Saturday, April 14, 2012

class 7 - Science - Ch1 - Nutrition in Plants

Nutrition in Plants

Q1: Why do organisms need to take food?

Answer: All organisms take food and utilise it to get energy for the growth and maintenance of their bodies.

Q2: Why do plants use the nitrogen present in soil? How is this nitrogen replenished in the soil?

Answer: Plants cannot absorb nitrogen in gas form; they need it in soluble form. Therefore, they use the nitrogen present in soil to prepare proteins.

Atmospheric nitrogen is fixed in soil by nitrogen-fixing bacteria such as Rhizobium,which live in the root nodules of leguminous plants such as gram, peas, beans, etc. In return, the plants provide food and shelter to the bacteria.

Q3: Define nutrition.

Answer: Nutrition is the process in which an organism consumes food, which is then utilized by the body.

Q4: Distinguish between a parasite and a saprotroph.

  • Organisms derive nutrition from the body of other living organisms (host) are parasites.E.g. Cuscata (amar bel)
  • Organisms which organisms derive nutrition from dead and decaying organisms are called saprotrophs.E.g. Mushrooms
Q5: Why do plants need nitrogen?

Answer: Plants need nitrogen to synthesize proteins.

Q6: What are insectivorous plants? Give an example.

Answer: Insect-eating plants are known as insectivorous plants. Example: pitcher plant.

Q7: Choose the correct option from the following:
Which part of the plant gets carbon dioxide from the air for photosynthesis.
(a) root hair (b) stomata (c) leaf veins (d) sepals

Answer :  Stomata

Q8: Lichens is a composite of which two organisms? What type of nutrition relationship exists here?

Answer:  Two partners are Algae and Fungi. They exhibit symbiotic relationship. The fungus provides shelter, water and minerals to the alga and, in return, the alga provides food which it prepares by photosynthesis.

Q9: Choose the right option. Green plants are:
a) herbivores
b) autotrophs
c) hetrotrophs
d) omnivores

Answer: Autotrophs  (Note: Here Green plants are mentioned. Non Plants (both green + non-green) together are autotrophs and hetrotrophs.)

Q10: Define Photosynthesis.

Answer: The process of preparing food with the help of water, carbon dioxide, sunlight and chlorophyll in plants is called photosynthesis.

Chlorophyll component present in leaves, in the presence of sunlight, converts Water and Carbon Dioxide into food.

See also Ch 1 Nutrition in Plants (MCQs) 


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  7. Q1. list of the main life characteristics of living things. Q2. define food and why do we aneed to it.

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  17. green plants are not always autotrophs mistletoe is a partial parasite it can prepare its own food ( contains chlorophyll ) but depends on host for nutrients . it is a heterotrophic green plant