a. C3 and C4 pathways
C3 pathways | C4 pathways | ||
---|---|---|---|
1 | The primary acceptor of CO2 is RUBP – a six-carbon compound. | 1 | The primary acceptor of CO2 is phosphonyl pyruvate – a three-carbon compound. |
2 | The first stable product is 3-phosphoglycerate. | 2 | The first stable product is oxaloacetic acid. |
3 | It occurs only in the mesophyll cells of the leaves. | 3 | It occurs in the mesophyll and bundle-sheath cells of the leaves. |
4 | It is a slower process of carbon fixation and photo-respiratory losses are high. | 4 | It is a faster process of carbon fixation and photo-respiratory losses are low. |
b. Cyclic and non-cyclic photophosphorylation
Cyclic photophosphorylation | Non-cyclic photophosphorylation | ||
---|---|---|---|
1 | It occurs only in photosystem I. | 1 | It occurs in photosystems I and II. |
2 | It involves only the synthesis of ATP | 2 | It involves the synthesis of ATP and NADPH2. |
3 | In this process, electrons move in a closed circle. | 3 | In this process, electrons move in a closed circle. |
c. Anatomy of leaf in C3 and C4 plants
C3 leaves | C4 leaves | ||
---|---|---|---|
1 | Photorespiration occurs | 1 | Photorespiration does not occur. |
2 | RuBisCo is present in the mesophyll cells. | 2 | RuBisCo is present in the bundle-sheath cells. |
3 | The first stable compound produced is 3-phosphoglycerate –a three-carbon compound. | 3 | The first stable compound produced is oxaloacetic acid – a four-carbon compound. |
Give reasons for the following.
(i) King Tut’s body has been subjected to repeated scrutiny.
(ii) Howard Carter’s investigation was resented.
(iii) Carter had to chisel away the solidified resins to raise the king’s remains.
(iv) Tut’s body was buried along with gilded treasures.
(v) The boy king changed his name from Tutankhaten to Tutankhamun.