Final answer:
Gravitropism affects the growth of different parts of the plant. The roots exhibit positive gravitropism by growing downward, while the stem and leaves show negative gravitropism by growing upwards.
Step-by-step explanation:
Gravitropism is the plant's growth response to gravity. When a plant in a pot is knocked over, gravitropism will affect the growth of different parts of the plant. The roots will exhibit positive gravitropism, meaning they will grow downward towards the soil, while the stem and leaves will show negative gravitropism, causing them to grow upwards.
Gravitropism is mediated by specialized cells called statoliths or amyloplasts, which settle to the bottom of gravity-sensing cells in the root or shoot. This triggers a signaling pathway that involves the release of calcium ions and the transport of the plant hormone IAA to the bottom of the cell. In roots, a high concentration of IAA inhibits cell elongation on the lower side, resulting in slower growth on that side. In shoots, a higher concentration of IAA on the lower side stimulates cell expansion, causing the shoot to grow up.