IGCSE Biology 7 Views 1 Answers
Identify in diagrams and images the following structures in the leaf of a dicotyledonous plant: chloroplasts, cuticle, guard cells and stomata, upper and lower epidermis, palisade mesophyll, spongy mesophyll, air spaces, vascular bundles, xylem and phloem
Identify in diagrams and images the following structures in the leaf of a dicotyledonous plant: chloroplasts, cuticle, guard cells and stomata, upper and lower epidermis, palisade mesophyll, spongy mesophyll, air spaces, vascular bundles, xylem and phloem
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The structures found in the leaf of a dicotyledonous plant can be identified and described as follows, based on the provided search results:
Structures in a Dicotyledonous Leaf
- Chloroplasts
- Description: Chloroplasts are organelles containing chlorophyll, which is essential for photosynthesis.
- Location: Predominantly found in the mesophyll cells, especially in the palisade mesophyll layer, where they are densely packed to maximize light absorption.
- Cuticle
- Description: The cuticle is a waxy layer that covers the outer surface of the leaf.
- Function: It serves to reduce water loss by preventing evaporation and protecting against environmental damage.
- Guard Cells
- Description: Guard cells are specialized cells that surround each stoma (the pore).
- Function: They regulate the opening and closing of stomata, controlling gas exchange (CO₂ in and O₂ out) and water vapor loss.
- Stomata
- Description: Stomata are small openings found primarily on the lower epidermis of the leaf.
- Function: They facilitate gas exchange between the leaf and the atmosphere, allowing carbon dioxide to enter for photosynthesis and oxygen to exit.
- Upper Epidermis
- Description: The upper epidermis is a single layer of cells on the top surface of the leaf.
- Function: It provides protection and is covered by a cuticle to minimize water loss.
- Lower Epidermis
- Description: The lower epidermis is similar to the upper epidermis but typically contains more stomata.
- Function: It also serves as a protective layer and facilitates gas exchange through stomata.
- Palisade Mesophyll
- Description: This layer consists of tightly packed, elongated cells located just beneath the upper epidermis.
- Function: It contains a high density of chloroplasts, making it the primary site for photosynthesis.
- Spongy Mesophyll
- Description: Located beneath the palisade mesophyll, this layer has loosely arranged cells with many air spaces.
- Function: The air spaces facilitate gas exchange within the leaf, allowing CO₂ to diffuse to photosynthesizing cells.
- Air Spaces
- Description: These are intercellular spaces found within the spongy mesophyll.
- Function: They allow for efficient gas exchange and help maintain buoyancy in aquatic plants.
- Vascular Bundles
- Description: Vascular bundles are composed of xylem and phloem tissues arranged together.
- Function: They transport water and nutrients (xylem) from roots to leaves and distribute sugars produced during photosynthesis (phloem) throughout the plant.
- Xylem
- Description: Xylem is a type of vascular tissue that transports water and dissolved minerals.
- Location: Typically located towards the upper part of vascular bundles in leaves.
- Phloem
- Description: Phloem is another type of vascular tissue responsible for transporting sugars and other metabolic products.
- Location: Positioned below the xylem within each vascular bundle.
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