Plant Biology: Specialized Cells Quiz
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Questions and Answers

What is the primary function of chlorenchyma cells?

  • To carry out photosynthesis (correct)
  • To conduct nutrients over long distances
  • To provide structural support for the plant
  • To secrete nectar, fragrance, and other substances

    • Which of the following is NOT a type of specialized parenchyma cell?

  • Sclerenchyma (correct)
  • Transfer
  • Glandular
  • Chlorenchyma

    • What is the primary characteristic that distinguishes parenchyma cells from other cell types?

  • Their thin, primary cell walls (correct)
  • Their thick, secondary cell walls
  • Their role in conducting water throughout the plant
  • Their ability to perform photosynthesis

    • Which of the following is a function of glandular cells?

    <p>Secrete substances like nectar and resins (D)</p> Signup and view all the answers

    What is the primary way that transfer cells facilitate short-distance transport?

    <p>By having a large surface area of plasma membrane with numerous pumps (D)</p> Signup and view all the answers

    Which of the following is a characteristic of collenchyma cells?

    <p>They have a thick primary wall that becomes thickened in other areas. (A)</p> Signup and view all the answers

    What is the primary function of mechanical sclerenchyma?

    <p>Providing support and strength to the plant. (B)</p> Signup and view all the answers

    What is the function of the cuticle in plant stems?

    <p>To prevent water loss. (B)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of conducting sclerenchyma?

    <p>They are long and flexible. (A)</p> Signup and view all the answers

    Which type of cell is responsible for gas exchange in plant stems?

    <p>Guard cells (D)</p> Signup and view all the answers

    Which of the following structures is responsible for the regulation of water loss in plants?

    <p>Stomata (A)</p> Signup and view all the answers

    What is the primary function of the cortex in plants?

    <p>Photosynthesis and storage (C)</p> Signup and view all the answers

    Which of the following is NOT a type of thickening found in xylem tracheary elements?

    <p>Spiral (A)</p> Signup and view all the answers

    What is the function of the pits on the walls of tracheary elements?

    <p>To allow for the passage of water between cells (B)</p> Signup and view all the answers

    Which of the following is TRUE about vessel elements?

    <p>They are connected to each other by perforations, forming a continuous vessel. (D)</p> Signup and view all the answers

    What is the primary benefit of having tracheids with circular bordered pits?

    <p>Increased strength and support (D)</p> Signup and view all the answers

    Which type of vascular tissue is responsible for transporting sugars produced during photosynthesis?

    <p>Phloem (D)</p> Signup and view all the answers

    Which of the following cellular structures helps minimize water loss from the plant?

    <p>Trichomes (A)</p> Signup and view all the answers

    What is the defining characteristic of a sieve tube member that distinguishes it from a sieve cell?

    <p>Sieve tube members have sieve plates on each end-wall, allowing for a more efficient flow of sap. (D)</p> Signup and view all the answers

    Which of these statements accurately describes the relationship between xylem and phloem within vascular bundles?

    <p>Xylem and phloem are arranged parallel to each other within each vascular bundle. (A)</p> Signup and view all the answers

    What is the primary function of the sieve cells?

    <p>To transport sugars and other organic molecules throughout the plant. (A)</p> Signup and view all the answers

    Which of the following statements CORRECTLY describes the difference in the arrangement of vascular bundles in monocots and eudicots?

    <p>Eudicots have vascular bundles arranged in a ring surrounding the pith, while monocots have vascular bundles distributed in a complex network throughout the inner part of the stem. (B)</p> Signup and view all the answers

    What is the role of companion cells in relation to sieve tube members?

    <p>Companion cells are involved in loading sugars into the sieve tube members. (C)</p> Signup and view all the answers

    Why do sieve elements typically have a degenerated nucleus?

    <p>Sieve elements are controlled by neighboring cells, eliminating the need for a nucleus in each element. (C)</p> Signup and view all the answers

    What is the defining characteristic of the xylem that differentiates it from phloem?

    <p>Xylem cells are dead at maturity, while phloem cells are alive. (B)</p> Signup and view all the answers

    Flashcards

    Angiosperms

    Flowering plants classified under Division Magnoliophyta.

    Parenchyma

    Basic plant tissue with thin primary walls, metabolically active.

    Chlorenchyma

    Photosynthetic parenchyma cells that contain chloroplasts.

