Science Chapter 1 - Improvements In Food Resources

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Nutrients are classified into three groups according to their sources.

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Plants get nutrients from air, water, and soil.
From these 16 essential elements, carbon and oxygen are obtained from air and hydrogen from water. Remaining 13 are supplied by the soil.

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The three most important nutrients required for plant growth are nitrogen, phosphorous, and potassium.

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Micronutrients: Iron, chlorine, copper, manganese, zinc, and molybdenum.
Macronutrients: Sulphur, nitrogen, calcium, potassium, magnesium, and phosphorous.

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Advantages of using manure are as follows:
1. It enriches the soil with nutrients, thereby decreasing the general deficiency of nutrients in the soil.
2. It adds humus to the soil. Humus restores the soil texture, improves the soil's water retention capacity, and causes soil aeration.
3. It provides food for the soil organisms, which help in providing nutrients to plants.

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 Limitations of using manure are as follows:
1. Manures have a low nutrient content and are very bulky. Hence, they are inconvenient to handle, store, and transport.
2. Manures are not nutrient-specific. Hence, they are not much useful when a particular nutrient is required in the soil for a particular crop.

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The advantages of fertiliser over manure are as follows:
1. Fertiliser is very rich in plant nutrients such as nitrogen, phosphorous, and potassium, whereas manure has a low nutrient content.
2. Fertiliser is soluble in water and hence readily absorbed by the crop plants, whereas nutrients in manure are absorbed very slowly as nutrients exist locked inside the organic compounds of humus.

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A sudden increase in the nitrogen and other soil compounds in the pond will lead to an increase in the population of algae and phytoplanktons (bloom of algae or bloom of phytoplanktons) as they nitrify very quickly and multiply. This will, eventually, alter the population of other organisms present in the pond.

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Eutrophication refers to alteration in the life of aquatic ecosystem due to increase in the concentration of certain organic compounds such as nitrates and phosphates. This generally occurs when fertilisers from a field are washed off by rainwater or irrigation to nearby ponds or rivers.
Example: Sudden increase in the population of algae or phytoplanktons in water body due to increase in the level of nutrients in water.

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Use of chemical fertilisers improve soil fertility for a short duration of time. Continued use of chemical fertilisers cause environmental hazards and lead to the destruction of soil fertility. The increased use of chemical fertilisers cause death of soil microorganisms by making the soil toxic for them. Excessive fertilisers added to the soil end up in the nearby water bodies and increase the nutrient content of the water. This leads to algal bloom.

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Fertilisers should be applied scientifically, in terms of proper dose, time, and pre- and post-application precautions for their complete utilisation.
Different methods of fertiliser application include:
1. Broadcasting: Uniform distribution of the fertiliser over the whole cropped field.
2. Placement: Application of fertiliser in bands or in pockets near the plants or plant rows.
3. Foliar application: Using low- or high-volume sprayers, fertilisers are sprayed covering the plants.

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Manures are natural fertilisers. They are the source of organic matter that supply nutrients in small quantities.
There are three types of manure:
1. Farmyard manure (FYM).
2. Compost.
3. Green manure.
Manure enriches the soil with nutrients and adds organic matter (humus) to the soil. Humus improves the soil texture for better water retention and soil aeration.

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Green manuring is a practice of ploughing and mixing of green crops in the soil for improving the physical structure as well as the fertility of the soil. Green manures are generally thick growing leguminous and non-leguminous plants.
Examples of green manures: Horse gram (Dolichos uniflorus), cowpea or lobia (Vigna sinensis), and lentil or masoor (Lens culinaris).

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Fertilisers are organic or inorganic materials that are mixed in the soil to provide plant nutrients essential to the growth of plants. Fertilisers supply nitrogen, phosphorous, and potassium (NPK).
Fertilisers are classified into four groups:
1. Nitrogenous fertilisers: They contain nitrogen as the major nutrient.
2. Phosphatic fertilisers: They contain phosphate or phosphorus as the major nutrient.
3. Potassic fertilisers: They contain potassium as the major nutrient.
4. Complex fertilisers: They contain a combination of multiple nutrients.

