There is a link between water absorption and respiration. It is evident from the fact that when respiratory inhibitors like KCN, Chloroform are applied there is a decrease in the rate of respiration and also the rate of absorption of water.

There are 3 types of carrier proteins classified on the basis of handling of molecules and direction of transport in facilitated diffusion. They are,
i) Uniport
ii) Symport
iii) Antiport.
i) Uniport: In this molecule of a single type move across a membrane independent of other molecules in one direction
ii) symport or co-transport: The term symport is used to denote an integral membrane protein that simultaneously transports two types of molecules across the membrane in the same direction.
iii) Antiport or Counter Transport: An antiport is an integral membrane transport protein that simultaneously transports two different molecules, in opposite directions, across the membrane.

1. ROQ tpressure is totally-absent in gymnosperms, which includes some of the tallest plants. 
2. Ascent of sap continues even in the absence of roots
3. The magnitude of root pressure is about 2atm, which can raise the water level up to few feet only, whereas the tallest trees are more than 100m high.

1. Reverse Osmosis follows the same principles of osmosis, but in the reverse direction, In this process movement of water is reversed by applying pressure to force the water against a concentration gradient of the solution
2. In reverse osmosis, the water molecules move from the lower concentration (salt water = hypertonic) to higher concentration (pure water = hypotonic) through a selectively permeable membrane.

3. Uses: Reverse osmosis is used for purification I of drinking water and desalination of seawater.

Phloem Loading:
The movement of photosynthates (products of photosynthesis) from mesophyll cells to phloem sieve elements of mature leaves is known as phloem loading. It consists of three steps.
1. Sieve tube conducts sucrose only. But the photosynthate in the chloroplast is mostly in the form of starch or trios-phosphate which has to be transported to the cytoplasm where it will be converted into sucrose for further translocation.
2. Sucrose moves from the mesophyll to nearby sieve elements by short-distance transport
3. From sieve tube to sink by long-distance transport.