Transport of water depends upon the ______

Answer

**Step-by-Step Solution:**

1. **Understanding Water Transport**: The transport of water in biological systems is primarily influenced by the osmotic gradient. Osmosis is the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

2. **Osmotic Gradient**: The osmotic gradient refers to the difference in concentration of solutes (and consequently, water) across a membrane. If the concentration of solutes is higher on one side of the membrane, water will move towards that side to balance the concentration.

3. **Water Absorption**: In the context of digestion and absorption, the amount of water that is absorbed into the bloodstream depends on the existing concentration of water in the blood. If the blood has a high concentration of water, less water will be absorbed from the digestive tract. Conversely, if the concentration of water in the blood is low, more water will be absorbed.

4. **Types of Transport Mechanisms**: Water transport can occur through different mechanisms:
- **Diffusion**: Some substances can passively diffuse through membranes.
- **Facilitated Diffusion**: Other substances, like fructose and amino acids, require carrier proteins to help them cross the membrane.
- **Active Transport**: This process requires energy to move substances against their concentration gradient.

5. **Conclusion**: Therefore, the transport of water depends on the osmotic gradient, which is influenced by the concentration of solutes in the blood and the digestive tract.

**Final Answer**: Transport of water depends upon the **osmotic gradient**.

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