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Organisms that increase the nutrient content of the soil are called as bio-fertilisers. They are nitrogen-fixing microorganisms used for specific crop plants such as pulses, legumes, oil seeds, and rice. They can play a supplementary role in supplying nitrogen to specific crops under specific soil conditions. They do not pollute and can be renewed.
Example: Rhizobium is a bio-fertiliser used by farmers who grow pulses, legumes, etc.

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Legume crop does not require nitrogenous fertilisers because Rhizobium, a bio-fertiliser, lives in symbiotic association with the roots of leguminous plants. It fixes the atmospheric nitrogen and makes it available to the crop plants. Hence, the nitrogen requirement of the plant is fulfilled.

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Irrigation of crop plants is mainly essential in drought-prone areas. To meet the water requirements of the crop plants, water is supplied to them via canals, wells, reservoirs, tube wells, etc. Irrigation also allows the cultivation of crops throughout the year instead of during rainy season only.

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Excessive irrigation leads to soil salinity as it causes water logging. The evaporation of excess water concentrates salt at the soil surface. This causes an increase in the soil salinity. The crops die as the roots of the crop plants have limited access to oxygen and increased salinity.

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Effects of excessive irrigation are as follows:
1. It causes water logging.
2. It increases soil salinity.
3. It causes the death of crop plants by limiting the amount of oxygen available to the roots of the plants.

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Water should be used judiciously because if water is supplied in more than adequate amount, it may harm the growth of the crop plants. If there is less water supply, then the seeds of crop plants will not germinate. Also, if water is supplied in excess, it will cause water logging and soil salinity that will ultimately lead to the death of crop plants by limiting the soil aeration.

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Advantages of irrigation are as follows:
1. It provides freshwater to the crop plants.
2. It provides moisture for the germination of seeds.
3. It is essential for the growth and elongation of the roots of the crop plants.
4. It is essential for the absorption of nutrient elements by the crop plants from the soil.

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Efficiency of irrigation can be increased by adopting the following measures:
1. Adopting modern methods of irrigation such as drip or sprinkler systems.
2. Time of irrigation is important. Some crops require water before ploughing, at the time of flowering, and at the time of development of the grain. 
3. Amount of water supplied should be appropriate. Some crop plants require more water, while others need less.
4. Type of soil also determines the efficiency of irrigation. Crops grown in sandy soil needs irrigation more frequently, whereas the crops grown in clayey soil needs less irrigation.

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Following are the two main factors that are responsible for the loss of stored food grains:
1. Biotic factors: These include insects, rodents, birds, mites, and bacteria.
2. Abiotic factors: These include temperature, moisture, and humidity.

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The various preventive measures that are taken before storing the food grains are as follows:
1. Drying: The harvested food grains are dried by spreading them over plastic sheets or on cemented floor.
2. Cleaning: The grains are cleaned properly before their storage. They are filled in gunny bags before storing in godowns, warehouses, and stores.

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Drying of food grains is a vital protective measure before storing them as food grains contain moisture between 15% and 35%, and for safe storage, the moisture content should be below 14%.
The harvested food grains are dried by spreading them over plastic sheets or on cemented floor. Sun-dried food grains are allowed to cool at room temperature. Commercially, mechanical driers are used for this purpose.

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Storage structures used for storing grains on a large scale are called grain silos. It has following unique features:
1. It is provided with outlets at different levels to withdraw the desired stock of grains.
2. They have different levels for storing different food items.
3. They have in-built arrangement for aeration, temperature control, fumigation, and inspection.

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The following two methods are used to control pest attack on the stored food grains:
1. Chemical control: The pesticide solution is sprayed over the gunny bags containing food grains by using a manual sprayer or a mechanical sprayer.
2. Fumigation: Fumigants (pesticides that destroy insects) react with moisture of the air forming poisonous fumes that kill the pests. This is the most effective method of destroying insects in stored food grains.

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The rise in temperature of stored food grains indicates the growth of moulds and fungi. Ideally, the temperature of the stored food grains lies below 30°C as insects and microorganisms are less active at lower temperature. Therefore, one can check the temperature of the grains to see whether or not pests are present.

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'Milk is a very nutritious food'. It has a high protein content. It is a major source of vitamins, including B1, B2, B12, D, and  E. The fat content of milk is appropriate. Hence, it is very important for the growth of the body.

