NCERT Class 9 Science Solutions: Chapter 15 Improvement in Food Resources Part 1

Download PDF of This Page (Size: 1.3M)

Q 1 Image Showing Energy Sources.

Q 1 Image Showing Energy Sources.

Q 1 Image Showing Energy Sources.

Question 1:

Q. What do we get from cereals, Pulses, fruits and vegetables?

Answer:

(i) Cereals provide us with carbohydrates. Also, they are a rich source of energy.

(ii) Pulses give us proteins,

(iii) Fruits and vegetables are a rich source of vitamins and minerals. A small amount of proteins, carbohydrates, and fats are also present in them.

Question 1:

Q. What do biotic and abiotic factors affect crop production?

Answer:

A variety of biotic factors such as pests, nematodes, diseases, etc. can reduce the net crop. For example, boll weevil is a pest on cotton. It attacks the cotton crop, thereby reducing its yield. Weeds also reduce crop productivity by competing with the main crop for nutrients, light and space.

Similarly, abiotic factors such as salinity, temperature, etc. affect the net crop production. Some natural calamities such as drought and floods are unpredictable. Their occurrence has a great impact on crops sometimes, destroying the entire crop.

Question 2:

Q. What are the desirable agronomic characteristics for crop improvements?

Answer:

The desirable agronomic characteristics for crop improvements are:

(i) Tallness and profuse branching in any fodder crop.

(ii) Dwarfness in cereals.

These desirable agronomic characteristic help in increasing crop productivity.

Question 1:

Q. What are macro-nutrients and why are they called macro-nutrients?

Q 1 Image Showing Macro Nutrients.

Q 1 Image Showing Macro Nutrients.

Q 1 Image Showing Macro Nutrients.

Answer:

Macro-nutrients are nutrients in required in relatively large quantities for growth and development of plants. They are six in number. Since they are required in large quantities, they are known as macro-nutrient. The six macro-nutrients required by plants are nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur.

Question 2:

Q. How do plants get nutrients?

Answer:

Plants require sixteen essential nutrients from nature for their growth and development. All these nutrients are obtained from air, water, and soil. Soil is the major source of nutrients. Thirteen of these nutrients are available from soil. The remaining three nutrients (Carbon, Oxygen, and hydrogen?) are obtained from air and water.

Question 1:

Q. Compare the use of manure and fertilizers in maintaining soil fertility.

Answer:

Manures increase soil fertility by enriching the soil with organic matter and nutrients as it is prepared by the decomposition of animal excreta and plant wastes. On the other hand, fertilizers are mostly inorganic compounds whose excessive use is harmful to the symbiotic micro-organisms living in soil. Their excessive use also reduces soil fertility. Hence, fertilizers are considered good for only short term use.