| 1. | Protection of pollen grains only |
| 2. | Nourishment and providing sporopollenin for exine formation |
| 3. | Separation of microspore tetrads |
| 4. | Formation of the anther wall |
The innermost layer of microsporangium, that has polyploid and multinucleate cells, is:
(1) Epidermis
(2) Endothecium
(3) Middle layers
(4) Tapetum
| 1. | Endothecium and it provides nutrition to pollens |
| 2. | Tapetum and it nourishes the developing pollen grains |
| 3. | Nucellus and it forms microspores |
| 4. | Endothecium and it helps in dehiscence of anther |
| List-I (Structure) |
List-II (Function) |
||
| A. | Tapetum | I. | Nourishment and development of microspores |
| B. | Endothecium | II. | Pollen tube guidance |
| C. | Pollen grains | III. | Dehiscence of anther |
| D. | Synergids | IV. | Male gametophyte |
| 1. | A-I, B-II, C-III, D-IV | 2. | A-III, B-I, C-II, D-IV |
| 3. | A-I, B-III, C-IV, D-II | 4. | A-II, B-I, C-III, D-IV |
| 1. | In a transverse section, a typical microsporangium appears near circular and is surrounded by four wall layers: the epidermis, endothecium, middle layers, and the tapetum. |
| 2. | The innermost wall layer, the tapetum, nourishes the developing pollen grains and possesses dense cytoplasm and often more than one nucleus. |
| 3. | The function of the outer three wall layers includes protection and aiding in the dehiscence of anther to release pollen. |
| 4. | The outer three wall layers of the microsporangium function solely for nourishment of the developing pollen grains. |
| I: | In over 60 per cent of angiosperms, pollen grains are shed at this 2-celled stage. |
| II: | In 40 per cent of angiosperms, the generative cell divides mitotically to give rise to the two male gametes before pollen grains are shed (3-celled stage). |