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Questions and Answers
What type of parenchyma tissue is characterized by extensive connected air spaces, often found in aquatic plants?
Which type of tissue contains cells that are typically dead at maturity and have thick secondary walls impregnated with lignin?
What characteristic is true for collenchyma cells?
Which type of sclerenchyma cell is characterized by being as long as wide and includes stone cells?
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What is a distinguishing feature of fibers found in sclerenchyma tissue?
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What is a tissue in the context of plant biology?
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Where are apical meristems located?
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What are complex tissues primarily composed of?
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What type of growth do apical meristems contribute to in plants?
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Which of the following best describes meristematic tissues?
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Which cells are primarily involved in the transportation of water and minerals in plants?
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What type of cell is mainly found in the periderm of woody plants?
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Which primary meristem is responsible for forming the protective outer layer of the plant?
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Which characteristic is true of vessel elements in xylem?
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How do cells change as they mature in meristematic tissues?
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What type of tissues do primary meristems produce?
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What function does the epidermis serve in plants?
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Which of the following options represents one of the three basic tissue patterns found in roots and stems?
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Which of the following statements is true about tracheids?
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Where are vascular tissues predominantly produced in woody plants?
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What role do cork cells play in the structure of plants?
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What function do rays primarily serve in woody plants?
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What type of cells compose the phloem?
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Which characteristic is true of sieve tube members?
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What is the primary role of the epidermis in plants?
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Which component of the epidermis helps prevent water loss?
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Which statement describes companion cells?
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What is the main feature of the cuticle formed by cutin and wax?
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Which of the following structures may produce root hairs?
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What is the main function of trichomes on above ground parts of plants?
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What is the primary composition of periderm in plants?
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What role do lenticels play in plant physiology?
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Which of the following is NOT a feature of secretory cells or tissues?
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Which types of meristematic tissues are responsible for the lengthening of plant organs?
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Which structure facilitates the regulation of gas exchange in leaves?
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What substance do cork cells secrete into their walls to make them waterproof?
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What type of plant tissue involves a mix of living and dead cells that conducts photosynthesis and provides storage?
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Study Notes
Introduction to Tissues
- Plants have major organs: roots, stems, leaves, and flowers
- Tissues are composed of cells performing the same function
- An organ can have more than one tissue
Roots and Stems
- Roots and stems possess three main tissue patterns:
- Woody dicots
- Herbaceous dicots
- Monocots
Meristematic Tissues
- Meristems: permanent regions of growth and active cell division
- Cells are typically small, box-like, with large nuclei and absent vacuoles
- When maturing, cells change shape, vacuoles grow larger, occupying up to 90% of the cell's volume
Apical Meristems
- Located at the tips of roots and shoots
- Roots and shoots increase in length due to apical meristems producing new cells (primary growth)
- Embryo leaves, buds, and three primary meristems develop from apical meristems
Primary Meristems
- Primary meristems are called:
- Protoderm
- Ground Meristem
- Procambium
- Primary meristems produce primary tissues
Simple Tissues
- Parenchyma: most common tissue, living, loosely packed cells with large vacuoles
- Function: storage & photosynthesis
- Collenchyma: flexible support tissue, living cells with unevenly thickened walls
- Function: support growing organs
- Sclerenchyma: dead, rigid support tissue, cells with thick walls impregnated with lignin
- Function: strength and support
- Composed of two types: sclereids and fibers
Sclereids
- Scattered in tissues, cells as long as they are wide
- Include stone cells
Fibers
- Found in fruits, stems, leaves, and roots
- Much longer than width and contain a lumen (tiny cavity)
- Used by humans for ropes, string, canvas, and textiles
Complex Tissues
- Complex tissues are made of two or more distinct cell types
- Some complex tissues are produced by apical meristems
- Include xylem, phloem, epidermis, and periderm
Xylem and Phloem
- Transport water, ions, and soluble food throughout plants
- In woody plants, complex vascular tissues are produced by the vascular cambium
Epidermis
- Protective outer layer, single-cell thick, covering all plant organs
- Composed of parenchyma or parenchyma-like cells
- Contains specialized cells regulating gas movement, glands, hairs, and crystal-isolating cells
Periderm
- Outer bark of woody plants, mainly composed of cork cells
- Contains parenchyma-like cell pockets
Xylem
- Primary tissue conducting water and minerals absorbed by roots
- Includes parenchyma cells, vessels, tracheids, fibres, and ray cells
Vessels
- Long tubes made of vessel elements
- Vessel elements:
- Thick secondary cell walls
- Open at both ends
- Walls develop irregularly
- Perforation plate between end walls
Tracheids
- Tapered at the ends with pairs of pits allowing water passage
- Pits: Areas without secondary cell walls
- Dead at maturity
- Thick secondary cell walls
- May have spiral thickenings on the cell wall
Rays
- Function in lateral conduction and food storage
- Composed of parenchyma cells
- Produced horizontally by ray initials of vascular cambium
- Radiate from the center of woody plants
Phloem
- Conducts dissolved food materials produced by photosynthesis
- Contains sieve tube members, companion cells, fibers, parenchyma cells, and ray cells
Companion Cells and Sieve Tube Members
- Companion cells: narrow, tapered cells attached to sieve tube members
- Sieve tube members:
- Lack secondary cell walls and nuclei
- Form sieve tubes
- Walls have sieve plates with pores
- Callose forms callus plugs to prevent leakage when injured
Epidermis
- Protective layer one-cell thick, covering all plant organs
Components of the Epidermis
- Usually one-cell thick
- May be multi-layered in some plants
- Cutin: fatty substance on the epidermis surface forming cuticle
- Wax secreted on the cuticle
- Cuticle and wax prevent water loss and protect from bacteria and disease organisms
Other Epidermal Components
- Root epidermal cells produce root hairs, increasing root absorptive area
- Above-ground plant parts may have trichomes, outgrowths of one to several cells
Stomata and Other Modifications
- Leaves have stomata bordered by pairs of guard cells
Glands or Modified Hairs
- Modified epidermal cells function as glands or hairs
Periderm
- Replaces the epidermis when cork cambium begins producing new tissue
- Outer bark, primarily composed of cork cells
- Dead at maturity
- While alive, cytoplasm secretes suberin (fatty substance) into walls, making cork cells waterproof and protecting phloem
Lenticels
- Loosely arranged pockets of parenchyma cells formed by cork cambium, protruding through the periderm
- Allow for gaseous exchange
Secretory Cells and Tissues
- Secretory cells can function individually or as part of a secretory tissue
- Examples: flower nectar, citrus oils, glandular hair mucilage, latex, resins
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Description
This quiz covers the fundamental concepts of plant tissues, including the major organs of plants and their tissue patterns. You'll learn about meristematic tissues, apical meristems, and the types of primary meristems that contribute to plant growth. Test your knowledge on how these components function together to support plant life.
