Nutrition in Plants
POINTS TO REMEMBER
1. All living organisms require food as a source of energy.
2. Nutrients: carbohydrates, proteins, fats, vitamins and minerals are the
components of food. These components of food are necessary for our body and
are called nutrients.
3. Nutrition: It is the mode of taking food by an organism and its utilization by the body.
4. Autotrophic: The mode of nutrition in which organism make food themselves
from simple substances is called autotrophic (auto = self, trophos = nourishment)
nutrition Therefore, green plants are called autotrophs.
5. Heterotrophs: The category of organisms that take readymade food prepared by
the plants are called heterotrophs (heteros = other, trophos = nourishment). For
example: Human animals etc.
6. Parasitism plants: Some plants take readymade food from other organism and
harms them. Such plants are called parasites and the organism, that suffers are
called host. For example: Cuscuta is a parasite.
7. Saprotrophs: The category of organism that take nutrients from dead and
decaying matter are called saprotrophs and the mode of nutrition is called
saprotrophic nutrition.
8. Symbiotic relationship: Some organism live together for their mutual
advantage. This is called symbiotic relationship. For example: Lichens. In
lichens, a chlorophyll containing partner which is an alga, and a fungus live
together.
9. Insectivorous plants: Some plants trap the insects and eat it that come in their
contact. Such insect eating plants are called insectivorous plants. For example:
pitcher plant.
10. Photosynthesis:
i. It is food making process in plants.
ii. The synthesis of food in plants occurs in all the green parts of it, especially leaves.
iii. During photosynthesis, chlorophyll containing cells of leaves in the presence
of sunlight, use carbon dioxide and water to synthesis carbohydrates.
Sunlight
Carbon dioxide + water
Carbohydrate + Oxygen
Chlorophyll
iv.Stomata: These are the tiny pores present on the surface of the leaves. These
pores are surrounded by ‘guard cells’. Such pores are called stomata.
11. Sun is the ultimate source of energy for all living organisms.
12. We have to add ferilizers and manures to soil from time to time to enrich the
fertility of soil that increases the production of crops.
13. Cholorophyll: A green plant pigment which absorb energy from sunlight,
enabling the plant to build up food as carbohydrates from carbon dioxide and
water by photosynthesis.
14. Host: A plant or an animal that supports a parasite is called host.
Q.1. Why do organisms need to take food?
Ans. Food is needed by all living species for the following purposes:
a) It meant for the general growth and development of an organism. If it is not
in sufficient amount, then it shows insufficient growth and development.
b) It is meant to provide energy. We need energy for movements such as
running, walking or raising our arm.
c) It is also needed by living being for repairing of their damaged parts.
d) It gives us resistance against diseases and protects us from infections.
Q.2. Distinguish between a parasite and a saprotroph.
Ans.
Parasite
Saprotroph
1. A parasite takes the food from the organism
1. They secrete digestive juices on the
on which it lives.
matter they live and convert it into a
solution and then absorb it.
2. They feed on a living organism.
2. They feed on dead and decaying
organism.
3. The organism on which it feeds is
3. They do not feed on a living organism.
called host.
4. It deprives the host of valuable nutrients 4. There is no host at all.
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 into blue black colour.
Q.4. Give a brief description of the process of synthesis of food in green plants.
Ans. Leave of a plant have a green pigment called chlorophyll. In the presence of
sunlight, they use carbon dioxide and water to synthesise carbohydrate.
Sunlight
Carbon dioxide + water
Carbohydrate + Oxygen
Chlorophyll
During the process oxygen is released. The carbohydrates ultimately get
converted into starch.
Carbon dioxide from air is taken through stomata. Water and minerals are
absorbed by the roots and transported to leaves.
Q.5. Show with the help of a sketch that the plants are the ultimate source of
food.
Ans.
Fig 1.1. Plants capture solar energy by unique process called Photosynthesis
Q. 6 Fill in the blanks:
a) Green plants are called …………… since they 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 …………
Ans. a) autotrophs
b) starch
c) chlorophyll
d) carbon dioxide, oxygen.
Q.7. Name the following:
i. A parasitic plant with yellow, slender and tabular stem.
ii. A plant that has both autotrophic and heterotrophic mode of nutrition.
iii. The pores through which leaves exchange gases.
Ans. i) Cascuta
ii) Insectivorous plants
iii) Stomata.
Q. 8 . Thick the correct answer:
a) Amarbel is an example of
( i) autotroph
(ii) parasite
(iii) saprotroph
(iv) host
b) The plant which traps and feeds on insects is
(i) Cascuta
(ii) China rose (iii) Pitcher Plant (iv) Rose
Ans.