    Glandular cells

    Specialized parenchyma that secrete substances like nectar and oils.

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    Phloem

    Type of parenchyma tissue that transports nutrients over long distances.

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    Collenchyma

    Plant cells with unevenly thickened cell walls that provide support while allowing flexibility.

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    Sclerenchyma

    Plant cells with thick, lignified secondary walls that provide strength and support; usually dead at maturity.

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    Guard Cells

    Specialized cells that control the opening and closing of stomata, regulating gas exchange and water loss.

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    Cuticle

    A waxy layer on the epidermis of plant leaves that helps prevent water loss but also limits gas exchange.

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    Stomata

    Tiny openings on leaves for gas exchange and transpiration.

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    Epidermis

    Outer layer of cells serving as protection for plants.

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    Cortex

    Layer beneath the epidermis, often involved in storage and photosynthesis.

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    Xylem

    Vascular tissue that conducts water and minerals from roots to shoots.

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    Tracheary Elements

    Components of xylem, including tracheids and vessel elements, for water conduction.

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    Vessels

    Stacks of vessel elements in xylem that facilitate efficient water movement.

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    Sieve Elements

    Conducting cells in phloem, including sieve cells and sieve tube members.

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    Sieve Cells

    Elongated, tapered cells found in older fossils, part of phloem.

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    Sieve Tube Members

    More complex phloem cells that align to form sieve tubes.

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    Companion Cells

    Cells that assist sieve tube members in phloem, involved in sugar loading.

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    Primary Xylem

    The xylem of a vascular bundle that develops first in a plant.

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    Study Notes

    Plant Tissues: Primary Structures and Development

    • Plants colonised land 420 million years ago, leading to specialised tissues and organs.
    • Flower parts (leaves, stems and roots) can be modified and not always easily recognisable.
    • Flowering plants are classified as the Division Magnoliophyta, also known as angiosperms.
    • Plant tissues are grouped according to cell wall structure (parenchyma, collenchyma, sclerenchyma).

    Basic Types of Cells and Tissues

    • Stems, leaves and roots have a simple, basic structure.
    • Plant cells are categorised into three classes based on cell wall structure
    • Parenchyma, collenchyma and sclerenchyma

    Parenchyma

    • Cells have thin primary walls.
    • A group of parenchyma cells forms parenchyma tissue.
    • Parenchyma cells are metabolically active and remain alive once mature.
    • Diverse forms of specialised parenchyma exist (e.g., chlorenchyma, transfer cells, glandular cells).
    • Specific functions include photosynthesis (chlorenchyma), secretion (glandular cells) and nutrient transport (transfer cells).

    Specialized Parenchyma

    • Chlorenchyma is photosynthetic parenchyma involved in light and carbon dioxide absorption for photosynthesis within the chloroplast.
    • Pigmented cells, such as those carrying pigments, allow pigments to be seen within thin walls, so these cells are essential for visual appeal.
    • Glandular cells are involved in secretion (e.g., nectar, fragrances, mucilage and oils)

    Specialized Parenchyma (Transfer Cells)

    • Transfer cells mediate short-distance movement of materials, with a large extensive plasma membrane that includes numerous molecular pumps.

    Specialized Parenchyma (Phloem)

    • Phloem, a type of parenchyma, conducts nutrients over long distances.
    • Some parenchyma cells function by dying at maturity to open areas.
    • Parenchyma cells are relatively economical to produce.

    Collenchyma

    • Cells have thin primary walls that thicken in some areas.
    • This allows for plasticity.
    • Often located beneath epidermis and supports vascular bundles.

    Sclerenchyma

    • Cells have a primary and thick secondary wall, usually lignified (strengthened).
    • Sclerenchyma walls are elastic and provide strength.
    • Cells are usually dead at maturity (types of sclerenchyma includes mechanical and conductive sclerenchyma)
    • Fibres are long and flexible.
    • Sclereids are short and hard, isodiametric, inflexible, and brittle.

    Sclerenchyma (Conducting Cells)

    • Conductive sclerenchyma (e.g., tracheary elements, xylem) transports water.
    • Xylem elements include tracheids and vessel elements, collectively known as tracheary elements.
    • Areas of the secondary wall free from deposition of cells become narrow pits, joined together in pairs (pit pairs) in tracheary elements.

