CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
Class X- Biology
Questions and Answers
PROGRESS CHECK
1. Answer the following in “Yes” or “No”
I.
All parts of a green plant carry out photosynthesis- Yes
II.
Photosynthesis is the only biological process that releases oxygen into the air. Yes
III.
Out of nine types of chlorophyll, chlorophyll a and b are most abundant.-Yes
IV.
Too much light destroys chlorophyll. – Yes
V.
VI.
No transpiration occurs during photosynthesis. No
During sunlight, the guard cells turn flaccid to open the stomata.- No
PROGRESS CHECK
1. Write the overall chemical equation of photosynthesis
-6CO2 + 12H2O
C6H12O6 + 6H2O + 6O2
2. Which substance in the above equation is repeated in raw materials as well as the end
products?
-
Water
3. What is the source of oxygen released in the photosynthesis- CO2 or H2O?
-
Water
4. What happens in photolysis?
-
The water molecules split into its components in the presence of light.
5. Dark reaction involves utilization of CO2 in producing C6H12O6 (glucose). Why is this called
dark phase?
-
Since this reactions are independent of light. It does not mean that the reaction occurs in
dark or at night.
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
6. Glucose produced during photosynthesis is soon polymerized into starch. What does
polymerization mean?
-
The process of conversion of smaller molecules into larger molecules (polymers) is
called polymerization.
7. Why is better to call the dark phase of photosynthesis as “light- independent phase”?
-
The dark phase does not mean that it occurs when it is dark or at night. It only meant
that the reactions not dependent on light. That’s why, it is now better to called it “lightindependent phase”
PROGRESS CHECK
1. How do the following favor increased photosynthesis?
I.
-
Large surface of the leaf
Larger the surface area maximum light absorption occurs. Therefore the rate of
photosynthesis is more.
II.
Thinness of the leaf
-it reduces the distance between cells facilitating the rapid transport. Thereby
increases the rate of photosynthesis.
III.
-
More numerous stomata
More numerous the stomata allow the exchange of gases (CO2 and O2). So the rate of
photosynthesis is increased.
2. Name three end- products of photosynthesis and mention the fate of each of them in the
plant
I.
Name………Glucose
Fate……….. Utilized by the cells or store in the form of starch/ sucrose.
II.
Name……...Water
Fate………. It’s re-utilized in the continuance of photosynthesis.
III.
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Name…….. Oxygen
CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
Fate ……… Used for respiration and releases into the atmosphere.
3. If we keep on increasing CO2 concentration in the air, will the rate of photosynthesis also
keep on increasing in the direct proportion?
Yes/No. Explain
No, the rate of photosynthesis will not increase in the direct proportion if we keep on
increasing the CO2 concentration. It’s due to the fact that the light intensity and CO2
concentration are both limiting factors for each other. The rate of the photosynthesis will
increase with the increase in CO2 concentration provided there should also increase in the
light intensity and vice versa.
PROGRESS CHECK
1. Why is it necessary to de-starch a plant before performing any experiment on
photosynthesis?
-
The removal of starch will not show the presence of starch and to give correct result
from the experiment.
2. Why do we perform the iodine-test?
-
To indicate the presence starch.
3. What chemical do you use to remove CO2 from inside a flask in certain experiments on
photosynthesis?
-KOH
4. All food chains start with a plant. Why is this so?
-
It the producers as it provides food for all living beings
5. The honey bee produced honey. In terms of the food chain, is the honey bee a producer
or consumer?
-
consumer
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
REVIEW QUESTIONS
A. VERY SHORT ANSWER TYPE.
1. Name the following:
I.
The category of organisms that prepare their own food from basic raw materials.
-
Plants
II.
The kind of plastids found in the mesophyll cells of the leaf.
-
Chlorophyll
III.
The compound which stores energy in the cells.
-
Mitochondria
IV.
The first form of food substance produced during photosynthesis.
-glucose
V.
