Science Ncert Exemplar 2019 Solutions for Class 9 Science Chapter 15 Improvement In Food Resources are provided here with simple step-by-step explanations. These solutions for Improvement In Food Resources are extremely popular among class 9 students for Science Improvement In Food Resources Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Science Ncert Exemplar 2019 Book of class 9 Science Chapter 15 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Science Ncert Exemplar 2019 Solutions. All Science Ncert Exemplar 2019 Solutions for class 9 Science are prepared by experts and are 100% accurate.

Page No 85:

Question 1:

Which one is an oil yielding plant among the following?
(a) Lentil
(b) Sunflower
(c) Cauliflower
(d) Hibiscus

Answer:

Lentils are pulse yielding plants. Cauliflower is a vegetable and Hibiscus is a flower, whereas sunflower is used to make oil.

Hence, the correct answer is option (b). 

Page No 85:

Question 2:

Which one is not a source of carbohydrate?
(a) Rice
(b) Millets
(c) Sorghum
(d) Gram

Answer:

Rice, millets and sorghum have carbohydrates in them as a major source of energy. Whereas gram is a dicotyledon and is rich in proteins.

Hence, the correct answer is option (d). 

 

Page No 85:

Question 3:

Find out the wrong statement from the following
(a) White revolution is meant for increase in milk production
(b) Blue revolution is meant for increase in fish production
(c) Increasing food production without compromising with environmental quality is called as sustainable agriculture
(d) None of the above

Answer:

White Revolution focused on the increase in the yield of dairy products. This was achieved by cross-breeding local and exotic varieties or by breeding high milk yielding an exotic variety of cattle like Jersey. It also focused on developing a supply chain that made milk and dairy products available in sufficient quantities all over India. White revolution is also known as operation flood and was led by Dr Verghese Kurien.

Hence, the correct answer is option (a). 

Page No 85:

Question 4:

To solve the food problem of the country, which among the following is necessary?
(a) Increased production and storage of food grains
(b) Easy access of people to the food grain
(c) People should have money to purchase the grains
(d) All of the above

Answer:

All three points are required to solve the food problem of a country. Once the production and storage of grains are increased, they will be easily available in the market for people to use. The stored food grains have to be easily available in the market for people to buy at a reasonable price. Consumers should have money to buy the grain. That means, there has to be a stable and sustainable income in every household. If we have sufficient food grain in the market but, people do not have money to buy it then the food problem will not be solved. Similarly, if there is enough money with the people but no grains available in the market, again the food problem cannot be solved. Finally, if there is ample money with people and the huge amount of grains also stocked up but if the grains do not reach the shelves in the market, stores, mart, malls and cooperative or subsidy shops, then people will not be able to buy them and therefore the food problem cannot be resolved.

Hence, the correct answer is option (d). 



Page No 86:

Question 5:

Find out the correct sentence
(i) Hybridisation means crossing between genetically dissimilar plants
(ii) Cross between two varieties is called as inter specific hybridisation
(iii) Introducing genes of desired character into a plant gives genetically modified crop
(iv) Cross between plants of two species is called as inter varietal hybridisation

(a) (i) and (iii)
(b) (ii) and (iv)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer:

Hybridization is defined as the process of interbreeding between two genetically divergent individuals or two individuals of different species.  Interspecific hybridization means cross-mating between two different species but sharing the same genera. For example, a crossbreed between a lion and a tiger, both are from the same genus Panthera but different species.  Introducing genes of the desired character into a plant gives a genetically modified crop.  When the parent plants crossbred are from the same species, but of a different variety is called intervarietal hybridization. For example, a crossbred between two different varieties of the wheat plant. They belong to the same species but they are of different varieties. 

Hence, the correct answer is option (a). 

Page No 86:

Question 6:

Weeds affect the crop plants by
(a) killing of plants in field before they grow
(b) dominating the plants to grow
(c) competing for various resources of crops (plants) causing low availability of nutrients
(d) all of the above.