(a) (ii) Parasite
(b) (iii) Pitcher plant.
Q. 9. Match the items given in Column I with those in Column II:
Column I
Column II
(i) Chlorophyll
Bacteria
(ii) Nitrogen
Heterotrophs
(iii) Amarbel
Pitcher plant
(iv) Animals
Leaf
(v) Insects
Paradise
Ans. Column I
(i) Chlorophyll
(ii) Nitrogen
(iii) Amarbel
(iv) Animals
(v) Insects
Column II
Leaf
Bacteria
Parasite
Heterotrophs
Pitcher plant
Q. 10. Match ‘T’ if the statement is true and ‘F’ if it is false:
(i) Carbon dioxide is released during photosynthesis.
F)
(ii) Plants which synthesis their food themselves are called saprotrophs.
F)
(iii) The product of photosynthesis is not a protein.
F)
(iv) Solar energy is converted into chemical energy during photosynthesis.
F)
Ans. (i) F
(ii) F
(iii) T
(iv) T.
(T /
(T /
(T /
(T /
Q. 11. Choose the correct option from the following:
Which part of the plant takes in carbon dioxide from the air for
photosynthesis?
(i) Root hair
(ii) Stomata
(iii) Leaf veins
(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) stem
(ii)
flowers
(iv) leaves
Ans. (iv) Leaves.
ADDITIONAL IMPORTANT QUESTIONS
Q. 1. Name the components of food which are necessary for our body?
Ans. Carbohydrates, proteins, fats, vitamins and minerals.
Q. 2. What is nutrition?
Ans. Nutrition is the mode of taking food by an organism and its utilization by the
body.
Q. 3. Why the leaves are generally green?
Ans. Leaves generally green because they contain a green pigment called
chlorophyll.
Q. 4. Food making process in plants is called photosynthesis. In which part of the
plant does photosynthesis occur?
Ans. Photosynthesis occurs in leaves.
Q. 5. What are stomata?
Ans. These are the tiny pores present on the surface of leaves.
Q. 6. Name various mode of nutrition.
Ans. Various modes of nutrition are:
(i) Autotrophic nutrition.
(ii) Heterotrophic nutrition.
(iii) Saprotrophic nutrition.
Q. 7. Why the plants are called autotrophs?
Ans. Plants can make their own food from simple substances. Therefore plants are
called autotrophs.
Q. 8. What is the ultimate source of energy for all living organisms?
Ans. The sun is the ultimate source of energy for all living organisms.
Q. 9. Why insectivorous plants eat insects?
Ans. To fulfill their needs of nitrogen.
Q. 10. Why the parasites are named so?
Ans. They are called parasites because they deprive the host’s valuable nutrients and
harm the host by causing diseases.
Q. 11. What are saprotrophs?
Ans. Organisms which take the nutrients in the form of solution from dead and
decaying matter are called saprotrophs.
Q. 12. What is symbiotic relationship?
Ans. Some organisms live together and share shelter and nutrients and mutually
benefited. This is called symbiotic relationship.
Q. 13. “All animals depend upon the plants for food.” Justify the statement.
Ans. We know that the source of energy for living organisms is food. All green
plants form the major part of food by simple inorganic substances like carbon
dioxide and water in the presence of sunlight and chlorophyll. This is known as
autotrophic (holophytic) nutrition. But in case of animals they cannot
synthesise their food themselves. So all animals depend on the green plants for
food.
Q. 14. Distinguish between an autotroph and a heterotrophy.
Ans.
Autotroph
1. They are capable of synthesizing
their own food.
2. They form the first trophic level
of any food chain.
3. They usually contain chlorophyll.
Heterotroph
1. They cannot manufacture their
own food.
2. They form the higher levels in
any food chain.
3. Chlorophyll are absent in them.
Q. 15. What are cells? Describe their structure in brief.
Fig. 1.2 Cell
Ans. Cell is defined as the structural and functional unit of life. Cells can be seen
only under the microscope. The cell is enclosed by a thin outer boundary called
cell membrane. Most cells have a distinct centrally located spherical structure
called the nucleus. The cell contains a jelly like substance, i.e., cytoplasm, that
contains a number of cell-organelles including nucleus.
Q. 16. Why the food making process in plants is called photosynthesis?
Ans. The chlorophyll present in the leaves of the green plants help them to capture the
solar energy. This energy is used to synthesise food from carbon dioxide and
water. Since the synthesis of food occurs in sunlight, it is called photosynthesis
(photo: light, synthesis: to combine).
Q. 17. “In the absence of photosynthesis, life is impossible on the earth.” Explain.
Ans. In the absence of green plants there would not be the process of photosynthesis.
