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NUTRITION IN PLANTS
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TEXTBOOK QUESTIONS AND ANSWERS
Q.1. How do plants prepare their own food ?
Ans. In plants, water and minerals present in the soil are absorbed
by roots and transported to leaves. Carbon dioxide from, air is
taken in through the stomata, present on the surface of leaves.
The leaves have green pigment called chlorophyll, which help
it to capture the energy of the sunlight. So, leaves of green
plants containing chlorophyll synthesize carbohydrates in the
presence of sunlight, water and carbon dioxide.
Sunlight
CO 2 + H 2 O ⎯⎯⎯⎯⎯⎯
Carbohydrate + water.
chlorophyll →
B
B
B
B
Q.2. Why our body cannot make food from the carbon dioxide,
water and minerals like plants do ?
Ans. Our body cannot make food from the carbon dioxide, water
and minerals like plants do because our body has no
chlorophyll which helps to capture the energy of the sunlight.
This energy is used to synthesize food from carbon dioxide
and water.
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Q.3. How water and minerals absorbed by roots reach the
leaves ?
Ans. Water and minerals are transported to the leaves by the vessels
which run like pipes throughout the root, stem, branches and
the leaves. They form a continuous path or passage for the
nutrients to reach the leaf.
Q.4. What is so special about the leaves that they can synthesize
food but other parts of the plant cannot ?
Ans. The leaves have a green pigment called chlorophyll which
helps leaves to capture the energy of the sunlight. Other parts
of the plant do not have chlorophyll.
Q.5. Some plants have deep red, violet or brown leaves. Can
these leaves also carry out photosynthesis ?
Ans. Yes, these leaves can carry out the process of photosynthesis
because they also contain chlorophyll. The large amount of
red, violet and brown pigment mask the green colour of
chlorophyll.
Q.6. Are mosquitoes, bed bugs, lice and leeches that suck our
blood also parasites ?
Ans. Yes.
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Q.7. If the pitcher plant is green and carries out photosynthesis,
then why does it feed on insects ?
Ans. Because the pitcher plant does not get all the required nutrients
from the soil in which it grows.
Q.8. Some animals do not have mouths like other animals. They
are not like green plants as they lack chlorophyll and
cannot make food by photosynthesis. How do these
organisms acquire nutrients ?
Ans. These organisms secrete digestive juices on the dead and
decaying matter and convert it into a solution. Then they
absorb the nutrients form it.
Q.9. Paheli’s beautiful shoes, which she wore on special
occasion, were spoiled by fungi during the rainy season.
She wants to know how fungi appear suddenly during the
rainy season.
Ans. Fungi grow on articles that are left in hot and humid weather
for a long time. The fungal spores are generally present in the
air. During the rainy season, they land on wet and warm things
and then germinate and grow.
Q.10. Do fungi cause disease also ?
Ans. Yes, fungi cause diseases in plants, animals and humans.
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TEXT BOOK EXERCISES AND ANSWERS PAGE NO. 9
Q.1. Why do organisms need to take food ?
Ans. Food is needed by all living organisms for different purposes –
1. All living organisms take food and utilize it to get energy
for growth and maintenance of their bodies.
2. Another important function of food is to provide energy to
carry out life - processes.
3. Food is also needed by living beings for replacement and
repairing their damaged parts.
4. Food gives us resistance against diseases and protect us
from infections.
Q.2. Distinguish between a parasite and a saprotroph.
Ans.
Parasite
Saprotroph
takes
They secrete digestive juices
readymade food from
on the matter they live and
the
convert it into a solution and
A
parasite
organism
on
then absorb it.
which it feeds.
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2. They
feed
They feed on dead and
on
decaying organisms.
living organisms.
3. The organism on
They do not feed on living
which it feeds is
organism.
called host.
4. It deprives the host
There is no host at all.
of valuable
nutrients.
Q.3. How would you test the presence of starch in leaves?
Ans. Presence of starch in leaves can be tested by iodine test. Iodine
turns starch solution blue-black. Pour few drops of dilute
iodine solution on the leaf. The leaf becomes blue-black which
proves the presence of starch in it.
