Mechanism of Water Absorption
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Mechanism of Water Absorption

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Questions and Answers

What is the primary requirement for the process of active transport as described?

  • Chemical energy (correct)
  • Diffusion of ions
  • Temperature change
  • Gravity

    • In what environment does Nitella algae primarily thrive?

  • Deserts
  • Swamps (correct)
  • Mountain lakes
  • Freshwater streams

    • What does the graph of ion concentrations in the roots and soil primarily illustrate?

  • Soil pH levels
  • The process of evaporation
  • Required ion concentrations for plant health (correct)
  • Nutrient absorption efficiency

    • If the concentration of K+ ions inside Nitella algae is at (Y) and it is known that (Y > Z) and (X > Y), which option represents the concentration of K+ ions in the surrounding pond?

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

    Which of the following accurately represents the phenomenon necessary for ion absorption in Nitella algae?

    <p>Active transport and selective permeability</p> Signup and view all the answers

    What is defined as the movement of water molecules through a semi-permeable membrane from high water concentration to low water concentration?

    <p>Osmosis</p> Signup and view all the answers

    Which of the following accurately describes osmotic pressure?

    <p>It is the pressure that develops due to differing solute concentrations.</p> Signup and view all the answers

    What is an example of a semi-permeable barrier?

    <p>Cellulose cell walls</p> Signup and view all the answers

    In the context of imbibition, which material is mentioned as easily absorbing water?

    <p>Cellulose</p> Signup and view all the answers

    Why are tissue papers effective in absorbing sweat during summer?

    <p>They utilize the process of imbibition.</p> Signup and view all the answers

    What is the primary function of the stomata found in the lower epidermis of a leaf?

    <p>To facilitate gas exchange</p> Signup and view all the answers

    Which cells in the mesophyll tissue are primarily responsible for maximizing sunlight absorption?

    <p>Palisade cells</p> Signup and view all the answers

    What type of tissue is responsible for transporting nutrients from the leaves to other parts of the plant?

    <p>Phloem</p> Signup and view all the answers

    What material covers the outer walls of the epidermal cells in a leaf?

    <p>Cutin</p> Signup and view all the answers

    Which component of vascular tissue is responsible for transporting water and minerals from the roots to the leaves?

    <p>Xylem</p> Signup and view all the answers

    What is the primary pigment responsible for the green color in chloroplasts?

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

    Which of the following pigments accounts for approximately 25% of the pigments in chloroplasts?

    <p>Xanthophyll</p> Signup and view all the answers

    What are grana within chloroplasts primarily composed of?

    <p>Membrane-bound discs</p> Signup and view all the answers

    Which type of pigment would contribute to the yellow color of yellow peppers?

    <p>Xanthophyll</p> Signup and view all the answers

    What is the function of chlorophyll in chloroplasts?

    <p>It absorbs light energy for photosynthesis.</p> Signup and view all the answers

    What is the main function of the palisade layer in mesophyll tissue?

    <p>Maximizing light absorption</p> Signup and view all the answers

    In which layer of the mesophyll tissue would you find irregular-shaped parenchyma cells?

    <p>Spongy Layer</p> Signup and view all the answers

    What role does the xylem play in vascular tissue?

    <p>Transporting water and minerals upward</p> Signup and view all the answers

    What is the structural arrangement of parenchyma cells in the palisade layer?

    <p>Cylindrical and tightly packed</p> Signup and view all the answers

    Which component of vascular tissue follows the xylem and is responsible for food transport?

    <p>Phloem</p> Signup and view all the answers

    What is the term used for the ability of cell walls and membranes to allow substances to pass through them?

    <p>Permeability</p> Signup and view all the answers

    Which of the following statements about osmosis is true?

    <p>Water moves through a semi-permeable membrane based on solute concentrations.</p> Signup and view all the answers

    Which of the following best describes a semi-permeable membrane?

    <p>Allows the passage of water but controls the movement of large molecules.</p> Signup and view all the answers

    Which phenomenon involves the movement of molecules from an area of high concentration to low concentration without energy input?

    <p>Diffusion</p> Signup and view all the answers

    What process describes the increase in volume of solid particles due to water absorption?

    <p>Imbibition</p> Signup and view all the answers

    What is the primary role of light in the light reactions of photosynthesis?

    <p>To excite electrons in chlorophyll</p> Signup and view all the answers

    What happens to chlorophyll after it has released stored energy?

    <p>It returns to its stable state, ready to absorb more light</p> Signup and view all the answers

    Which product is formed when hydrogen combines with NADP+ during light reactions?

    <p>NADPH₂</p> Signup and view all the answers

    During the light reactions, how is ATP produced?

    <p>Through photosynthetic phosphorylation of ADP</p> Signup and view all the answers

    What is released as a byproduct when water is split during the light reactions?

