Specialized Plant Cells Types

Specialized Plant Cells Types-Plants have different types of specialized cells grouped into three main tissue systems: Ground Tissue, Dermal Tissue, and Vascular Tissue. Each system has unique cells that perform essential functions like support, transport, and protection.

1. Cells of the Ground Tissue System

These cells mainly provide support, store nutrients, and perform photosynthesis.

Parenchyma Cells

Structure: Thin-walled, soft, and flexible cells with varying shapes (spherical to barrel-like).
Functions:
- Store nutrients (e.g., starch in potato tubers).
- Perform photosynthesis (chlorenchyma cells contain many chloroplasts).
- Help transport solutes by increasing the inner surface area.
- Specialized transfer cells in nectaries secrete sugars and nectar.

PARENCHYMA CELL

Collenchyma Cells

Structure: Long, narrow cells with unevenly thickened primary walls.
Functions:
- Provide flexible support to growing stems and leaves.
- Form strong tissue strands, like the strings in celery stalks.

Sclerenchyma Cells

Structure: Thick, rigid secondary walls; dead at maturity.
Functions:
- Provide structural support to mature plant parts.
- Form fibers in wood, hemp, and sisal, used for making ropes.
- Short sclereids (stone cells) give hardness to seed coats, nut shells, and pear fruits.

2. Cells of the Dermal Tissue System

This system forms the outer protective layer of plants and helps in gas exchange and water retention.

Epidermal Cells

Structure: Flat cells forming a continuous layer without gaps.
Functions:
- Secrete cutin and waxes to prevent water loss.
- Contain chloroplasts in green leaves, aiding photosynthesis.
- In flower petals, store pigments (e.g., anthocyanins) that give bright colors.

Guard Cells

Structure: Bean-shaped cells with chloroplasts.
Functions:
- Control the opening and closing of stomata (tiny pores for gas exchange).
- Respond to water availability—swelling opens stomata, shrinking closes them.

Trichomes (Hair-like Cells)

Structure: Tiny hair-like projections on leaves and stems.
Functions:
- Reduce water loss by trapping moisture.
- Protect against insects—some trichomes secrete sticky or toxic substances.

3. Cells of the Vascular Tissue System

This system transports water, minerals, and food throughout the plant. It consists of xylem (water transport) and phloem (food transport).

Xylem Cells (Transport water & minerals)

Vessel Elements:
- Long, hollow, tube-like cells with thick secondary walls.
- Dead at maturity, allowing water to move freely.
- Perforated cell ends create a continuous pipeline for efficient water flow.
Tracheids:
- Also transport water but are less efficient due to the absence of perforations.
Sclerenchyma & Parenchyma Cells:
- Provide support and assist in water movement.

Phloem Cells (Transport food & nutrients)

Sieve Elements:
- Long, living cells with perforated end walls (sieve plates) to allow sugar flow.
- Lack a nucleus and some organelles for uninterrupted transport.
Companion Cells:
- Support sieve elements by directing their metabolism.
- Have a nucleus and supply nutrients to sieve cells.

MCQ’s

1. Cells of the Ground Tissue System

Which of the following is a characteristic of parenchyma cells?
a) Thick secondary walls
b) Dead at maturity
c) Thin primary walls and flexible structure ✅
d) Provide structural support
Which type of parenchyma cells are specialized for photosynthesis?
a) Sclereids
b) Chlorenchyma ✅
c) Collenchyma
d) Xylem vessels
What is the primary function of transfer cells?
a) Support the plant
b) Transport solutes across membranes ✅
c) Provide mechanical strength
d) Store food
Collenchyma cells have thickened walls that provide:
a) Transport
b) Storage
c) Support and flexibility ✅
d) Water conduction
The stringy part of celery consists mainly of:
a) Parenchyma
b) Xylem
c) Collenchyma ✅
d) Sclerenchyma
Sclerenchyma cells are different from collenchyma because they:
a) Are living at maturity
b) Have thin walls
c) Are dead at maturity ✅
d) Store food
Sclerenchyma fibers are commonly found in:
a) Soft leaves
b) Wood, hemp, and sisal ✅
c) Nectar glands
d) Root hairs
What type of sclerenchyma cells are found in pear fruit?
a) Fibers
b) Parenchyma
c) Sclereids ✅
d) Xylem vessels
The main function of collenchyma is:
a) Photosynthesis
b) Nutrient storage
c) Structural support during growth ✅
d) Water conduction
Which plant cell type is involved in food storage in potato tubers?
a) Collenchyma
b) Sclerenchyma
c) Parenchyma ✅
d) Trichomes