Q.4. Give a brief description of the process of synthesis of food
in green plants.
Ans. The synthesis of food in plants occurs in leaves. The leaves
have a green pigment called chlorophyll. It helps leaves to
capture the energy of the sunlight. This energy is used to
synthesize food from carbon dioxide and water. Thus,
chlorophyll, sunlight, carbon dioxide and water help to carry
out the process of photosynthesis. The solar energy captured
by the leaves is stored in the plant in the form of food.
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Sunlight
Carbon dioxide + water ⎯⎯⎯⎯⎯⎯
chlorophyll → Carbohydrate + oxygen.
Q.5. Show with the help of a sketch that the plants are the
ultimate source of food.
Ans.
Plants
Herbivores
Carnivores
SAPROPHYTES
Plants (The ultimate source of food)
Q.6. Fill in the blanks :
(a) Green plants are called _____ since they synthesis
synthesise their own food.
(b) The food synthesised by the plants is stored as _______.
(c) In photosynthesis, solar energy is captured by the pigment
called _____.
(d) During photosynthesis plants take in _____ and release
________.
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Ans. (a) autotrophs, (b) starch (c) chlorophyll, (d) carbon dioxide,
oxygen.
Q.7. Name the following :
(i) A parasitic plant with yellow, slender and tubular stem.
(ii) A plant that has both autotrophic and heterotrophic mode
of nutrition.
(iii) The pores through which leaves exchange gases.
Ans. (i) Cuscuta (Amarbel), (ii) Insectivorous plant, (iii) Stomata.
Q.8. Tick the correct answer :
(a) Amarbel is an example of :
(i) Autotroph , (ii) Parasite , (iii) Saprotroph , (iv) host
Ans. (ii) Parasite.
(b) The plant which traps and feeds on insects is :
(i) cuscuta , (ii) china rose , (iii) pitcher plant , (iv) rose
Ans. (iii) Pitcher plant.
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Q.9. Match the items given in column I with those in column II :
Column I
Column II
Chlorophyll
Bacteria
Nitrogen
Heterotrophs
Amarbel
Pitcher plant
Animals
Leaf
Insects
Parasite
Ans.
Column I
Column II
Chlorophyll
Leaf
Nitrogen
Bacteria
Amarbel
Parasite
Animals
Heterotrophs
Insects
Pitcher plant
Q.10. Mark ‘T’ if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis. (T/F)
Ans. False
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(ii) Plants which synthesise their food themselves are called
saprotrophs. (T/F)
(iii) The product of photosynthesis is not a protein. (T/F)
Ans. True.
(iv) Solar energy is converted into chemical energy during
photosynthesis. (T/F)
Ans. True.
Q.11. Choose the correct option from the following :
Which part of the plant gets carbon dioxide from the air
for photosynthesis.
(i)
root hair
(iii) leaf veins
(ii)
stomata
(iv)
sepals
Ans. (ii) Stomata.
Q.12. Choose the correct option from the following :
Plants take carbon dioxide from the atmosphere mainly
through their :
(i)
roots
(ii)
(iii) flowers
stem
(iv) leaves
Ans. (iv) Leaves.
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EXTENDED LEARNING – ACTIVITIES AND PROJECTS
1. Project
Take a potted plant with broad leaves. Take two strips of black
paper and cut out a small square in their centres. Cover a part
of two leaves with these paper and secure them with paper
clips. Keep the plant in the sunlight for 2-5 days. Observe the
difference in the colour of the covered and the uncovered
portions on the one leaf. Perform iodine test on this leaf. Did
the two parts show any difference in results ? Now, take
another leaf. Remove the strip and expose the covered part to
the sunlight for 2-3 days and do the iodine test again. Describe
your observations.
Ans. (i) The covered part will turn pale, whereas the uncovered
part will be bright green in colour.
(ii) The covered part on testing with iodine solution does not
turn blue black, whereas the uncovered part turns blue
black on testing with iodine solution showing the presence
of starch.
If the covered part is removed of the strip and exposed to
sunlight for 2 to 3 days and tested with iodine solution it will
turn blue black (showing the presence of starch).
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