You have seen that multicellular organisms are broadly classified into two types – plants and animals. Do these organisms have different types of tissues? Why? The Science Chapter 6 Class 9th syllabus addresses this question first. Plants and animals have different needs due to their fundamental difference – plants are stationary, whereas animals are mobile. Thus, the tissues in each have to perform different functions. So, plant tissues differ from animal tissues. When you study the Tissues Chapter in Class 9 Science, you will learn about the different classifications within the broad categories of plant tissues and animal tissues.

 

The Class 9th Science Chapter 6 talks about plant tissues in great detail. The growth in plants is restricted to certain specific regions. To support this phenomenon, plant tissues are primarily of the following two types:

1. Meristematic Tissues

2. Permanent Tissues

Meristematic tissues help in the growth of the plant by dividing. Because of their function, they are located in the regions where there is plant growth, like the roots, stem, etc. Depending on the location, these tissues are further divided into the following types:

1. Apical Meristem – located at the end of the growing stem or root.

2. Lateral Meristem – situated in the girth that expands the diameter of the stem or the root.

3. Intercalary Meristem – these are generally located near the node.

The other types of plant tissues, as explained in the Class 9th Science Chapter 6 are permanent Tissues. As the name suggests, these are the tissues located in the regions of the plant that do not grow. Once they grow to an extent, the meristematic tissues take up a specific role in the plant’s functioning, stop growing further and become permanent. This process is called Differentiation. Differentiation is essential as it gives rise to different types of permanent tissues. These different types of tissues are explained further below:

1. Simple Permanent Tissues – These tissues contain cells that are found in a few layers under the epidermis. The simple permanent tissues are made of the same type of cells. Each of these can be further divided into the following types:

1. Parenchyma – typically unspecialized and have a lot of intercellular space, used to store food
2. Chlorenchyma – has chlorophyll and carries out photosynthesis
3. Aerenchyma – parenchyma that contains large cavities (in aquatic plants)
4. Collenchyma – helps in flexibility and bending of plants, has very little intercellular space, living and active tissue cells
5. Sclerenchyma – made out of dead cells, make the plants hard and stiff

Epidermis – The plant tissues visible on the outermost surface are called epidermal tissues or epidermis. These are protective cells that protect the plant from external factors like water loss, parasitic attacks, or any mechanical injury. Epidermal cells in the roots generally have hair-like parts to increase water and mineral absorption due to enlarged surface area.

Stomata – The pores on the epidermis of a leaf are called stomata. These are important for the exchange of gases and water with the environment. The stomata are protected by two guard cells.

2. Complex Permanent Tissues – These tissues are made up of more than one type of cell that performs a single function with other cells. Some common types of complex permanent tissues in plants include the following:

1. Xylem – made of tracheids, xylem parenchyma, vessels, and xylem fibres.
2. Phloem – made up of sieve cells, sieve tubes, companion cells, phloem fibres, and phloem parenchyma. Helps in transporting food from one part to another.

Both are part of vascular tissues.

Now that you have learned in detail about plant tissues, the Class 9th Science Chapter 6 moves to more complex tissues – the animal tissues. Like you have studied the different types of plant tissues, here you will learn about the different types of animal tissues and the functionality of each.

These are the protective tissues in the animals that form the covering of the animal body. Epithelial tissues also help to ensure that different body parts stay separate from each other. Some examples where epithelial tissues are present include blood vessel lining, skin, and kidney tubules. The epithelial tissues present at different places in the body have different structures. These structures can be of the following types:

1. 1. Squamous epithelium

   2. Stratified squamous

   3. Columnar epithelium

   4. Cuboidal epithelium

As the name suggests, these tissues ensure connectivity between the different body parts. Some common connective tissues found in the animal body include blood, bones, and cartilage. The connective tissues are flexible and loosely spaced to ensure easier connectivity. They are embedded in an intercellular matrix which can be of the following types.

1. Fluid – for example, blood

2. Hard matrix – for example, bones, which are dense and unflexible

3. Minimal matrix – for example, ligament, which is very elastic

4. Solid matrix – for example, cartilage, where the cells are widely spaced

A very important type of tissue that helps in the movement of animals is muscular tissue. These consist of elongated cells called muscle fibres, which aid in the movement of different body parts. The muscles contain a special type of protein called contractile proteins. These proteins help in motion by contracting and relaxing alternately. As you know, there are broadly two types of movements in animals:

1. Voluntary Movement – caused when the animal wants to move a body part, like an arm or a leg.  The muscular tissues aiding this type of movement are called striated muscles and have a cylindrical, long, and multinucleate structure.

2. Involuntary Movement – caused without the animal doing anything like the beating of the heart or contraction and relaxation of blood vessels. This type of movement is supported by muscular tissues that are smooth and also called unstriated. The cells that form these tissues are uninucleated and have a spindle shape.

     Cardiac Muscles – a special type of involuntary movement is by the heart tissues, which are also known as cardiac                 muscles. These tissues are cylindrical in shape, uninucleated and have a branched structure.

A type of tissue that specializes in getting stimulated and responding to the stimulus, that aids in communication and information transfer within the body, is the nervous tissue. In animals, these tissues are present in the brain, the spinal cord, and the nerves. A nerve cell also called a neuron, forms the nervous tissue. A neuron has two parts:

1. Axon – single long part

2. Dendrite – multiple short and branched parts

In this chapter, you first learned about what tissue is and why it is important for both plants and animals. Next, you learned about the reasons for the difference between plant tissues and animal tissues. Then, you went into further detail about the different types of plant tissues, their needs, and their functionality. Similarly, you also studied the different types of animal tissues, how they help and what are the structures of these tissues like.