    <p>Oxygen</p> Signup and view all the answers

    Who first identified the source of the evolved oxygen in photosynthesis?

    <p>Van Neil</p> Signup and view all the answers

    What pigment do green and purple sulfur bacteria use for photosynthesis?

    <p>Bacteriochlorophyll</p> Signup and view all the answers

    During Van Neil's light reactions in green plants, water is broken down into which of the following?

    <p>Hydrogen and oxygen</p> Signup and view all the answers

    In the context of photosynthesis, what does Van Neil suggest happens during the dark reactions?

    <p>Hydrogen reduces carbon dioxide to form carbohydrates</p> Signup and view all the answers

    The general chemical equation for the photosynthesis process in green plants is which of the following?

    <p>6CO₂ + 12H₂O → C₆H₁₂O₆ + 6H₂O + 6O₂</p> Signup and view all the answers

    What phenomenon allows ions to move from the soil solution into the plant cells based on concentration gradients?

    <p>Diffusion</p> Signup and view all the answers

    Which of the following ions is categorized as a positive ion (cation)?

    <p>Sodium ion (Na⁺)</p> Signup and view all the answers

    What role does the semi-permeable plasma membrane play in mineral absorption?

    <p>It allows only specific ions to pass based on plant needs.</p> Signup and view all the answers

    Which phenomenon requires chemical energy for the movement of ions into plant cells?

    <p>Active transport</p> Signup and view all the answers

    What is a possible application for soaking vegetables in a diluted salt solution?

    <p>To remove agricultural pesticide traces</p> Signup and view all the answers

    Which of the following ions does NOT pass through the plant cell membrane by diffusion?

    <p>Phosphate ion (PO₄)³⁻</p> Signup and view all the answers

    Which type of ions tends to diffuse more readily from the soil into plant tissues?

    <p>Positive ions</p> Signup and view all the answers

    What is the main characteristic of selective permeability in plant cells?

    <p>It selectively permits certain ions based on necessity.</p> Signup and view all the answers

    What consequence may occur due to the shortage of essential elements in plants?

    <p>Disturbance or complete halt in growth</p> Signup and view all the answers

    Which of the following is NOT considered a macro-nutrient for plants?

    <p>Copper</p> Signup and view all the answers

    What is the role of phosphorus in plants?

    <p>Forms energy carrier compounds like ATP</p> Signup and view all the answers

    Which of the following statements about micro-nutrients is true?

    <p>They act mainly as activators for enzymes</p> Signup and view all the answers

    Which of the following elements is essential for the synthesis of some co-enzymes in plants?

    <p>Iron</p> Signup and view all the answers

    Study Notes

    Mechanism of Water Absorption

    • Diffusion: Movement of molecules from high to low concentration due to continuous motion of molecules.
    • Permeability: Cell walls and membranes allowing substances to pass through.
      • Permeable: Allows water and mineral salts.
      • Impermeable: Does not allow water or mineral salts.
      • Semi-permeable (Selective Permeability): Allows passage of water but controls the passage of salts, preventing large molecules like sugars and amino acids.
        • Examples: Cellulose walls, walls covered by lignin, cutin, or suberin, plasma membranes.
    • Osmosis: Passage of water molecules through a semi-permeable membrane from high to low water concentration (low to high solute concentration).
      • Osmotic Pressure: Pressure caused by differences in solute concentrations across a membrane.
    • Imbibition: Absorption of water by solid particles, causing an increase in volume.

    Osmosis and Imbibition

    • Osmosis: Movement of water across semi-permeable membranes from high to low water concentration.
      • Osmotic pressure is directly proportional to the concentration of solutes.
    • Imbibition: Absorption of water by solid particles, especially colloidal ones, causing swelling.
      • Examples: Plant cell walls (cellulose, pectin, protoplasmic proteins).

    Examples of Semi-permeable Barriers

    • Cellulose/Cellulose walls
    • Walls covered by lignin, cutin or suberin
    • Plasma membranes

    Mechanism of Mineral Salt Absorption

    • Diffusion: Solute molecules (element ions) diffuse independently from high to low concentration.
      • Positive ions (cations), such as K⁺ and Ca²⁺.
      • Negative ions (anions), such as (SO₄)²⁻, (NO₃)⁻, (NO₂⁻) and (Cl⁻).
      • They pass through the wet cellulose cell walls.
    • Selective permeability: Ions are selected and allowed to pass through the semi-permeable plasma membrane based on the plant's need, regardless of their size, concentration, or charge.
    • Active transport: Ions diffuse from low to high concentration, requiring energy.
      • Plant cells actively absorb ions based on their needs.

    Active Transport Phenomenon

    • Ions move from low to high concentration, requiring chemical energy.
    • Demonstrated by an experiment with Nitella algae showing higher concentration of ions in the cellular sap compared to the surrounding water.

