Crop Improvement - Free MCQ Practice Test with solutions, Class 9 Science

The focus is on addressing food demand for a growing population, especially where land for cultivation is limited.

The Green Revolution significantly increased food-grain production through the following methods:

• Introduction of high-yield crop varieties
• Increased use of chemical fertilizers
• Improved irrigation systems

These advancements effectively addressed food shortages.

• Environmental Degradation: Intensive agriculture often leads to soil depletion, water scarcity, and loss of biodiversity.
• Ecological Imbalances: Overuse of fertilizers and pesticides can harm beneficial insects and disrupt ecosystems.
• Water Resource Strain: Excessive irrigation can deplete freshwater sources, affecting both agriculture and local communities.
• Climate Change: Intensive farming practices contribute to greenhouse gas emissions, exacerbating global warming.

Cereals, such as rice, wheat, and oats, are the primary sources of dietary carbohydrates. They provide a significant amount of energy due to their high starch content.

• Pulses are rich in proteins.
• Oilseeds contain fats.
• Fruits offer vitamins and sugars.

However, fruits do not have the same carbohydrate density as cereals.

Crop improvement targets better yield, disease resistance, and efficient fertilizer use.

Hybridization is the correct term for the process described, as it involves:

• Crossing different plants
• Combining genetic material
• Creating new varieties

Short-duration crops increase annual productivity by enabling multiple harvests.

Dwarfness is desirable in cereals, but tallness is not ideal for vegetable crops.

Farmers’ financial capacity determines their ability to invest in better practices.

Manure improves soil fertility by adding organic matter and enhancing its structure.

Excessive use of chemical fertilizers can lead to:

• Water pollution through runoff
• Causing algal blooms
• Creating dead zones in water bodies

Additionally, it can:

• Degrade soil fertility
• Alter soil pH and nutrient balance
• Make soil less conducive for plant growth over time

Mixed cropping minimises risks by growing diverse crops together. This practice:

• Promotes efficient resource use
• Improves soil fertility
• Provides ecological balance
• Reduces dependence on external inputs

Intercropping is a farming practice that involves growing two or more different crops in close proximity. This method aims to:

• Enhance resource use efficiency
• Reduce pest and disease pressure
• Promote soil health

This approach optimises nutrient utilisation by leveraging differences in:

• Growth patterns
• Nutrient requirements between the crops

Therefore, option C accurately describes intercropping.

Biotic Factors: These are living organisms that can affect agricultural produce.
Examples include:

• Insects: They can damage crops by feeding on them.
• Rodents: They consume and contaminate stored produce.
• Fungi: They can cause rot and spoilage in crops.

Abiotic Factors: These are non-living elements. Inappropriate temperature is one such factor that can affect storage but is not a living organism.