Simple plant Tissue Class 9th(to be done in note book as the topic is done in the class)

Simple Plant Tissue

The type of tissue which consist of one type of cells is called simple plant tissue .
They are of three types:-

1 Parenchyma
2 collenchyma
3 sclerenchyma

                                

      

simple permanent tissue

These are also known as homogenous tissues. They are made up of a single cell type, usually with the same origin, structure, and function.

Simple permanent tissue is further classified into three types:

Parenchyma

• The cells have an oval or round shape.
• The cell wall is made up of hemicellulose or cellulose.
• The cell is thin-walled.
• The cells have vacuoles and very small nucleus.
• It is found in all parts of the plant.
• The protoplasm is living and dense.
• If parenchyma cells are rich in chloroplast ,they are called chlrenchyma and function is photosynthesis 
• If they have leucoplast then they store food .
• If they have lot of intercellular spaces between them they are called aerenchyma ,They are mainly present in hydrophytes and help in maintaining buoyancy,e.g. lotus stem. 

Collenchyma

• Cells are long and thick walled.
• The cell wall is made up of cellulose and pectin.
• It is the only tissue with the highest refractive index due to the presence of pectin.
• It is found in hypodermis of dicot stem and the vascular bundle of dicot leaf.
• The amount of chloroplast is less in the cells.
• The cells have no intercellular spaces.

Sclerenchyma

• These are dead tissues, very hard and rigid in texture.
• Cells are thick walled with various size and shapes.
• These provide mechanical support and rigidity to the plant.

Stomata ----They are present mostly in the lower surface of leaf and help in 

(1)Transpiration 

(2)Exchange of gases

Epidermis 

• The role of the epidermis in plants are as follows:
• Provides protection against water loss
• Regulates the process of gas exchange
• Epidermis secretes metabolic compounds
• Absorption of water and essential minerals
• Protects inner cells from germs

Complex permanent Tissue

The complex tissues are made up of different types of cells performing diverse functions. These are of two types:

Xylem

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Xylem

This complex permanent tissue is made up of different cells like xylem parenchyma, vessels, tracheids and xylem fibres. Xylem parenchyma is living cell whereas, vessels, tracheids and xylem fibres are dead cells. Function of xylem is conduction of water and minerals in the plant body. This complex permanent tissue transport water and minerals only in one direction from root towards the upper part of the plants. Tracheids and vessels are responsible for transport of water and minerals from root to upper part of plant, whereas, xylem parenchyma allows sideways conduction of water. Also, xylem parenchyma also allows the storage of food. Xylem fibres are found in between vessels and tracheids. Moreover, it provides mechanical strength to plants.

Phloem

This complex permanent tissue is made up of different cells like companion cells, sieve tubes, phloem fibres and phloem parenchyma. Phloem fibres are dead cells whereas, all others are living cells. Function of phloem is to transport food in all parts of the body. Sieve tubes are tube like structures having pores in its walls. Thus, the food material is transported through sieve tubes. Phloem fibres provides strength to plant. Phloem parenchyma is used to prepare and store food. Also, the chlorenchyma of phloem parenchyma prepares food by process of photosynthesis. Lastly, the transportation through phloem occurs in both directions.

Difference between Xylem and phloem

Xylem :---It has three dead cells ie vessels , tracheis, sclerenchyma (fibres) and only one living cell ie xylem parenchyma.

It trasports water only in one direction  without use of energy

Phloem
It has three living cells ie sieve tube cells ,companion cells and phloem parenchymma and only one dead cell ie phloem sclerenchyma.
phloem tranlocates food in both the directions up and dpown and requires energy to traslocate food 

Test Assignment   (Meristematic tissue)

Activity ______________ 

• Take two glass jars and fill them with water.
• Now, take two onion bulbs and place one on each jar, as shown in Fig. 6.1.
• Observe the growth of roots in both the bulbs for a few days.
• Measure the length of roots on day 1, 2 and 3.
• On day 4, cut the root tips of the onion bulb in jar 2 by about 1 cm. After this, observe the growth of roots in both the jars and measure their lengths each day for five more days and record the observations in tables, like the table below:

From the above observations, answer the following questions:
1. Which of the two onions has longer roots? Why?
2. Do the roots continue growing even after we have removed their tips?
3. Why would the tips stop growing in jar 2 after we cut them?

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