Final answer:
Proton pumps are responsible for plant growth activities such as generating root pressure and facilitating phloem loading by moving hydrogen ions across membrane, utilizing ATP.
Step-by-step explanation:
The membrane protein used in plant growth, generating root pressure and phloem loading is a proton pump. These active transport mechanisms use energy, typically from ATP, to move ions across cell membranes against their concentration gradients, creating an electrochemical potential.
The proton pump, specifically, moves hydrogen ions (H+) out of the cell, which can lead to the movement of water into the cell by osmosis, generating root pressure. In the case of phloem loading, proton pumps create a gradient that symporters can use to actively transport sucrose into the phloem against its concentration gradient. This is a primary active transport process that is crucial for distributing nutrients throughout the plant.