NCERT Solutions for Class 9 Science Chapter 6 Tissues

1. What is a tissue?

Solution:

A tissue is defined as a cluster of cells that are similar in structure and work together to perform a particular function. These cells are organized to carry out specific tasks within an organism, such as providing support, enabling movement, or transporting nutrients. Tissues are the building blocks of organs and play a crucial role in the overall functioning of living organisms.

2. What is the utility of tissues in multicellular organisms?

Solution:

In multicellular organisms, tissues provide structural and mechanical strength, allowing the organism to maintain its shape and withstand various forces. Tissues enable the division of labor, where different types of tissues perform specialized functions. This specialization allows for more efficient and effective functioning of the organism, as each tissue type can focus on a specific task, such as movement, nutrient

CBSE Class 9 Sample Paper

Class 9 Science Chapter 6 Tissues Exercise 6.2 Page: 65

3. Name the types of simple tissues.

Solution:

The types of simple tissues are as follows:

1. Parenchyma
2. Collenchyma
3. Sclerenchyma

4. Where is apical meristem found?

Solution:

In plants, apical meristem is typically found at:

• The tip of the shoot
• Root of the plant

5. Which tissue makes up the husk of a coconut?

Solution:

Sclerenchymatous tissue is a type of permanent tissue found in plants, including in the husk of the coconut. This tissue provides structural support and makes the plant parts stiff and hard. The cells of sclerenchyma tissue are dead at maturity, and their cell walls are heavily thickened with lignin, a substance that strengthens the cell walls and makes them resistant to bending and stretching. This characteristic helps in providing mechanical support and protection to the plant.

6. What are the constituents of phloem?

Solution:

The phloem constitutes of the following four elements, they are:

1. Sieve tube
2. Companion cells
3. Phloem parenchyma
4. Phloem fibres

Science Chapter 6 Solutions Exercise 6.3 Page: 69

7. Name the tissue responsible for movement of our body.

Solution:

Two tissues jointly are responsible for the movement of our body, namely:

1. Muscular tissue
2. Nervous tissue

8. What does a neuron look like?

Solution:

A neuron, or nerve cell, is composed of a cell body containing a nucleus and cytoplasm. It features a unique structure with a long, thin extension known as an axon, which transmits electrical signals to other cells or neurons. Neurons possess several shorter, branched structures called dendrites, which receive signals from other neurons and convey them towards the cell body. Neurons are remarkable for their varied sizes; some axons can extend up to a meter in length, facilitating communication across considerable distances within the body's nervous system.

9. Give three features of cardiac muscles.

Solution:

Cardiac muscles are specialized tissues designed to pump blood throughout the body. They exhibit several distinct features:

• Cylindrical Shape: Cardiac muscle cells are cylindrical in shape.
• Striated Muscle Fibers: Like skeletal muscles, cardiac muscle fibers have a striped appearance due to the arrangement of contractile proteins.
• Uninucleated and Branched: Each cardiac muscle cell has a single nucleus and often branches to connect with neighboring cells.
• Involuntary Nature: Contractions of cardiac muscles are involuntary, meaning they occur without conscious control, ensuring continuous pumping of blood throughout the body.

10. What is areolar tissue?

Solution:

Areolar tissue is a type of connective tissue commonly found in animals.

• Location: Areolar tissue is located between the skin and muscles, around blood vessels and nerves, and within organs such as the bone marrow.
• Function: It fills the spaces inside organs, providing support to delicate structures and facilitating tissue repair in case of damage.
• Structure: Areolar tissue is characterized by its loose arrangement of collagen and elastin fibers, which give it flexibility and resilience.

Chapter 6 Tissues Exercise Page: 70

1. Define the term ’tissue’.

Solution:

A tissue is a group of cells that are similar in structure and work together to perform a specific function in an organism. These cells are organized to perform specialized tasks that contribute to the overall function and health of the organism. Tissues can be found in plants and animals, where they play essential roles in maintaining structure, providing support, and facilitating various physiological processes necessary for survival.

2. How many types of elements together make up the xylem tissue? Name them.

Solution:

The xylem tissue in plants is composed of four main elements:

• Vessels: These are elongated cells aligned end-to-end, forming continuous tubes for water and mineral transport.
• Tracheids: Similar to vessels but narrower and with tapered ends, tracheids also transport water and provide structural support.
• Xylem Fibers: These cells are long and slender, providing mechanical support to the plant.
• Xylem Parenchyma: These are living cells that store starch, oils, and other substances, and also facilitate lateral movement of water and nutrients.

3. How are simple tissues different from complex tissues in plants?

Solution:

The following are the differences:

• Simple tissues: These are composed of a single type of cell that performs a specific function. Examples include parenchyma, collenchyma, and sclerenchyma in plants, each serving roles like storage, support, or protection.
• Complex tissues: These involve multiple types of cells working together to perform specialized functions. For instance, xylem and phloem in plants coordinate to transport water, nutrients, and organic substances throughout the plant.

4. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.

Solution:

The following are the differences between different tissues based on cell wall:

Parenchyma:

• Cell walls are thin and primarily made up of cellulose.
• These tissues are often involved in functions like photosynthesis, storage, and secretion.

Collenchyma:

• Cell walls are thicker at the corners due to the deposition of pectin.
• They provide flexible structural support to young parts of the plant, such as stems and petioles.

Sclerenchyma:

• Cell walls are very thick due to the deposition of lignin, making them rigid and strong.
• These tissues provide mechanical support and protection to mature parts of the plant, such as the seed coats and vascular bundles.

5. What are the functions of the stomata?

Solution:

Stomata are small pores found on the outer layer (epidermis) of leaves and stems of plants. They play several important roles:

• Gas Exchange: Stomata allow for the exchange of gases, such as oxygen and carbon dioxide, between the plant and its environment. This process is crucial for photosynthesis (uptake of carbon dioxide) and respiration (release of oxygen).
• Transpiration: Stomata also regulate the process of transpiration, where water vapor exits the plant through these pores. This helps in cooling the plant and maintaining its internal water balance.

6. Show the difference between the three types of muscle fibres diagrammatically.

Solution:

There are three types of muscle fibres, they are: 1. Cardiac muscles

• Present in the heart.
• Involuntary in nature.
• They have 1 nucleus.
• The muscle fibers are branched.

2. Smooth muscles

• Found in lungs and alimentary canal.
• Involuntary in nature.
• They have 1 nucleus.
• They are spindle-shaped.

3. Striated muscles

• They are connected with bones
• Voluntary in nature.
• They are long and cylindrical muscle fibers.
• They possess many nuclei.
• Striated muscles are unbranched.

7. What is the specific function of the cardiac muscle?

Solution:

15. Complete the following chart.

Solution:

The completed chart is as follows: