What is the basis for designating C3 and C4 pathways of photosynthesis?
In C4 cycle, 3-phosphoglyceric acid is first stable product which is 3-carbon compound. In C4 cycle, oxaloacetic acid is the first stable product which is 4-carbon compound. Accord ing to the fi rst stable productsC3 and C4 pathways of photosynthesis are designated.
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
By looking at which internal structure of a plant can you tell whether a plant is C3 or C4 ? Explain.
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?
Find out how Melvin Calvin worked out the complete biosynthetic pathway for synthesis of sugar.
Where is NADP reductase enzyme located in the chloroplast? What is the role of this enzyme in proton gradient development?
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?
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?
Succulents are known to keep their stomata closed during the day to check transpiration. How do they meet their photosynthetic CO2 requirements?
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?
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?
(a)NADP reductase enzyme is located on__________
(b) Breakdown of proton gradient leads to release of__________
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?
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?
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?
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?
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?
Cyanobacteria and some other photosynthetic bacteria do not have chloroplasts. How do they conduct photosynthesis?
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?
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?
What’can we conclude from the statement that the action and absorption spectrum of photosynthesis overlap? At which wavelength do they show peaks?
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).
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.
The given figure shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions.
(a) At which point/s (A, B or C) in the curve is light limiting factor?
(b) What could be the limiting factor/s in region A?
(c) What do C and D represent on the curve?
