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Let’s start the “Tissues class 9 notes science chapter 6”.
We have already covered the followings:
- All the living organisms are made up of cells.
- In unicellular organisms, like Amoeba, a single cell performs all basic functions like movement, intake of food, gaseous exchange, excretion etc.
- On the other hand, multi-cellular organisms have specialized functions are taken up by a different group of cells.
- In human beings, muscle cells contract and relax to cause movement, nerve cells carry messages, blood flows to transport oxygen, food, hormones and waste materials.
- In plants, vascular tissues conduct food and water from one part to another parts.
Multi-cellular organisms show division of labour.
Tissue: A particular function is carried out by a cluster of cells at a definite place in the body. This cluster of cells are called a tissue.
Tissue: The cluster of cells which takes a particular function at a definite place in the body is called as Tissue.
- The tissues are in well arranged and designed, so that they having the highest possible efficiency of function.
- Example: blood, phloem, muscle
A group of cells that are similar in structure and work together to achieve a particular function – tissue.
6.1 Are Plants and Animals Made of Same Types of Tissues?
There are noticeable differences between Animals and Plants, like
- Plants are stationary or fixed – they don’t move.
- Plants have large quantity of supportive tissue.
- The supportive tissue generally has dead cells.
- Animals move around search food, mates and shelter.
- Animals are consumed more energy as compared to plants.
- Most of the animals tissues are living.
The growth in plants are limited in certain regions, while this not seen in animals.
Based on the dividing capacity of the tissues, plant cells can be classified as,
(i) Growth or Meristematic tissue
(ii) Permanent tissue
1. What is a tissue?
A group of cells that are similar in structure and work together to achieve a particular function – tissue.
2. What is the utility of tissues in multi-cellular organisms?
In multi-cellular organisms, the uses of tissues as follows,
- contract and relax to cause movement.
- division of labour.
- nerve cells carry messages.
- blood flows to transport oxygen, food, hormones and waste materials.
6.2 Plant Tissues
6.2.1 Meristematic Tissue
Activity 6.1 tells us to take two glass jars and fill them with water. Place two onion bulbs on each jar. Now note the root lengths of the two onions. Then start observations with noted for a few days.
After measuring the roots by day 1, day 2, day 3, now cut the jar 2 onion root by 1 cm. After these observe the growth of roots in both the jars and measure their lengths for 5 more days.
|Length||Day 1||Day 2||Day 3||Day 4||Day 5|
Let’s answer the below questions,
1. Which of the two onions has longer roots? why?
The roots of Jar 1 have longer roots. Cause it has epical meristem dividing tissue present on the tips of the roots.
2. Do the roots continue growing even after we have removed their tips?
No, hey can not continue on growth. Because the epical meristematic tissues are essential for growth, which have already cut in jar 2.
3. Why would the tips stop growing in jar 2 after we cut them?
When the roots tips are cut in jar 2, it loosed the growth due to absence of epical meristematic tissue, which was essential for the growth.
- Due to dividing tissue, the growth of plants occurs only in certain regions.
- The growth helping tissues are called as meristematic tissues.
The meristematic tissues are classified as,
- Apical meristem is present at the growing tips of stems and roots as well as increases the length of stem and root.
- The growth of stem or root increases due to lateral meristem(cambium).
- Intercalary seen some plants is located near the node.
- Cells of meristematic tissue are very active.
- Meristematic tissue have have dense cytoplasm, thin cellulose walls and prominent nuclei.
- Meristematic tissues lack vacuoles.
6.2.2 Permanent Tissue
Permanent Tissue: The tissue which has a specific role and lose the ability to divide is called as permanent tissue.
Differentiation: The permanent tissues have permanent shape, size and a function is called as differentiation. It leads to development of various types of permanent tissues.
Activity 6.2 refers to take a plant stem with cutting very thin slices or sections. Stain the slices with safranin. Now place the cutting section on a slide and put a drop of glycerine on it and cove with a cover-slip. Then we have to observe it under microscope to see their types of cells and arrangement.
