Tissue
6.1-Tissue
A cluster of cells in the body that performs a particular type of functions are called tissues.
Eg- Blood, phloem and muscle etc
Plants -•They contain supportive tissues generally made up of dead cells.
Animal -•Tissues are generally made up of living cells.
6.2-Plant Tissues
- 6.2.1-Meristematic tissue-
• It is the dividing tissue which is responsible for growth in certain specific regions of plants.
Cells of this tissue are –
-Very active.
-Dense cytoplasm.
-Thin cellulose wall.
– Prominent nuclei.
-They lack vacuoles.
•Classified as –
– Apical meristem= growing tips of stem and root and increases the length of the stem and root.
-Lateral meristem= the birth of the stems or roots.
-Intercalary meristem= located near the node.
- 6.2.2-Permanent Tissue-
•They lose the ability to divide and take permanent shape, size and function.
•They are of two types-
(A) Simple permanent tissue-
-Parenchyma- Contain living cells They have thin cell walls and they are usually loose arranged. They have large intercellular space. This tissue generally stores food.
-Chlorenchyma- When parenchyma contains chlorophyll and it helps to perform photosynthesis.
– Aerenchyma- Present in the aquatic animal.Large air cavities present in Parenchyma which help them to float.
-Collenchyma- It helps to make plants flexible. It helps to bend various parts of the plant. It provides mechanical support
-Sclerenchyma- It helps to make plant hard and stiff.
-Sclerenchymatous- The cells of this tissue are dead. They are long and narrow. This is present in the hard covering of seeds and nuts. It provides strength to the plant parts.
•••The outermost layer of cells which are usually made up of a single layer of cells is called Epidermis. The epidermis of the leaf is called stomata which are enclosed by two kidney-shaped cells called guard cells. These are useful for exchanging gases into the atmosphere. Transpiration also takes place through stomata.
(B)-Complex permanent tissue-
•They are made up of more than one type of cells.
-Xylem- consists of tracheids, xylem parenchyma and xylem fibres. Tracheids and vessels are tubular structures which allow them to transport water and minerals vertically.
-Phloem – It is made up of five types of cells- sieve cells, sieve tubes, companion cells, phloem fibres and phloem parenchyma. Phloem transports food from leaves to other parts of the plants.
6.3-Animal Tissue-
• Blood and muscles are both example of tissues found in our body and on the basis of function there are different type of animal tissues which areas:
- 6.3.1-Epithelial tissue-
•It cover most of the organs and cavities within the body and it keeps different body systems
separate from each other.
•They are of 4 types:
-Squamous-simple flat kind of epithelial. They are extremely thin and flat and form delicate linings.
-Stratified Squamous-epithelial is arranged in various layers.
-Columnar -It facilitates movement across the epithelial barrier.
-Cuboidal -It provides mechanical support to kidney tubules.
- 6.3.2- Connective Tissue-
The cell of connective tissue is loosely spaced and embedded in an intercellular matrix.
– Bloods-It contains RBC (red blood corpuscles), WBC (white blood corpuscles)and platelets.
-Bones-It forms the framework that supports the body. It also anchors the muscles and supports the main organs of the body.
–Ligament- It connects two bones with each other.
-Tendons-It connects bones with muscles.
-Cartilages-It smoothens bone surfaces at joints and also present in the nose, ear, trachea and larynx.
-Areolar- It fills the space inside organs, supports internal organs and helps in the repair of tissues.
-Fat – storing adipose – It stores fat. It found below the skin and between internal organs.
- 6.3.3-Muscular Tissue-
•It consists of elongated cells and are responsible for movement in our body.
•Muscles contain special proteins called contractile proteins.
-Voluntary muscles- It present in limbs and helps in body movement. These muscles show alternate light and dark bands when strained appropriately, therefore they are called striated muscles. The cells of these tissues are long cylindrical, unbranched and multinucleated.
-Smooth muscles- cells of these tissues are long with pointed ends and uninucleate. These are also called unstrained muscles. These muscles are responsible for the movements of food in the alimentary canal, iris of the eye and bronchi of the lungs.
-Cardiac muscles- Cells of these muscles are cylindrical, branched and uninucleate. The heart is made up of cardiac muscles which show rhythmic contraction and relaxation throughout life.
- 6.3.4-Nervous Tissue-
Cells of the nervous tissues are highly specialised for been stimulated and then transmit the stimulus very rapidly from one part of the body to another part. Brain, spinal cord and nerves are all composed of nervous tissue.
NCERT SOLUTION
Page: 69
1. What is tissue?
Answer:
A cluster of cells in the body that performs a particular type of functions.
2. What is the utility of tissues in multicellular organisms?
Answer:
Tissues provide strength to multicellular organisms.
