Botany Introduction PDF

# Botany ## Biology & Botany - Biology is defined as the study of life. - Botany is the scientific study of plants and plant-like organisms. - Botany helps us understand why plants are important to the world. - Plants provide the basis for most food and energy chains, and they provide us with oxyge...

# Botany ## Biology & Botany - Biology is defined as the study of life. - Botany is the scientific study of plants and plant-like organisms. - Botany helps us understand why plants are important to the world. - Plants provide the basis for most food and energy chains, and they provide us with oxygen, food, and medicine. ## Types of Plants ### Plants1 - Photosynthetic organisms which use light, water, and carbon dioxide to make organic compounds and oxygen. - Defined ecologically by their role in nature. - Some Plants1 can be bacteria or even animals. - One example is a green slug (Elysia chlorotica) which collects chloroplasts from algae (Vaucheria litorea) and uses them for food production. ### Plants2 - All organisms from the _Plantae_ kingdom. - Usually green organisms with a stem and leaves. - Defined as multi-tissue, primarily terrestrial, and photosynthetic eukaryotes. - The definition is taxonomical (based on evolution), but some Plants2 organisms may not be Plants1. - Fully parasitic plants: - Mycoparasites: Pterospora - Root parasites: Hydnora - Stem parasites: Cuscuta - Internal parasites: Pilostyles ## Organisms Have Levels of Organization - Chemical level: atoms and molecules. - An atom is the smallest unit of a chemical element. - Cellular level: cells. - Cells are composed of atoms and molecules that associate with each other. - Tissue level: tissues. - Tissues are composed of similar cells working to perform a specific function. - Organ level: organs. - Organs are composed of different tissues working together. - Organ system level: organ systems. - Organ systems are composed of multiple organs working together. - Organism level: organisms. - Organisms are composed of multiple organ systems working together. ## Levels of Ecological Organization - Organisms interact to form more complex levels of organization: - Population: All members of a species living in the same geographic area at the same time. - Community: Populations of various types of organisms that inhabit a particular area. - Ecosystem: A community, together with its nonliving environment. - Biosphere: All of Earth's ecosystems together. ## Biology & Binomial Systems - Biologists use a binomial system for naming organisms. - Biologists have identified about 1.8 million species of extant organisms and estimate that several million more remain to be discovered. ## Taxonomy - Taxonomy is the science of naming and classifying organisms. - Plant Taxonomy is the science of classifying and identifying plants. - Scientific names are necessary because the same common name is used for different plants in different areas of the world. ## The Linnaean System of Classification - Developed by Carolus Linnaeus, a Swedish botanist, during the 18th century. - A hierarchical system of naming and classifying organisms. - Still used today, but with some modifications. - Composed of a hierarchy called _taxa_, which is a grouping of organisms. - _Taxa_ range from kingdom to species: - Kingdom: The broadest level of organization, including organisms that share only a few basic similarities. - Species: The most specific level of organization, including only organisms that can produce fertile offspring together. - Closely related species are grouped together into a _genus_. - The _Linnaean system_ is known as the _binomial system of nomenclature_, because each species is assigned a two-part name: - The first part of the name is the _genus_; the generic name is always capitalized. - The second part is the _specific epithet_ which designates a particular species belonging to a particular genus; it is not capitalized. - Both names are always italicized or underlined. ## The International Code of Botanical Nomenclature (ICBN) - Proposed by botanists to ensure a stable and universal system for naming plants. - An essential process to overcome the problems of common names. - The botanists agreed to lay down certain rules and conditions: - The main suggestion is that language should be in Latin (as it is not a national language of any country and is a dead language). ## The ICBN - History - The ICBN is an agreement between botanists around the world to follow the binomial system of naming. - Before the middle of the 18th century, the names of plants were polynomials, which are names consisting of several