Selina Textbook Solutions: Photosynthesis - Provider of Food for All | Biology Class 10 ICSE PDF Download

 Page 1


 
Exercise 1 
Solution A.1. 
b) glucose formed in photosynthesis soon gets converted into starch 
Solution A.2. 
b) twelve 
Solution A.3. 
b) humidity 
Solution A.4. 
c) trapping light energy 
Solution A.5. 
a) continue to live, but will not be able to store food 
Solution A.6. 
a) Carbon dioxide is reduced and water is oxidised 
Solution A.7. 
c) activate chlorophyll 
Solution A.8. 
d) ensure that the leaves are free from starch 
Solution A.9. 
a) CO 2 
Solution B.1. 
(a) Producers / Autotrophs 
(b) Chloroplasts 
(c) ATP (Adenosine triphosphate) 
(d) Glucose 
(e) Green plants 
(f) Carbon dioxide dissolved in water 
(g) Stroma 
(h) Phloem 
Chapter 5 - Photosynthesis : Provider of Food for All 
Page 2


 
Exercise 1 
Solution A.1. 
b) glucose formed in photosynthesis soon gets converted into starch 
Solution A.2. 
b) twelve 
Solution A.3. 
b) humidity 
Solution A.4. 
c) trapping light energy 
Solution A.5. 
a) continue to live, but will not be able to store food 
Solution A.6. 
a) Carbon dioxide is reduced and water is oxidised 
Solution A.7. 
c) activate chlorophyll 
Solution A.8. 
d) ensure that the leaves are free from starch 
Solution A.9. 
a) CO 2 
Solution B.1. 
(a) Producers / Autotrophs 
(b) Chloroplasts 
(c) ATP (Adenosine triphosphate) 
(d) Glucose 
(e) Green plants 
(f) Carbon dioxide dissolved in water 
(g) Stroma 
(h) Phloem 
Chapter 5 - Photosynthesis : Provider of Food for All 
Solution C.1. 
(a) 
Respiration Photosynthesis 
The gas released during respiration is carbon dioxide. The gas released during photosynthesis is oxygen. 
 
(b) 
Light Reaction Dark Reaction 
Hydrogen and oxygen are produced here, along with 
release of electrons, which converts ADP into ATP. 
Glucose is the main product formed during dark 
reaction. 
 
(c) 
Producers Consumers 
Producers show autotrophic mode of nutrition i.e. 
they are able to produce their own food from basic 
raw materials. 
For example: green plants 
Consumers show heterotrophic mode of nutrition 
i.e. they depend directly or indirectly on the 
producers for their food. 
For example: Animals 
 
(d) 
Grass Grasshopper 
Green grass being a producer is capable of producing 
its own food by photosynthesis. 
Grasshopper is a primary consumer (herbivore) 
and directly feeds on producers like grass. 
 
(e) 
Chlorophyll Chloroplast 
Chlorophyll is the green pigment present in cell 
organelles called chloroplasts. 
Chloroplasts are cell organelles, situated in the 
cytoplasm of plant cells. They are present mainly in 
the mesophyll cells and in the guard cells of 
stomata. 
 
Solution C.2. 
(a) False 
Correct Statement: Dark reaction of photosynthesis is independent of light and occurs 
simultaneously with light reaction. 
(b) True 
Page 3


 
Exercise 1 
Solution A.1. 
b) glucose formed in photosynthesis soon gets converted into starch 
Solution A.2. 
b) twelve 
Solution A.3. 
b) humidity 
Solution A.4. 
c) trapping light energy 
Solution A.5. 
a) continue to live, but will not be able to store food 
Solution A.6. 
a) Carbon dioxide is reduced and water is oxidised 
Solution A.7. 
c) activate chlorophyll 
Solution A.8. 
d) ensure that the leaves are free from starch 
Solution A.9. 
a) CO 2 
Solution B.1. 
(a) Producers / Autotrophs 
(b) Chloroplasts 
(c) ATP (Adenosine triphosphate) 
(d) Glucose 
(e) Green plants 
(f) Carbon dioxide dissolved in water 
(g) Stroma 
(h) Phloem 
Chapter 5 - Photosynthesis : Provider of Food for All 
Solution C.1. 
(a) 
Respiration Photosynthesis 
The gas released during respiration is carbon dioxide. The gas released during photosynthesis is oxygen. 
 
(b) 
Light Reaction Dark Reaction 
Hydrogen and oxygen are produced here, along with 
release of electrons, which converts ADP into ATP. 
Glucose is the main product formed during dark 
reaction. 
 
