A plant was placed in darkness with a light on its left side, describe and explain the direction of growth the plant will take

The plant will grow towards the light. This is due to auxins in the plant stem which control growth. These auxins inhibit plant growth in the stem. They are attracted to light so will migrate into the side of the plant exposed to light. So, other side of the plant grows more, causing the plant to grow in a curve towards the light as the other side grows faster.