Answer:

Weeds are unwanted plants in the cultivated field. They compete with the crop plants for food, space and light. They take up the nutrients and reduce the crop yield. 

Hence, the correct answer is option (c). 

Page No 86:

Question 7:

Which one of the following species of honey bee is an Italian species?
(a) Apis dorsata
(b) Apis florae
(c) Apis cerana indica
(d) Apis mellifera

Answer:

Apis mellifera is an Italian bee that produces a large amount of honey. They originated in Africa and spread to Northern Europe, India and China. It is less prone to swarming and absconding. It is a docile bee and stings less, thus it is most preferred for apiculture. 

Hence, the correct answer is option (a). 

 

Page No 86:

Question 8:

Find out the correct sentence about manure
(i) Manure contains large quantities of organic matter and small quantities of nutrients.
(ii) It increases the water holding capacity of sandy soil.
(iii) It helps in draining out of excess of water from clayey soil.
(iv) Its excessive use pollutes environment because it is made of animal excretory waste.

(a) (i) and (iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer:

Manure is prepared from the breakdown of plant and animal waste products and is rich in organic matter. It contributes to the fertility of the soil by adding organic matter and some essential nutrients like N, P and K that help in enhancing the growth of plants. It helps in increasing soil structure by keeping the soil intact and this also decreases soil erosion. It helps in regulating the water holding capacity of soil so that water is not lost from the plant soil early by evaporation. It also makes the clayey soil aerated because of their small pores and increase the water holding capacity of the sandy soil due to their large size. Manure is made from animal excretory waste it is completely organic and replenishes the soil with its nutrient content. 

Hence, the correct answer is option (b)



Page No 87:

Question 9:

Cattle husbandry is done for the following purposes
(i) Milk Production
(ii) Agricultural work
(iii) Meat production
(iv) Egg production

(a) (i), (ii) and (iii)
(b) (ii), (iii) and (iv)
(c) (iii) and (iv)
(d) (i) and (iv)

Answer:

Cattle husbandry is done for the purpose of milk production, agricultural work and meat production. But poultry farming is done for egg production. 

Hence, the correct answer is option (a). 

Page No 87:

Question 10:

Which of the following are Indian cattle?
(i) Bos indicus
(ii) Bos domestica
(iii) Bos bubalis
(iv) Bos vulgaris

(a) (i) and (iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer:

Bos domestica is found in Africa and Bos Vulgaris does not belong to Bos family.

Hence, the correct answer is option (a). 

Page No 87:

Question 11:

Which of the following are exotic breeds?
(i) Brawn
(ii) Jersey
(iii) Brown Swiss
(iv) Jersey Swiss

(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)

Answer:

The breeds that are brought from outside are called exotic breeds. The quality and quantity of milk of some breeds are comparatively much better than others, exotic breeds of cattle have long lactation periods and give more amounts of milk, e.g., Brown Swiss, Jersey and Holstein etc. 

Hence, the correct answer is option (b). 

Page No 87:

Question 12:

Poultry farming is undertaken to raise following
(i) Egg production
(ii) Feather production
(iii) Chicken meat
(iv) Milk production

(a) (i) and (iii)
(b) (i) and (ii)
(c) (ii) and (iii)
(d) (iii) and (iv)

Answer:

In poultry farming, domestic fowls are raised to produce eggs and chicken. In poultry, the improved varieties are developed for improving the quality and quantity of chicks. Improved varieties will have the desirable characteristics of good yield and better nutrition, whereas cattle farming is done for milk production.

Hence, the correct answer is option (a). 



Page No 88:

Question 13:

Poultry fowl are susceptible to the following pathogens
(a) Viruses
(b) Bacteria
(c) Fungi
(d) All of the above

Answer:

Poultry fowl are susceptible to all the pathogens like viruses, bacteria, and fungi. For example:
Viral disease- Bird flu and Ranikhet
Bacterial disease- Salmonellosis and Tuberculosis
Fungal disease- Aspergillosis. 