The organisms that can be called “natural purifiers” of the air.
- Plants
VI.
The source of O2 for aquatic plants.
-water
VII.
The part of the chloroplast where dark reaction of the photosynthesis takes place.
-stoma
VIII.
The tissue that transports manufactured type of starch from leaves to all parts of the
plants.
-Phloem
B. MULTIPLE CHOICE TYPE
2. The statements given below are followed by four options each. Tick- mark the correct
option in each case.
a) Production of starch, and not glucose, is often used as a measure of photosynthesis in
the leaves.
i.
Starch is the immediate product of photosynthesis
ii.
Glucose formed in photosynthesis soon gets converted into starch
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
iii.
Starch is soluble in water.
iv.
Sugar cannot be tested
-ii. Glucose formed in the photosynthesis soon gets converted into starch.
b) The number of water molecules required in the chemical reactions to produce one
molecule of glucose during photosynthesis is.
i.
Six
-
ii. Twelve
iii. Eighteen
iv. Twenty-four
i. Six
c) The rate of photosynthesis is NOT affected by.
i.
Light intensity
ii. Humidity
ii.
Temperature
iv. CO2 concentration
-ii. Humidity.
d) Chlorophyll in a leaf is required for
i.
Breaking down water into hydrogen and oxygen
ii.
Emitting green light
iii.
Trapping light energy
iv.
Storing starch in the leaves
-
iii. Trapping light energy.
e) If the rate of respiration becomes more than the rate of photosynthesis, plants will:
i.
Continue to live, but will not be able to store food
ii.
Be killed instantly
iii.
Grow more vigorously because more energy will be available
iv.
Stop growing and die gradually of starvation.
-
iv. Stop growing and die gradually of starvation.
f) Which one of the following reactions occurs during photosynthesis?
i.
Carbon dioxide is reduced and water is oxidized
ii.
water is reduced and carbon dioxide is oxidized
iii.
both carbon dioxide and water are oxidized
iv.
both carbon dioxide and water are reduced
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
-ii. Water is reduced and carbon dioxide is oxidized.
g) the specific function of light energy in the process of photosynthesis is to
i.
reduce carbon dioxide
ii.
synthesis glucose
iii.
activate chlorophyll
iv.
split water
-
split water
h) a plant is kept in a dark cupboard for about 48 hours before conducting any
experiment on photosynthesis in order to
i.
remove chlorophyll from the leaves
ii.
remove starch from the leaves
iii.
ensure that no photosynthesis occurs
iv.
ensure that leaves are free from starch
-ii. Remove starch from the leaves.
i) during photosynthesis, oxygen in glucose comes from
i.
CO2
ii.
Both CO2 and water
-
ii. water
iv. Oxygen via air
ii. water
C. SHORT ANSWER TYPE
3. Mention one difference between the following on the basis of what is given in the
brackets.
a. Respiration and photosynthesis( gas released)
-respiration releases carbon dioxide and photosynthesis releases oxygen.
b. Light and dark reactions (products formed)
-
Light reactions produces more molecules of ATP and no NADP production and dark
reactions produces less ATP and NADP is produced
c. Producers and consumers (mode of nutrition)
-producers are autotrophs and consumers are heterotrophs
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
d. Grass and grasshopper (mode of nutrition)
-Grass- autotrophs and grasshopper- heterotrophs.
e.
Chlorophyll and chloroplast (part of the plant cell)
-Chlorophyll- upper part of the mesophyll cells (palisade cells) / walls of thylakoids and
chloroplast- in mesophyll cells between upper and lower epidermis.
4. Identify the false statements and rewrite them correctly by changing the first or the last
word only
i.
The dark reaction of photosynthesis occurs during night time. (False)
- The dark reaction of photosynthesis occurs are not dependent on the light.
ii.
The immediate product of photosynthesis is glucose. (True)
iii.
All the starch produced in a leaf remains stored in it for 2-3 weeks before it is used by
other parts of the plant. (True)
iv.
v.
vi.
