AP 9th Biology Textbook Solutions – 2. Tissues (2026-27)

2 Tissues

• Do plants and animals have the same structure? Do they both perform similar functions?
  No, plants and animals do not have the same structure nor do they perform identical functions. Plants are stationary and have supportive tissues largely made of dead cells to withstand environmental stress, whereas animals are motile, consume more energy, and are composed predominantly of living tissues.

Questions

• 1. What is a tissue?
  A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue.
• 2. What is the utility of tissues in multi-cellular organisms?
  Tissues provide division of labour in multicellular organisms. By grouping specialised cells together to carry out a specific function at a definite place in the body, tissues ensure the highest possible efficiency of function.

Activity 2.1

• 1. Which of the two onions has longer roots? Why?
  The onion in Jar 1 has longer roots. This is because its root tips, which contain dividing apical meristematic tissue, remained intact and continued to grow.
• 2. Do the roots continue growing even after we have removed their tips?
  No, the roots stop growing after their tips are removed.
• 3. Why would the tips stop growing in jar 2 after we cut them?
  The root tips stopped growing in Jar 2 because cutting the tips removed the apical meristem, which is responsible for cell division and lengthening of the root.

• Can we think why they would lack vacuoles?
  Meristematic cells are actively dividing cells that do not need to store food or waste products. Having large vacuoles would restrict cell division and slow down metabolic activities.
• What happens to the cells formed by meristematic tissue?
  They take up a specific role and lose the ability to divide. As a result, they undergo differentiation to form permanent tissues.
• 3. Can we think of reasons why there would be so many types of cells?
  Different types of cells are required to perform diverse specialised physiological functions in a plant body, such as storage, photosynthesis, mechanical support, and transport of water and food.

Activity 2.2

• 1. Are all cells similar in structure?
  No, all cells are not similar in structure. They vary in shape, size, wall thickness, and presence of intercellular spaces.
• 2. How many types of cells can be seen?
  Multiple types of cells can be seen, including epidermal cells, parenchyma, collenchyma, sclerenchyma, and vascular bundle cells (xylem and phloem).

• Recall which gas is required for photosynthesis.
  Carbon dioxide (CO₂) is required for photosynthesis.
• Find out the role of transpiration in plants.
  Transpiration helps in the upward movement of water and dissolved minerals from roots to leaves (transpiration pull), aids in temperature regulation, and provides a cooling effect to the plant.
• In some plants like desert plants, epidermis has a thick waxy coating of cutin on its outer surface. Can we think of a reason for this?
  Cutin provides a waterproof layer that prevents excessive water loss through transpiration, which is crucial for survival in hot, dry desert conditions.
• Is the outer layer of a branch of a tree different from the outer layer of a young stem?
  Yes. The outer layer of a young stem is a single layer of living epidermis, whereas the outer layer of a mature tree branch consists of several layers of dead, compactly arranged cork cells with suberin walls.
• In Fig. 2.3 showing a section of stem, can you see different types of cells in the vascular bundle?
  Yes, the vascular bundle clearly shows distinct conducting cells: xylem vessels, tracheids, xylem parenchyma, and phloem sieve tubes, companion cells, and phloem parenchyma.

Questions

• 1. Name types of simple tissues.
  The types of simple permanent tissues are:
  1. Parenchyma
  2. Collenchyma
  3. Sclerenchyma
• 2. Where is apical meristem found?
  Apical meristem is found at the growing tips of stems and roots.
• 3. Which tissue makes up the husk of coconut?
  Sclerenchymatous tissue.
• 4. What are the constituents of phloem?
  Phloem is made up of five constituents:
  1. Sieve cells
  2. Sieve tubes
  3. Companion cells
  4. Phloem fibres
  5. Phloem parenchyma
• How do these body parts move?
  Body parts move due to the contraction and relaxation of specialised cells called muscle cells (muscle fibres).
• During breathing we inhale oxygen. Where does this oxygen go?
  The oxygen is absorbed into the blood in the lungs and is then transported by blood to all the body cells.
• Why would cells need oxygen?
  Cells need oxygen for cellular respiration in the mitochondria to break down glucose and release energy in the form of ATP.

