A. MULTIPLE-CHOICE QUESTIONS: Choose the most appropriate answer.
Which of these is not a cereal?
a. maize b. gram c. wheat d. rice
Which of these is not a kharif crop?
a. wheat b. rice c. maize d. groundnut
Which of these nutrients is compost rich in?
a. organic nutrients b. nitrogen c. phosphorus d. potassium
Which of these is not a fungal disease of plants?
a. wilt b. rust c. smut d. blight (of potatoes)
Which one of the following is not true about ploughing?
a. It loosens the soil. b. It aerates the soil. c. It prevents soil erosion. d. It allows easy penetration of roots into the soil.
Compost lacks which of the following nutrients?
a. nitrogen b. phosphorous c. potassium d. all of these
7. Which one of the following does not add nutrients to the soil?
a. crop rotation b. field fallow c. manures d. ploughing
8. Which of the following machines can be used to harvest a crop and also to beat out the grain from the chaff? a. harvester b. combine c. thresher d. harrow
B. VERY SHORT-ANSWER QUESTIONS: Give one-word answers.
- About how many years ago did agriculture begin?
- Large grasses cultivated for their nutritious seeds are called -----------
- Preparation of the soil involves ----- and ------ it.
- The agricultural implement used to sow seeds is called a seed --------
- Mowing a field to remain free of crops for ---- one or more seasons is called field .It allows the field to regain ---------.
- All crops require approximately the same amount of water at roughly the same time periods of their growth. True or false?
- Name one pesticide you will use to kill insects that harm crops.
- Pesticides are used to kill small pests, but they are not strong enough to cause harm to humans. True or false?
- Name the nitrogen fixing bacteria in root nodules of leguminous plants.
- Conversion of proteins into ammonia is called
- Some bacteria can convert nitrate salts in the soil to free nitrogen. True or false?
- A mulch animal is one that yields -------------------
- Rearing honeybees for honey is called ----------
1. Name three natural methods of adding nutrients to soil.
2. What are weeds?
3. Why should grains be dried before storage?
4. Why does the government usually maintain a buffer stock of grains?
5. What is hybridization?
6. List the steps involved in the nitrogen cycle.
7. What do you mean by nitrogen fixation? S. What is nitrogen assimilation?
9. What enables leguminous plants to fix nitrogen?
10. What is animal husbandry?
D. SHORT-ANSWER QUESTIONS (TYPE II): Answer in about 30 words.
1. Distinguish between kharif and rabi crops, giving two examples of each.
2. List the steps involved in crop production, in sequential order.
3. Why is it important to plant seeds at the correct distances from each other?
4. Why do farmers normally use a mixture of manures and fertilizers in their fields?
5. What method of irrigation will you use if you live in a dry area with shortage of water? Explain the method.
6. What is water logging? How does it harm the crops? How can it be prevented?
7. Discuss two methods of weeding in which poisonous chemicals are not used.
8. Differentiate between insecticides, rodenticides and fungicides. Which of these are pesticides?
9. Discuss with an example how hybridization is used for developing new varieties of crops with desired characteristics.
10. Differentiate between nitrification and denitrification.
LONG ANSWER QUESTIONS: Answer in about 60 words.
1. What are the advantages of ploughing the soil before sowing seeds?
2. What precautions must be kept in mind while sowing seeds in a field?
3. Discuss two natural methods of manuring.
4. Draw a labelled diagram to illustrate the nitrogen cycle.
HOTS QUESTIONS: Think and answer.
1. Which method, according to you, can bring about the maximum increase in crop produce in our country in future?
a. increasing land under cultivation c. less wastage in storage
b. using more manures and fertilizers d. using better varieties of crop plants
2. What do you think are the drawbacks of seeds being unevenly distributed in a field while sowing?
3. Do you expect to find fully-grown crop plants in a nursery? Why? Why not?
4. Crop rotation is practised by farmers so that they have different products to sell in the market in every season. Do you agree? Give reasons.
5. I have grown a few wheat plants in my garden because I like the plants. Am I growing a wheat crop? Give reasons.
6. It is observed that melon fruits growing in the fields sometimes crack, exposing the contents inside. What do you think can be the reason? (HINT: This generally happens in fields where drainage is not proper.)
8th Crop Production _Living Science Solution
A. Multiple choice questions:
1. (a) Gram 2.(a) wheat 3.(a) organic nutrients 4.(a) wilt 5. (c) it prevent soil erosion 6. (d) All of these 7. (d) Ploughing 8. (b) Combine.
B. Very short type Questions
1. Ten thousands yrs ago
3.Loosing and turning
5.Fielf fallow, nutrients
6. False. All crops require different amounts of water. For example, a paddy field needs more water compared to a wheat field.
7. BHC or Malathion
8.False Cause irritation of skin and respiratory problems, So fruits and vegetable washed before use.
9. Rhizobium 10.Ammonification
11.True they are called denitrifying bacteria
C. Short type Questions - I
1. The three natural methods of adding nutrients to soil are: Field fallow, Crop rotation and Mixed cropping
2. The unwanted plants that grow along with the crops and share nutrients are called weeds. Weeds decrease the crop yield as they compete with crops for water, nutrients and sunlight and limit their growth.
3. Grains should be dried before storage to remove moisture. This excess moisture helps growth of microbes that may destroy the grains.
4. The government usually maintains a buffer stock of grains to avoid shortage of grains during natural disaster.
5. Hybridisation is a technique to develop new varieties of crops by crossbreeding two different varieties.
6. The steps involved in the nitrogen cycle are as follows:
Nitrogen fixation ® Nitrogen assimilation ® Ammonification ® Nitrification ® Denitrification
7. Nitrogen fixation is the process of converting free atmospheric nitrogen gas into nitrogen compounds nitrites and nitrates .
8. Nitrogen assimilation is the process by which inorganic nitrogen compounds are converted into organic compounds such as proteins that become a part of living beings.
9. The nitrogen fixing bacterium Rhizobium ive in the root nodules of leguminous plants enables them to fix nitrogen.
10. Animal husbandry is defined as the rearing of domestic animals to obtain food and other products from them.
D. Short type Questions- II
They are sown during June or July
They are sown from October to December
They are harvested in September or October
They are harvested in March or April
Examples: rice, maize
Examples: wheat, pea
2. The steps involved in crop production are as follows: Preparation of soil, selection of seed and sowing Manuring, irrigation and weeding, Protection from pests and diseases, Harvesting, threshing and winnowing and Storage
3. Seeds should be planted at a proper distance from each other so that they cannot compete for water, nutrients and sunlight.
4. Farmers normally use a mixture of manure and fertilizers in their fields to increase the yield and production of crops. Manure is good for plants as it provides them with organic nutrients but it lacks some important nutrients like nitrogen, phosphorous and potassium. So, along with manure, farmers also use fertilizers such as NPK fertilizers that provide nitrogen, phosphorous and potassium.
5. Drip irrigation is the method of irrigation useful for dry areas which have a shortage of water. In this method, water is. Water is allowed to fall drop by drop from a pipe placed near the roots of plant.
6. When an excess of water is supplied to the field it is called water logging. As a result of this, the air supply to the roots reduces and in extreme cases, gets totally cut off. This results in the retarded growth of plants. Water logging can be prevented by supplying just the adequate amount of water to the field using a proper drainage system.
7. The two methods of weeding in which chemicals are not used are:
Manual method: Weeds are pulled out by hand or uprooted using a trowel or a harrow.
Introducing Insect: Insects that feed upon only specific weeds are used control weeds.
8. Insecticides are chemicals used to kill insects like locusts. Rodenticides are chemicals used to kill rodents like rats and Fungicides are chemicals used to destroy fungi.
Insects, rodents and fungi are pests. So insecticides, rodenticides and fungicides are all pesticides.
9. Hybridization method of obtaining new variety of desirable traits by crossbreeding two different varieties of crops for example if two varieties of crops, one with high yield and other with disease resistance, can be crossbred to obtain a variety that has both the traits, i.e., high yield and disease resistance.
10. Nitrification is the process of conversion of ammonia into nitrates .It is carried out by nitrifying bacteria.
Denitrification is the process of conversion of nitrates into free nitrogen gas. It is carried out by denitrifying bacteria.
1. (d) using better varieties of crop plants. Better varieties of crop plants will result in increased production as they give higher yield as well as high resistance to diseases.
2. The drawbacks of uneven distribution of seeds in a field, while sowing, are:
(i) They will compete for water, nutrients and sunlight that result limited growth. (ii) If they are sown far apart, it will result in the wastage of field area. (iii) If seeds are not sown at the proper depth and covered by soil, they may be eaten up by birds.
3. We won't find fully grown crop plants in a nursery like rice, tomato, onion, etc because they are transferred to the fields from nurseries in their seedling stage.
4. No, farmers adopt crop rotation to maintain the fertility of the soil. For examples , wheat and rice use large amount of nitrogen from soil therefore legumes plants are grown next to the wheat or rice to replenish nitrogen naturally in field.
5. No. Growing a few plants in a garden is not crop production. Crop production is the practice of growing wheat on a large scale in a field to cultivate grains
6. Melons growing in waterlogged fields with poor drainage tend to absorb more water than they require. Melons cannot hold this excess water, therefore, they crack.