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Four animals that provide us food are:
1. Cow.
2. Fish.
3. Buffalo.
4. Fowl.

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The following animal products are used as food:
1. Milk: It is obtained from cow, buffalo, and goat.
2. Meat: It is obtained from goat, fowl, buffalo, and fish.
3. Egg: Fowl is the main source of egg.

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An average daily feed of a cow is given below:
1. Green fodder and dry grasses (roughage) = 15–20 kg.
2. Grain mixture (concentrates) = 4–5 kg.
3. Water = 30–35 l.

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The sources of 'concentrates' given in a cattle feed include cotton seeds, oil seeds, grains of maize, oats, barley, jowar, gram, and their by-products such as wheat barn, rice barn, gram husk, oil seed cakes and molasses.

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Following are the main characteristics of a good cattle shelter:
1. It should be cleaned regularly to avoid any infection to the animals.
2. It should be big enough to accommodate the animals properly.
3. It should have a hygienic method of disposing animal excreta.
​4. It should be able to protect the animals from cold, heat, and rain.

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I would suggest the method of artificial insemination for improving the cattle breed because we can raise animals of desired characteristics through this method and also it is a more hygienic method of breeding animals. In this method, rate of successful fertilisation is higher than that of natural breeding methods.

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(a) General utility breeds of cow:
General utility breeds of cow refer to those breeds of cow that are raised for multiple purposes such as providing milk as well as helping in agricultural tasks. Some of the following are the general utility breeds:
  ​        ​(i) ​Ongole (Andhra Pradesh).
          (ii) Kankrej (Gujarat).
          (iii)​Tharparkar (Gujarat and Andhra Pradesh).
(b) Breeds of buffalo:
There are 10 breeds of buffaloes in India that are raised for a higher yield of milk. Some of these are as follows:

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Steps of artificial insemination are as follows:
(i) Selection of a healthy and tough animal having high milk yield.
(ii) Collection of semen from the selected animal.
(iii) Preservation of semen by freezing or chemical methods.
(iv) Injecting semen into the genital tract of the female animal during fertility period.

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Artificial insemination is the process of cross-breeding in which semen is collected from a desired bull of high milk yielding breed and injected into the genital tract of a female animal during its fertility period.
Advantages of artificial insemination:
1. It helps in raising animals with desirable traits.
2. It is cheaper as semen from a single bull can be used to impregnate several thousand cows.

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Following are the symptoms of sick animals:
1. Fever with appearance of nodules on skin (in cowpox).
2. Irritation, blisters, and eruptions on the skin surface (in dermatitis).
3. Fever with body swelling and reduced milk secretion (in anthrax).
4. Fever and diarrhoea with blood clots (in salmonellosis).

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(a) Symptoms of mastitis include high fever, swelling of udders, and watery milk production.
(b) Symptoms of foot-and-mouth disease include appearance of blisters on mouth and foot causing extreme soreness of these parts, loss of appetite, increase in secretion of saliva, high fever with shivering, and inability to work.

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High yielding breeds have following advantages over indigenous breeds:
(i) They have a higher egg-producing capacity.
(ii) They have high immunity against various diseases.
(iii) They have a better quality of meat.

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Some of the advantages of fishery are listed below:
1. Increment in fish production with more consistency.
2. Better quality of fish with high protein content and low fat content can be raised.
3. Requires less area as compared to dairy and poultry farms.
4. Helps to meet the current seafood demands with the addition of aquaculture stocks in the marketplace.

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Prevention of poultry diseases:
Poultry fowls suffer from various diseases that are caused by virus, bacteria, fungi, etc.
These diseases can be prevented by adopting the following methods:
(i) Proper cleaning and sanitation.
(ii) Spraying disinfectants regularly.
(iii) Appropriate vaccination on a regular basis.

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Some of the advantages of bee-keeping are as follows:
(i) It increases the production of honey.
(ii) Wax collected from the beehives helps in various medicinal preparations.
(iii) They provide propolis and balms that are used in repairing and fastening of comb.
(iv) Poison of bee is used in manufacturing of Ayurvedic and homeopathic medicines.

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Advantages of composite fish cultures are listed below:
(i) It is cost-effective as different varieties of fishes are cultured at the same price.
(ii) It increases the yield of fish in terms of variety.