words. - Carl Linnaeus proposed rules in his 1751 book _Philosophia Botanica_ regarding plant nomenclature. - In 1813, A.P. de Candolle proposed details of the rules regarding plant nomenclature in his book _Théorie Elémentaire de la Botanique_. - In 1867, Alphonse de Candolle (son of A.P. de Candolle) convened a meeting of botanists to present these rules, which became known as the Paris Code. ## Taxonomy, Systematics, and Classification - These terms have similar meanings. - They all concern the diversity of living organisms, of which there are more than 2,000,000 species (with around 300,000 belonging to the _Plantae_ kingdom). ## Phylogenetics - Phylogenetics emphasizes the evolutionary history (phylogeny) of taxonomic groups. - Plant taxonomy is a hierarchical classification system based on morphological and phylogenetic similarities among plants. ## Classification, Nomenclature, and Hierarchy - Classification: A grouping of organisms according to shared characteristics. - Nomenclature: A formed system of names attached to taxonomic groups. - Hierarchy: A system of grouping in which each classification is a subset of a superior grouping and may contain subordinate categories. - Morphology: The appearance (shape and structure) of plants. - Phylogeny: Ancestral evolutionary relationships among plants. ## Taxonomy Ranks - Most scientists accept seven main levels of taxonomy (ranks): 1. Kingdom 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species ## Three Domains - The tree of life includes three domains and several kingdoms. - Biologists classify organisms based on evolutionary relationships. - A clade is a group of organisms with a common ancestor. - Systematists have developed a tree of life, which is a family tree showing evolutionary relationships among organisms. - These relationships are based on shared characteristics, including structural, developmental, behavioral, and molecular similarities. - The three domains are: - Bacteria - Archaea - Eukarya ## Prokaryotic Domain - Bacteria have long been recognized as unicellular prokaryotic cells, which differ from all other organisms (except archaea) in that they are prokaryotes. - Carl Woese was a pioneer in developing molecular approaches to systematics. - He argued, on the basis of differences in 16S rRNA genes, that bacteria, archaea, and eukaryotes each arose separately from an ancestor with poorly developed genetic machinery, called the progenote. - He treated each as a domain, which are divided into several different kingdoms. - He originally split prokaryotes into _eubacteria_ (now bacteria) and _archeabacteria_ (now archaea). - Woese initially used the term _kingdom_ to refer to these three primarily phylogenetic groupings, and this nomenclature was widely used until the term _domain_ became widely adopted in 1990. ## Two Kingdoms of Prokaryotes - Bacteria & Archaea. - The two kingdoms of prokaryotes correspond to these domains: - Kingdom Archaea corresponds to domain Archaea. - Kingdom Bacteria corresponds to domain Bacteria. ## Viruses - Viruses are not living things, but merely pieces of DNA or RNA that have "gone astray" from the cells of living organisms. ## Eukaryotic Domain - The remaining kingdoms and groups belong to the _Eukarya_ domain. ## The Main 4 Kingdoms - Protists: Unicellular, colonial, or simple multicellular organisms that have a eukaryotic cell organization. - Examples: algae, slime molds, amoebas, and ciliates. - Plantae: Complex multicellular organisms adapted to carry out photosynthesis. - Examples: mosses, ferns, conifers, and flowering plants. - Fungi: Composed of yeasts, mildews, molds, and mushrooms. - Animalia: Multicellular organisms that obtain their nutrition by eating other organisms. ## Ranks and Ending of Taxa Names - The plant kingdom is divided into a number of categories that differ in their rank and size. - In biological classification, rank is the level (the relative position) in a taxonomic hierarchy. - Ranks are used to compare taxonomic groups (taxa) from different major groups. - Taxonomic ranks are: - Species - Genus - Family - Order - Each rank subsumes a number of less general categories. - A basic unit in plant classification is a _species_. - A _genus_ is a group of closely related species. - A _family_ is a group of closely related _genera_ and ends with _aceae_. - An _order_ is a group of closely related families and ends with _ales_. ## Exception - Some families do not end with _aceae_ and are provided with alternative names. - Examples: - Cruciferae: Brassicaceae ## Binomial System - The first word in a binomial name is the _generic name_ which is always