Answer: Option A. -> weeds
:
A
Weeds are fast growing, unwanted plants growing incultivated fields which take up nutrients and reduce the growth of the crop. Therefore, removal of weeds from cultivated fields during the early stages of crop growth is essential for a good harvest. Weedicides can be effective forremoval of weeds.Xanthium, parthenium andcyperinusare some examples of weeds.

Answer: Option A. -> Mixed cropping
:
A
Mixed cropping is a method in which two or more crops of a completely different type is grown simultaneously on the same piece of land. For example, wheat and gram are grown using this pattern. Multiple cropping is the practice of growing two or more crops in the same piece of land in the same growing seasons instead of one crop. Crop rotation is growing of different crops on a piece of land in a pre-planned succession. Inter-cropping is growing two or more crops simultaneously on the same field in a definite pattern.

Answer: Option C. -> Macrobrachium rosenbergii
:
C

Fresh-water prawns are prawns grown in freshwater for human consumption. Among the given options, Macrobrachium rosenbergiiis the only fresh-water prawn.Peneaus monodon is a marine prawn, common carp is a fresh-water fish and bombay duck is a marine fish.

Answer: Option A. -> True
:
A
Crop variety improvement plays a very important role in order to improve crop yield.
This can be done by finding a crop variety that can give a good yield. The desired quality of this crop can be introduced into other crops by introducing its gene of desired quality, like high yield. These are genetically modified crops.

Answer: Option B. -> Only statement (ii) is incorrect
:
B
Food security depends upon both, the availability of food and access to it. Just over production does not guaranteefood security. People should have money to buy food for themselves.
Mixed farming involves the growth of multiple plants simultaneously on the same field. This increases the quality of soil, if the leguminous plants are grown along with crops. Fertilisers, like urea, are commercially produced plant nutrients.

Answer: Option A. -> micronutrients
:
A
The nutrients required by an organism can be broadly classified into two depending on the quantity required by the organism.
Macronutrients are required in large quantities while micronutrients are required in trace or very small amounts.
In plants, the macronutrients are nitrogen, phosphorus and potassium (NPK) while the micronutrients include boron, iron, manganese, etc.

Answer: Option A. -> weeds
:
A

Weeds are fast growing, unwanted plants growing in cultivated fields which take up nutrients and reduce the growth of the crop. Therefore, removal of weeds from cultivated fields during the early stages of crop growth is essential for a good harvest. Weedicides can be effective for removal of weeds. Xanthium, parthenium and cyperinus are some examples of weeds. 

Answer: Option B. -> Aquaculture
:
B

Aquaculture is farming of aquatic organisms like fish, molluscs, algae, etc. Both freshwater and saltwater organisms can be cultured in controlled conditions.

Answer: Option A. -> True
:
A

India is an agricultural country. More than 60 per cent of the population is engaged in agriculture and allied activities like animal husbandry. Agricultural activities have seen immense growth since independence. The fertile land, favourable weather conditions and the growing population has played a major role in the growth of agriculture.

Answer: Option A. -> Mixed cropping
:
A

Mixed cropping is a method in which two or more crops of a completely different type is grown simultaneously on the same piece of land. For example, wheat and gram are grown using this pattern. Multiple cropping is the practice of growing two or more crops in the same piece of land in the same growing seasons instead of one crop. Crop rotation is growing of different crops on a piece of land in a pre-planned succession. Inter-cropping is growing two or more crops simultaneously on the same field in a definite pattern.