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Plants and animals as sources of food:
We get various food products from plants and animals that are very important for the growth and maintenance of our body.
Some of the foods that we obtain from plants are given below:
(i) Fruit is one major food obtained from plants.
(ii) Vegetables of various types (roots, stems, and leaves) are obtained from plants.
(iii) Edible seeds, including cereals, pulses, and nuts are obtained from plants. These are very high in energy and protein content.
Some of the foods that we obtain from animals are given below:
(i) Milk is a major food obtained from cow and buffalo.
(ii) Egg is obtained from fowl.
(iii) Meat is obtained from fowl, fish, cow, goat, and buffalo.
Plants and animals are raised naturally and artificially to meet the food requirements of the growing population.

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Green revolution refers to an increase in the production of food grains, especially wheat crops. It has helped India to grow economically.
Main objectives of crop improvement include:
(i) Increase in the yield of crops.
(ii) To improve the quality of food crops.
(iii) To generate crops highly resistant to biotic and abiotic stresses.
(iv) To develop food crops with desired agronomic traits.
(v) To develop wider adaptability in food crops so that, they can withstand various environmental conditions.
(vi) To change the duration of maturity of food crops such that they mature uniformly.

Graphics: draw the figure showing the preparation of compost from P.S.Verma and V.K.Aggarwal- biology (grade 9) - pg no. 8

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We get different nutrients from cereals, pulses, fruits, and vegetables that are very essential for the growth of an individual.
(i) Cereals are a rich source of carbohydrates. They include wheat, rice, maize, etc.
(ii) Pulses provide large amount of proteins. They include lentil, black gram, pigeon pea, etc.
(iii) Fruits are a good source of vitamins, minerals, roughage, proteins, carbohydrates, and fats. They include apple, mango, banana, etc.
(iv) Vegetables are good source of vitamins and minerals. They also provide roughage, proteins, carbohydrates, and fats. They include potato, spinach, onion, etc.

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Objective of mixed cropping:
The main objective of mixed cropping is to reduce the risk of crop failure during environmental stresses.
Following criteria are used while selecting a crop for mixed farming:
(i) Crops that are to be grown together are selected such that the waste materials and products of one crop facilitates the growth of the other crop.
(ii) Crops that are selected must not compete with each other in terms of nutrition. This will ensure an optimum production of both the crops.

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Following are the advantages of mixed cropping:
(i) It reduces the risk of crop failure due to environmental stress.
(ii) Pest infestation of crops is greatly reduced.
(iii) It increases soil fertility.
(iv) It increases the yield of both the crops due to complementary effect of each crop.
Following are the disadvantages of mixed cropping:
(i) Applying fertilisers to individual crops is very difficult.
(ii) Spraying pesticides to individual crops is difficult.
(iii) Harvesting and threshing of crops separately are not possible.

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Intercropping is a method of growing two or more crops simultaneously in a definite pattern of rows in the same field. Its main aim is to increase the productivity per unit area. It is an improved version of mixed cropping.
Difference between mixed cropping and intercropping:

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Disadvantages of crop rotation are as follows:
(i) It is more concerned about the need of the soil and not of the crops.
(ii) It may lead to lower yield of crops in a specific growing season due to plantation on un-preferred soil.

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The main criteria for selecting crops for rotation are as follows:
(i) Duration of crops (whether short or long).
(ii) Availability of water via rainfall or irrigation.
(iii) Availability of fertilisers, pesticides, machines, and labour.

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Leguminous crops are desirable in crop rotation because they maintain the supply of nitrogen in the crop fields. These crops are alternated with others so as to minimise the need of nitrogenous fertilisers. Nitrogen fixers in leguminous crops fix the atmospheric nitrogen and makes it available to the crop plants. These are mostly used in the crop fields where nitrogen supply is less.

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Steps of hybridisation are explained below:
(i) Varieties of plant with desirable characters are selected. These plants are genetically dissimilar. There are two patterns of selection: mass selection and pure-line selection.
(ii) Pollens are collected from the male flower by the process of emasculation.
(iii) Collected pollens are transferred onto the stigma of female flower.
(iv) Stigma containing the pollen grains is bagged to avoid unnecessary pollination by other pollen grains.