Hence, the correct answer is option (d). 

 

Page No 88:

Question 14:

Which one of the following fishes is a surface feeder?
(a) Rohus
(b) Mrigals
(c) Common carps
(d) Catlas

Answer:

Surface feeder fish are those fish that have a straight back and helps their upturned mouth or supra terminal mouth to easily reach the surface and perfectly grab the food without being revealed to the prey.  These species are selected so that they do not compete for food among them. As they have different types of food habits. As a result, the food available in all the parts of the pond is used. The Catla fish known as Catla catla eats phytoplanktons and is a surface feeder.

Hence, the correct answer is option (d). 

Page No 88:

Question 15:

Animal husbandry is the scientific management of
(i) animal breeding
(ii) culture of animals
(iii) animal livestock
(iv) rearing of animals

(a) (i), (ii) and (iii)
(b) (ii), (iii) and (iv)
(c) (i), (ii) and (iv)
(d) (i), (iii) and (iv)

Answer:

Animal husbandry is the farming or management of animal livestock, which includes various aspects such as animal shelter, feeding, health, and disease control.  As animal husbandry is the scientific management of farm animals, it serves many uses for human beings.

  • It helps in enhancing milk production.
  •  It increases egg production and meat production.
  •  It increases fish production.
  •  It helps in the proper management of agricultural wastes.
Hence, the correct answer is option (d). 

Page No 88:

Question 16:

Which one of the following nutrients is not available in fertilizers?
(a) Nitrogen
(b) Phosphorus
(c) Iron
(d) Potassium

Answer:

Fertilizers are chemical substances supplied to the crops to increase their productivity. The fertilizers contain the essential nutrients required by the plants, including nitrogen, potassium, and phosphorus. Iron is a nutrient that is not available in fertilizers. 

Hence, the correct answer is option (c). 

Page No 88:

Question 17:

Preventive and control measures adopted for the storage of grains include
(a) strict cleaning
(b) proper disjoining
(c) fumigation
(d) all of the above

Answer:

The grains are stored in huge stores and warehouses. These stores and warehouses should be regularly and strictly cleaned, disinfected and kept dry to avoid ants, insects, worms or rodents infestations. To keep the grains safe and hygienic for consumption at any time. There should be proper space or be disjoining between the grain sacks for fumigation and regular inspection of the grains is required.  The grains are stored in mass scale in huge chambers called silos. They have a proper outlet to withdraw the desired quantity of grains. The silos have built-in arrangements for aeration, fumigation, protection from rodents, insects, birds etc. 

Therefore, the correct answer is option (d).



Page No 89:

Question 18:

Match the column A with the column B

(A) (B)
(a) Catla (i) Bottom feeders
(b) Rohu (ii) Surface feeders
(c) Mrigal (iii) Middle-zone feeders
(d) Fish farming (iv) Culture fishery

Answer:

Correct Match:

(a) Catla – (ii) Surface feeders

(b) Rohu – (iii) Middle-zone feeders

(c) Mrigal – (i) Bottom feeders

(d) Fish farming – (iv) Culture fishery

Page No 89:

Question 19:

Fill in the blanks
(a) Pigeon pea is a good source of ———.
(b) Berseem is an important———crop.
(c) The crops which are grown in rainy season are called ——— crops.
(d) ——— are rich in vitamins.
(e) ——— crop grows in winter season.

Answer:

(a) Pigeon pea is a good source of protein
(b) Berseem is an important fodder crop.
(c) The crops which are grown in the rainy season are called Kharif crops.
(d) Vegetables are rich in vitamins.
(e)  Rabi crop grows in the winter season.

Page No 89:

Question 20:

What is a GM crop? Name any one such crop which is grown in India.

