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By Savita S. More

PSEB solutions class 7 science chapter 1 

Short answer type question:

 

  • What do you mean by parasitic mode of nutrition?
  • Nutrition in which the organism derives its food from other organisms is called parasitic nutrition.

 

  • Explain symbiotic relationship.
  • In a symbiotic relationship, two types of organisms live together and share shelter and nutrients. As a result, both organisms benefit from each other. A lichen is a good example.

 

  • How does a pitcher plant catch insects?
  • The leaves of pitcher plants are modified as pitcher-shaped bodies to trap the insects. Whenever an insect sits on the opening of the pitcher, it slips down, is unable to climb back, and becomes trapped.

 

Long answer type questions:

 

  • How are nutrients …………….in the soil?
  • Plants absorb minerals, water, and nutrients from the soil and these nutrients must be replenished to keep the soil fertile. Farms enrich soil by adding manure and fertilizers, while forests enrich soil by decomposing dead leaves and animal matter.

 

 

  • What do you mean by nutrients? explain various modes of nutrition in plants.

The main nutrients in food are  carbohydrates, fats, proteins, vitamins, and minerals.

An organism that makes its food from simple substances is called an autotroph and this type of nutrition is called autotrophic nutrition. Autotrophs include all green plants and some bacteria.

Heterotrophic nutrition

Organisms that cannot prepare their own food and rely on others for food are heterotrophs, and this type of nutrition is called heterotrophic nutrition. Examples are Animals and  few plants .

 

Points to Remember

 

The initial products of photosynthesis are oxygen gas and glucose.

Stomata are surrounded by guard cells.

 

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