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Plant breeding is the process of producing new varieties of plants by artificial selection. It is a method of improving the genetic make-up of plants.
Following are the various methods of plant breeding:
(i) Hybridisation: It is the crossing between two genetically dissimilar plants to produce a new variety of plant.
(ii) Recombinant DNA technology: It is the method of transferring genes from one organism to another to modify the genetic make-up of latter. It gives rise to transgenic plants.
(iii) Polyploidy: It refers to increasing the chromosome number of a plant that leads to increase in the plant production.

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Biological methods of weed control are described below:
(i) Introducing the insects or some other organisms in the field that specifically consumes and destroys the weed plants.
(ii) Using grass carp (a freshwater fish) to destroy the aquatic weeds.

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Depending upon the occurrence and transmission, plant diseases are classified into four categories:
1. Seed-borne diseases: These diseases spread through seeds. Example: Leaf spot of rice caused by fungi.
2. Soil-borne diseases: These diseases spread through the soil and usually affect the roots and stems of the crop plants. Example: Smut of bajra.
3. Air-borne diseases: These diseases spread by air and attack the aerial parts of the plants. Example: Blast of rice.
4.Water-borne diseases: These diseases are transmitted by water. Example: Bacterial blight of rice.

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Following are the three ways in which an insect pest can attack the crop plants:
1. Chewing insects: They destroy all kinds of crop plants by cutting root, stem, and leaf of plants with their chewing mouth parts. Examples: Locusts, grasshoppers, etc.
2. Sucking insects: They destroy the crop plant by sucking the cell sap from its various parts. Examples: Aphids, leaf hoppers, etc.
3. Internal feeders: They live inside the parts of plants. These are called borers (if they live in twigs or roots) or weevils (if they live in fruits and seeds). Examples: Pod borers and grain weevil.

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Insect pests can be controlled by adopting the following methods:
(i) Mixing insecticides with the soil helps in controlling root-cutting type of insects. Example: Chloropyriphos.
(ii) Dusting or spraying the insecticides over the crops helps in getting rid of stem- and leaf-cutting and boring type of insects. Example: Malathion.
(iii) Spraying systemic insecticides (that enters the plant tissues via roots or shoots) helps in controlling sap-sucking insects such as aphids. Example: Dimethoate and metasystox.

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(a) Examples of narrow-leaved Rabi season weed: Mandoosi (Phalaris) and wild oat or jungali jaii. 
(b) Examples of broad-leaved Kharif season weed: Chaulii (Amaranthus viridis) and saathi (Trianth).

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The four methods of weed control are as follows:
1. Mechanical method: These include uprooting, weeding, hand hoeing, interculture, ploughing, burning, and flooding.
2. Cultural method: These include proper bed preparation, sowing crops timely, intercropping, and crop rotation.
3. Chemical method: These include spraying of chemicals called weedicides or herbicides that kill the weeds.
4. Biological method: These include the use of insects and other microorganisms that feed and destroy specific weeds.

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Weeds affect the growth of crop plants in the following ways:
(i) They compete with the crop plant for nutrients, water, space, and light, depriving the crop plants of essential nutrients.
(ii) They spread crop pests by acting as hosts to insects and other microorganisms.
(iii) Some produce toxic substances that harm the growth of crop plants.
(iv) Some weeds get mixed up with crops during harvesting and lead to poor quality of crop production.

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Crop's pests are the organisms that destroy the growing crop plants by causing great economic loss. There are various pests of crop plants such as weeds, insects, mites, rodents, fungi, bacteria, and viruses.
Crop's pests can be controlled by following measures:
(i) Use of pesticides (insecticides, weedicides, and fungicides) that kill the insects, weeds, and fungal pests.
(ii) Use of resistant crop varieties.
(iii) Crop rotation and multiple cropping.
(iv) Clean cultivation.
(v) Sowing crops at optimum time.

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Advantage of using insect-resistant varieties is that it reduces the use of insecticides. This will help in maintaining the soil fertility for a longer period of time, as harmful chemicals present in insecticides will not be added to the soil. It will also reduce the cost of crop production by removing the expenditure of buying insecticides.

