? How can we control them?

Soln:

In a field many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. Weeds can be controlled by methods called weeding. Tilling before sowing of crops helps in uprooting and killing of weeds, which may then dry up and get mixed with the soil. Weeds are also controlled by using certain chemicals, called weedicides.

10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

Soln:

11. Complete the following word puzzle with the help of clues given below.

Down

1. Providing water to the crops.

2. Keeping crop grains for a long time under proper conditions.

5. Certain plants of the same kind grown on a large scale.

Across

3. A machine used for cutting the matured crop.

4. A rabi crop that is also one of the pulses.

6. A process of separating the grain from chaff.

Soln: