CBSE Important Questions Class 9 Science Chapter 12 – Improvement in Food Resources

Class 9 Science Chapter 12 Improvement in Food Resources is part of the CBSE Class 9 Science syllabus. It explains how we can grow more food from the same land. Students learn about crop variety improvement, crop production management including manure, fertilizers and irrigation, cropping patterns such as mixed cropping, intercropping and crop rotation, and crop protection from weeds, insects and diseases. The chapter also covers animal husbandry: cattle farming, poultry, fish production and bee-keeping.

These CBSE important questions for Class 9 Science Chapter 12 cover cross breeding of cattle, the difference between manure and fertilizers, Kharif and Rabi crops, transpiration and photosynthesis, the site of transpiration, why the time of sowing depends on the maturation period, and the macronutrients supplied by the soil. Every question has a clear step-by-step answer in simple English with a figure, so students can practise on their own, parents can check the answers, and teachers can use them for class tests.

Q1. Sam is a dairy farmer. He wants to develop a variety of cow which has a long lactation period and disease resistance. The given flow chart shows the species of cows and the method used to produce the desired variety. Identify the desired qualities of cows (A and B) and the method used (C).
(a) A – Long lactation period, B – Resistance to disease, C – Interbreeding
(b) A – Long lactation period, B – Resistance to disease, C – Cross breeding
(c) A – Resistance to disease, B – Long lactation period, C – Cross breeding
(d) A – Resistance to disease, B – Long lactation period, C – Interbreeding

Cross breeding of the Jersey foreign breed with the Red Sindhi indigenous breed

Answer: (b) A – Long lactation period, B – Resistance to disease, C – Cross breeding
The Jersey is a foreign breed known for its long lactation period, so A is that quality. The Red Sindhi is an Indian breed known for its resistance to disease, so B is that quality. Mating two animals of different breeds is called cross breeding, so C is cross breeding. The calf born has both good qualities.

Q2. Which of the following statements are correct?
i. Cochineal insect is used to remove Opuntia.
ii. Fertilizers are readily soluble in water, so they are absorbed by the plant easily.
iii. Citrus canker is a bacterial disease.
iv. The practice of growing two or more crops in the same field one after the other is called mixed cropping.
v. Healthy seeds, being lighter, float on the surface of water.
(a) i, ii, iii
(b) ii and iii only
(c) i, iv, v
(d) iii and v only

Answer: (a) i, ii, iii
Statement i is correct: the cochineal insect is used as a biological method to control the Opuntia (prickly pear) weed.
Statement ii is correct: fertilizers dissolve easily in water, so plants absorb them quickly.
Statement iii is correct: citrus canker is caused by bacteria.
Statement iv is wrong: growing crops one after the other in the same field is crop rotation, not mixed cropping.
Statement v is wrong: healthy seeds are heavier and sink, while damaged or hollow seeds float.

Q3. Fertilisers are
(a) biological waste material
(b) commercially produced plant nutrients
(c) prepared by the decomposition of animal excreta and plant waste
(d) micro-nutrients used in irrigation

Answer: (b) commercially produced plant nutrients
Fertilisers are made in factories and supply particular nutrients, mainly nitrogen, phosphorus and potassium. Option (c) describes manure, which is natural and is made by rotting animal dung and plant waste.

Q4. An example of a Kharif crop is
(a) paddy
(b) mustard
(c) gram
(d) linseed

Answer: (a) paddy
Kharif crops are sown with the start of the monsoon, around June, and harvested around September to October. Paddy, maize, soyabean and cotton are Kharif crops. Mustard, gram and linseed are Rabi crops, which are grown in the winter season.

Q5. When a polythene bag is tied around the leaf of a plant, water droplets appear on it due to
(a) perspiration
(b) transpiration
(c) evaporation
(d) condensation

Answer: (b) transpiration
The leaf gives out water as water vapour through its stomata; this is called transpiration. Inside the closed polythene bag the vapour cools and turns back into tiny drops of water, which we see on the inner surface of the bag.

Q6. Green leaves prepare their food in the presence of sunlight using
(a) carbon dioxide and water
(b) water and oxygen
(c) oxygen and nitrogen
(d) oxygen and carbon dioxide

Answer: (a) carbon dioxide and water
In photosynthesis, green leaves use carbon dioxide from the air and water from the soil, in the presence of sunlight and chlorophyll, to make glucose. Oxygen is given out as a by-product, not used up.

Q7. CO2 is required in
(a) respiration
(b) excretion
(c) phototropism
(d) photosynthesis

Answer: (d) photosynthesis
Carbon dioxide is one of the raw materials of photosynthesis. In respiration carbon dioxide is given out, not taken in. Phototropism is the bending of a plant towards light and does not need carbon dioxide.

Q8. The primary site of transpiration in green plants is
(a) leaf
(b) flower
(c) root
(d) fruit

Answer: (a) leaf
Leaves have a large surface area and many tiny pores called stomata. Most of the water lost by a plant escapes through these stomata, so the leaf is the main site of transpiration.

Q9. Transpiration is the loss of
(a) air
(b) soil
(c) sunlight
(d) water

Answer: (d) water
Transpiration is the loss of excess water from a plant in the form of water vapour, mainly through the stomata of the leaves. It also helps to cool the plant and to pull water up from the roots.

Q10. The time of cultivation of a crop is decided according to
(a) its water requirements
(b) its nutritional requirements
(c) its vulnerability to pests
(d) its maturation period

Answer: (d) its maturation period
The maturation period is the time a crop takes to grow and be ready for harvest. The farmer sows the crop so that it matures in the right season and the right weather. Water needs, nutrients and pests matter too, but the sowing time is decided mainly by the maturation period.

Q11. The water requirements of different crops are different due to
(a) different transpiration rates
(b) same transpiration rates
(c) water holding capacity of the soil
(d) climate changes

Answer: (a) different transpiration rates
Each kind of plant loses water at its own rate through transpiration, depending on the size and number of its leaves and its stomata. A crop that transpires faster needs more water, so the water requirement differs from crop to crop.

Q12. Macronutrients supplied by soil are
(a) carbon, oxygen and nitrogen
(b) carbon, oxygen and hydrogen
(c) nitrogen, phosphorus and potassium
(d) iron, manganese and boron

Answer: (c) nitrogen, phosphorus and potassium
Plants need macronutrients in large amounts, and the soil supplies six of them: nitrogen, phosphorus, potassium, calcium, magnesium and sulphur. Carbon, hydrogen and oxygen come from air and water, not soil. Iron, manganese and boron are micronutrients, needed only in very small amounts.

Related Study Material on Extramarks

Q.1 Answer the following questions:
(a) Explain why evaporation is considered a surface phenomenon.
(b) Out of nail polish remover and water, which liquid gives a better cooling effect. Why?
(c) What is the difference between evaporation and boiling?

Marks:5
Ans

(a) Evaporation of liquids to gaseous form occurs from the surface of liquids. A small proportion of particles at the surface of liquids with higher kinetic energy break free from the forces of attraction of other particles and escape into the air as vapours. Thus, evaporation is considered a surface phenomenon.

(b) Nail paint remover gives a better cooling effect as compared to water because it has a lower boiling point compared to water. So, it evaporates more easily.

(c)

Evaporation Boiling
1. It is a surface phenomenon. 1. It is a bulk phenomenon.
2. It occurs at a temperature below the boiling point of the liquid. 2. It occurs at the boiling point of the liquid.

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