    Chloroplast Structure and Function

    • Responsible for photosynthesis in plant cells.

    Chloroplast Pigments

    • Chlorophyll (A): Bluish green, approximately 70%.
    • Chlorophyll (B): Yellowish green, approximately 25%.
    • Xanthophyll: Lemon yellow.
    • Carotene: Orangish yellow, approximately 5%.

    Chloroplast Structure:

    • Double-thin external membrane, approximately 10 nanometers thick.
    • Matrix (stroma): Colorless protein substance containing starch granules.
    • Grana: Disc-shaped structures embedded in the stroma, interconnected by membranes.
      • Granum diameter: approximately 0.5 micron.
      • Granum thickness: approximately 0.7 micron.
      • Grana consist of 15 or more hollow discs stacked above each other.

    Importance of Chlorophyll

    • Absorbs light energy required for photosynthesis.

    Life Application:

    • The color of pepper fruits is determined by the pigments present in the cells.
      • Green peppers contain chlorophyll.
      • Yellow peppers contain carotenoids.
      • Orange peppers contain carotenes.

    Structure of a Leaf

    • Upper and Lower Epidermis: Single layer of flattened cells covered with a waxy layer called cutin.
      • The upper epidermis is transparent to allow sunlight to pass through.
      • The lower epidermis contains stomata for gas exchange.
    • Mesophyll Tissue: Between the upper and lower epidermis, composed of palisade and spongy cells.
      • Palisade cells: Cylindrical and elongated, packed with chloroplasts, located in the upper part of the leaf.
      • Spongy cells: Loosely arranged, containing some chloroplasts, located in the lower part of the mesophyll.
    • **Vascular Tissue:**Contains vascular bundles made up of xylem and phloem.
      • Xylem: Transports water and minerals upwards.
      • Phloem: Transports food downwards.

    Mesophyll Tissue

    • Palisade Layer: One row of cylindrical and elongated parenchyma cells, tightly packed with chloroplasts, maximizing light absorption.
    • Spongy Layer: Irregular-shaped, loosely arranged parenchyma cells, allowing for gas exchange and movement of water and nutrients.

    Vascular Tissue

    • Contains numerous vascular bundles extending inside the veins and venules.
      • Xylem: Found in vertical rows, separated by parenchyma cells, transporting water and minerals upwards.
      • Phloem: Follows the xylem towards the lower leaf surface, transporting food downwards.

    Mechanism of Photosynthesis

    • Source of the Evolved Oxygen During Photosynthesis: Water is the source of oxygen in photosynthesis.
      • Green and Purple Sulfur Bacteria: Use hydrogen sulfide as the hydrogen source and bacteriochlorophyll.
        • Light Reactions: Light energy breaks down hydrogen sulfide into hydrogen and sulfur.
        • Dark Reactions: Hydrogen reduces carbon dioxide to create carbohydrates.
      • Green Plants: Use water as the hydrogen source and chlorophyll.
        • Light Reactions: Light energy breaks down water into hydrogen and oxygen.
        • Dark Reactions: Hydrogen reduces carbon dioxide to create carbohydrates.

    Light Reactions

    • Take place in the grana of chloroplasts, with light as the limiting factor.
    • Steps:
      1. Light strikes chlorophyll, causing electrons to gain energy.
      2. Kinetic energy is stored as chemical potential energy in chlorophyll.
      3. Energy is released as electrons return to their original energy levels.
      4. Energy is used to split water molecules. Hydrogen combines with NADP+ to form NADPH₂, and oxygen is released.
      5. Remaining energy is used to create ATP from ADP and a phosphate group.

    Definitions:

    • ATP: Adenosine triphosphate (energy currency).
    • ADP: Adenosine diphosphate.
    • NADPH₂: Hydrogen carrier/coenzyme.
    • NADP⁺: Nicotinamide adenine dinucleotide phosphate.

    Absorption of Mineral Salts

    • Plants need essential elements besides carbon, hydrogen, and oxygen, absorbed through the roots.
    • Shortage can lead to disturbed vegetative growth or lack of flowers and fruits.

    Macro-Nutrients

    • Needed in considerable quantities.
      • Nitrogen (N)
      • Phosphorus (P)
      • Potassium (K)
      • Calcium (Ca)
      • Magnesium (Mg)
      • Sulfur (S)

    Micro-Nutrients

    • Needed in small quantities.
      • Manganese (Mn)
      • Zinc (Zn)
      • Boron (B)
      • Aluminum (Al)
      • Chlorine (Cl)
      • Copper (Cu)
      • Molybdenum (Mo)
      • Iodine (I)

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    Description

    This quiz explores the mechanisms involved in water absorption, including diffusion, osmosis, and imbibition. It also delves into the concepts of permeability and osmotic pressure, detailing how these processes facilitate water movement in cells. Test your understanding of these fundamental biological principles.

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