The very function, or job of CELL MEMBRANES is to protect the cell from it's surroundings, or in other words, to keep it safe. It controls the movement of substances in and out of cells and organelles, like a guard watching for suspicious activity and protecting something.
The cell membrane itself is a thin, flexible layer around the cells of all living things. It separates the inside of the cells from the outside of the cells.
Every cell in the body goes through a life cycle. Cells grow and divide to replace cells that are lost because of normal wear and tear or injury. Different cells grow and die at different rates. Some cells, such as epithelial<span>epithelialA thin layer of epithelial cells that makes up the outer surfaces of the body (the skin) and lines hollow organs, glands and all passages of the respiratory, digestive, reproductive and urinary systems.</span> cells, reproduce quickly. Other cells, like nerve cells, grow slowly. Both normal cells and cancer cells go through a sequence of steps, or phases, when they form new cells. This is called the cell cycle.
<span>
<span>
</span></span>
They are descended from wild plants.
<h2>Xylem;phloem and cork</h2>
Explanation:
Wood is mainly known as secondary xylem found in trees
- Xylem is basically the vascular tissue which is responsible for the conduction of water and nutrients from the roots to shoots and leaves
- Secondary xylem is formed from secondary growth and is associated with lateral growth and grows from the vascular cambium
- Its cell walls are thickened by deposition of lignin which provides mechanical support to plants and consists of tracheids and vessels that are shorter and wider
- In large woody plants secondary xylem get differentiated into heartwood and sapwood
Bark is essentially made of phloem and cork
- Bark sole purpose is to provide protection to trees
- The inner bark is produced by vascular cambium which consists of secondary phloem whose innermost layer transports food from the leaves to rest of the plant
- The outer bark is a dead tissue which is the product of cork cambium