The survival of almost all living organisms directly or indirectly depends upon
the food made by the plants. Besides oxygen it is an example of interspecific
interaction in which both the partners are benefited which is essential for the
survival of all living organisms is produced during photosynthesis. Thus we
can say that life would be impossible on the earth in the absence of
photosynthesis.
Q. 18. What are lichens?
Ans. Lichens are organisms in which an alga and a fungus live together. The fungus
provides shelter, water and minerals to the alga and in return, alga provides food
which is prepares by photosynthesis.
Q. 19. What is the mode of nutrition in fungi?
Ans. Fungi secrete digestive juices on the dead and decaying matter and convert it
into a solution. Then they absorb nutrients from it. This mode of nutrition in
which organisms take in nutrients in solution form from dead decaying matter is
called saprotrophic nutrition.
Q. 20. Discuss in brief about the mechanism of eating insects by pitcher plant.
Ans. Pitcher plant: In insectivorous plant leaves are modified into a pitcher like
structure. The apex of the leaf forms a lid which can open and close the mouth
of the pitcher. Inside the pitcher there are hair which are downwardly directed.
When an inside lands in the pitcher, it slips inside and the lid closes. The
trapped insect is entangled into the hair. The insect is digested by the digestive
juices secreted in the pitcher.
Q. 21. What are parasites? Explain by taking the example of Cuscuta (Amarbel).
Cuscuta is a plant which looks like yellow thread like structures twining
around the stem and branches of some trees (Fig. 1.4).
It lacks chlorophyll but takes readymade food from the host plant. The plant
on which it climbs is called a host. Since it deprives the host’s valuable nutrients, it is
called a parasite.
Q. 22. Explain why fertilizers and manures are needed to the fields from time to
time.
Ans. We know that plants absorb minerals nutrients from the soil. So their amounts in
the soil keep on declining. Fertilizers and manures contain nutrients such as
nitrogen, potassium, phosphorous etc. Therefore, to overcome the deficit of
these nutrients in the soil we need to add these fertilizers and manures from time
to time.
Q. 23. How symbiotic bacterium called Rhizobium is important for the farmers?
Ans. Usually a crop requires a lot of nitrogen. But they can not utilize atmospheric
nitrogen. They need it in soluble form. The bacterium called Rhizobium can
convert atmospheric nitrogen into a soluble form. But Rhizobium cannot make
its own food. So it lives in the roots of gram, peas, moong, beans and other
legumes and provides them nitrogen. In return, the plant provides food and
shelter to the bacteria. They have symbiotic relationship. This association is of
great importance for the farmers.
Q. 24. What is autotrophic mode of nutrition? How plants prepare their own
food?
Ans. Autotrophic mode of nutrition. The mode of nutrition in which organisms
make food themselves from simple substances is called autotrophic (auto =
self, trophos = nourishment) nutrition. Therefore, plants are called autotrophs.
Photosynthesis-Food making process in plants. The synthesis of food in plants
takes place in leaves. Therefore all the raw materials must reach there. Water and
minerals present in the soil are absorbed by roots and transported to leaves through
stems. Carbon dioxide from air is taken in through the tiny pores present on the
surface of leaves called stomata.
The leaves have a green pigment called chlorophyll. It helps leaves to capture the
solar energy. This energy is used to synthesise food by the process called
photosynthesis.
During photosynthesis, chlorophyll containing cells of leaves (Fig. 1.5) in the
presence of sunlight, using carbon dioxide and water to synthesise carbohydrates. The
process can be represented as an equation:
Sunlight
Carbon dioxide + Water
Carbohydrate + Oxygen
Chlorophyll
During this process is released. The carbohydrate ultimately gets converted into
starch.
Fig. 1.5. Schematic diagram showing photosynthesis
OBJECTIVE TYPE QUESTIONS
Q. 1. Match the items given in Column I with those given in Column II.
Column I
(i)
(ii)
(iii)
(iv)
(v)
(vi)
Autotrophs
Heterotroph
Parasite
Saprophyte
Symbiont
Insectivorous
Column II
(a)
(b)
(c)
(d)
(e)
(f)
Fungi
Lichen
Pitcher plant
Algae
Man
Cuscuta
Q. 2. Fill in the blanks space in the following statements:
(i) All organisms take …………. and utilize it to get energy for the growth and
the maintenance of their bodies.
(ii) Green plants synthesis their food themselves by the process of
…………… they are called …………..
(iii) …………… energy is stored by the leaves with the help of chlorophyll.
(iv) …………… derive nutrition from dead, decaying matter.