Answer:

A GM (Genetically modified) crop is developed by introducing the desired gene from a different source into the target crop. Crops are genetically modified to obtain the desired character. For example, Bt cotton is a genetically modified pest-resistant plant cotton variety, that produces an insecticide to combat bollworms. 

Page No 89:

Question 21:

List out some useful traits in improved crop?

Answer:

Traits for improved crop varieties are: 

High yield of the crop
Improved crop quality
Pest and weed resistance
Wider adaptability
Expression of desired agronomic characters.

Page No 89:

Question 22:

Why is organic matter important for crop production?

Answer:

Organic matter is very important for crop production because of the following reasons-

It provides all the required minerals for the crops.
It loosens the soil structure to provide necessary aeration for the roots.
It improves the water holding capacity of the soil.
It helps in drainage and to avoid waterlogging in clayey soil.

Page No 89:

Question 23:

Why is excess use of fertilizers detrimental for environment?

Answer:

Excessive use of fertilizers causes environmental pollution as their residual and unused amounts will become pollutants for air, water and soil, by causing eutrophication in the water bodies, decreasing the soil quality by killing the soil microflora. 

Page No 89:

Question 24:

Give one word for the following
(a) Farming without the use of chemicals as fertilizers, herbicides and pesticides is known as __________.
(b) Growing of wheat and groundnut on the same field is called as __________.
(c) Planting soyabean and maize in alternate rows in the same field is called as __________.
(d) Growing different crops on a piece of land in pre-planned succession is known as __________.
(e) Xanthium and Parthenium are commonly known as __________.
(f) Causal organism of any disease is called as __________.

Answer:

(a) Farming without the use of chemicals such as fertilizers, herbicides and pesticides is known as organic farming
(b) Growing of wheat and groundnut on the same field is called as mixed cropping.
(c) Planting soybean and maize in alternate rows in the same field is called as intercropping.
(d) Growing different crops on a piece of land in pre-planned succession is known as crop rotation.
(e) Xanthium and Parthenium are commonly known as weeds .
(f) Causal organism of any disease is called as pathogen.

Page No 89:

Question 25:

Match the following A and B

(A) (B)
(a) Cattle used for tilling and carting (i) Milk producing female
(b) Indian breed of chicken (ii) Broiler
(c) Sahiwal, Red Sindhi (iii) Drought animals
(d) Milch (iv) Local breed of cattle
(e) Chicken better fed for obtaining meat (v) Aseel

Answer:

Correct match:

(A) (B)
 (a) Cattle used for tilling and carting (iii) Drought animals
(b) Indian breed of chicken (v) Aseel
(c) Sahiwal, Red Sindhi (iv) Local breed of cattle
(d) Milch (i) Milk producing female
(e) Chicken better fed for obtaining (ii) Broiler

 



Page No 90:

Question 26:

If there is low rainfall in a village throughout the year, what measures will you suggest to the farmers for better cropping?

Answer:

Irrigation help to overcome the problem of low rainfall and helps to increase productivity by maintaining soil-water balance. Surface water and groundwater resources are used for irrigation purposes. Several irrigation methods are used to supply water to the crop fields. These are wells, tanks, canals, rivers, sprinkler methods and drip irrigation systems. The nature of the soil plays an important role in the determination of irrigation requirements. 

Page No 90:

Question 27:

Group the following and tabulate them as energy yielding, protein yielding, oil yielding and fodder crop.
Wheat, rice, berseem, maize, gram, oat, pigeon gram, sudan grass, lentil, soyabean, groundnut, castor and mustard.

Answer:

Energy Yielding crop- Wheat, rice, Maize
Protein Yielding crop- gram, pigeon gram, lentil, soybean
Oil yielding crop- groundnut, castor, mustard, soybean
​Fodder crop- berseem, oat, sudangrass

Page No 90:

Question 28:

Define the term hybridisation and photoperiod.

Answer:

Hybridisation– A cross between two genetically different organisms to produce desired characteristics in the offspring is known as hybridisation.