(c) 
Producers Consumers 
Producers show autotrophic mode of nutrition i.e. 
they are able to produce their own food from basic 
raw materials. 
For example: green plants 
Consumers show heterotrophic mode of nutrition 
i.e. they depend directly or indirectly on the 
producers for their food. 
For example: Animals 
 
(d) 
Grass Grasshopper 
Green grass being a producer is capable of producing 
its own food by photosynthesis. 
Grasshopper is a primary consumer (herbivore) 
and directly feeds on producers like grass. 
 
(e) 
Chlorophyll Chloroplast 
Chlorophyll is the green pigment present in cell 
organelles called chloroplasts. 
Chloroplasts are cell organelles, situated in the 
cytoplasm of plant cells. They are present mainly in 
the mesophyll cells and in the guard cells of 
stomata. 
 
Solution C.2. 
(a) False 
Correct Statement: Dark reaction of photosynthesis is independent of light and occurs 
simultaneously with light reaction. 
(b) True 
(c) False 
Correct Statement: Starch produced in a leaf is stored temporarily in the leaf until the 
process of photosynthesis. At night it is converted back into soluble sugar and 
translocated to different part of the body either for the utilization or for the storage. 
(d) True 
(e) False 
Correct Statement: Green plants are producers. 
(f) False 
Correct Statement: Respiration results in loss of dry weight of the plants. 
(g) False 
Correct Statement: Photosynthesis stops at a temperature of above 40oC. 
(h) True 
(i) True 
(j) True 
Solution C.3. 
(a) grana 
(b) iodine solution 
(c) chloroplast 
(d) Calvin cycle 
(e) Sucrose 
Solution C.4. 
(a) False 
Photosynthesis increases with the light intensity up to a certain limit only and then it 
gets stabilized. 
(b) False 
The atmospheric temperature is an important external factor affecting photosynthesis. 
The rate of photosynthesis increases up to the temperature 35
o
C after which the rate 
falls and the photosynthesis stops after 40
o
C. 
(c) False 
Ice cold water will hamper the process of photosynthesis in the immersed leaf, even if 
there is sufficient sunshine because the temperature is an important factor for the rate 
of photosynthesis. 
Page 4


 
Exercise 1 
Solution A.1. 
b) glucose formed in photosynthesis soon gets converted into starch 
Solution A.2. 
b) twelve 
Solution A.3. 
b) humidity 
Solution A.4. 
c) trapping light energy 
Solution A.5. 
a) continue to live, but will not be able to store food 
Solution A.6. 
a) Carbon dioxide is reduced and water is oxidised 
Solution A.7. 
c) activate chlorophyll 
Solution A.8. 
d) ensure that the leaves are free from starch 
Solution A.9. 
a) CO 2 
Solution B.1. 
(a) Producers / Autotrophs 
(b) Chloroplasts 
(c) ATP (Adenosine triphosphate) 
(d) Glucose 
(e) Green plants 
(f) Carbon dioxide dissolved in water 
(g) Stroma 
(h) Phloem 
Chapter 5 - Photosynthesis : Provider of Food for All 
Solution C.1. 
(a) 
Respiration Photosynthesis 
The gas released during respiration is carbon dioxide. The gas released during photosynthesis is oxygen. 
 
(b) 
Light Reaction Dark Reaction 
Hydrogen and oxygen are produced here, along with 
release of electrons, which converts ADP into ATP. 
Glucose is the main product formed during dark 
reaction. 
 
(c) 
Producers Consumers 
Producers show autotrophic mode of nutrition i.e. 
they are able to produce their own food from basic 
raw materials. 
For example: green plants 
Consumers show heterotrophic mode of nutrition 
i.e. they depend directly or indirectly on the 
producers for their food. 
For example: Animals 
 
(d) 
Grass Grasshopper 
Green grass being a producer is capable of producing 
its own food by photosynthesis. 
Grasshopper is a primary consumer (herbivore) 
and directly feeds on producers like grass. 
 
(e) 
Chlorophyll Chloroplast 
Chlorophyll is the green pigment present in cell 
organelles called chloroplasts. 
Chloroplasts are cell organelles, situated in the 
cytoplasm of plant cells. They are present mainly in 
the mesophyll cells and in the guard cells of 
stomata. 
 
