Question

Plant stems bend toward a light source as a result of:

• A. inability to synthesise chemical regulators.
  
• B. increased amount of food synthesised by leaves.
• C. necessity of light for transpiration.
• D. unequal auxin distribution in their stems.

Answer 1

The correct option is D unequal auxin distribution in their stems.

• Phototropism is the growth of organisms in response to a light stimulus.
• The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs.
• This causes the plant to have elongated cells on the farthest side from the light. Phototropism is one of the many plant tropisms or movements which respond to external stimuli.
• Growth towards a light source is called positive phototropism, while growth away from light is called negative phototropism.
• Thus, correct answer is option D.