    Internal Organization of Stems: Primary Tissues

    • Epidermis is the outer protective layer of the stem, a single layer of parenchyma cells, controlling exchange between the plant and its environment and preventing water loss.
    • The outer tangential walls of the epidermis are coated with cutin, forming a waterproof cuticle.
    • Under dry conditions, a wax layer may be added external to the cuticle.
    • Stomata are pores in the epidermis, used for gas exchange (open and close).
    • Guard cells surrounding stomata regulate opening and closing, influenced by water levels and/or conditions.
    • Some epidermal cells develop into trichomes (hairs) that deter herbivory, minimise water loss and protect from sunlight.

    Primary Tissues: Cortex

    • Cortex lies inner to epidermis, often homogeneous parenchyma cells, sometimes mixed with collenchyma cells.
    • Cells are tightly fitted or loosely fitted with large intercellular airspaces (e.g., aerenchyma) in some plants.

    Primary Tissues: Vascular Tissues

    • Vascular tissues (xylem and phloem) transport materials throughout the plant.
    • Xylem transports water and minerals; phloem transports sugars and minerals.
    • Xylem elements are dead at maturity and hollow, whereas phloem cells are alive at maturity..

    Vascular Tissues: Xylem

    • Xylem consists of tracheids and vessel elements (tracheary elements).
    • Strength of xylem cells is derived from secondary cell walls with varied thickening patterns (annular, helical, scalariform, reticulate).
    • Structures called pits are present near the secondary wall of the xylem elements as a weakness point.
    • Water moves between tracheids/vessels through pit membranes.
    • Vessel elements facilitate fast water movement by perforations forming between vertically stacked xylem elements (vessels).
    • Tracheids occur in all vascular plants; vessel elements only occur in flowering plants.

    Vascular Tissues: Phloem

    • Phloem consists of sieve cells and sieve tube members (sieve elements).
    • Sieve elements develop from parenchyma cells and remain alive.
    • Plasmodesmata enlarge to become sieve pores; aggregation of pores forms sieve areas within sieve tubes.
    • Sieve cells are similar in shape to tracheids and contain sieve areas over their entire surface.
    • Sieve tube members have sieve plates on their end walls to enhance flow rate and can be found in angiosperms.
    • Nuclei of sieve elements degenerate.
    • They are controlled by companion cells, which are involved in the loading of sugars into the sieve tubes.

    Organization of Vascular Tissues

    • Xylem and phloem are located together in vascular bundles in the plant cortex.
    • Arrangement of bundles differs between monocots and eudicots and may be arranged in a ring, or complex network.
    • Xylem is located adjacent to the phloem in bundles.
    • Primary xylem and phloem are produced by apical meristems.

    Stem Growth and Differentiation

    • Stems elongate by cell proliferation from apical meristems.
    • Differentiation begins in the subapical meristem where some cells stop dividing and differentiate into protoxylem.
    • Protoxylem needs flexibility to elongate, so their secondary wall thickening patterns are limited to annular or helical.
    • Elongating cells eventually differentiate into metaxylem.
    • Similar process occurs in the outer tissue layers of the bundle (protophloem to metaphloem).
    • Additional differentiation of epidermal, pith and cortex layers occurs in the shoot.

    External Organization of Stems

    • Shoot systems contain leaves attached at nodes, and regions between nodes are internodes.
    • Terminal buds at the stem's apex, and axillary buds in the axils of leaves (leaf axil, where leaf attaches). Phyllotaxy is the arrangement of leaves in a systematic way.
    • Arrangement may be alternate or spiral (alternate phyllotaxy), opposite or whorled (opposite/whorled phyllotaxy)
    • Apical dominance refers to the terminal bud inhibiting growth of lateral buds.

    Stem Modifications

    • Stems are modified into various forms in some plants, used for various purposes.
    • Some stems, such as rhizomes or stolons, allow for spread.

    Leaf Modifications

    • Leaves are modified for various functions, such as tendrils for climbing, spines for water conservation, or traps for capturing insects.

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    Chapter 5 Lecture Notes Cells and Tissues Cont. PDF

    Description

    Test your knowledge on the various specialized cells found in plants, such as chlorenchyma, parenchyma, and sclerenchyma. This quiz covers their functions, characteristics, and roles in plant physiology, helping you to deepen your understanding of plant biology.

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