capitalized, and in the singular form. - The generic name may be based on the following things: - In honor of a botanist: _Linnea_ for _Linnaeus_ - To express some feature of the plant: _Adansonia_ (from the features of the Baobab tree). - After a particular geographical area: _Pterospermum_ (from the winged seeds) or _Araucaria_ (from the Arauco province of Chile. - The second word is the _specific epithet_ which is always in the lower case and is an _adjective_ describing the species. ## Plant Kingdom - _Plantae_ - The _Plantae_ kingdom includes all plants, which are eukaryotic, multicellular, and autotrophic organisms. - The plant cell contains a rigid _cell wall_. - Plants also have chloroplasts which contain _chlorophyll_, which is necessary for _photosynthesis_. - The _Plantae_ kingdom contains more than 300,000 species, which are often divided into subgroups. ## Plant Kingdom Subgroup Classification - The _Plantae_ kingdom is classified into subgroups according to the following criteria: 1. **Plant body:** Presence or absence of a well-differentiated plant body (e.g., root, stem, and leaves). 2. **Vascular system:** Presence or absence of a vascular system to transport water and other substances (e.g., phloem and xylem). 3. **Seed formation:** Presence or absence of flowers and seeds; whether seeds are naked or enclosed in a fruit. ## Cryptogams - Less evolved seedless plants that reproduce by the production of spores. ## Phanerogams - Highly evolved plants that bear flowers and seeds for reproduction. ## Classifying the Plant Kingdom into Subgroups - Five subgroups: 1. **Thallophyta** - Primitive plants where the body is not differentiated. 2. **Bryophyta** - Small, non-vascular plants that prefer moist environments. 3. **Pteridophyta** - Vascular plants that disperse spores. 4. **Gymnosperms** - Have a well-differentiated plant body and vascular tissues; bear naked seeds (not enclosed within a fruit). - Examples: _Cycas_, _Pinus_, and _Ephedra_ - Conifers are gymnosperms that bear cones instead of flowers and are pollinated by the wind. 5. **Angiosperms** - Seed-bearing vascular plants with a well-differentiated plant body; have seeds enclosed within the fruit. - Angiosperms are further divided into _monocotyledons_ (Magnoliopsida) and _dicotyledons_ (Liliopsida) according to the number of cotyledons present in the seeds. - Examples: mango, rose, tomato, onion, wheat, maize, etc. ## Styles of Life and Basic Chemistry - Organisms obtain energy in a few ways: 1. From sunlight. 2. From chemical reactions with inorganic matter. 3. From breaking organic molecules into inorganic molecules, typically carbon dioxide and water. ## Mode of Nutrition - Plants can be divided into two groups on the basis of their mode of nutrition: 1. **Autotrophic nutrition:** - Organic compounds are manufactured from available inorganic raw material. - Two types: - **Phototrophic nutrition:** Organic molecules are manufactured from simple inorganic molecules using light energy (e.g., green plants, photosynthetic bacteria). - Photosynthetic bacteria are unique because they are the only organisms that can synthesize carbohydrates without chlorophyll. - **Differences between photosynthetic bacteria and green plants:** - Photosynthetic bacteria grow in sulfide springs where H2S is present. - Hydrogen is provided by H2S instead of H2O. - Free oxygen is not released as a product. - The process takes place at a lower expenditure of energy. - **Chemotrophic nutrition (chemosynthesis):** Organic molecules are manufactured from simple inorganic molecules by using energy produced by the oxidation of ferrous ions and other inorganic substances like ammonia, nitrates, and nitrites. 2. **Heterotrophic nutrition:** - Plants are not capable of manufacturing their own organic molecules so they rely on external sources of organic molecules. - Heterotrophic plants depend on other organisms for their food. ## Classification of Heterotrophic Plants - **Parasitic plants:** Depend on living plants or animals for their nutritional requirements. - **Saprophytic plants:** Depend on dead or rotten organic remains of plants or animals. ## Special Mode of Nutrition: Carnivorous or Insectivorous Plants - Carnivorous plants have insects and small birds as their prey. - They are partially autotrophic and partially heterotrophic. - They contain chloroplasts and chlorophyll which mean that they are capable of making their own food, but they cannot synthesize nitrogenous compounds or proteins. - They are classified as carnivores, because they obtain the nitrogen they need from insects and other small organisms. - Good Luck!