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Method of compost formation:



Compost is prepared from farm and town refuse, including vegetable and animal refuse, faecal matter of humans, sewage waste, weeds, crop stubble, straw, forest litter, etc.
Steps in preparation of compost:
(i) A trench of suitable size (4–5 cm long, 1.5–1.8 cm broad, and 1.0–1.8 cm deep) is dug.
(ii) A layer of mixed refuse (about 30 cm thick) is spread in the trench that is well moistened by slurry of cattle dung and water.
(iii) A second layer of mixed refuse is spread in trench till the heap rises to about 45–60 cm above the ground level.
(iv) Top of the heap is then covered by a thin layer of moist earth. This is left for about three months.
(v) Partially decomposed biomass is taken out of the trench and collected in a conical heap that is moistened with earth and is again left for one to two months. The compost is then ready for use.
 

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Manure are poor in nutrient content than fertilisers; however, they are rich in organic matter.
If only manure is added to a field, then the plants of that field will have stunted growth. This is because the field has a low nutrient content. Also, the plants will have nutrient deficiency that arise due to lack of specific nutrients. However, the soil of the field will have a better water-retention capability due to the presence of humus in the soil.
On the other hand, if we add only fertilisers in a field, then the plants of that field will have a better and healthier plants. This is because the fertilisers are very rich in plant nutrients. However, the continuous use of fertilisers may cause disturbance in the aquatic ecosystem due to passage of chemicals from the field to nearby ponds and rivers via rain or irrigation.

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Irrigation is the process of supplying water to the crop plants via canals, wells, reservoirs, tube wells, etc.

Irrigation of crops is essential because water is an important growth factor for the plants. The only natural source of water to the plants is by rain, and if there is no rain, plants will get deprived of water and will not grow efficiently. Also, there are many areas where there is no rain, so in such conditions water has to be applied to the growing crop plants by artificial means. Thus, irrigation forms an essential need for the growth and development of the plants.

Harmful effects of excessive irrigation are listed below:
(i) It promotes soil salinity.
(ii) It decreases the availability of oxygen to the roots of plants by forming a layer of salt on the soil surface.

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There are various types of irrigation systems in India.
1. Canal system: In this system, man-made canals receive water from different reservoirs or rivers. There are unlined field channels that serve individual fields or a group of fields. Rotation system is followed in canal irrigated areas. This ensures adequate irrigation to all the fields in water shortage.
2. Tanks: These are small storage reservoirs that catch and store the run-off of smaller catchment areas. In the tanks, outflows are controlled as per the availability of water to prevent uneven distribution of water.
3. Wells: They are of two types:
  (a) Dug wells: Water is collected from water-bearing strata that slowly accumulates in the pit. Mechanical means are used to collect water from dug wells.
  (b) Tube wells: It gets water from deeper strata. Diesel or electrical pumps are used to lift water from tube wells.
4. River lift system: Water is directly drawn from the rivers for supplement irrigation.
5. River valley system: In this system, plants are cultivated in riverine valleys and on the slopes of these valleys.
6. Drip and sprinkler system: Overhead pipes and water sprayers are used in this system. This method is more common in USA, Britain, Europe, and parts of India.

Efficiency of applied water can be increased in agriculture by:
(i) rainwater harvesting and
(ii) watershed management.

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(i) It reduces the risk of crop failure due to monsoon stress.
(ii) Pest infestation of crops is greatly reduced.
(iii) It increases the soil fertility.
(iv) It increases the yield of both the crops due to complementary effect of each crop.

Answer:

Methods of crop improvement are explained below:

1. Hybridisation: It is the crossing between two genetically dissimilar plants to produce a new variety of plants.
Crossing may be between two different varieties (intervarietal cross-breeding), between two different species of the same genus (interspecific cross-breeding), and between different genera (intergeneric cross-breeding). It incorporates desirable traits of both the parents in one variety.
2. Recombinant DNA technology: It is a method of transferring genes from one organism to another to modify the genetic make-up of latter. It gives rise to transgenic plants called as genetically modified foods (GMFs). Example: Bt cotton is a genetically modified crop that carries bacterial genes that protect plants from insects.
3. Polyploidy: It refers to increasing the chromosome number of a plant that leads to increase in the plant production. Example: Potato.
4. Mutation breeding: In this method, new crop varieties are generated by inducing mutations. Example: Mexican varieties of wheat.

