SEBA Class 9 Science: Tissues
INTEXT QUESTION
1. What is a tissue?
Answer: A tissue is a group of cells that are similar in structure and work together to perform a particular function.
2. What is the utility of tissues in multicellular organisms?
Answer: In multicellular organisms, tissues group similar cells to perform particular functions. This division of labour makes the work more efficient. For example, muscle tissue helps in movement, nerve tissue carries messages, blood transports substances, and vascular tissue in plants conducts food and water.
INTEXT QUESTION
1. Name types of simple tissues.
Answer: Simple permanent tissues are of three types: Parenchyma, Collenchyma, and Sclerenchyma. Parenchyma tissue is of further two types - aerenchyma and chlorenchyma.
2. Where is the apical meristem found?
Answer: Apical meristem is found at the growing tips of stems and roots.
3. Which tissue makes up the husk of a coconut?
Answer: The husk of a coconut is made up of sclerenchyma tissue.
4. What are the constituents of phloem?
Answer: The constituents of phloem are sieve tubes, sieve cells, companion cells, phloem fibres and phloem parenchyma.
INTEXT QUESTION
1. Name the tissue responsible for movement in our body.
Answer: The tissue responsible for movement in our body is muscular tissue.
2. What does a neuron look like?
Answer: A neuron has a cell body with nucleus and cytoplasm. From it arise long, thin hair-like parts called processes. It usually has a single long part called the axon and many short, branched parts called dendrites.
3. Give three features of cardiac muscles.
Answer: Three features of cardiac muscles are:
1. The cells are cylindrical, branched and uninucleate.
2. They are involuntary muscles which contract and relax throughout life.
3. They show rhythmic contraction and relaxation, enabling the heart to pump blood continuously.
4. What are the functions of areolar tissue?
Answer: The functions of areolar tissue are:
1. It fills the space inside organs.
2. It supports internal organs.
3. It helps in the repair of tissues.
EXERCISE QUESTIONS
1. Define the term “tissue”.
Answer: Written in the above.
2. How many types of elements together make up the xylem tissue? Name them.
Answer: Xylem tissue is made up of four types of elements. They are:
1. Tracheids.
2. Vessels.
3. Xylem parenchyma.
4. Xylem fibres.
3. How are simple tissues different from complex tissues in plants?
Answer: Simple tissues are made up of only one type of cells which are similar in structure and function. Example: parenchyma, collenchyma, sclerenchyma.
Complex tissues are made up of more than one type of cells which coordinate to perform a common function. Example: xylem and phloem.
4. Differentiate between parenchyma, collenchyma, and sclerenchyma on the basis of their cell wall.
Answer:
5. What are the functions of the stomata?
Answer: The functions of stomata are:
1. They help in exchange of gases with the atmosphere.
2. They also allow transpiration, i.e., loss of water in the form of water vapour.
6. Diagrammatically show the difference between the three types of muscle fibres.
Answer: (a) Striated Muscles: Striated muscles are long, cylindrical and unbranched. They have many nuclei and show striations. They are mostly attached to bones and help in body movement.
Smooth muscles: Smooth muscles are spindle-shaped with pointed ends. They have one nucleus and no striations. They control involuntary movements.
Cardiac Muscles: Cardiac muscles are cylindrical and branched. They have one nucleus and show striations. They contract and relax rhythmically throughout life.
7. What is the specific function of the cardiac muscle?
Answer: The main work of cardiac muscles is to contract and relax in a rhythmic way so that the heart keeps pumping blood continuously throughout life.
8. Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.
Answer:
9. Draw a labelled diagram of a neuron.
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) Tissue that forms the inner lining of our mouth → Squamous epithelium
(b) Tissue that connects muscle to bone in humans → Tendon
(c) Tissue that transports food in plants → Phloem
(d) Tissue that stores fat in our body → Adipose tissue
(e) Connective tissue with a fluid matrix → Blood
(f) Tissue present in the brain → Nervous tissue
11. Identify the type of tissue in the following: skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
Answer: Skin → Stratified squamous epithelium (epithelial tissue)
Bark of tree → Cork (protective tissue)
Bone → Bone (connective tissue)
Lining of kidney tubule → Cuboidal epithelium (epithelial tissue)
Vascular bundle → Xylem and Phloem (complex permanent tissue)
12. Name the regions in which parenchyma tissue is present.
Answer: Parenchyma tissue is present in many regions of plants, such as the stem, roots, leaves, and fruits.
13. What is the role of the epidermis in plants?
Answer: The epidermis in plants acts as a protective covering. It protects all parts of the plant against water loss, mechanical injury and infection by parasitic fungi. It also helps in absorption of water in roots and gas exchange through stomata.
14. How does the cork act as a protective tissue?
Answer: Cork acts as a protective tissue because its cells are dead and compactly arranged without intercellular spaces. Their walls have a substance called suberin, which makes them impervious to gases and water, thus protecting the plant.