2. Cells of the Dermal System

The outermost protective layer of a plant is the:
a) Xylem
b) Epidermis ✅
c) Phloem
d) Cortex
The waxy layer secreted by epidermal cells is called:
a) Cuticle ✅
b) Chlorenchyma
c) Phloem
d) Stomata
The primary function of the cuticle is to:
a) Absorb water
b) Transport nutrients
c) Reduce water loss ✅
d) Produce food
What are stomata?
a) Cells that produce wax
b) Openings in the epidermis for gas exchange ✅
c) Structural support cells
d) Water-conducting cells
Guard cells regulate:
a) Water transport in xylem
b) The opening and closing of stomata ✅
c) Phloem sap movement
d) Epidermal cell growth
The shape of guard cells is:
a) Square
b) Crescent-shaped ✅
c) Circular
d) Irregular
Trichomes help plants by:
a) Providing structural support
b) Conducting water
c) Reducing water loss and repelling insects ✅
d) Storing food
The bright colors of flower petals are due to pigments in:
a) Xylem
b) Phloem
c) Epidermal cells ✅
d) Sclerenchyma
What type of plant cells contain anthocyanins?
a) Xylem cells
b) Guard cells
c) Epidermal cells ✅
d) Phloem cells
The function of trichomes in some plants is to:
a) Transport water
b) Absorb nutrients
c) Secrete sticky or toxic substances ✅
d) Store starch

3. Cells of the Vascular Tissue System

The vascular tissue system includes:
a) Epidermis and stomata
b) Xylem and phloem ✅
c) Cuticle and trichomes
d) Parenchyma and sclerenchyma
Xylem transports:
a) Sugar
b) Water and minerals ✅
c) Oxygen
d) Proteins
The major water-conducting cells in xylem are:
a) Parenchyma
b) Sclereids
c) Vessel elements ✅
d) Phloem fibers
Xylem vessel elements are:
a) Living at maturity
b) Dead at maturity ✅
c) Involved in photosynthesis
d) Found in phloem
Tracheids differ from vessel elements because they:
a) Lack perforations ✅
b) Are larger
c) Store starch
d) Have thick primary walls
Phloem transports:
a) Water
b) Minerals
c) Sugars and nutrients ✅
d) Oxygen
The main conducting cells in phloem are:
a) Vessel elements
b) Sieve elements ✅
c) Tracheids
d) Sclerenchyma fibers
Sieve plates allow:
a) Water transport
b) Nutrient movement between sieve elements ✅
c) Starch storage
d) Gas exchange
Companion cells are found in:
a) Xylem
b) Phloem ✅
c) Epidermis
d) Guard cells
Phloem sap moves under:
a) Negative pressure
b) Positive pressure ✅
c) No pressure
d) Gravity

4. General Questions

The primary function of sclerenchyma fibers is:
a) Nutrient storage
b) Structural support ✅
c) Photosynthesis
d) Secretion
Which of the following is a living cell at maturity?
a) Xylem vessels
b) Tracheids
c) Phloem sieve elements ✅
d) Sclerenchyma fibers
The sugar-transporting tissue in plants is called:
a) Xylem
b) Phloem ✅
c) Epidermis
d) Cortex
Water transport in plants occurs mainly in the:
a) Phloem
b) Parenchyma
c) Xylem ✅
d) Epidermis
The part of the plant that secretes nectar is called:
a) Stomata
b) Nectarines ✅
c) Trichomes
d) Phloem

5. Additional Questions on Specialized Plant Cells

Which ground tissue cell type is involved in storing starch?
a) Collenchyma
b) Sclerenchyma
c) Parenchyma ✅
d) Tracheids
The secondary walls of sclerenchyma cells are rich in:
a) Cellulose
b) Lignin ✅
c) Starch
d) Cutin
What is the function of xylem fibers?
a) Transport water
b) Provide structural support ✅
c) Transport sugars
d) Store nutrients
The living cells that assist sieve tube elements in transporting nutrients are:
a) Tracheids
b) Companion cells ✅
c) Vessel elements
d) Collenchyma cells
What is the role of perforation plates in xylem vessels?
a) Store starch
b) Allow water to flow between cells ✅
c) Prevent water loss
d) Control the opening of stomata
In which plant tissue do you find sieve plates?
a) Xylem
b) Phloem ✅
c) Epidermis
d) Collenchyma
The epidermis of a plant mainly functions in:
a) Transporting nutrients
b) Protecting against water loss ✅
c) Storing food
d) Conducting photosynthesis
Which type of vascular tissue transports organic nutrients like sugars?
a) Xylem
b) Phloem ✅
c) Collenchyma
d) Sclerenchyma
What is the role of stomata in plants?
a) Absorbing minerals
b) Allowing gas exchange ✅
c) Storing carbohydrates
d) Transporting nutrients
Which specialized plant cells help in defense against herbivores?
a) Tracheids
b) Parenchyma cells
c) Glandular trichomes ✅
d) Guard cells
Which type of sclerenchyma cells are commonly found in nutshells and seed coats?
a) Tracheids
b) Fibers
c) Sclereids ✅
d) Parenchyma
Phloem sap movement is powered by:
a) Root pressure
b) Capillary action
c) Positive pressure ✅
d) Negative pressure
The transport of sugars in phloem is called:
a) Transpiration
b) Translocation ✅
c) Diffusion
d) Osmosis
Which cells in leaves contain the highest number of chloroplasts?
a) Guard cells
b) Epidermal cells
c) Palisade parenchyma ✅
d) Sclerenchyma
Which plant tissue system includes stomata and guard cells?
a) Vascular tissue
b) Ground tissue
c) Dermal tissue ✅
d) Collenchyma