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:

SOLUTIONS OF WORKSHEET 1 , FOOD: Where does it come from CHAPTER 1, CLASS 6

 1.  Mustard — seeds and leaves,

Pumpkin — fruit and flowers.

2. Lotus — Stem of lotus is eaten as food.

3. (i) Avoid leaving food uneaten in meals.

(ii) “Eat to live” and not “live to eat” — excess eating should be avoided.
(iii) Raw food like pulses, grains should be stored properly.

4. (a) Sugarcane                                           (b) Sugarbeet.

5. Mushroom.

6. Food habit.

7. My food habit: Chapatti, pulses, lassi, rice, vegetables, mustard oil.

Food habit of my friend: Idli, dosa, sambhar, bara, rasam, upma and coconut oil, etc.

8. Raw rice and water.

9. Yes, they have some common ingredients like: water, salt and oil or ghee.

10. (i) Plants                                                  (ii) Animals

11. Plant products: Grains, cereals and vegetables.

Animal products: Milk, egg and meat.

12. (i) Roots                                        (ii) Fmits                                (iii) Leaves

13. We generally eat fruits of many plants.

14. Sprouted seeds give more energy than normal seeds.

15. A sweet substance (liquid) prepared by bees from the riectar, i.e., sweet juice collected from flowers is called honey.

WORKSHEET 1 , FOOD: Where does it come from CHAPTER 1, CLASS 6

Q. 1. Give two examples where two or more parts of a single plant are used as food.

Q.2. Name any one plant that grows in water and is eaten as food.

Q.3. Suggest any three ways you can think of to avoid wastage of food.

Q.4. Name two sugar producing plants.

Q.5. Name a non-green plant that we eat.

Q.6. What do you call the habit of an individual to eat a particular type of food items commonly?

Q.7. Compare your food habits with food habits of your friend who lives in Tamil Nadu.

Q.8. What items are used to prepare cooked rice?

Q.9. Study the ingredients of various food items. Do they have some common food ingredients?

Q.10. What are the two common sources of most of the ingredients of food items?

Q.11. Name the three products each provided by plants and animals.

Q.12. Name three edible (eatable) parts of plants.

Q.13. Which part of the plants do we eat generally?

Q. 14. Which type of seeds give more energy, sprouted seeds or normal seeds?

Q.15. What is honey? 

FOOD: Where does it come from(NCERT SOLUTIONS) CHAPTER 1, CLASS 6

 NCERT SOLUTIONS

FOOD: Where does it come from

CHAPTER 1, CLASS 6

Q. 1. Do you find that all living beings need the same kind of food?
Ans. No, all living beings do not need same kind of food.

Q.2. Name five plants and their parts that we eat.
Ans. The names of five plants and their parts that we eat are:

    Name of the plant                            Plant Part

(i) Paddy                                             seeds
(ii) Wheat                                            seeds
(iii) Mustard plants                              seeds and leaves
(iv) Brinjal plant                                   fruits
(v) Potato plant                                    stems

Q. 3. Match the items given in column A with those in column B.

Q. 4. Fill up the blanks with the words given:
herbivore, plant, milk, sugarcane, carnivore.
(a) Tiger is a__________ because it eats only meat.
(b) Deer eats only plant products and so is called______________ .
(c) Parrot eats only__________
(d) The_________ that we drink, which comes from cows, buffaloes and goats is
an animal product.
(e) We get sugar from___________ .
Ans. (a) carnivore                                   (b) herbivore                 (c) plant
(d) milk                                     (e) sugarcane