Botany Study Notes PDF

# Botany ## General Botany - Botany is a branch of biology that deals with plant life. - Botany is considered a discipline within biology concerned with the study of organisms known as plants. ### What is a plant? - A multicellular, eukaryotic organism. - Generally lacks sensory organs and volun...

# Botany ## General Botany - Botany is a branch of biology that deals with plant life. - Botany is considered a discipline within biology concerned with the study of organisms known as plants. ### What is a plant? - A multicellular, eukaryotic organism. - Generally lacks sensory organs and voluntary motion. - A complete plant typically has a root and shoot system. - Performs photosynthesis, using sunlight to produce its own food. ### Importance of plants - **Food:** Plants are an essential source of energy for all organisms. - **Air:** They release oxygen as a byproduct of photosynthesis. - **Water:** Plants play a major role in the water cycle. - **Habitat:** They form a major part of natural habitats. - **Medicine, Chemicals, and Dyes:** Plants provide raw materials for these. - **Climate:** Help recycle CO2, impacting climate. ## Botanical Disciplines 1. **Morphology:** Study of the structure and development of a plant that is concerned with its external appearance. 2. **Cytology:** Study of structure and function within a cell. 3. **Anatomy:** Study of a plant's internal structure and functions. 4. **Plant Physiology:** Study of internal processes, including nutrition, environmental effects, plant product, and growth and development events. 5. **Systematics:** Identification, classification, and evolutionary relationships of plants. 6. **Genetics:** Study of inheritance and variation in plants. 7. **Phycology:** Study of algae. 8. **Mycology:** Study of fungi. 9. **Bacteriology:** Study of bacteria. 10. **Plant Ecology:** Study of environmental influences on plant communities or individual plants. 11. **Biotechnology:** Using biological organisms to create useful products. Plant biotechnology focuses on inserting desirable genes into plants and ensuring those genes are expressed. ## Types of Plants 1. **Vascular Plants:** Have tubular systems (phloem + xylem) for circulating water and nutrients. Examples include ferns, conifers, and flowering plants. 2. **Non-Vascular Plants:** Lack vascular tissue and grow close to the ground, such as mosses. ## Modes of Nutrition in Plants ### Nutrients - Chemical substances that provide nourishment to living organisms. ### Autotrophs - Organisms that use CO2 as their carbon source to create organic food through photosynthesis. ### Heterotrophs - Organisms unable to perform photosynthesis; they rely on organic compounds from autotrophs. ## Types of Heterotrophic - **Parasites:** Obtain nutrition from other plants through physical contact, e.g., Cuscuta (dodder). - **Saprophytes:** Derive nutrition from dead or decaying organic matter, e.g., fungi. - **Insectivorous Plants:** Partially autotrophic and partially heterotrophic; obtain nutrients by trapping insects, e.g., Pitcher plants and Drosera. ## Symbiotic association - Two organisms live in close physical contact. - Both organisms benefit mutually from the association. ### Examples: - **Lichen:** A partnership between algae and fungi. - **Mycorrhizae:** A relationship between fungi and plant roots. ### Lichen: - Symbiotic relation between fungi and algae. - Lichen breaks down rock into soil. - Food source for some animals. - Used as a source for dyes. ### Mycorrhizae: - Mutualistic association between a fungus (myco) and plant roots (rhiza). - Symbiotic relationship beneficial to both organisms. - The plant gains improved soil exploration through fungal hyphae, enhancing water and nutrient uptake. - The fungus uses carbon from the plant for its growth, development, and physiological function. ## Plant Cell - **cytoplasm:** Includes the cytosol and organelles. - **cytosol:** The cell membrane (cytosol is a gel-like substance within the cell) is also known as intracellular fluid (ICF) or cytoplasmic matrix. ### Protoplasm: - Living contents of a cell surrounded by a plasma membrane. - Parts of the cell: plasma membrane + protoplasm. - **Protoplast:** Plasma membrane + protoplasm. ### Plasma Membrane Functions: - Represents the boundary between the living and nonliving world. - Selectively permeable, allowing some materials to pass through while blocking others. - Controls the exchange of materials between the cell and its environment. - Maintains essential differences between the cell and its surroundings. ## Composition of Biological Membrane - **Lipids:** The most abundant in membranes, including phospholipids, fats, oils, and glycolipids. - **Amphipathic molecules:** With two hydrophobic (non-polar) hydrocarbon tails and hydrophilic (polar) head. - The bilayer structure provides two key properties. - **High fluidity** - **Impermeability to most polar molecules** - **Proteins:** Make up 50% of the membrane by weight. - **Integral proteins:** Embedded within the bilayer. - **Peripheral proteins:** Bound to hydrophilic surfaces. - **Intrinsic proteins:** May be single proteins or large complexes with non-protein components. - Functions - Act as enzymes. - Aid in selective transport of solute molecules across the cell. ## Cytoplasm - Includes the cytosol and organelles. - **Cytosol:** The cell membrane (cytosol is a gel-like substance within the cell) is also known as intracellular fluid (ICF) or cytoplasmic matrix. ### Organelles - **Vacuole:** Large and centrally located in mature cells. - Can occupy 80-90% of cell volume in mature cells. - Surrounded by a membrane called vacuolar membrane. - Contains various substances: - Inorganic ions - Organic acids - Sugars - Enzymes - Secondary metabolic products (pigments). - The high solute content in the vacuole aids in water uptake needed for cell enlargement. - Young, actively dividing cells usually contain multiple small vacuoles. - As the cell matures, these small vacuoles merge and expand to form a single large vacuole- typical of mature cells. ## Endoplasmic Reticulum (ER) - A single, highly convoluted membrane continuous with the outer nuclear envelope. - Has a lumen (central structure) surrounded by double membrane. ### Types of Endoplasmic Reticulum (ER) - **Rough ER:** Contains ribosomes; synthesizes proteins that move through the membrane into the lumen, where they transition to the smooth ER for modification and glycoprotein formation. - **Smooth ER:** Major site for lipid biosynthesis and membrane formation. ## Golgi Complex - Consists of stacks of flattened, membranous sacs called cisternae. ### Functions of the Golgi Complex: - It assembles and processes carbohydrate (oligosaccharide) chains that are transferred to it from the ER via transport vesicles. - Transport vesicle membranes fuse with Golgi membranes, delivering their contents to Golgi cisternae, where sugar chains are modified, enlarged, and additional sugars are added. - Modified glycoproteins leave the Golgi Complex in secretory vesicles, which deliver their contents to: - Sites inside the cell for protein storage (protein bodies). - The plasma membrane for discharge. - It synthesizes complex polysaccharides that constitute the cell wall matrix. - Delivers those polysaccharides to the site of wall formation in dividing and growing cells.