Photoperiod- The duration of the sunlight available for a plant is called photoperiod. It is responsible for the growth of the plant.

Page No 90:

Question 29:

Fill in the blanks
(a) Photoperiod affect the ————.
(b) Kharif crops are cultivated from ———— to ————.
(c) Rabi crops are cultivated from ————to ————.
(d) Paddy, maize, green gram and black gram are ———— crops.
(e) Wheat, gram, pea, mustard are ———— crops.

Answer:

 (a) Photoperiod affect the flowering process .
(b) Kharif crops are cultivated from June to October.
(c) Rabi crops are cultivated from Novemeber to April .
(d) Paddy, maize, green gram and black gram are Kharif crops.
(e) Wheat, gram, pea, mustard are  Rabi  crops.

Page No 90:

Question 30:

Cultivation practices and crop yield are related to environmental condition. Explain.

Answer:

Crops are grown under several different conditions. There are many factors that affect crop yield and growth. Some crops require high temperature, some low temperature, longer duration of sunlight, shorter duration of sunlight, more humidity, low humidity, moderate humidity, loamy soil, sandy soil etc. The crops grown in the rainy season are called Kharif and some crops that grow in the winter season is called Rabi crops.

(i) Weather: Climatic conditions should be favourable for the growth of crops, like duration of sunlight, temperature, rainfall etc.

(ii) Quality of soil: All plants require nutrients for their growth. Soil acts as a medium. Soil should be rich in nutrients and should have a balanced pH for the growth of crops.

(iii) Water availability : Irrigation should be proper for the better production of crops.

Page No 90:

Question 31:

Fill in the blanks
(a) A total of ——— nutrients are essential to plants.
(b) ——— and——— are supplied by air to plants.
(c) ——— is supplied by water to plants.
(d) Soil supply ——— nutrients to plants.
(e) ——— nutrients are required in large quantity and called as ———.
(f) ——— nutrients are needed in small quantity for plants and are called ———.

Answer:

(a) A total of  16 nutrients are essential to plants.
(b) Carbon dioxide and oxygen are supplied by air to plants.
(c) Hydrogen is supplied by water to plants.
(d) Soil supply 13  nutrients to plants.
(e)  6 nutrients are required in large quantities and are called macronutrients
(f)  nutrients are needed in small quantities for plants and are called micronutrients.

Page No 90:

Question 32:

Differentiate between compost and vermicompost?

Answer:

Compost is the end product formed by the biodegradation of organic matter such as yard waste and food waste. This is done by microorganisms, such as bacteria. Yeast also helps in this process.

Vermicompost is the end-product formed by the degradation of organic matter. This process is done only by worms, such as red wrigglers, white worms and earthworms.

Page No 90:

Question 33:

Arrange these statements in correct sequence of preparation of green manure.
(a) Green plants are decomposed in soil.
(b) Green plants are cultivated for preparing manure or crop plant parts are used.
(c) Plants are ploughed and mixed into the soil.
(d) After decomposition it becomes green manure.

Answer:

Correct sequence: 

(b) Green plants are cultivated for preparing manure or crop plant parts are used.

(c) Plants are ploughed and mixed into the soil.

(a) Green plants are decomposed in soil.

(d) After decomposition, it becomes green manure.

Page No 90:

Question 34:

An Italian bee variety A. mellifera has been introduced in India for honey production. Write about its merits over other varieties.

Answer:

Merits of A. mellifera are- 
(a) It has a high honey collection capacity and yields more honey.
(b) It is stingless, hence easy to handle.
(c) It breeds at a faster rate.
(d) It has less tendency for swarming, hence stays in the given beehive for long periods and breeds very well.

Page No 90:

Question 35:

In agricultural practices, higher input gives higher yield. Discuss how?

Answer:

Higher inputs give higher yield refers to the facilities and financial status of a farmer. The good financial status allows farmers to take up new methodologies and technologies to increase the yield. Higher buying capacity decides to crop methods and agricultural practices.



