which of the following is needed for water to be absorbed by the roots?
#1
Protein pumps
#2
Diffusion of mineral ions
#3
A concentration gradient
#4
Energy
A concentration gradient
The correct answer is #3: A concentration gradient.
To determine which of the options is needed for water to be absorbed by the roots, we will need to analyze each option and understand its role in the process of water absorption.
#1 Protein pumps: Protein pumps are indeed involved in the active transport of mineral ions across the root cell membranes. While this process is important for the overall nutrient intake of the plant, it is not directly related to the absorption of water by the roots.
#2 Diffusion of mineral ions: Mineral ions are moved across the root cell membranes through a process called diffusion, which relies on the concentration gradient of the ions. However, the diffusion of mineral ions itself is not directly related to the absorption of water by the roots.
#3 A concentration gradient: This option refers to the difference in solute concentration on either side of a membrane. The presence of a concentration gradient is crucial for the process of osmosis, which plays a vital role in water absorption by the roots. When there is a higher solute concentration in the soil than inside the root, water moves into the roots by osmosis.
#4 Energy: Energy is required for various physiological processes within plants, including the overall growth and maintenance. However, in terms of water absorption by the roots, energy is not directly involved. The movement of water into the roots through osmosis is a passive process that does not require energy input.
Based on the explanations above, the correct answer is #3 - A concentration gradient. A concentration gradient is necessary for water absorption by the roots through the process of osmosis.