NEET BIOLOGY

Detailed explanation-1: -Growth movements which occur in the direction of the stimulus are known as tropic movements. In this, the response acts on the protoplasm from one side. A tropic movement may be towards or away from the stimulus.

Detailed explanation-2: -Shoots and roots grow very slowly (typically mm h–1 or µm s–1), while some seeds and spores are dispersed explosively (>10 m s–1), so the speeds of plant motion span at least seven orders of magnitude.

Detailed explanation-3: -In chemotropism, the movement of a plant’s part is either towards the chemical or away from it. In order to do this these movements are positive or negative chemotropism. For example, during fertilization in a flora, the growth of a pollen tube towards the ovule is called positive chemotropism.

Detailed explanation-4: -Positive phototropism refers to plant development more towards the source of light, whereas negative phototropism refers to plant growth away from the direction of light. The stem is positive phototropic since it grows in the direction of light.