AP BIOLOGY

Detailed explanation-1: -Phototropism, or the differential cell elongation exhibited by a plant organ in response to directional blue light, provides the plant with a means to optimize photosynthetic light capture in the aerial portion and water and nutrient acquisition in the roots.

Detailed explanation-2: -In phototropism a plant bends or grows directionally in response to light. Shoots usually move towards the light; roots usually move away from it. In photoperiodism flowering and other developmental processes are regulated in response to the photoperiod, or day length.

Detailed explanation-3: -Sunlight acts as a stimulus for the growth of organisms towards the light (positive phototropism) or away from light (negative phototropism).

Detailed explanation-4: -Phototropism is the directional response of a plant that allows the plant to grow towards or in some cases away from the light. Process of phototropism: Leaf tips and stem tips have a hormone called auxin which is sensitive to light. It allows the plant to positively grow towards the light source.

Detailed explanation-5: -Phototropism in plants such as Arabidopsis thaliana is directed by blue light receptors called phototropins. Other photosensitive receptors in plants include phytochromes that sense red light and cryptochromes that sense blue light.