Compare the following: (a) C3 and C4 pathways(b) Cyclic and non- cyclic photophophorylation (c) Anatomy of leaf in C3 and C4 plants

Question

Compare the following: (a) C3 and C4 pathways(b) Cyclic and non- cyclic photophophorylation  (c) Anatomy of leaf in C3 and C4 plants

Philoid · Accepted Answer

(a) C3 and C4 pathways. Characters C3 plants C4 plants1. CO2 acceptor  The CO2 acceptor is ribulose 1.5 diphosphate.The CO2 acceptor is phosphoenol-pyruvate. 2. First stable productThe fist stable product is phosphoglyceric acid. Oxaloacetate is the first stable product.3. Type of chloroplast All cells participating in photosynthesis have one type not chloroplast. The chloroplast of parenchymatous bundle sheath is different from that of mesophyll cells. Leaves have ‘Kranz’ type of anatomy. The bundle sheath chloroplasts lack grana. Mesophyll cells have normal chloroplasts.4. CyclesOnly reductive pentose phosphate cycle is found. Both C4- dicarbodylic acid and reductive pentose phosphate cycles are found.5. Optimum temperatureThe optimum temperature for the process is 10-250C.In C4 plants it is 30-450C.6. Oxygen inhibitionOxygen present in air (= 21% O2). markedly inhibit the photosynthetic process as compared to an external atmosphere containing no oxygen.The process of photosynthesis is not inhibited in air as compared to an external atmosphere containing no oxygen.7. PS I and PS II In each chloroplast, Photosystems I and II are present. Thus the Calvin cycle occurs.In the chloroplasts of bundle sheath cells, the photosystem II is absent. Therefore, these are dependent to mesophyll chloroplast of the supply of NADPH + H+.8. Enzymes The Calvin cycle enzymes are present in mesophyll chloroplastThe calvin cycle enzymes are absent in mesophyll chloroplasts. The cycle occurs only in the chloroplasts of sheath cells.9. Compensation pointThe CO2 compensation point is 50-150 ppm. CO2 compensation point is 0-10 ppm.10. PhotorespirationPhotorespiration is present and easily detectable. Photorespiration is present only to a slight degree and difficult to detect.11. Net rateNet rate of photosynthesis in full sunlight (10,000- 12,000 ft.c) is 15-35 mg of CO2 per dm2 of leaf area per h. It is 40-80 mg. Of CO2 per dm2 of leaf area per h that is photosynthetic rate is quite high. The plants are efficient.12. Saturation intensity The saturation intensity reached is in the range of 100-4000 ft.c. It is difficult to reach saturation even in full sunlight. (b) Differences between cyclic and non- cyclic photophosphorylation.CharactersCyclic- PhotophosphorylationNon- cyclic photophosphorylation1. Synthesis It synthesizes only ATP. It forms ATP as well as NADPH2.2. Oxygen Oxygen is not evolved. Oxygen is liberated due to photolysis of water. 3. Requirement It requires only PS-I. It is performed with collaboration of PS-I and PS-II. 4. Cycling Electron emitted by P700 is recycled back and no external source of electron is needed. It needs external electron donor. 5. Performance This process is operative at low light intensity. Less availability of CO2 and under anaerobic conditions. It performs best under optimum light presence of CO2 and under aerobic conditions. 6. Operation It does not usually operate for photosynthesis except bacteria. It is functional for normal CO2 fixation.  (c) Differences in Anatomy of leaf in C3 and C4 plants.C4 plantsC3 plants1. Chloroplasts are present in mmesophyll cells as well as in bundle sheath cells.1. Chloroplasts are present in mesophyll cells only.2. Kranz type of anatomy present. 2. Kranz type of anatomy absent. 3. Intercellular spaces between mesophyll cells are smaller. 3. Intercellular spaces are larger. 4. Dimorphic chloroplasts are present. 4. Only one type of normal chloroplasts is present.

Compare the following: (a) C₃ and C₄ pathways(b) Cyclic and non- cyclic photophophorylation (c) Anatomy of leaf in C₃ and C₄plants

More from this chapter

Similar questions

Similar questions

Report submitted

Characters	C₃ plants	C₄ plants
1. CO₂ acceptor	The CO₂ acceptor is ribulose 1.5 diphosphate.	The CO₂ acceptor is phosphoenol-pyruvate.
2. First stable product	The fist stable product is phosphoglyceric acid.	Oxaloacetate is the first stable product.
3. Type of chloroplast	All cells participating in photosynthesis have one type not chloroplast.	The chloroplast of parenchymatous bundle sheath is different from that of mesophyll cells. Leaves have ‘Kranz’ type of anatomy. The bundle sheath chloroplasts lack grana. Mesophyll cells have normal chloroplasts.
4. Cycles	Only reductive pentose phosphate cycle is found.	Both C₄- dicarbodylic acid and reductive pentose phosphate cycles are found.
5. Optimum temperature	The optimum temperature for the process is 10-25⁰C.	In C₄ plants it is 30-45⁰C.
6. Oxygen inhibition	Oxygen present in air (= 21% O₂). markedly inhibit the photosynthetic process as compared to an external atmosphere containing no oxygen.	The process of photosynthesis is not inhibited in air as compared to an external atmosphere containing no oxygen.
7. PS I and PS II	In each chloroplast, Photosystems I and II are present. Thus the Calvin cycle occurs.	In the chloroplasts of bundle sheath cells, the photosystem II is absent. Therefore, these are dependent to mesophyll chloroplast of the supply of NADPH + H⁺.
8. Enzymes	The Calvin cycle enzymes are present in mesophyll chloroplast	The calvin cycle enzymes are absent in mesophyll chloroplasts. The cycle occurs only in the chloroplasts of sheath cells.
9. Compensation point	The CO₂ compensation point is 50-150 ppm.	CO₂ compensation point is 0-10 ppm.
10. Photorespiration	Photorespiration is present and easily detectable.	Photorespiration is present only to a slight degree and difficult to detect.
11. Net rate	Net rate of photosynthesis in full sunlight (10,000- 12,000 ft.c) is 15-35 mg of CO₂ per dm² of leaf area per h.	It is 40-80 mg. Of CO₂ per dm² of leaf area per h that is photosynthetic rate is quite high. The plants are efficient.
12. Saturation intensity	The saturation intensity reached is in the range of 100-4000 ft.c.	It is difficult to reach saturation even in full sunlight.

Characters	Cyclic- Photophosphorylation	Non- cyclic photophosphorylation
1. Synthesis	It synthesizes only ATP.	It forms ATP as well as NADPH₂.
2. Oxygen	Oxygen is not evolved.	Oxygen is liberated due to photolysis of water.
3. Requirement	It requires only PS-I.	It is performed with collaboration of PS-I and PS-II.
4. Cycling	Electron emitted by P₇₀₀is recycled back and no external source of electron is needed.	It needs external electron donor.
5. Performance	This process is operative at low light intensity. Less availability of CO₂ and under anaerobic conditions.	It performs best under optimum light presence of CO₂ and under aerobic conditions.
6. Operation	It does not usually operate for photosynthesis except bacteria.	It is functional for normal CO₂ fixation.

C₄ plants	C₃ plants
1. Chloroplasts are present in mmesophyll cells as well as in bundle sheath cells.	1. Chloroplasts are present in mesophyll cells only.
2. Kranz type of anatomy present.	2. Kranz type of anatomy absent.
3. Intercellular spaces between mesophyll cells are smaller.	3. Intercellular spaces are larger.
4. Dimorphic chloroplasts are present.	4. Only one type of normal chloroplasts is present.