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Questions and Answers
What is the primary function of the apical meristem?
What is the primary function of the apical meristem?
What specialized function do guard cells serve in dermal tissue?
What specialized function do guard cells serve in dermal tissue?
Which type of tissue is characterized by thick cell walls and provides structural support in plants?
Which type of tissue is characterized by thick cell walls and provides structural support in plants?
Which of the following statements correctly describes parenchyma tissue?
Which of the following statements correctly describes parenchyma tissue?
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What is the unique feature of the epidermis in dermal tissue?
What is the unique feature of the epidermis in dermal tissue?
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Which cell type is primarily responsible for the transport of water and mineral salts in plants?
Which cell type is primarily responsible for the transport of water and mineral salts in plants?
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What is the role of sclereids and fibers in plants?
What is the role of sclereids and fibers in plants?
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In which root region does active cell division occur?
In which root region does active cell division occur?
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What is the main function of the endodermis in root anatomy?
What is the main function of the endodermis in root anatomy?
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Which characteristic is specific to phloem tissue?
Which characteristic is specific to phloem tissue?
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Study Notes
Tissues
- A group of similar cells adapted for a particular function
Organs
- A group of different tissues performing a specific function
Cell Differentiation
- Cells develop specific structures for specific functions
Meristematic Tissue
- Tissue responsible for growth
-
Apical Meristem
- Found at the growing tip of stem and root
- Increases the length
-
Lateral Meristem
- Found on the lateral sides of roots and stem
- Increases the width
- Also called cambium
Permanent Tissue
- Tissues that have lost the ability to divide
- Composed of three main tissue types: dermal, vascular, and ground tissue
Dermal Tissue
- Outer layer of the plant
-
Epidermis
- Outer layer of the root, stem, and leaves
- Function: protects underlying tissues, regulates gas and water loss.
- Characterized by:
- Single layer of brick-shaped cells
- Transparent cells with no air gaps to allow light to pass through
- Waxy cuticle on the stem and leaves to reduce water loss
- Specialized epidermal cells:
- Root hairs: Increase surface area for water absorption
- Guard cells: Control the opening and closing of stomata, allowing for transpiration (water loss)
Ground Tissue
- Found in the interior of the plant
-
Parenchyma
- Thin cell walls with large intercellular spaces
- Function: storage of food and water, and gas exchange
- Characterized by: large vacuoles
-
Sclerenchyma
- Thick cells walls made of lignin
- Function: structural support for the plant
- Characterized by: cells are dead and hollow
- Two types: sclereids and fibres
-
Collenchyma
- Thickened cells walls in the corners
- Function: structural support
-
Chlorenchyma
- Specialized parenchyma cells with chloroplasts
- Function: photosynthesis
Vascular Tissue
- Responsible for the transport of water and nutrients throughout the plant.
-
Xylem
- Consists of xylem vessels and tracheids
- Function: Transports water and minerals from roots to the rest of the plant
- Characterized by:
- Elongated cells
- Lacking living material (dead cells)
- Thickened cell wall made of lignin (strengthens the plant)
- Perforation plates for easy transport of water
- Pits in the walls of vessels and tracheids for lateral transport
-
Phloem
- Living, elongated cells without thickened walls
- Function: transports organic substances from leaves to the rest of the plant
- Consists of sieve tubes and companion cells: companion cells support the sieve tubes
- Characterized by:
- End walls of sieve tubes have sieve plates to form continuous tubes
Root Anatomy
-
Functions:
- Anchorage
- Support
- Storage of food
- Absorption of water and mineral salts
- Transport of nutrients
- Reproduction
-
Regions:
-
Root cap:
- Function: Protects the meristematic region and helps the root tip slide through soil easily.
-
Meristematic region:
- Function: Site of active cell division, responsible for root growth.
-
Region of elongation:
- Function: area where the root grows longer
-
Mature region:
- Function: Absorption of water and mineral salts. Characterized by root hairs to increase the surface area for absorption, lateral roots and fully differentiated tissues
-
Root cap:
-
Internal structure:
- Epidermis: outer layer of the root that contains root hairs for absorption.
- Cortex: Composed of parenchyma cells with large intercellular spaces. The innermost layer is the endodermis, which contains the Casparian strips, which regulate the movement of water and dissolved nutrients into the vascular tissue.
-
Central cylinder:
- Pericycle: layer of thin-walled cells that produce lateral roots.
- Vascular tissue: xylem and phloem.
- Vascular cambium: layer of meristematic cells between the xylem and phloem that produces new xylem and phloem.
Stem Anatomy
-
Functions:
- Transport of food, water, and nutrients between the roots and leaves
- Support and positioning
- Storage
- Reproduction (asexually, via tubers, bulbs, rhizomes, and stolons)
- Anchorage
- Protection (thorns or spines)
- Photosynthesis in some cases (stems can have chlorophyll and perform photosynthesis)
-
Internal Structure:
- Epidermis: Outer layer of the stem.
- Cortex: Consists of collenchyma, parenchyma, and endodermis.
-
Central cylinder:
- Contains vascular bundles, which consist of xylem and phloem.
- Xylem is on the inside, phloem is on the outside.
- Cambium: layer of meristematic tissue that forms the boundary between the xylem and phloem, allowing for secondary thickening (growth in diameter of the stem)
- Pith: Central region of the stem, made up of parenchyma cells, acts as storage tissue.
Leaf Anatomy
-
Functions:
- Photosynthesis
- Transpiration (water vapour loss)
- Gas exchange
-
Internal Structure:
-
Epidermis: Covers the upper and lower surfaces of the leaf, protects the underlying tissues and allows light to pass through.
- Covered by a waxy cuticle to reduce excessive water loss.
- Contains stomata (pores) for gas exchange and transpiration.
-
Mesophyll: The inner part of the leaf:
- Palisade mesophyll: Elongated, columnar cells located under the upper epidermis. Contains a large number of chloroplasts, for maximum utilization of light for photosynthesis.
- Spongy mesophyll: Looser arrangement of cells, with large air spaces for gas exchange.
-
Epidermis: Covers the upper and lower surfaces of the leaf, protects the underlying tissues and allows light to pass through.
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