One kind of cell or many?
Simple and complex permanent tissues.
A bowl of fruit and a fruit salad
A bowl holds only mangoes. A fruit salad holds mango, apple, banana and grapes.
If tissues were bowls, what would make a tissue "simple"?
What this lesson covers
The idea
Permanent tissues are specialised for specific functions and are either simple, made of only one type of cell, or complex, made of more than one type of cell.
A bowl of fruit and a fruit salad
A bowl holds only mangoes. A fruit salad holds mango, apple, banana and grapes.
If tissues were bowls, what would make a tissue "simple"?
- Only one type of cell in it
- It is very small
- Its cells are all dead
Count the kinds of cells
Look at each tissue and count how many colours (types of cell) it has.
Simple and complex
A simple permanent tissue is made of only one type of cell. A complex permanent tissue is made of more than one type of cell. Permanent tissues are specialised for specific functions.
In a T.S. (cross-section) of a sunflower stem you can see these permanent tissues side by side, each a different group of cells.
- Tissue | Kind
- Parenchyma, collenchyma, sclerenchyma | simple
- Xylem, phloem | complex
Notes
Simple permanent tissue: one type of cell (parenchyma, collenchyma, sclerenchyma). Complex permanent tissue: more than one type (xylem, phloem).
Check yourself
A complex permanent tissue is made of…
Xylem is made of tracheids, vessels, xylem parenchyma and xylem fibres. How many types of cells is that?
Answer: 4 types
4 types of cells, so xylem is complex.
Why is phloem called a complex tissue?
- only one type of cell. That is a simple tissue.
- dividing cells only. Dividing cells form meristematic tissue.
- more than one type of cell — correct. Yes.
- It is made of different types of cells working together — correct. Yes.
- It is made of one type of cell. Then it would be simple.
- It is made of dead cells only. Phloem is mostly living cells.