Page No 91:

Question 36:

Discuss the role of hybridisation in crop improvement.

Answer:

Hybridization is a method of crossing two dissimilar varieties to get desirable characters in the off-springs. This improves the crop in the following attributes:

High yield: It helps to improve crop yield.

Pest resistance: Crop can obtain pest resistance by incorporating pest resistance genes. For example,  Bt Cotton

Draught resistance: Plants obtain drought-resistant genes from drought-resistant varieties.

Disease resistance: Plants can be immune to certain disease against which genes are incorporated.

Page No 91:

Question 37:

Define
(i) Vermicompost
(ii) Green manure
(iii) Bio fertilizer

Answer:


(i) Vermicompost: Manure is rich in organic materials. It is prepared by using earthworms, plant and animal waste. Earthworms help in composting organic waste to give nutrient-rich manure. 

(ii) Green manure: Manure prepared by composting green plants is known as green manure. It is usually made in the field. For example,  Hemp is allowed to decompose to get green manure.

(iii) Biofertilizer: Usage of living organisms to provide nutrient to plant and to make the soil fertile is known as biofertilizers. For example, blue-green algae used as bio-fertilizer in paddy fields.
 

Page No 91:

Question 38:

Discuss various methods for weed control.

Answer:

Different methods of weed control are-

  • Mechanical removal
  • Preparation of seed bed
  • Timely sowing of the desired crop
  • Crop rotation

Page No 91:

Question 39:

Differentiate between the following
(i) Capture fishery and Culture fishery
(ii) Mixed cropping and Inter cropping
(iii) Bee keeping and Poultry farming

Answer:


(i)  Capture fishery and Culture fishery

Capture fishery  Culture fishery
It is traditional fishing where a fisherman catches the fish from natural resources like the sea and rives.  It is the one where the fishes are obtained/reared for commercial purposes.
\

(ii)  Mixed cropping and Inter cropping
 
Mixed cropping  Intercropping
It is the method of growing two or more crops in a single field. It is a type of mixed cropping where two or more crops are grown in a single field in a definite pattern.
\
(iii) Bee keeping and Poultry farming
 
Bee keeping Poultry farming
It is the method of rearing bees to obtain honey.  It is a method of raising domestic fowl for the purpose of egg and meat.

Page No 91:

Question 40:

Give the merits and demerits of fish culture?

Answer:

Merits of Fish culture:

Fishes with desired characters can be obtained in a large amount in a small area.

Quality of food is impoves as fishes are the cheap source of proteins.

Demerits of fish culture:

Only desired varieties of fishes are reared.

It is a threat to biodiversity.

Page No 91:

Question 41:

What do you understand by composite fish culture?

Answer:

Composite fish culture is a method of rearing five to six varieties of fish species in a single pond. In this process, the fish species are selected in such a way that they should not compete with other fishes for food because of changes in their food habits.


For example,  
Catla is a surface feeder.
Rohu is a middle zone feeder
Mrigal and common carp are feeders for the bottom, and 
grass carp feeds on weeds.

Page No 91:

Question 42:

Why beekeeping should be done in good pasturage?

Answer:

Beekeeping should be done in good pasturage because -

  • Bees need quality nectar to produce honey.
  • A good pasturage consists of many flowers that can be used by bees to get quality nectar.
  • This increases the quality as well as the quantity of the bees. 
  • A sufficient quantity of pasturage and the kind of flowers available will determine the taste of the honey. 

Page No 91:

Question 43:

Write the modes by which insects affect the crop yield.

Answer:

 

a) Cutting:

Insects cut plant parts such as leaves, fruits, flowers, etc and they damage the plant, damaged leaves result in a decreased rate of photosynthesis, reduced number of flower decreases the production of seeds.

b) Borers:

Some pests boreholes in specific plant parts and start living inside and such pests utilize plant nutrients and food that results in a decrease in yield.

c) Suckers:

Some pests suck cell sap by using their proboscis gland and this result in an adverse effect on the plant that reduces their yield.

