Question

Given below are the representation of four coleoptiles for experiment.

Which coleoptile will bend towards the light? Choose the correct option.

• A. A and B
• B. C and D
• C. A and D
• D. C and B

Answer 1

Answer: (B)

In the labelled figure ' $C$ ' and ' $D$ ', coleoptile (plant organ) will bend towards the light source due to auxin. This is because
Figure $(A)$ shows incomplete blockage of auxin. But the movement of auxin from apical part to lateral part is not possible. Therefore, it does not favour the bending of coleoptile towards the light source.
Figure $(B)$ shows complete blockage of auxin movement from apical part to lateral part. So, no bending of coleoptile will occur.
Figure $(C)$ shows incomplete blockage, but the direction favours the bending of coleoptile towards the source.
Figure $(D)$ shows no blockage, hence, the bending of coleoptile towards the light source will take place easily.