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Which of the following polysaccharides serves as a structural material of a plant?
Proteins are only found in crystalline form in plants.
False
What are the two main types of lipids mentioned?
Oils and fats
Alkaloids found in plants are known for their ________ action.
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Which substance is known for its curative properties and acts as a protective material against animal or insect attacks?
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Match the following substances with their respective functions:
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What is the primary function of sclerenchyma tissue?
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Sclerenchyma fibers have a large lumen and thin walls.
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Which of the following examples contains lipids?
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Sclerenchyma tissue can be found abundantly in the _____, _____, and _____ of plants.
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Name an example of a medicinal glycoside.
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Name the two main elements of sclerenchyma tissue.
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Match the elements of sclerenchyma with their characteristics:
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What is true about resins?
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Volatile oils are soluble in water.
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Name two families of plants where latex is present.
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The main crystal types found in plants are calcium __________ and calcium __________.
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Match the secretory products with their primary roles:
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Which of the following describes meristematic tissues?
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Which of the following is a characteristic of minerals in plants?
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Permanent tissues have the capacity to multiply.
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Gums are found in suspended form in plants.
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What are the two main classifications of plant tissues?
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What are the primary components found in latex?
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___ is a sugary solution secreted by many flowers.
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Match the types of permanent tissues with their characteristics:
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Which feature is NOT typical of meristematic tissues?
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Permanent tissues can change into other types of tissues.
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How are permanent tissues produced?
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What is the primary function of phloem in plants?
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Phloem fibers are primarily involved in the transport of food.
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What type of cells make up the sieve tubes in phloem?
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The process by which secretory structures form through the splitting of cells is called __________.
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Match the following types of secretions with their respective categories:
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Study Notes
Ergastic Substances
- Ergastic substances are non-living products produced in the cytoplasm of plant cells.
- They may be stored in the cell vacuole, cells, or intercellular spaces.
- These substances are important for plant survival and growth.
- They are grouped by function – reserve food, excretory products, or secretory products.
Reserve Foods
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Polysaccharides
- Complex polysaccharides function as structural material in plants.
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Mucilage
- Forms gummy solutions in epidermal cells of plants.
- Found in plants like Senna, Isapgol, and linseed.
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Proteins
- Nitrogenous compounds, soluble or insoluble in water.
- Essential for the structure and function of living cells.
- Produced and associated with living matter.
- Can be amorphous (like in the aleuronic layer of maize) or crystalline (like in aleuronic grains of castor seeds).
- Converted into amino acids by proteolytic enzymes.
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Lipids
- Oils are liquid at room temperature.
- Fats are solid at room temperature.
- Composed of fatty acids and glycerin oils.
- Found in the endosperm of seeds, such as castor, peanut, and sesame.
Excretory Products
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Alkaloids
- Basic secondary metabolites containing nitrogen.
- Have marked physiological actions.
- Occur as salts with acids like nicotinic, quinic, citric, or oxalic acids.
- Found in seeds, barks, leaves, and roots.
- Serve as potent medicaments and possess curative properties.
- Protect the plant against animal or insect attack.
- Act as detoxifying agents for the plant.
- Reservoirs for protein synthesis.
- Examples include ergot, Vinca, and Datura.
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Glycosides
- Condensation products of sugar and glycol.
- Secondary metabolites with pharmaceutical significance.
- Dissolve in water and alcohol.
- Examples include Digitalis, Senna, and Rhubarb.
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Tannins
- Present in cell sap.
- Soluble in water and alcohol.
- Gives blue-black or green color in the presence of iron.
- Possess several medicinal properties, and are used in drugs.
- Examples include Nutgalls and Myrobalan.
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Resins
- Found in resin ducts.
- Insoluble in water.
- Semisolid or solid.
- Associated with gums and volatile oils.
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Latex
- A white suspension with microscopic particles or oil globules suspended in it.
- Contains protein, sugars, minerals, and alkaloid salts in true solution.
- Also contains gums, starch, and resins in a suspended form.
- Present in lactiferous tissue.
- Examples include Euphorbiaceae, Caricaceae, Papaveraceae, Banyan, madar, Papaya, Poppy, and Ficus.
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Volatile Oils
- Fragrant liquids found in plants.
- Volatile, liquid, and aromatic.
- Present in leaves, stems, bark, and fruits.
- Insoluble in water but soluble in alcohol.
- Possess carminative stimulant and antiseptic properties.
- Used as drugs.
- Examples include orange, lemon, coriander, cinnamon, ginger.
