exam 2 bio 1104
Based on the provided presentation slides, here is a note outline that answers your questions about plant anatomy:
I. Basic Plant Structure: Organs
The three organs found in flowering plants (Angiosperms) are:
* Leaves
* Stems
* Roots
II. Plant Tissues
The three basic tissue types found in flowering plants are Dermal tissue, Ground tissue, and Vascular tissue. These tissues are found in all three plant organs (roots, stems, and leaves).
A. Dermal Tissue
* Primary function: Protection and absorption (especially in roots). It covers and protects the surface of the plant.
* Location: The outermost layer of the plant, like plant skin.
* Structures and Functions:
* Waxy protective layer (Cuticle): Secreted by the dermal tissue to provide a protective layer.
* Trichomes: Small hairs found on the dermal layer. Their function is to deter herbivores and maintain moisture.
* Stomata: Tiny pores (holes) bordered by guard cells, found in the dermal tissue.
* Function of Stomata: To let Carbon dioxide in and oxygen out. This facilitates gas exchange in stems and leaves.
B. Ground Tissue
* Main Functions:
* Responsible for most photosynthesis (especially in leaves).
* Store products of photosynthesis (food storage).
* Provide support.
* Location: Found between the dermal and vascular tissues. It makes up the majority (bulk) of the tissue within plants.
* Three Main Types:
* Parenchyma: Food storage cells. Responsible for photosynthesis and hormone production.
* Collenchyma: Flexible structural cells. They enable the plant to twist and bend.
* Sclerenchyma: Rigid structural cells. They have very thick cell walls containing lignin and function to resist the force of gravity (like steel girders).
C. Vascular Tissue
* Main Function: Transportation of materials throughout the plant (like arteries and veins).
* Two Types:
* Xylem: Transports water and minerals. Flow is one-way only, from the roots up.
* Phloem: Transports water and food (products of photosynthesis). Flow is two-way.
III. Plant Organs
A. Roots
* Three Main Functions:
* Absorb water and minerals from the soil.
* Anchor the plant in place.
* Note: Roots also have functions related to absorption and protection via the dermal tissue, and support/storage via the ground and vascular tissues.
* Root Types:
* Taproot: Characterized by a single, large, central root (e.g., the dandelion plant shown).
* Fibrous Roots: Characterized by a network of many small roots (e.g., the grass plant shown).
* Note: Monocots typically have fibrous roots, and Eudicots (a type of dicot) typically have taproots, but this specific detail about the monocot/dicot distinction for root type is not explicitly provided in the notes.
* Basic Structure (Root Anatomy):
* The vascular tissue (xylem and phloem) is typically located in the center (forming a "vascular bundle").
* The center is surrounded by ground tissue (e.g., the cortex and pith).
* The entire structure is covered by an outer layer of Dermal tissue (epidermis).
* Root Hairs greatly increase the surface area for absorption.
B. Stems
* Three Main Functions:
* Provide structural support for the plant.
* Position leaves so that they can be exposed to sunlight for photosynthesis.
* Conduct food, water, and nutrients throughout the plant.
* Basic Structure (Stem Anatomy):
* An outer layer of dermal tissue.
* Mostly ground tissue (cortex and pith).
* Vascular bundles (containing xylem and phloem) scattered throughout the ground tissue (in a monocot stem) or arranged in a ring (in a eudicot stem).
C. Leaves
* Main Function: The primary site of photosynthesis, which is the conversion of energy from the sun into food for the plant.
* Leaf Anatomy Notes:
* Waxy Cuticle: A protective layer on the epidermis.
* Photosynthetic Cells: Includes palisade mesophyll and spongy mesophyll cells (ground tissue).
* Vascular Tissue: Xylem and Phloem located in the veins.
* Stomata: Found on the epidermis, often on the lower surface, bordered by guard cells.
* Function of Stomata: To let Carbon dioxide in and oxygen out.