Let’s answer the following questions…
1. Are all cells similar in structure?
No, never, all cells are not similar in structure.
2. How many types of cells can be seen?
There are 5 types of cells are seen. i.e. cell wall, cell membrane, cytoplasm, nucleus, large vacuole etc.
3. Can we think of reasons why there would be so many types of cells?
There are so many types of cells causing cells are adopted according to that types of function they have to perform.
We have already covered the tissue from tissues class 9 notes science chapter 6. Now we will go for different types of tissue.
6.2.2 (i) Simple Permanent Tissue
Simple Permanent Tissue: The epidermis having few layers of sells are generally simple permanent tissue.
- Parenchyma is the most common simple permanent tissue.
- It consists of relatively unspecialized cells with thin cell walls.
- They are living cells.
- They have large intercellular spaces due to loosely arranged.
- Simple permanent tissue stores food.
Chlorenchyama: Sometimes simple permanent tissue contains chlorophyll and performs photosynthesis, so it is called as Chlorenchyama.
Aerenchyma: In aquatic plants, large air cavities are present in parenchyma to help them float, this type of parenchyma is called as aerenchyma.
Collenchyma: The permanent tissue which keep a plant in flexible is called as collenchyma.
- Collenchyma allows bending of various parts of a plant.
- Collenchyma also provides mechanical support.
- This tissue present in leaf stalks below the epidermis.
- The cells of this tissues are living, elongated and irregularly thickened at the corners.
- Collenchyma has very little intercellular space.
Sclerenchyma: The tissue which makes the plant hard and stiff is called sclerenchyma.
- Sclerenchyma is made up of sclerenchymatous tissue.
- The cells of sclerenchyma tissue are dead.
- Sclerenchymas are long and narrow as the walls are thickened due to liginin.
- Sclerenchyma present in stems, around vascular bundles, veins of leaves, hard covering of seeds and nuts.
- Sclerenchyma provides strength to the plant parts.
Activity 6.3 guides us to take freshly plucked Rhoeo leaf. Stretch it and break it by applying pressure. Some peels or skin projects out from the cut and remove the peel then put it in a petri dish filled with water.
After it, add few drops of safranin and wait for a couple of minutes. Then set it to the slide and place it with cover slip hen observe.
- Epidermis: The outer most layer of the cells is called as epidermis.
- The epidermis made up of single layer of cells.
- The entire surfaces of plant has an outer covering epidermis which protects all the parts of the plant.
- Epidermal cells on the areal parts of the plant secrets waxy which act as water resistance layer for the outer surface.
- This waxy protect the loss of water, mechanical injury and invasion by parasitic fungi.
- The epidermis play the protective role.
- Most epidermal tissues are relatively flat.
- It has no intercellular spaces.
- Stomata: The small pores in epidermis of the leaf are called stomata.
- Stomata are enclosed by two kidney-shaped cells, called guard cell.
- Stomata are necessary for the exchange of gases with the atmosphere.
- Transpiration takes place through stomata.
Transpiration: Loss of water in the form of water vapour.
Epidermical cells of the roots helps on water absorption. They are commonly long-hair like parts for increasing absorptive surface area.
The desert plants have epidermis with thick waxy coating of cutin.
In the old plants a strip of secondary meristem appears in the cortex which forms layers of cells which constitute the cork. The Cells of cork are dead and has no intercellular spaces.
The cork have a substance called suberin in their walls that makes them impervious to gases and water.
Now it has completed the simple permanent tissue by “tissues class 9 notes science chapter 6“. Now it will start complex permanent tissue.
6.2.2 (ii) Complex Permanent Tissue
- Complex Permanent Tissues: The tissues which are made of more than one type of cells is called Complex Permanent Tissues.
- They coordinately perform a common function.
- Example: Xylem and phloem
- They are conducting tissues and constitute a vascular bundle.
- Vascular tissue is a distinctive feature of the complex plants.
- Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres.
