Nutrition in Plants
Nutrition in Plants - NCERT Guide Science Class 7
Q1: Why do organisms need to take food?
View Answer
Ans:
Food is required by all living organisms mainly for four reasons or purposes:
- Food helps a living organism to grow. If enough food is not given or if, the food given is not of right kind, the organism will not have proper growth.
- Another important function of food is to provide energy which is required for any living organism for movements and other activities.
- Food is also needed by living organisms for replacement and repairing of their damaged parts.
- Food provide us the power to fight against infections and diseases.
Q2:Distinguish between a parasite and a saprotroph.
View Answer
Ans:
| Parasite |
Saprotroph |
- A parasite takes readymade food from the organism on which it feeds.
- They feed on a living organism.
- The organism on which it feeds is called host.
- It deprives the host of valuable nutrients.
|
- They secrete the digestive juices on the matter they live and convert it into a solutionand then absorb it.
- They feed on dead and decaying organism.
- They do not feed on a living organism.
- There is no host at all.
|
Q3: How would you test the presence of starch on leaves?
View Answer
Ans:
The presence of starch on leaves can be tested by Iodine Test. Iodine turns starch solution blue.
Q4: Give a brief description of the process of synthesis of food in green plants.
View Answer
Ans:
Leaves have a green pigment called chlorophyll. In presence of sunlight, they use carbon dioxide and water to synthesize carbohydrate. During this process oxygen is released. The carbohydrates ultimately get converted into starch.
Carbon dioxide from air is taken through stomata. Water and minera;ls are absorbed by roots and transported to leaves.
Q5: Fill in the blanks:
- Green plants are called _______ since they synthesize their own food.
- The foods synthesized by the plants are stored as _______.
- In photosynthesis solar energy is captured by the pigment called ______.
- During photosynthesis plants take in ____________ and release ______.
View Answer
Ans:
- autotrophs
- starch
- chlorophyll
- carbon dioxide, oxygen.
Q6: Name the following:
- A parasitic plant with yellow, slender, tubular stem.
- A plant that has both autotrophic and heterotrophic mode of nutrition.
- The pores through which leaves exchange gases.
View Answer
Ans:
- Cascuta
- Insectivorous plants
- Stomata.
Q7: Tick the correct answer:
- Amarbel is an example of -
- Autotroph
- Parasite
- Saprotroph
- Host
- The plant which taps and feeds on insects is -
- Cuscuta
- China rose
- Pitcher plant
- Rose
View Answer
Ans:
- Parasite
- Pitcher Plant.
Q8: Match the items in column I with those in column II:
| Column I |
Column II |
Chlorophyll
Nitrogen
Amarbel
Animals
Insects |
Bacteria
Heterotrophs
Pitcher Plant
Leaf
Parasite |
View Answer
Ans:
Chlorophyll ---- Leaf.
Nitrogen --- Bacteria.
Amarbel --- Parasite.
Animals --- Heterotrophs.
Insects --- Pitcher Plant.
Q9: Mark “T” if the statement is true and “F” if it is false :
- Carbon dioxide is released during photosynthesis.
- Plants which synthesize their food themselves are called saprotroph.
- The product of photosynthesis is not a protein.
- Solar energy is converted into chemical energy during photosynthesis.
View Answer
Q10: Choose the correct option in the following:
Which part of the plant gets carbon dioxide from the air for photosynthesis?
- Root hair
- Stomata
- Leaf veins
- Sepals.
View Answer
Ans:
(ii) Stomata
Q11: Which is the correct option in the following:
Plants take carbon dioxide from the atmosphere mainly through their -
- Roots
- Stem
- Flowers
- Leaves.
View Answer
Ans:
(iv) Leaves.