-
Photosynthesis requires enzymes. (False)
Photosynthesis requires light energy.
All green plants are consumers. (False)
All green plants are producers.
Photosynthesis results in loss of dry weight of the plants. (False)
Transpiration results in the lost of dry weight of the plants.
vii.
Photosynthesis stops at a temperature at about 350C. (True)
viii.
Photosynthesis occurs only in cells containing chloroplast. ( True)
ix.
All green plants perform photosynthesis. (True)
x.
All algae are autotrophs. (False)
- All algae are heterotrophs
5. Fill in the blanks with the appropriate word from the choices given in the brackets
a. The site of light reaction in the cells of a leaf is………………………( cytoplasm, stoma)
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
b. The chemical substance used to test the presence of starch in the cell
of a leaf
is……………..( CaCl2, iodine solution, Benedict solution)
c. Stoma is ground substance in………………………(cytoplasm, chloroplast, ribosomes)
d. The dark reaction of photosynthesis is known as…………….. (Hill reaction, cyclic
phosphorylation, Calvin cycle)
e. In the flowering plants, food is transported in the form of………………………….
i.
Sucrose
ii. Glucose
iii. Starch
6. Are the following statements true or false? Give reason in support of your answer.
a. The rate of photosynthesis continues to rise as long as the intensity of the light rises.
-False. The rate of photosynthesis increases with increase of intensity of light provided the CO 2
concentration also increases. Not simply a rise in intensity of the light will increase the intensity
of the light but CO2 too is necessary.
b. The outside atmospheric temperature has no effect on the rate of photosynthesis.
-False. With the rise in the outside atmospheric temperature, the rate of the photosynthesis rises.
The rise up to optimum temperature is suitable yet it the outside temperature is above the
optimum temperature the rate falls as the enzymes will be destroyed.
c. If I immerse a leaf intact on the plant in ice water, it will continue to photosynthesize
only at night.
-False. An immersed leaf intact on the plant in ice water will continue to photosynthesize even on
during the day if it’s in ice water because all the necessary requirements for photosynthesis are
present.
d. Destarching of the leaves of a potted plant can occur only at night.
-False. Destarching if the leaves of a potted plant do not occur simply at night but it occurs even
in day but in dark areas as there is no light for photosynthesis to occur.
e. The starting point of carbon cycle is the release of CO2 by the animals during respiration.
(True)
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
f. If a plant is kept at bright light all the 24 hours for few days, the dark reaction
(biosynthetic phase) will fail to occur.
-The intensity of light required by photosynthetic process is optimum. The intensity of light
become more when its expose more and continuously. Therefore, dark reaction will fail to occur.
7. Given below are five terms. Rewrite the terms in the correct order so as to be in logical
sequence with regard to photosynthesis: water molecules, oxygen, grana, hydrogen and
hydroxyl ions, photons.
-grana, photons, water molecules, hydrogen and hydroxyl ions, , oxygen.
8. State any four differences between photosynthesis and respiration.
Sl no.
Photosynthesis
Respiration
1
Uses CO2 and produces O2
Uses O2 and produces CO2
2
Occurs only in plants
Occurs in both plants and animals
3
Produces
Uses carbohydrates( energy consumers)
carbohydrates(energy
producers)
4
Occurs during day
Occurs throughout 24 hours
9. “Oxygen is a waste product of photosynthesis”. Comment
-Oxygen is a waste product of photosynthesis. Some of the oxygen produced may used in
respiration in the leaf cells but major portion of it not required by and difuse in to the
atmosphere through the stomata.
10. Why is it necessary to place a plant in the dark before starting an experiment on
photosynthesis? Explain.
-It is necessary to place a plant in the dark before staring an experiment on photosynthesis to
destarch the leaf so that the destrached parts of the plants won’t show the presence of starch.
Whereas other non-desatrched parts will indicate the presence of starch.