Improved varieties of:
(i) Rice is Jawahar.
(ii) Maize is HIM128.
(iii) Soya bean is Pusa 24.
(iv) Sunflower is MSF H 8.
(v) Mustard is Agarni.

Answer:

There are two broad methods to control plant diseases as stated below:
1. Weed control:
Weeds are unwanted plants growing in the cultivated fields that compete with the crops for food, space, and light. Hence, they deprive the crops of nutrients leading to the growth of unhealthy plants. There are four methods to control weeds:
(i) Mechanical method: These include uprooting, weeding, hand hoeing, interculture, ploughing, burning, and flooding.
(ii) Cultural method: These include proper bed preparation, timely sowing of crops, intercropping, and crop rotation.
(iii) Chemical method: These include spraying of chemicals called weedicides or herbicides that kill the weeds.
(iv) Biological method: These include the use of insects and other microorganisms that feed and destroy the specific weeds.

2. Insect pest control: 
Many of the insects are pests of crop plants. They attack the parts and products of plants and lowers the yield of crops.
Insect can attack the plant in three ways—that is, by chewing the crop plants, by sucking the cell sap from various parts of plants, and by damaging the crop internally.
There are three methods to control insect pests:
(i) Mixing insecticides with the soil helps in controlling root-cutting type insects. Example: Chloropyriphos.
(ii) Dusting or spraying the insecticides helps in getting rid of stem- and leaf-cutting and boring type of insects. Example: Malathion.
(iii) Spraying systemic insecticides (that enters the plant tissues via roots or shoots) helps in controlling sap-sucking insects such as aphids. Example: Dimethoate and metasystox.

Answer:

Insect pests are serious plant destroyers. They attack the parts and products of plants at all the stages of their life.
Insects can attack the plant in three ways—that is, by chewing the crop plants, by sucking the cell sap from various parts of plants, and by damaging the crop internally.
Methods to control insect pests are as follows:
(i) Mixing insecticides with the soil helps in controlling root-cutting-type insects. In this method, the insecticides are mixed in the soil of the field before sowing the crops, for example, chloropyriphos.
(ii) Dusting or spraying the insecticides helps in getting rid of stem- and leaf-cutting insects. Here, the insecticides are sprayed on the stems and leaves of the plants, for example, malathion.
(iii) Spraying systemic insecticides (insecticides that enters the plant tissues via roots or shoots) helps in controlling sap-sucking insects. A systemic insecticide penetrates the tissues of the host plant without causing any harm to the plant. Insects feed on the insecticide and die, for example, dimethoate and metasystox.

Answer:

Feed refers to the food that is eaten by farm animals.
There are two types of feeds:
1. Roughage: It contains fibres such as green fodder, silage, hay, and legumes.
2. Concentrates: They are a mixture of substances that are rich in one or more of the nutrients. They are low in fibres and have relatively high protein and other nutrient contents. They include oil seeds, grains of maize, oats, barley, gram, etc.
The daily average feed of a cow are as follows:
1. Green fodder and dry grasses (roughage) = 15–20 kg.
2. Grain mixture (concentrates) = 4–5 kg.
3. Water = 30–35 l.
A younger animal needs more food and nutrients than an older one because more energy is needed for the growth and development process of the young animal.

Answer:

Artificial insemination is the process of cross-breeding in which semen is collected from the desired bull of high milk yielding breed and injected into the genital tract of female animal during fertility period.
This method is used to improve the breeds of animals, generally cows, buffaloes, poultry, horses, sheep, goats, and pigs.
Examples of breeds of cows raised by this method are Karan Swiss (breed of brown Swiss and Sahiwal), Frieswal (breed of Holstein-Friesian and Sahiwal), and Karan Fries (breed of Holstein-Friesian and Thaparkar).
Steps of artificial insemination are as follows:
(i) Selection of a healthy and tough animals having high milk yield.
(ii) Collection of semen from the selected animal.
(iii) Preservation  of semen by freezing or chemical methods.
(iv) Injecting semen into the genital tract of female animal during fertility period or heat period (during this period, cows and buffaloes are sexually excited and ready to mate).

Advantages of artificial insemination:
1. It helps in raising animals with desirable traits.
2. It is cheaper as semen from a single bull can be used to impregnate several thousand cows.

