Question

Which response is a result of geotropism?

Answer 1

Plant roots growing downwards.

Explanation:

When plant roots grow downwards, it is an example of positive geotropism, because they are growing towards the stimulus, the soil.

However, when plant shoots grow upwards, it is an example of negative geotropism as they grow away from the stimulus, the soil.

I think that it is caused due to the shift of auxins (plant hormones) to the tips, increasing the rate of growth.

This is also the reason why sunflowers tend to turn towards the sun as the auxins get concentrated to the opposite side and the shoot elongates from that side. This is an example of positive phototropism.