NEET BIOLOGY

Detailed explanation-1: -A plant laid on its side in the dark will send shoots upward when given enough time. Gravitropism ensures that roots grow into the soil and that shoots grow toward sunlight. Growth of the shoot apical tip upward is called negative gravitropism, whereas growth of the roots downward is called positive gravitropism.

Detailed explanation-2: -Thus, plant shoots are ‘negatively gravitropic’, preferring a vertically upward state opposing gravity, while roots are ‘positively gravitropic’, preferring a vertically downward posture.

Detailed explanation-3: -The shoots or aerial parts of a plant grow away from gravity–that is, they grow up. This is negative gravitropism, since the shoot of the plant is growing in the opposite direction of gravity.

Detailed explanation-4: -Shoot growth is mostly negatively geotropic since shoots grow upwards even in complete darkness. Phototropism can therefore be understood as a secondary process, usually of the same direction as the negative geotropism. Transversal geotropism is a direction of growth that is vertical to the shoot axis.

Detailed explanation-5: -For instance, the roots of the plants grow towards the gravitational field whereas the stem grows away from the gravitational field. The downward growth of roots is an example of a positive gravitropism whereas the upward growth of roots is an example of negative gravitropism.