- The tracheids and vessels have thick walls and many are dead cells at mature.
- Structurally the tracheids and vessels are tubular.
- This allows them to transport water and minerals vertically.
- The parenchyma stores food.
- Xylem fibres are mainly supportive in function.
- Phloem is made up of five types of cells: sieve cells, sieve tubes, companion cells, phloem fibres and the phloem parenchyma.
- Sieve tubes are tubular cells with perforated walls.
- Phloem transports food from leaves to other parts of the plant.
- Except phloem fibres, other phloem cells are living cells.
1. Name types of simple tissues?
The simple tissues are Parenchyma, Collenchyma and Sclerenchyma.
2. Where is epical meristem found?
Epical meristem found in the buds and growing tips of roots in plants.
3. Which tissue makes up the husk of coconut?
The Sclerenchymatous tissue makes husk of coconut.
4. What are the constituents od phloem?
The constituents of phloem are sieve tubes, companion cells, phloem fibres and phloem parenchyma.
This is the end part of the tissue types and more with tissues class 9 notes science chapter 6. Let’s go for animal tissue.
6.3 Animal Tissues
- Muscle cells: The specialized cells which helps movement of chest at contraction and relaxation at the time of breathe are called muscle cells.
- Oxygen is absorbed in the lungs and then is transported to all the body cells through blood.
- Blood flows and carries various substances from one part of the body to the other.
- For example, it carries oxygen and food to all cells.
- Oxugen also collects wastes from all parts of the body and carries them to the liver and kidney for disposal.
- Examples of tissues in our body: Blood and muscles On the basis of the functions different types of animal tissues like Epithelial tissue, Connective tissue, Muscular tissue and Nervous tissue.
- Blood is a connective tissue, and muscle forms muscular tissue.
6.3.1 Epithelial Tissue
- The covering or protective tissues in the animal body are called Epithelial Tissues.
- Epithelium covers most organs and cavities within the body.
- Epithelium acts as a barrier to keep different body systems separate.
- Epithelial tissue made parts like skin, mouth lining, blood vessels lining, lung alveoli and kidney tubules.
- Epithelial tissue cells are tightly packed and form a continuous sheet.
- These tissues have only a small amount of cementing material between them.
- There are no intercellular spaces.
- Anything entering or leaving the body must cross at least one layer of epithelium.
- various epithelia play an important role in regulating the exchange of materials between the body and the external environment and also between different parts of the body.
- All epithelium is usually separated from the underlying tissue by an extracellular fibrous basement membrane.
- Squamous Epithelium: The transportation of substances occurs by a simple flat kind of epithelium with selectively permeable surface is called as simple Squamous Epithelium.
- Simple squamous epithelial cells thin and flat.
- They able to form a delicate lining.
- The oesophagus, mouth lining, skin are covered with squamous epithelium.
- Stratified Squamous Epithelium: The epithelial cells are arranged in skin with many layers to prevent wear and tear is called as Stratified Squamous Epithelium.
- Where absorption and secretion occur, as in the inner lining of the intestine.
- Tall epithelial cells are present in absorption and secretion with inner lining of the intestine are called as columnar epithelium.
- This columnar epithelium facilitates movement across the epithelial barrier.
- In the respiratory tract, the columnar epithelial tissue has cilia, which hair-like projections epithelial cells.
- The movement of cilia pushes the mucus forward to clear it, so that this epithelium is called as Ciliated Columnar Epithelium.
- Cuboidal Epithelium: The cube-shaped like cells who forms the lining of kidney tubules and ducts of salivary glands is called as Cuboidal Epithelium.
- Cuboidal epithelium provides mechanical support.
6.3.2 Connective Tissue
- Blood is a connective tissue.
- The cells of connective tissue are loosely spaced.
- They have embedded in an intercellular matrix.
- The matrix may be jelly like, fluid, dense or rigid.
- The nature of matrix differs with functions of particular connective tissues.
- Blood has a fluid (liquid) matrix called plasma.
- In the blood red blood corpuscles (RBCs), white blood corpuscles (WBCs) and platelets are present.
- The plasma contains proteins, salts and hormones.
- Blood flows and transports gases, digested food, hormones and waste materials to different parts of the body.
- Bone is a connective tissue.
- It forms the framework that supports the body.
- It is a strong and non-flexible tissue.
- Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds.
- Ligament: The connective tissue by which two bones can be connected to each other is called as Ligament.
- This tissues are very elastic.
- Ligaments contain very little matrix and connect bones with bones.
- Tendons is a connective tissue who connects muscles to bones.
- Tendons are fibrous tissue with great strength.
- Tendons have limited flexibility.
- Cartilage: The widely spaced cells connective tissues are called as Cartilage.
- The solid matrix is composed of proteins and sugars.
- Cartilage smoothens bone surfaces at joints.
- Cartilage present in nose, ear, trachea and larynx.
- Areolar Connective Tissue: The connective tissue which found between skin and muscles are called Areolar Connective Tissue.
- Areolar Connective Tissues are seen at around blood vessels, nerves and in bone marrow.
- It fills the space inside the organs.
- It supports internal organs and helps in repair of tissues.
- Fatstoring Adipose Tissue: The connective tissue which found below the skin and between internal organs are called as Fatstoring Adipose Tissue.
- It filled with fat globules.
- It Stores fats.
- It act as an insulator.
6.3.3 Muscular Tissue
- Muscular Tissue: The tissues which consists of elongated cells and responsible for body movements are called as Muscular Tissue. Muscular Tissue also called Muscle Fibres.
- Muscles contain special proteins called Contractile Proteins.
- It contraction and relaxation cause movement.
- Voluntary Muscles: The muscles which obeys our wanting and decides with move and stop are called as Voluntary Muscles.
- Skeletal Muscles: The muscles which are mostly attached to the bones and help in body movement is called as Skeletal Muscles.
- These muscles show alternate light and dark bands or striations when stained appropriately, called Striated Muscles.
- The cells of this tissue are long, cylindrical, unbranched and multinucleate.
- The movement of food in the alimentary canal or the contraction and relaxation of blood vessels are involuntary movements.
- involuntary cells are found in the iris of the eye, in ureters and in the bronchi of the lungs.
- involuntary cells are long with pointed ends.
- involuntary cells are uninucleate.
- Unstriated Muscles: The muscles of the heart show rhythmic contraction and relaxation throughout life, called Unstriated Muscles.
- These involuntary muscles are called Cardiac Muscles.
- Heart muscle cells are cylindrical, branched and uninucleate.
6.3.4 Nervous Tissue
- Nervous Tissue: The cells which possess the ability to respond to stimuli are called as Nervous Tissue.
- Cells of the nervous tissue are highly specialised for being stimulated and then transmitting the stimulus very rapidly from one place to another within the body.
- Nervous Tissues are found at brain, spinal cord and nerves.
- The cells of this Nervous Tissue are called Nerve Cells or Neurons.
- A neuron consists of a cell body with a nucleus and cytoplasm.
- Each neuron has a single long part, called the Axon.
- There are many short, branched parts, called Dendrites.
- An individual nerve cell may be up to a metre long.
- Many nerve fibres bound together by connective tissue make up a nerve.
- The signal that passes along the nerve fibre is called a Nerve impulse.
- Nerve impulses allow us to move our muscles when we want to.
- The functional combination of nerve and muscle tissue is fundamental in most animals.
- This combination enables animals to move rapidly in response to stimuli.
1. Name the tissue responsible for movement in our body.
Muscular tissue or muscle fibres.
2. What does a neuron look like?
Small tree with fine hair like structures.
3. Give three features of cardiac muscles.
Three features of cardiac muscles are as follows;
- Cardiac muscles cause the rhythmic contraction and relaxation.
- These are uninucleate, cylindrical, elongated.
- It displays faint cross-striations.
4. What are the functions of areolar tissue?
Support and binding of other tissues.
Best of luck….
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