Answer:

Prevention of animal diseases:
Animals suffer from a large number of diseases that are caused by viruses, bacteria, fungi, parasites, and other pathogens. They also suffer from various diseases due to certain nutritional deficiencies. Example: Dermatitis is caused by viruses and infect cows, buffaloes, and fowls. It leads to irritation and eruptions of blisters on skin surface.
These diseases can be prevented by adopting the following methods:
(i) Proper cleaning and sanitation: This is the best method to decrease the growth of germs and other causal organisms that lead to various health hazards.
(ii) Spraying disinfectants regularly: After cleaning and sanitation, the farm should be sprayed with disinfectants, so as to minimise the growth of pathogens.
(iii) Vaccinating: To prevent infectious diseases, appropriate vaccination is important.
(iv) Diet: Providing appropriate diet to the animals prevents the nutritional deficiencies.
(v) Quarantining: Isolating the infected animals from other animals prevent the disease from spreading among other animals.

Answer:

Honeybees live in a colony and divide their tasks among different groups (castes) in the same colony. There are mainly three types of castes in the colony of bees:
(i) Queen:
The queen is the mother of the colony and is responsible for laying eggs. She lays up to 2,000 eggs every day of each season.
(ii) Drone:
The main role of the drone is to mate with the queen and remain in the colony to sleep and eat honey. They stay in the hive only during the breeding season.
(iii) Worker:
They are the most active members of the colony. They are responsible for almost all the work. They collect the nectar and change it into honey. They are of three types, namely scavenger bees, nurse bees, and foraging or field bees.

Organisation of a bee colony sets an excellent example of teamwork and division of labour. They live in a single colony and divide their work in different groups according to their capabilities and body organisation. It tells us how to coordinate in an organisation with other members.

Answer:

The desirable characteristics of selecting a bee variety for bee-keeping are listed below:
1. The bee variety should be carrying a gentle nature. Otherwise, they may bite human beings and harm them.
2. It must have a good honey collection capacity because the main purpose of bee-keeping is to increase the yield of honey.
3. It should be able to protect itself from pathogens such as viruses, bacteria, fungi, and protozoa. These organisms cause various infections in bees.
4. It must have a prolific queen with less swarming i.e., it should be able to produce higher number of offsprings or lay higher number of eggs.

Answer:

Pasturage is the availability of flowers to the bees for nectar and pollen collection.
Pasturage determines the taste, quality, and quantity of honey. Pasturage of honeybees include different variety of flowering plants such as mango, coconut, almond, tamarind, ber, berseem, litchi, cotton, sesame, apple, mahua, coriander, cashew, coffee, rubber plants, guava, sunflower, and neem.

Answer:

Cross-breeding is the common method used for increasing the production among poultry, fisheries, and bee-keeping.
The exotic species of the fowls, fishes, and bees with desirable traits are selected and allowed to breed with the local breeds of desirable characters. This technique produces offsprings with specific traits having a higher yielding capacity.
In case of poultry, such breeds of fowls that are produced have the following traits:
(a) A higher egg production.
(b) Better quality meat.
(c) Immunity against various pathogens.
In case of fisheries, breeding of fish is done to improve the nutritional content of fish and to increase its production.
In case of bee-keeping, a high honey-yielding breeds are selected and grown artificially to have a higher honey production.

Answer:

Answer:

Role of workers in a bee colony:
Workers are diploid, sterile females. They are the most active members of the colony and have most of the responsibilities on their shoulders. They perform different indoor and outdoor activities with their various organs such as hypopharyngeal glands, wax glands, pollen baskets, sucking-type mouth parts, higher invertase enzyme secretion, and a sting at the tip of the abdomen.
They live for 3‒12 months. During the first half of their life, they perform indoor functions as scavengers, nurse bees and guard bees. During the next half, they perform outdoor activities as scout and forager bees.
Depending upon the nature of work and age, the worker bees are divided into three groups:
(i) Scavenger bees: They clean the walls and floor of empty cells of the colony for reuse during the first three days.
(ii) Nurse bees: They work like a foster mother, by feeding the entire brood from the fourth day. They also guard the colony from intruders.
(iii) Foraging bees: These collect nectar, pollen, and propolis in their crops, where they are converted into honey.