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
11. In most of the experiment on photosynthesis, we use a de-starched leaf or plant? What is
the purpose of destarching?
-The purpose of destarching is to remove the starch form the leaf.
12. Why is it not possible to demonstrate respiration in a green plant kept in sunlight?
-The green plant in sunlight would perform photosynthetic process faster. During this process
CO2 produced by respiration will be used up quickly by the green plants as it requires for the
process.
13. Most leaves have upper surface more green and shiny than lower one. Why?
-It is due to the fact that on the upper surface of the leaves photosynthetic process occurs only in
presence of chlorophyll which are found only in green parts of the plants mostly leaves.
14. How would you demonstrate that green plants release oxygen when exposed to light?
The green plants that release oxygen when exposed to light can be demonstrated by:
1. A water plant either Elodea or hydrilla to place in a beaker containing pond water and
cover them by a short-stemmed funnel.
2. Invert a test tube full of water over the stem of the funnel provided the water level in the
beaker is above the level of stem of the inverted funnel.
3. Place the apparatus in the sun for a few hours. Bubbles of the gas will collect in the test
tube
4. Test the gas in the test tube. Glowing splinter burst into the flame indicates the presence
of oxygen.
15. Describe the main chemical changes which occur during photosynthesis in
i.
Light reaction- after the activation of chlorophyll by photons it splits the water
molecule into two components (Hydrogen and Oxygen)a s show below
2H2O energy of 4 photons
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4H+ + 4e- + O2.
CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
H+ ions are picked up by a compound NAPD to form NADPH.
NADP+ + e- + H+
enzyme
NADPH
Oxygen (O) produced is given out as molecular Oxygen (O2).
The electrons (e-) are used in converting ADP into ATP by adding one phosphate group.
ADP + P
ii.
ATP this process is called phosphorylations.
Dark reaction- the hydrogen of NADPH is combined with CO2 utlising ATP for
produce glucose (C6H12O6).
The CO2 is fixed in number of steps by a compound RuBP and it’s catalyzed by RuBP
carboxylase.
16. Complete the following food chains by writing the names of appropriate organisms in
the blanks.
i.
Grass
ii.
Grass
Rat
Snake
Hawk
mouse……..Snake
peacock
17. How do non- green plants such as fungi and bacteria obtain their nourishment?
-The non-green plants such as bacteria and fungi obtain their nourishment from organic matter
like dead remains of plants and animals through decomposition process.
18. All life owes its existence to chlorophyll. Give reason.
-Chlorophyll is the site of the leaves where photosynthesis takes place. This process occurs in the
green plants and produces the glucose/ carbohydrates the food for the survival all living beings.
D. STRUCTURED/ APPLICATION/ SKILL TYPE
19. A candidate studied the importance of certain factors in photosynthesis. He took a potted
plant and kept in the dark for 24 hours. In the early hours of the next morning, he covered
one of the leaves with dark paper in the centre only. Then he placed the plant in sunlight
for few hours and tested the leaf which was covered with black paper for starch.
a. What aspect of photosynthesis was being investigated?
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
-He tested to show that sunlight is necessary for photosynthesis.
b. Is there any control in this experiment? If so, state it
-Yes, the rest of the paper he haven’t covered with dark paper was control as he covered only
one of the leaves.
c. Why was the plant kept in the dark before the experiment?
-To destarch the leaf for the experiment to indicvate the presence of the starch.
d. Describe step by step, how the candidate proceeded to test the leaf for the presence of
starch.
The steps proceeded by the candidate are as follows:
1. Fix the paper on one of the one of the destarched leaves
2. Make a sketch of the leaf showing the covered and uncovered parts.
3. The experimental set up is exposed to sunlight for 2-6 hours.
4. The paper is removed and the leaf is tested for starch.
5.
Starch
is
produced
only
in
areas
that
received
light,
showing
light is necessary for photosynthesis.
