ICSE Class 8 Answered
1. Differences between self-pollination and cross-pollination:
Self-pollination |
Cross-pollination |
It is the transfer of pollen grains from the anther to the stigma of the same flower. |
It is the transfer of pollen grains from the anther of one flower to the stigma of another flower of a different plant of the same species. |
It does not require any external agent, such as wind, water and insects, to carry out pollination. |
It requires an external agent for pollination to occur. |
It can take place even when the flower is closed. |
It can occur only when the flower is open. |
In self-pollinated flowers, the anther and stigma mature at the same time. |
In cross-pollinated flowers, the anther and stigma mature at different times. |
It preserves parental characters |
It does not preserve parental characters. |
New varieties are not possible. |
New varieties can be produced. |
As new variations are not possible, the offspring cannot adapt to changing environmental conditions. |
As new variations are possible, the offspring are healthier and are able to adapt to changing environmental conditions. |
2. Differences between tuber and rhizome:
Rhizome |
Tuber |
Stout, dorsoventrally flattened underground stem |
Swollen, underground stem |
Dorsoventrally flattened |
Spherical, oblong or oval |
Less stouter than tubers |
More stouter than rhizomes |
Nodes bear adventitious root on the lower side |
Nodes do not bear roots |
Buds are present in the axils of scaly leaves and also as terminal buds |
Buds in the form of eyes present on the surface |