Plants don't actually "detect" gravity in the same way we do with our ears. Instead, they use a fascinating mechanism called gravitropism, which involves specialized cells called statoliths.

Here's how it works:

1. Statoliths: These are dense, starch-filled organelles found within specialized cells called statocytes. They are located in the root cap of roots and in the endodermis of shoots.

2. Gravity's Pull: Due to their density, statoliths settle to the lowest point of the cell in response to gravity.

3. Signal Transduction: This settling of the statoliths triggers a series of biochemical reactions within the statocytes. These reactions involve various signaling molecules and enzymes.

4. Hormonal Response: The signaling cascade ultimately leads to the uneven distribution of plant hormones, primarily auxin. This hormone is responsible for regulating growth and development in plants.

5. Differential Growth: Auxin accumulates on the lower side of the root, promoting cell elongation on the upper side. This causes the root to bend downwards, growing in the direction of gravity. In shoots, the opposite happens: auxin accumulates on the lower side, inhibiting cell elongation on that side, causing the shoot to bend upwards, growing against gravity.

In summary:

* Plants don't "feel" gravity like we do.

* They use statoliths, dense organelles, to sense gravity's pull.

* This triggers a signaling pathway that leads to an uneven distribution of auxin, a growth hormone.

* The uneven auxin distribution causes differential growth, leading to roots growing downwards and shoots growing upwards.

This mechanism ensures that roots grow towards the soil, providing anchorage and access to water and nutrients, while shoots grow towards sunlight, essential for photosynthesis.