Suppose Euphorbia and maize are grown in the tropical area.
(a) Which one of them do you think will be able to survive under such conditions?
(b) Which one of them is more efficient in terms of photosynthetic activity?
(c) What difference do you think are there in their leaf anatomy?
(a) Euphorbia is a CAM plant. It fixes CO2 during night and uses it in daytime. It will be able to survive in hot tropical climate. Maize is a tropical plant. It undergoesC4 cycle (Hatch Slack Pathway) and can easily survive in tropical climate (hot).
(b) Maize being a C4 plant is more efficient in terms of photosynthetic activity C4 plants
have lowCO2 compensation point (0-10 ppm) and rate of carbon assimilation is rapid. Rate of photorespiration is negligible. C4 plants can perform photosynthesis even when the stomata are closed (from CO2 produced in respiration).
(c) Euphorbia has large sized succulent cells and stomata having reniform guard cells closed during the day. Maize plant leaves have kranz anatomy. Stomata possess dumb-bell shaped guard cells. The stomata remain open during the day.
Which products formed during the light reactidn of photosynthesis are used to drive the dark reaction?
Suppose Euphorbia and maize are grown in the tropical area.
(a) Which one of them do you think will be able to survive under such conditions?
(b) Which one of them is more efficient in terms of photosynthetic activity?
(c) What difference do you think are there in their leaf anatomy?
By looking at a plant externally can you tell whether a plant is C3 or C4 ? Why and how?
Tomatoes, carrots and chillies are red in colour due to the presence of one pigment. Name the pigment. Is it a photosynthetic pigment?
Some of these terms/chemicals are associated with the C4 cycle. Explain.
(a) Hatch Slack pathway
(b) Calvin cycle
(c) PEP carboxylase
(d) Bundle sheath cells
Suppose there were plants that had a high concentration of chlorophyll b, but lacked chlorophyll a, would it carry out photosynthesis? Then why do plants have chlorophyll b and other accessory pigments?
By looking at which internal structure of a plant can you tell whether a plant is C3 or C4 ? Explain.
Find out how Melvin Calvin worked out the complete biosynthetic pathway for synthesis of sugar.
Look at leaves of the same plant on the shady side and compare it with the leaves on the sunny side. Or ompare the potted plants kept in the sunlight with those in the shade. Which of them has leaves that are darker green? Why?
Where is NADP reductase enzyme located in the chloroplast? What is the role of this enzyme in proton gradient development?
Succulents are known to keep their stomata closed during the day to check transpiration. How do they meet their photosynthetic CO2 requirements?
Photosynthetic organisms occur at different depths in the ocean. Do they receive qualitatively and quantitatively the same light? How do they adapt to carry out photosynthesis under these conditions?
Why is the colour of a leaf kept in the dark frequently becomes yellow, or pale green? Which pigment do you think is more stable?
What conditions enable RuBisCO to function as an oxygenase? Explain the ensuing process.
The entire process of photosynthesis consists of a number of reactions. Where in the ceil do each of these take place?
(a) Synthesis of ATP & NADPH__________
(b) Photolysis of water__________
(c) Fixation of CO2__________
(d) Synthesis of sugar molecule __________
(e) Synthesis of starch __________
Observe the diagram and answer the following.
(a) Which group of plants exibits these two types of cells?
(b) What is the first product of C4 cycle?
(c) Which enzyme is there in bundle sheath cells and mesophyll cells?
(a)NADP reductase enzyme is located on__________
(b) Breakdown of proton gradient leads to release of__________
In what kind of plants do you come across ‘kranz’ anatomy? To which conditions are those plants better adapted? How are these plants better adapted than the plants, which lack this anatomy?
A cyclic process is occurring in C3 plant, which is light dependent, and needs O2. This process doesn’t produce energy rather it consumes energy.
(a) Can you name the given process?
(b) Is it essential for survival?
(c) What are the end products of this process?
(d) Where does it occur?
2H2O -->2H+ + O2 + 4e– Based on the above equation, answer the ; following questions:
‘(a) Where does this reaction take place in plants?
(b) What is the significance of this reaction?
Which property of the pigment is responsible for its ability to initiate the process of photosynthesis? Why is the rate of photosynthesis higher in the red and blue regions of the spectrum of light?
RuBisCO is an enzyme that acts both as a carboxylase and oxygenase. Why do you think RuBisCO carries out more carboxylation in C4 plants?
3CO2 + 9ATP + 6NADPH + Water -->glyceraldehyde 3 phosphate + 9 ADP + 6 NADP+ + 8 Pi Analyse the above reaction and answer the following questions:
(a) How many molecules of ATP & NADPH are required to fix one molecule of CO2?
(b) Where in the chloroplast does this process occur?
If a green plant is kept in dark with proper ventilation, can this plant carry out photosynthesis? Can anything be given as supplement to maintain its growth or survival?
A process is occurring throughout the day, in ‘X’ organism. Cells are participating in this process. During this process ATP, CO2 and water are evolved. It is not a light dependent process.
(a) Name the process.
(b) Is it a catabolic or an anabolic process?
(c) What could be the raw material of this process?
Cyanobacteria and some other photosynthetic bacteria do not have chloroplasts. How do they conduct photosynthesis?
Name the two important enzymes of C3and C4 pathway, respectively? What important role do they play in fixing CO2 ?
In tropical rainforests, the canopy is thick and shorter plants growing below it, receive filtered light. How are they able to carry out photosynthesis ?
Explain how during light reaction of photosynthesis, ATP synthesis is a chemiosmotic phenomenon.
ATPase enzyme consists of two parts. What are those parts? How are they arranged in the thylakoid membrane? Conformational change occur in which part of the enzyme?
Why is the RuBisCO enzyme more appropriately called RUBP Carboxylase-Oxygenase and what important role does it play in photosynthesis?
Chlorophyll ‘a’ is the primary pigment for light reaction. What are accessory pigments? What is their role in photosynthesis?
Examine the figure.
(a) Is this structure present in animal cell or plant cell?
(b) Can these be passed on to the progeny? How?
(c) Name the metabolic processes taking place in the places marked (1) and (2).
What’can we conclude from the statement that the action and absorption spectrum of photosynthesis overlap? At which wavelength do they show peaks?
In the figure given below, the black line (upper) indicates action spectrum for photosynthesis and the lighter line (lower) indicates the absorption spectrum of chlorophyll a, answer the following:
(a) What does the action spectrum indicate? How can we plot an action spectrum? Explain with an example.
(b) How can we derive an absorption spectrum for any substance?
(c) If chlorophyll a is responsible for light reaction of photosynthesis, why do the action spectrum and absorption spectrum not overlap?
Is it correct to say that photosynthesis occurs only in leaves of a plant? Besides leaves, what are the other parts that may be capable of carrying out photosynthesis? Justify.