• Blood is a type of connective tissue. Why would it be called 'connective' tissue?
  Blood flows to all parts of the body, connecting various organs and tissues by transporting gases, nutrients, hormones, and waste materials between them.

Activity 2.4

• Take a drop of blood on a slide and observe different cells present in it under a microscope.
  We observe numerous biconcave disc-shaped Red Blood Cells (RBCs) without nuclei, fewer nucleated White Blood Cells (WBCs) of different shapes (like neutrophils, lymphocytes, and monocytes), and small cell fragments known as platelets floating in the fluid plasma.

• It is a strong and nonflexible tissue (what would be the advantage of these properties for bone functions?).
  Being strong and nonflexible allows bone to provide a sturdy framework, protect delicate internal organs from mechanical shock, and give rigid anchoring points for muscles to enable locomotion.
• We can fold the cartilage of the ears, but we cannot bend the bones in our arms. Think of how the two tissues are different!
  Bone has a hard, rigid matrix composed of calcium and phosphorus compounds with non-flexible properties, whereas cartilage has a flexible, solid matrix composed of proteins and sugars with widely spaced cells.
• Where are fats stored in our body?
  Fats are stored in adipose tissue, which is found below the skin and between internal organs.

• They are also called unstriated muscles - why would they be called that?
  They are called unstriated muscles because they do not show any alternate light and dark bands (striations) under a microscope.

Activity 2.5

• Compare the structures of different types of muscular tissues. Note down their shape, number of nuclei and position of nuclei within the cell in the Table 2.1.

Features	Striated	Smooth	Cardiac
Shape	Long, cylindrical, unbranched	Spindle-shaped with pointed ends	Cylindrical, branched
Number of nuclei	Multinucleate (many nuclei)	Uninucleate (single nucleus)	Uninucleate (single nucleus)
Position of nuclei	Peripheral (near the cell membrane)	Centrally located	Centrally located

Questions

• 1. Name the tissue responsible for movement in our body.
  Muscular tissue.
• 2. What does a neuron look like?
  A neuron resembles a tiny branched tree. It consists of a cell body (cyton) containing a nucleus and cytoplasm, from which many short, branched hair-like parts called dendrites arise, along with a single long process called the axon terminating in nerve endings.
• 3. Give three features of cardiac muscles.
  Three features of cardiac muscles are:
  1. They are involuntary muscles that show rhythmic contraction and relaxation throughout life without fatigue.
  2. The cells are cylindrical, branched, and uninucleate.
  3. They possess faint striations and intercalated discs.
• 4. What are the functions of areolar tissue?
  Functions of areolar tissue:
  1. It fills the spaces inside organs.
  2. It supports internal organs.
  3. It helps in the repair of tissues.

Exercises

• 1. Define the term "tissue".
  A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue.
• 2. How many types of elements together make up the xylem tissue? Name them.
  Four types of elements make up xylem tissue:
  1. Tracheids
  2. Vessels
  3. Xylem parenchyma
  4. Xylem fibres
• 3. How are simple tissues different from complex tissues in plants?
  Simple tissues are made up of only one type of cells that look similar to each other (e.g., parenchyma, collenchyma, sclerenchyma).
  Complex tissues are made up of more than one type of cells which coordinate together to perform a common function (e.g., xylem and phloem).
• 4. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
  Differences based on cell walls:

Feature	Parenchyma	Collenchyma	Sclerenchyma
Cell Wall Nature	Thin cell walls made of cellulose.	Irregularly thickened at the corners with cellulose and pectin.	Uniformly thickened, hard, and lignified with no internal space.