Page: 73
3. Name types of simple tissues.
Answer:
Parenchyma, Aerenchyma, Sclerenchymatous, Collenchyma, Sclerenchyma are single tissues.
4. Where is apical meristem found?
Answer:
-They are found in:
-The tip of the shoot.
-The root of the plant.
5. Which tissue makes up the husk of coconut?
Answer:
Sclerenchymatous tissue makes up the husk of the coconut.
6. What are the constituents of phloem?
Answer:
It is made up of five types of cells- sieve cells, sieve tubes, companion cells, phloem fibres and phloem parenchyma.
Page: 77
7. Name the tissue responsible for the movement of our body.
Answer:
Muscular tissue and Nervous tissue are responsible for the movement of our body,
8. What does a neuron look like?
Answer:
It consists of a cell body with nucleus and cytoplasm from which long thin hair-like parts arise. Usually, each neuron has a single long part called an axon and many short and branched parts are called dendrites.
9. Give three features of cardiac muscles.
Answer:
Cells of these muscles are cylindrical and branched.
•They have a single nucleus.
•Shows involuntary movements.
10. What are the functions of areolar tissue?
Answer:
Areolar tissue fills the space inside organs, supports internal organs and helps in the repair of tissues.
Exercise
Page: 78
1. Define the term ’tissue’?
Answer:
A cluster of cells in the body that performs a particular type of functions are called tissue.
2. How many types of elements together make up the xylem tissue? Name them.
Answer:
Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibres.
3. How are simple tissues different from complex tissues in plants?
Answer:
Simple tissues are made up of only one kind of cell whereas complex tissues made up of two or more types of cells.
4. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
Answer:
Parenchyma- Cell walls are thin.
Collenchyma Cell walls are thick at the edges.
sclerenchyma -Cell walls are thick due to the deposition of lignin.
5. What are the functions of the stomata?
Answer:
Epidermis of the leaf are called stomata which are enclosed by two kidney-shaped cells called guard cells. These are useful for exchanging gases into the atmosphere. Transpiration also, take place through stomata.
6. Diagrammatically show the difference between the three types of muscle fibres.
Answer: There are three types of muscle fibres, they are:
Voluntary muscles-• it present in limbs and helps in body movement.
•These muscles show alternate light and dark bands when strained appropriately, therefore they are called striated muscles.
•The cells of these tissues are long cylindrical, unbranched and multinucleated.
-Smooth muscles- •These muscles are responsible for the movements of food in the
alimentary canal, iris of the eye and bronchi of the lungs.
• These are also called unstrained muscles.
•cells of these tissues are long with pointed ends and uninucleate.
Cardiac muscles- •Cells of these muscles are cylindrical, branched and uninucleate .H
•Heart is made up of cardiac muscles which show rhythmic contraction and
relaxation throughout life.
7. What is the specific function of the cardiac muscle?
Answer:
It brings out rhythmic relaxations and contraction throughout life.
8-Differentiate between striated, un-striated and cardiac muscles on the basis of their structure and site/location in the body.
Answer:
• striated muscles.- long cylindrical, unbranched and multinucleated.
– present in limbs.
•unstrained muscles.- cells of these tissues are long with pointed ends and uninucleate.
– present in Alimentary canal, iris of the eye and bronchi of the lungs.
•Cardiac muscles- -Cells of these muscles are cylindrical, branched and uninucleate.
-present in Heart.
9. Draw a labelled diagram of a neuron.
Answer:
10. Name the following.
(a) Tissue that forms the inner lining of our mouth.
(b) Tissue that connects muscle to bone in humans.
(c) Tissue that transports food in plants.
(d) Tissue that stores fat in our body.
(e) Connective tissue with a fluid matrix.
(f) Tissue present in the brain.
Answer:
(a) Squamous epithelium.
(b) Tendon
(c) Phloem
(d) Adipose tissue
(e) Blood
(f) Nervous tissue
11. Identify the type of tissue in the following:
Skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
Answer:
•Skin: squamous epithelial tissue
•Bark of the tree: Protective tissue
•Bone: Connective tissue
•Lining of kidney tubule: Cuboidal epithelial tissue
•Vascular bundle: Conducting tissue(xylem and phloem).
12. Name the regions in which parenchyma tissue is present.
Answer:
Parenchyma is found in pith of stems and roots, green leaf where it contains chlorophyll called chlorenchyma) and in aquatic plants. (aerenchyma).
13. What is the role of the epidermis in plants?
Answer:
It provides protection to all the parts of the plants and protects the loss of water in case of
aquatic plants.
14. How does the cork act as a protective tissue?
Answer:
Cork has dead cells and is compactly arranged without intercellular spaces. They also contain substances called suberin that make them impervious to gases and water.
15-Complete the following chart.
Answer:
