Tissues - Questions and Answers

Basic Concepts
Plant Tissues
Animal Tissues
Exercises

Basic Tissue Concepts

1. What is a tissue?

A tissue is a group of cells that are similar in structure and function and work together to perform a specific function.

2. What is the utility of tissues in multi-cellular organisms?

In multi-cellular organisms, tissues provide:

  • Division of labor: Different tissues perform different specialized functions
  • Efficiency: Specialized tissues can perform their functions more efficiently
  • Organization: Tissues organize cells into functional units
  • Complexity: Enable development of complex body structures and organs
  • Coordination: Allow for better coordination of body functions
3. Define the term "tissue".

A tissue is defined as a group of cells that are similar in structure, origin, and function, working together to perform a specific activity.

Plant Tissues

1. Name types of simple tissues.

Simple tissues in plants are of three types:

  1. Parenchyma - Basic packing tissue
  2. Collenchyma - Provides mechanical support
  3. Sclerenchyma - Provides strength and rigidity
2. Where is apical meristem found?

Apical meristem is found at the growing tips of stems and roots. It is responsible for the primary growth (increase in length) of the plant.

3. Which tissue makes up the husk of coconut?

The husk of coconut is made up of sclerenchyma tissue, which consists of thick-walled dead cells that provide mechanical strength and protection.

4. What are the constituents of phloem?

Phloem is composed of four types of elements:

  1. Sieve tubes - Main conducting elements
  2. Companion cells - Assist sieve tubes
  3. Phloem parenchyma - Storage function
  4. Phloem fibers - Provide mechanical support
5. How many types of elements together make up the xylem tissue? Name them.

Xylem tissue is made up of four types of elements:

  1. Tracheids - Tubular cells with tapered ends
  2. Vessels - Long tubular structures
  3. Xylem parenchyma - Living storage cells
  4. Xylem fibers - Provide mechanical support
6. How are simple tissues different from complex tissues in plants?
Simple Tissues Complex Tissues
Made of only one type of cells Made of more than one type of cells
All cells perform similar functions Different cells perform different functions
Examples: Parenchyma, Collenchyma, Sclerenchyma Examples: Xylem, Phloem
Mainly for storage, support, and packing Mainly for conduction and mechanical support
7. Differentiate between parenchyma, collenchyma and sclerenchyma on the basis of their cell wall.
Tissue Cell Wall Characteristics
Parenchyma Thin cell walls made of cellulose
Collenchyma Unevenly thickened cell walls at corners (cellulose and pectin)
Sclerenchyma Thick, lignified cell walls; often dead at maturity
8. What are the functions of the stomata?

Stomata perform the following functions:

  • Gas exchange: Allow intake of CO₂ and release of O₂ during photosynthesis
  • Transpiration: Regulate the loss of water vapor from plants
  • Temperature regulation: Help in cooling the plant through transpiration
9. Name the regions in which parenchyma tissue is present.

Parenchyma tissue is present in:

  • Cortex and pith of stems and roots
  • Mesophyll of leaves
  • Storage tissues in fruits and seeds
  • Xylem and phloem as packing tissue
10. What is the role of epidermis in plants?

The epidermis in plants serves several important functions:

  • Protection: Acts as a protective layer against mechanical injury, pathogens, and water loss
  • Regulation: Regulates gas exchange through stomata
  • Prevention: Prevents water loss through cuticle
  • Absorption: In roots, helps in water and mineral absorption
11. How does the cork act as a protective tissue?

Cork acts as a protective tissue by:

  • Having dead cells with suberin deposits in their walls that make them impermeable to water and gases
  • Preventing loss of water from the plant body
  • Protecting against mechanical injury and infection by microorganisms
  • Providing insulation against temperature extremes

Animal Tissues

1. Name the tissue responsible for movement in our body.

Muscular tissue is responsible for movement in our body.

2. What does a neuron look like?

A neuron (nerve cell) has a star-shaped cell body with:

  • Dendrites: Short, branched projections that receive signals
  • Axon: A long, thin fiber that conducts nerve impulses away from the cell body
  • Terminal branches: Fine branches at the end of axon that connect to other neurons
3. Give three features of cardiac muscles.

Three features of cardiac muscles are:

  1. They are involuntary muscles
  2. They show rhythmic contractions and relaxations throughout life
  3. They are branched and interconnected with intercalated discs
4. What are the functions of areolar tissue?

Areolar tissue functions as:

  • Packing material: Fills space between organs
  • Support: Provides support to delicate organs
  • Repair: Helps in repair of tissues after injury
  • Defense: Contains macrophages that phagocytose pathogens
5. What is the specific function of the cardiac muscle?

The specific function of cardiac muscle is to contract and relax rhythmically to pump blood throughout the body via the heart. It works continuously and involuntarily throughout life.

6. Differentiate between striated, unstriated and cardiac muscles on the basis of their structure and site/location in the body.
Muscle Type Structure Location
Striated (Skeletal) Long, cylindrical, unbranched, multinucleated, with light and dark bands Attached to bones
Unstriated (Smooth) Spindle-shaped, uninucleated, no striations Walls of internal organs (stomach, intestine, blood vessels)
Cardiac Branched, uninucleated, with intercalated discs, faint striations Heart
7. Name the following:

(a) Tissue that forms the inner lining of our mouth. - Stratified 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

8. Identify the type of tissue in the following: skin, bark of tree, bone, lining of kidney tubule, vascular bundle.
  • Skin: Epithelial tissue (stratified squamous epithelium)
  • Bark of tree: Cork (protective tissue)
  • Bone: Connective tissue (skeletal tissue)
  • Lining of kidney tubule: Epithelial tissue (cuboidal epithelium)
  • Vascular bundle: Complex tissue (xylem and phloem)

Exercises

1. Diagrammatically show the difference between the three types of muscle fibres.

Note: This would typically include diagrams showing:

  • Striated muscle: Long, cylindrical fibers with distinct light and dark bands
  • Smooth muscle: Spindle-shaped cells without striations
  • Cardiac muscle: Branched fibers with intercalated discs and faint striations
2. Draw a labelled diagram of a neuron.

Note: A labelled diagram of a neuron would show:

  • Cell body (cyton) with nucleus
  • Dendrites - receiving ends
  • Axon - long conducting fiber
  • Myelin sheath - insulating covering
  • Nodes of Ranvier - gaps in myelin sheath
  • Terminal branches - ends of axon
3. Complete the following chart:
Permanent Tissue
Simple Complex
Parenchyma Xylem
Collenchyma Phloem
Sclerenchyma