• 5. What are the functions of the stomata?
  Functions of stomata:
  1. Exchange of gases (CO₂ and O₂) between the plant and the atmosphere.
  2. Transpiration (loss of excess water in the form of water vapour).
• 6. Diagrammatically show the difference between the three types of muscle fibres.
  The structural differences between the three muscle fibres are:
  Striated muscle: Long, cylindrical, unbranched, and multinucleate with prominent alternate dark and light striations.
  Smooth muscle: Spindle-shaped, tapering ends, unbranched, uninucleate, and without striations.
  Cardiac muscle: Cylindrical, branched, uninucleate, with faint striations and interconnected fibres.
• 7. What is the specific function of the cardiac muscle?
  The specific function of cardiac muscle is to cause rhythmic, tireless, involuntary contraction and relaxation of the heart to pump blood continuously throughout the body.
• 8. Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.
  Differences based on structure and location:

Feature	Striated Muscle	Unstriated (Smooth) Muscle	Cardiac Muscle
Structure	Cylindrical, unbranched, multinucleate, with distinct dark and light striations.	Spindle-shaped, unbranched, uninucleate, without striations.	Cylindrical, branched, uninucleate, with faint striations.
Location	Attached to bones in limbs, body wall, face, and neck (skeletal muscles).	Walls of internal organs like alimentary canal, blood vessels, iris, ureters, and bronchi.	Present exclusively in the walls of the heart.

• 9. Draw a labelled diagram of a neuron.
  A neuron consists of:
  1. Cell body (Cyton): Contains a centrally located nucleus and cytoplasm.
  2. Dendrites: Short, branching projections arising from the cell body that receive signals.
  3. Axon: A single long cylindrical projection carrying impulses away from the cyton.
  4. Nerve ending: Terminal branch endings that transmit impulses to adjacent neurons or effector muscles.
• 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.
  (a) Squamous epithelium (Simple 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.
  Skin: Stratified squamous epithelium
  Bark of tree: Protective tissue (Cork / Phellem)
  Bone: Connective tissue (Skeletal connective tissue)
  Lining of kidney tubule: Cuboidal epithelium
  Vascular bundle: Complex permanent tissue (Xylem and Phloem)
• 12. Name the regions in which parenchyma tissue is present.
  Parenchyma is present in the cortex and pith of stems and roots, mesophyll of leaves (as chlorenchyma), flowers, fruits, and in the vascular tissues (xylem parenchyma and phloem parenchyma).
• 13. What is the role of epidermis in plants?
  Role of epidermis:
  1. Protects the internal plant parts against mechanical injury, desiccation, and infection.
  2. Secretes a waxy, water-resistant cutin coating to prevent loss of water.
  3. Bears stomata that facilitate gas exchange and transpiration.
  4. Forms root hairs in root epidermis that significantly increase surface area for water absorption.
• 14. How does the cork act as a protective tissue?
  Cork acts as a protective tissue because its cells are dead and compactly arranged in multiple layers without intercellular spaces. Furthermore, the cell walls are impregnated with suberin, which makes them impervious to gases and water, shielding inner plant tissues from desiccating, catching infections, and mechanical injury.
• 15. Complete the following chart:

Simple			Complex
Parenchyma	Collenchyma	Sclerenchyma	Xylem	Phloem

• 16. A Student has classified the cells into two different groups as shown below.

Group - A	Group - B
Xylem parenchyma	Phloem fibres
Sieve cells	Tracheids
Sieve tubes	Vessels

• What might be Group A and Group - B respectively?
  A) Simple, Complex

  B) Cells in Xylem, cells in phloem

  C) Living, non living

  D) Meristematic, Permanent
  Answer: C) Living, non living
• 17. Choose the correct answer based on the given assertion and reason
  Assertion (A): Differentiation leads to development of various types of permanent tissues.
  Reason (R): It is the process by which cells develop permanent shape, size and function.
  A) A is true but R is false.

  B) A is false but R is true.

  C) Both A and R are true. R is the correct explanation of A.

  D) Both A and R are true. R is not be correct explanation of A.
  Answer: C) Both A and R are true. R is the correct explanation of A.
• 18. Why do Eskimos living in tundras have a thicker layer of adipose tissue under their skin?
  A) To help muscles contract and relax faster in cold weather

  B) To store extra oxygen for breathing in cold condition

  C) To reduce heat loss and act as an insulator

  D) To make their skin harder and stronger
  Answer: C) To reduce heat loss and act as an insulator

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