Solution C.2. 
(a) False 
Correct Statement: Dark reaction of photosynthesis is independent of light and occurs 
simultaneously with light reaction. 
(b) True 
(c) False 
Correct Statement: Starch produced in a leaf is stored temporarily in the leaf until the 
process of photosynthesis. At night it is converted back into soluble sugar and 
translocated to different part of the body either for the utilization or for the storage. 
(d) True 
(e) False 
Correct Statement: Green plants are producers. 
(f) False 
Correct Statement: Respiration results in loss of dry weight of the plants. 
(g) False 
Correct Statement: Photosynthesis stops at a temperature of above 40oC. 
(h) True 
(i) True 
(j) True 
Solution C.3. 
(a) grana 
(b) iodine solution 
(c) chloroplast 
(d) Calvin cycle 
(e) Sucrose 
Solution C.4. 
(a) False 
Photosynthesis increases with the light intensity up to a certain limit only and then it 
gets stabilized. 
(b) False 
The atmospheric temperature is an important external factor affecting photosynthesis. 
The rate of photosynthesis increases up to the temperature 35
o
C after which the rate 
falls and the photosynthesis stops after 40
o
C. 
(c) False 
Ice cold water will hamper the process of photosynthesis in the immersed leaf, even if 
there is sufficient sunshine because the temperature is an important factor for the rate 
of photosynthesis. 
(d) False 
For destarching, the potted plant can kept in a dark room for 24-48 hours. 
(e) False 
There is no start point or end point in the carbon cycle, the carbon is constantly 
circulated between the atmosphere and the living organisms. 
(f) False 
If a plant is kept in bright light all the 24 hours for a few days, the dark reaction 
(biosynthetic phase) will continue to occur because the dark reaction is independent of 
light and it occurs simultaneously with the light dependent reaction. 
(g) True 
Solution C.5. 
Photons, grana, water molecules, hydrogen and hydroxyl ions, oxygen 
Solution C.6. 
Photosynthesis Respiration 
Carbon dioxide is used up and oxygen is released. Oxygen is used up and carbon dioxide is released. 
Photosynthesis occurs in plants and some 
bacteria. 
Respiration occurs in all living organisms. 
Photosynthesis results in gain of dry weight of the 
plants. 
Respiration results in loss of dry weight of the 
plants. 
Glucose is produced which is utilized by the plants. Glucose is broken down to obtain energy. 
The raw materials for the photosynthesis are 
water, carbon dioxide and sunlight. 
The raw material for respiration is glucose. 
 
(Any 4) 
Solution C.7. 
Oxygen is released during photosynthesis. Some of this oxygen may be used in 
respiration in the leaf cells, but the major portion of it is not required and it diffuses out 
into the atmosphere through the stomata. However, in a sense, even this oxygen is not 
a waste because all organisms require it for their existence including the plants. 
Solution C.8. 
The presence of starch is regarded as evidence of photosynthesis. Hence before 
starting an experiment on photosynthesis, the plant should be placed in the dark for 24-
48 hours to destarch the leaves. During this period, all the starch from the leaves will be 
sent to the storage organs and the leaves will not show the presence of starch. So the 
various experiments on photosynthesis can be carried out effectively. 
Page 5


 
Exercise 1 
Solution A.1. 
b) glucose formed in photosynthesis soon gets converted into starch 
Solution A.2. 
b) twelve 
Solution A.3. 
b) humidity 
Solution A.4. 
c) trapping light energy 
Solution A.5. 
a) continue to live, but will not be able to store food 
Solution A.6. 
a) Carbon dioxide is reduced and water is oxidised 
Solution A.7. 
c) activate chlorophyll 
Solution A.8. 
d) ensure that the leaves are free from starch 
Solution A.9. 
a) CO 2 
Solution B.1. 
(a) Producers / Autotrophs 
(b) Chloroplasts 
(c) ATP (Adenosine triphosphate) 
(d) Glucose 
(e) Green plants 
(f) Carbon dioxide dissolved in water 
(g) Stroma 
(h) Phloem 
Chapter 5 - Photosynthesis : Provider of Food for All 
Solution C.1. 
(a) 
Respiration Photosynthesis 
The gas released during respiration is carbon dioxide. The gas released during photosynthesis is oxygen. 
 
(b) 
Light Reaction Dark Reaction 
Hydrogen and oxygen are produced here, along with 
release of electrons, which converts ADP into ATP. 
Glucose is the main product formed during dark 
reaction. 
 
(c) 
Producers Consumers 
Producers show autotrophic mode of nutrition i.e. 
they are able to produce their own food from basic 
raw materials. 
For example: green plants 
Consumers show heterotrophic mode of nutrition 
i.e. they depend directly or indirectly on the 
producers for their food. 
For example: Animals 
 
(d) 
Grass Grasshopper 
Green grass being a producer is capable of producing 
its own food by photosynthesis. 
Grasshopper is a primary consumer (herbivore) 
and directly feeds on producers like grass. 
 
(e) 
Chlorophyll Chloroplast 
Chlorophyll is the green pigment present in cell 
organelles called chloroplasts. 
Chloroplasts are cell organelles, situated in the 
cytoplasm of plant cells. They are present mainly in 
the mesophyll cells and in the guard cells of 
stomata. 
 