20. Given below is a schematic diagram to illustrate some aspects of photosynthesis.
a. Fill up the gaps, in the blank spaces (1-4), by writing the names of the correct items.
-1. Sunlight
2. Glucose
3. Oxygen ions
4. Xylem
b. What phenomenon do the thick arrows A and B indicate respectively?
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that
CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
A. Transpiration
B. Translocation
21. Photosynthesis in green plants is directly and indirectly dependent on so many plant
structures. Explain briefly the role of the following structures in this process.
a. Guard cells: the opening and closing of stomata for movement of water in and out.
b. Cuticle: prevent the dehydradation of the leaves.
c. Mesophyll cells: site of photosynthesis due to present of chlorophyll
d. Xylem tissue in the leaf veins: Conduction of water and other dissolved minerals
e. Phloem tissue in the leaf veins: transport the prepared food materials from lea to the
rest of the plants.
f. Stoma: Site of dark reactions.
22. Given below is the representation of a certain phenomenon in nature. With four
organisms 1-4.
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
a. Name the phenomenon represented.
-Food chain is represented.
b. Name any one organism that could be shown at No. 5.
-Hawk/Eagle
c. Name biological process which was the starting point of the whole chain.
-Producers
d. Name one natural element which all the organisms 2-4 and even 5 are getting from No. 1
for their survival.
-Glucose/starch/ carbohydrates.
23. Enumerate the steps involved in testing a green leaf for the presence of starch.
The steps involved in testing the presence of starch in green plants:
1. Boil pieces of leaves in a beaker of water TO KILL THE CELLS AND BREAK THE
WALL OF LEAF CELL
2. Heat the pieces of leaf in alcohol for few minutes TO REMOVE CHLOROPHYLL
3. Soak the pieces of leaf in hot water for a little while TO SOFTEN THE LEAF
4. Using a dropper, add a few drops of iodine solution onto the pieces of leaf TO TEST FOR
STARCH
5. On observing the leaves that contains starch turn to DARK BLUE COLOUR
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
24. Given alongside is the diagram of experiment set-up:
a. What is the purpose of this experiment?
-The purpose of this experiment is to prove that CO2 is necessary for photosynthesis.
b. Will it work satisfactorily? Give reason
-Yes. It will work satisfactorily because the leaf to be tested is inserted inside the conical flask
containing to KOH which absorbs CO2. The inserted inside will not indicate the presence of CO2
whereas those leaves outside will indicate the presence of starch on testing.
c. What alteration(s) will you make in it for obtaining expected result?
-It can be altered by inserting a leaf half inside and half outside.
d. Would you take any step before starting the experiment? Describe this step and explain
its necessity.
-Before starting the experiment I would destarch the leave by keeping the potted plant in the
room for 24-48 hours. Therefore, it can indicate the presence of starch in the leaf which is the
product of photosynthesis.
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CLASS-X BIOLOGY-Questions- PHOTOSYNTHESIS 2012
25. Draw a neat diagram of the stomata apparatus found in the epidermis of the leaves and
label the stoma, guard cells, and chloroplast, epidermal cells, cell wall and nucleus.
ANSWER THE FOLLOWING SIMPLY IN “YES” OR “NO”
1. Chloroplast and chlorophyll are one and the same thing.
NO
2. Oxygen given out in photosynthesis comes from the atmosphere.
3. The dark reaction of photosynthesis occurs during nightmare.
NO
NO
4. The immediate product of photosynthesis is glucose. YES
5. Photosynthesis can also occur in artificial light such as that of a 100 watt electric lamp.
YES
6. All the starch produced in a leaf remains stored in it for 2-3 weeks before it is used by
other parts of the plant. NO
7. Photosynthesis requires involvement of enzymes. YES
8. Plant requires several nutrients such as nitrogen sulfur and iron. Yes
9. Every green plant produces glucose as well as proteins and many other compounds. YES
10. All green plants are categorized as consumers. NO
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