Nutrient Replenishment in Soil

The video explains how nutrients are replenished in soil, focusing on the role of fertilizers and manures. It highlights the importance of nitrogen for crops and how Rhizobium bacteria help in nitrogen fixation through a symbiotic relationship with leguminous plants. The video also covers different modes of plant nutrition, including autotrophic, parasitic, and saprotrophic nutrition, and categorizes animals as heterotrophs.

Why do plants need fertilizers and manures?

• To control pests

• To improve soil texture

• To replenish declining mineral nutrients

• To increase soil moisture

What happens to the soil after a crop harvest?

• It becomes deficient in nitrogen

• It becomes rich in nitrogen

• It becomes acidic

• It becomes waterlogged

Why can't plants use atmospheric nitrogen directly?

• It is toxic to plants

• It is too cold

• It is not in a soluble form

• It is too dense

What is the role of Rhizobium bacteria in soil?

• To absorb water from the soil

• To convert atmospheric nitrogen into a soluble form

• To produce oxygen

• To decompose organic matter

What type of relationship do Rhizobium bacteria have with leguminous plants?

• Parasitic

• Competitive

• Symbiotic

• Predatory

Which of the following is NOT a mode of plant nutrition?

• Parasitic

• Autotrophic

• Heterotrophic

• Saprotrophic

How are animals classified in terms of nutrition?

• Autotrophs

• Heterotrophs

• Saprotrophs

• Phototrophs