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Week 11, Types of leaves, Explain:, image - Coggle Diagram

- - - - Simple Tissue, made up of one cell type, but does lots of different jobs
        
        Parenchyma = thin-walled singlle cell wall, abundant, and highly flexible ground tissue.
      - Leaf parenchyma is filled with chloroplasts, making these cells the primary cells for photosynthesis.
      - Organs unlike leaves, like roots or shoots, parenchyma cells store starch particles, granules. So its in both roots and shoots
    - - Shoot support, in stems and leaves
      - Unevenly thickened primary cell wall + longer and thinner than parenchyma
      - Found just under the epidermis, on the outside of the vascular bundles.
      - Not rigid, which prevents tearing in wind exposure
        
        Young plant tissues need support that is strong but flexible because nearby cells are still elongating and the entire region is easily bent by wind. These areas rely on collenchyma, whose thickened yet unlignified primary walls give enough strength to prevent tearing while still allowing the tissue to bend and stretch during growth. If these tissues instead contained sparse patches of rigid sclerenchyma, the elongating cells would end up pushing against isolated “stiff boards” of lignified secondary walls; the mismatch between soft growing tissue and hard, non-stretchable spots would cause cracking or tearing, especially under wind. Once growth ends and the organ no longer needs to stretch, the plant replaces flexible support with abundant, continuous sclerenchyma and lignified xylem to form a mature, rigid framework that resists bending.
      - Only shoots
    - - Sclerids
        
        Protective structures short with variable shapes - form the tough outer layer of seeds and thick nut shells.
      - Fibers
        
        Extremely elongated, support in stems and leaves.
      - These are cells that are dead at maturity, and provide rigidity and support to the plant allowing it to grow tall.
        
        Loose their cytoplasm and become a skeleton
      - Have thick and rigid secondary cell wall with a thin primary cell wall
        
        Primary cell wall = cellulose
        
        Secondary cell wall = lignin
      - Only shoots
    - - Most photosynthesis and carbohydrate storage
      - Synthesis and storage of pigments, hormones, toxins for defense.
    - - they can divide and regenerate, forming new tissues and even an entire plant. This allows them to heal wounds and enable asexual reproduction (e.g., cuttings, callus formation).
        
        Callus = undifferentiated mass formed by the parenchyma dividing. Roots emerge from this callus which allows soil transplant.
  - - - Lack chloroplasts, flattened
      - Secrete Cuticle
        
        the waxy layer formed as a continuous sheet on the surface of leaves and stems
        
        Minimize water loss, protective barrier against viruses and bacteria and parasitic fungi (the first line of defense for the latters)
      - Functions
        
        Protect the plants
        
        Shoots: protections from water loss (cuticle), disease causing agents, herbivores
    - - Ensure that epidermal cells don't prevent gas exchange from occuring. Pores in the dermal tissue formed by two gaurd cells.
        Allow for the movement of O2, CO2, and water vapor between the atmosphere and the interior of the leaf. Movement occurs via diffusion
        
        Open when there is sufficient water in the atmosphere/less risk for water loss and when there is light and when CO2 is needed for for photosynthesis.
        Close when the plant is in a dry atmosphere and faces too many risks from losing water via evaporation
    - - Specialzied epidermal cells that are a hairlike project, found on the shoot systems. Diverse in shape and size and abundance
        
        Functions:
        
        Keep surface cool by reflecting sunlight
        
        Reduce water loss by forming a dense mat that limits the evaporation of water in transpiration
        
        Have barbs that can store toxic compounds which are a put off for herbivores
        
        Can trap and help digest insects.
      - Either unicellular or multicellular
  - - - Responsible for long-distance transport of water and dissolved nutrients within vascular plants, which allow them to grow taller and larger
      - Moves products made and stored in ground tissue
    - - Xylem
        
        The water and ion conducting part of the vascular tissue. Transports contents from root to shoot (unidirectional).
        
        Tracheids
        
        These are tapered cells that allow for the movement of water. They are dead at maturity, and have a secondary cell wall that lignified
        
        Vessel elements
        
        Essentially form a hollow tube, they are dead at maturity, and have no ends, allowing for "unobstructed" water transport.
      - Phloem
        
        tissue that transports nutrients (hormones, amino acids, and other substances) and sugars multi directionally (roots to shoots, or shoots to roots).
        
        Sieve-plate Cells
- - - - Has a tube like structure that has a high surface area to take in as many nutrients and water molecules as possible. Also decreases the diffusion distance to get to the vasculature
      - Continues to grow outwards, so that it can be more anchored to the soil and get access to new soil that is rich with nutrients.
      - Nutrients: nitrogen, phosphorus, potassium, magnesium, dissolved in soil water
        
        Needed to construct and maintain cells, these are the derivations of carbohydrates, proteins, nucleic acid and lipids.
    - - The tube like structure is great for surface area, but its also great for strong structures to anchor the plant in place. The plant takes this "trade off" so that it can anchor better and find more nutrient rich soil.
    - - It means the root xylem forms a continuous, low-resistance tube that moves water upward by tension. Water enters root hairs by osmosis, moves through the cortex into the vascular cylinder, then is pulled up the xylem toward the leaves because transpiration creates negative pressure at the top.
- - - - These are nodes where leaves attatch straight to the stem, which form form right above the site of leaf attatchment.
      - Can develop into flowers or other reproductive structures in "correct conditions"
    - - In between areas where the leaf attatches
    - - Where the leaf attatches
        
        Increases flexibility and reduces damage from wind or herbivory
    - - Photosynthetic organ that extends lterally from the stem on a stalk called the petiole.
      - Function: flat with a large surface are which can be used to absorb more light and exchange more gases with the atmosphere to allow for photosynthesis and cellular respiration.
        CO2, required for photosynthesis, can easilly diffuse to the photosynthetic cells in the leaf through the pores of the leaf.
        
        This idea is backed by fick's law.
  - - - Also circulates hormones, ions and other particles in these elements, its the "circulatory system"
- - - - Has large surface areas, stomata, that allow for efficient exchange of gases and increased light absorption for photosynthesis.
        
        Specifically, high surface area to volume ratio, analogous to alveoli in the sense that it maximizes surface area of the respiratory surface, increasing the A variable in fick's law, which increases the diffusion of gases into the plant and an increase in photosynthesis.
- - - - Provides a rigid structure outside the plasma membrane, porus so items can still make it through.
        
        Cellulose-rich primary cell wall for support and shape
        
        Some plants have a rigid secondary cell inside the primary one.
    - - small cytoplasm channels between plant cells, like a tunnel, which include some organelles (like the ER).
        
        Passes through cell wall gaps
    - - Chloroplasts
        
        Site of photosynthesis
      - Large Vacuole
        
        Vacuoles store waste, water, nutrients, pigments, or poisons, and can digest waste like animal lysosomes.
        
        Vacuoles store waste, water, nutrients, pigments, or poisons, and can digest waste like animal lysosomes.