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Mineral Crystals
- Occur in the cell wall or cell cavity
- Insoluble in water
- Found in roots, stems, leaves, and fruits.
- Common crystals include calcium carbonate and calcium oxalate.
- Calcium oxalate occurs in various types like acicular, raphides, and cluster of rosettes.
- Example – acicular, Raphides, Cluster of rosettes.
Secretory Products
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Enzymes
- Coloring substances or pigments (e.g., Chlorophyll – essential for photosynthesis; Anthocyanin – other pigments.)
- Flavonoid glycosides – provide attractive colors to flowers.
- Nitrogenous water-soluble compounds – involved in the hydrolysis of carbohydrates and proteins.
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Nectar
- Sugary solution secreted by many flowers in special cells and glands.
Plant Tissues
- Plant or animal organs are formed of various tissues.
- In a specific organ, different tissues perform interrelated functions.
- A tissue is an aggregation of cells or elements with the same function.
Tissue Classification
- Based on origin, structure, and physiology:
- Meristematic or embryonic
- Permanent tissues
Meristematic or Embryonic Tissue
- Characteristics:
- Small and isodiametric cells.
- Cells are compact with no intercellular spaces.
- Cells have thin walls, are cubical, and have prominent nuclei.
- Vacuoles are very small or absent.
- Cells have the capacity to multiply.
- Newly formed cells develop by enlargement or morphological differentiation.
Permanent Tissues
- Characteristics:
- Cells vary in size, shape, and nature of protoplast.
- Cells can be living or dead.
- Produced by meristematic cells.
- Lack the capacity to multiply.
- Generally retain their structural and physiological characteristics.
- Not usually changed into other types of tissues.
- Composed of one or more types of cells.
- Classified as simple or complex tissues.
Simple Permanent Tissues
- Consists of one type of cell.
- Includes:
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Parenchyma:
- Cells are living, thin-walled, and usually have large vacuoles.
- Involved in storage, photosynthesis, and secretion.
- Found in all organs of the plant.
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Collenchyma:
- Living cells with thickened cell walls.
- Provides mechanical support to young, growing parts of the plant.
- Found in stems, leaves, and petioles.
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Sclerenchyma:
- Dead cells with thickened, lignified cell walls.
- Provides rigidity and strength to the plant.
- Found in roots, leaves, stems, xylem, and other parts.
- Two elements:
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Stone cells:
- Isodiametric, elongated, or branched.
- Pitted or stratified.
- Found in groups, singly, or as complete layers.
- Abundant in cortex, phloem, stems, leaves, roots, seeds, and flesh of fruits.
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Fibers:
- Develop in bundles or layers.
- Thick-walled, with a narrow lumen and pointed ends.
- Lignified walls.
- Contain cellulose.
- Found in pericyclic, xylem, or phloem fibers.
- Sheath of crystals can develop around sclerenchyma (e.g., Senna leaf).
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Stone cells:
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Parenchyma:
Complex Permanent Tissues
- Consists of two or more types of cells.
- Includes:
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Xylem:
- Responsible for the transport of water and dissolved minerals upwards from the roots to the rest of the plant.
- Composed of:
- Tracheids: Long, narrow, dead cells with tapered ends.
- Vessels: Short, wide, dead cells joined end to end to form continuous tubes.
- Xylem Parenchyma: Stores food and provides support.
- Xylem fibers: Provide strength and support.
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Phloem:
- Transports food manufactured in the leaves downward to the stem and roots.
- Composed of:
- Phloem Parenchyma: Stores food (also called ray cells).
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Sieve tubes:
- Living cells containing protoplasm.
- End walls have circular perforations called sieve plates.
- Sieve plates occur between sieve tubes and companion cells.
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Companion cells:
- Small, living cells associated with sieve tubes.
- Help in regulating the activities of sieve tubes.
- Phloem fibers: Provide strength and support.
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Secretory Structures:
- Important to secretory plants.
- Can be internal or external.
- Unicellular: Oil glands and resins.
- Multicellular: Ducts and glands.
- Formed by:
- Schizogenous: By splitting of cells.
- Lysigenous: Breaking down of groups of cells.
- Schizolysigenous: Combination of schizogenous and lysigenous.
- Secretions: Tannins, oils (volatile and fixed), mucilage.
-
Xylem:
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Description
This quiz explores the role of ergastic substances in plant cells, focusing on their types and functions. Learn about the different reserve foods such as polysaccharides, proteins, and lipids and their significance for plant survival and growth.