Solution C.2. 
(a) False 
Correct Statement: Dark reaction of photosynthesis is independent of light and occurs 
simultaneously with light reaction. 
(b) True 
(c) False 
Correct Statement: Starch produced in a leaf is stored temporarily in the leaf until the 
process of photosynthesis. At night it is converted back into soluble sugar and 
translocated to different part of the body either for the utilization or for the storage. 
(d) True 
(e) False 
Correct Statement: Green plants are producers. 
(f) False 
Correct Statement: Respiration results in loss of dry weight of the plants. 
(g) False 
Correct Statement: Photosynthesis stops at a temperature of above 40oC. 
(h) True 
(i) True 
(j) True 
Solution C.3. 
(a) grana 
(b) iodine solution 
(c) chloroplast 
(d) Calvin cycle 
(e) Sucrose 
Solution C.4. 
(a) False 
Photosynthesis increases with the light intensity up to a certain limit only and then it 
gets stabilized. 
(b) False 
The atmospheric temperature is an important external factor affecting photosynthesis. 
The rate of photosynthesis increases up to the temperature 35
o
C after which the rate 
falls and the photosynthesis stops after 40
o
C. 
(c) False 
Ice cold water will hamper the process of photosynthesis in the immersed leaf, even if 
there is sufficient sunshine because the temperature is an important factor for the rate 
of photosynthesis. 
(d) False 
For destarching, the potted plant can kept in a dark room for 24-48 hours. 
(e) False 
There is no start point or end point in the carbon cycle, the carbon is constantly 
circulated between the atmosphere and the living organisms. 
(f) False 
If a plant is kept in bright light all the 24 hours for a few days, the dark reaction 
(biosynthetic phase) will continue to occur because the dark reaction is independent of 
light and it occurs simultaneously with the light dependent reaction. 
(g) True 
Solution C.5. 
Photons, grana, water molecules, hydrogen and hydroxyl ions, oxygen 
Solution C.6. 
Photosynthesis Respiration 
Carbon dioxide is used up and oxygen is released. Oxygen is used up and carbon dioxide is released. 
Photosynthesis occurs in plants and some 
bacteria. 
Respiration occurs in all living organisms. 
Photosynthesis results in gain of dry weight of the 
plants. 
Respiration results in loss of dry weight of the 
plants. 
Glucose is produced which is utilized by the plants. Glucose is broken down to obtain energy. 
The raw materials for the photosynthesis are 
water, carbon dioxide and sunlight. 
The raw material for respiration is glucose. 
 
(Any 4) 
Solution C.7. 
Oxygen is released during photosynthesis. Some of this oxygen may be used in 
respiration in the leaf cells, but the major portion of it is not required and it diffuses out 
into the atmosphere through the stomata. However, in a sense, even this oxygen is not 
a waste because all organisms require it for their existence including the plants. 
Solution C.8. 
The presence of starch is regarded as evidence of photosynthesis. Hence before 
starting an experiment on photosynthesis, the plant should be placed in the dark for 24-
48 hours to destarch the leaves. During this period, all the starch from the leaves will be 
sent to the storage organs and the leaves will not show the presence of starch. So the 
various experiments on photosynthesis can be carried out effectively. 
Solution C.9. 
Destarching means removal of starch. Destarching is carried out so that all the starch 
from the leaves will be sent to the storage organs. Hence all the leaves will not show the 
presence of starch and photosynthesis can be studied. Destarching ensures that any 
starch present after the experiment has been formed under experimental conditions. 
Solution C.10. 
If a green plant is kept in bright light, it tends to use up all the CO 2 produced during 
respiration, for photosynthesis. Thus, the release of CO 2cannot be demonstrated. 
Hence, it is difficult to demonstrate respiration as these two processes occur 
simultaneously. 
Solution C.11. 
The chloroplasts are concentrated in the upper layers of the leaf which helps cells to 
trap the sunlight quickly. Also the epidermis is covered by a waxy, waterproof layer of 
cuticle. This layer is thicker on the upper surface than the lower one. Hence most leaves 
have the upper surface more green and shiny than the lower one. 
Solution C.12. 
? Place hydrilla plant (a water plant) in a beaker containing pond water and cover it 
by a short-stemmed funnel. (Make sure the level of water in the beaker is above 
the level of the stem of the funnel) 
? Invert a test tube full of water over the stem of the funnel. 
? Place the set up in the sun light for a few hours. 
Observation: 
Bubbles appear in the stem which rise and are collected in the test tube. When 
sufficient gas gets collected, a glowing splinter will be introduced in the test tube, which 
will burst into flames. 
Inference: 
The splinter glows due the presence of oxygen in the test tube which proves that the 
gas collected in the test is released by hydrilla during photosynthesis.