(v) Plants like cuscuta take food from ………….. plant.
(iv) All animals are categorized as ………… .
(vii) …………… is produced and …………. is utilized during photosynthesis.
(viii) …………… is the site of reception of light energy in leaves.
Q. 3. Choose the true and false statements from the following:
(i) Food is essential for all living organisms.
(ii) Leaves are the food factories of plant.
(iii) Water comes into leaves through stomata in the form of vapours.
(iv) Plants utilize the carbon dioxide dissolved in the water absorbed by the root
for photosynthesis.
(v) The sun is the ultimate source of energy for all living organisms.
(vi) Algae are saprotrophs.
(vii) Cuscuta is a parasite.
(viii) Saprotrophs take their food in solution form from dead and decaying matter.
(ix) Insectivorous plants are partial heterotrophs.
(x) Plants take atmospheric nitrogen through stomata and utilize as a nutrient.
Q. 4. Choose the correct option in the following.
(i) Which of the following is a nutrient?
(a) Protein
(b) Fat
(c) Vitamins
(d) All of these.
(ii) Human being can be categorised as
(a) heterotrophs
(b) autotrophs
(c) parasites
(d) saprotrophs.
(iii) The food making process in plants is called as
(a) glycolysis
(b) photosynthesis
(c) photolysis
(d) chemosynthesis
(iv) Which part of the plant is called its food factory?
(a) Fruits
(b) Seeds
(c) Leaves
(d) Flowers
(v) Tiny pores present on the surface of leaves through which gaseous
exchange occurs are called
(a) stomata
(b) guard cells
(c) food holes
(d) gas holes
(vi) What is the ultimate source of energy for all living organisms?
(a) Water energy
(b) Wind energy
(c) Solar energy
(d) Chemical energy
(vii) Green pigment present in the leaves is called
(a) hemoglobin
(b) globulin
(c) albumin
(d) chlorophyll
(viii) During photosynthesis plants
(a) take oxygen and release carbon dioxide.
(b) take carbon dioxide and release oxygen
(c) take carbon dioxide but do not release oxygen
(d) take oxygen but do not release carbon dioxide
(ix) During photosynthesis
(a) solar energy is converted into chemical energy
(b) solar energy is converted into mechanical energy
(c) chemical energy is converted into mechanical energy
(d) bio energy is converted into chemical energy.
(x) The raw materials for photosynthesis are
(a) CO2, water
(b) CO2, O2, H2
(c) N2, water
(d) O2, water
(xi) The end products of photosynthesis are
(a) carbohydrates, oxygen
(b) carbohydrates, hydrogen
(c) carbohydrates, water vapours
(d) carbohydrates, oxygen and water vapours
(xii) Which one of the following is a parasite?
(a) Lichen
(b) Cuscuta
(c) Pitcher plant
(d) Rhizobium
(xiii) Which of the following class of organisms belongs to saprotrophs?
(a) Fungi
(b) Algae
(c) Lichens
(d) Bryophytes
(xiv) Which one of the following is a pair of symbolic organisms?
(a) Lichens
(b) Rhizobium and a legume
(c) Cuscuta
(d) Both (a) and (b)
(xv) Which of the following is an insectivorous plant?
(a) Pitcher plant
(b) Indian telegraph plant
(c) 4 O’clock plant
(d) Cuscuta
(xvi) Insectivorous plants eat insects to fulfill their needs of
(a) energy
(b) nitrogen
(c) phosphorous
(d) potassium
ANSWERS TO OBJECTIVE TYPE QUESTIONS
Q. 1. Match the items in Column I with Column II
Column I
Column II
i) Autotrophs
d) Algae
ii) Heterotroph
e) Man
iii) Parasite
f) Cuscuta
iv) Saprotroph
a) Fungi
v) Symbiont
b) Lichen
vi) Insectivorous
c) Pitcher Plant
Q. 2. Fill in the blanks:
i) Food
iii) Solar
v) Host
vii) Oxygen, carbon dioxide
ii) photosynthesis, autotrophs
iv) Fungi/saprotrophs
vi) heterotrophs
viii) chlorophyll.
Q. 3. True/False:
i) True
ii) True
vi) False
vii) True
Q. 4. Choose the correct option:
(i) (d)
(ii) (a)
iii) False
viii) True
iv) False
ix) True
v) True
x) False.
(iii) (b)
(iv) (c)
(v) (a)
(vi) (c)
(vii) (d)
(viii) (b)
(ix) (a)
(x) (a)
(xi) (a)
(xii) (b)
(xiii) (a)
(xiv) (d)
(xv) (a)
(xvi) (b).