Page No 91:

Question 44:

Discuss why pesticides are used in very accurate concentration and in very appropriate manner?

Answer:

Pesticides are used in a very accurate and very appropriate manner because of the following reasons:

  • The excessive use of pesticides will reduce the fertility of the soil.
  • It reduces the organic matter present in the soil.
  • It kills useful microorganisms present in the soil.
  • It leads to air, water, and soil pollution.

Page No 91:

Question 45:

Name two types of animal feed and write their functions.

Answer:


Roughage: They are made of husk, grass, and chopped leaves.
It provides complete nourishment to animals and helps in proper digestion in animals.

Concentrates:  These are prepared as per the requirement of particular cattle.
They contain proteins and minerals.
 

Page No 91:

Question 46:

What would happen if poultry birds are larger in size and have no summer adaptation capacity? In order to get small sized poultry birds, having summer adaptability, what method will be employed?

Answer:

Larger-sized birds need more food and summer adaptation reduces the process of egg-laying.

In order to obtain small sized poultry birds that have summer adaptability, it is desirable to
(i) Either introduce the required exotic birds from outside. 
(ii) or to crossbreed the local birds with exotic birds from outside.

Small-sized birds are preferred for -
(a) Low food requirement. 
(b) High egg-laying capacity.
(c) Low space requirement.

Page No 91:

Question 47:

Suggest some preventive measures for the diseases of poultry birds.

Answer:

The preventive measures of poultry bird diseases are- 

(a) Cleaning of poultry farms on regular basis

(b) Proper sanitation of poultry farms is required

(c) Spraying of disinfectants at regular intervals

(d) Proper vaccination of birds.

Page No 91:

Question 48:

Figure shows the two crop fields [Plots A and B] have been treated by manures and chemical fertilizers respectively, keeping other environmental factors same. Observe the graph and answer the following questions.
(i) Why does plot B show sudden increase and then gradual decrease in yield?
(ii) Why is the highest peak in plot A graph slightly delayed?
(iii) What is the reason for the different pattern of the two graphs?

Answer:

i) With the addition of chemical fertilizer there is a sudden increase in yield due to the release of nutrients Nitrogen, Phosphorus, and Potassium in high quantity. There will be a gradual decline in the graph that may be due to continuous use and a high quantity of chemicals. It may kill the microbes that are useful for replenishing the organic matter in the soil and also decreases soil fertility.

(ii) Manures supply small quantities of nutrients to the soil slowly as it contains large amounts of organic matter. It enriches the soil with nutrients thereby increasing soil fertility continuously.

(iii) The difference in the two graphs represents that the use of manure is beneficial for a long duration in cropping as the yield tends to remain high when the number of manure increases.



Page No 92:

Question 49:

Complete the crossword puzzle table.
 

    10              
  1     2     6    
                   
8                 7
                   
                   
        3   4      
9                  
                   
    5              
                   

Across
1. Oil yielding plant (9)
3. Crop grown in winter season (4)
5. Fixed by Rhizobium (8)
9. Common honey bee (4)

Downward
2. Animal feed (6)
4. A micronutrient (5)
6. Unwanted plant in crop fields (4)
7. An exotic breed of chicken (7)
8. Bottom feeders in fish pond (7)
10. A marine fish (4)

Answer:


Across:
1. Sunflower
3. Rabi
5. Nitrogen
9. Apis

Down:
2. Fodder
4.Boron
6.Weed
7. Leghorn
8.Mrigals
10.Tuna

    10T              
  1S U N 2F L O 6W E R
    N   O     E    
8M   A   D     E   7L
R       D     D   E
I       E         G
G       3R A 4B I   H
9A P I S     O     O
L           R     R
S   5N I T R O G E N
            N      

 



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