Plant Groups Notes (LAB EDITION) PDF

WORKSHEET 1: Major Plant Groups: 1. Liverworts - Non-vascular plants. - Grow in moist habitats, often found near water. - Do not have true roots, stems, or leaves. - Reproduce via spores, not seeds. - Typically small, flat plants with a thallus (leaf-like structure). - Have structures cal...

WORKSHEET 1: Major Plant Groups: 1. Liverworts - Non-vascular plants. - Grow in moist habitats, often found near water. - Do not have true roots, stems, or leaves. - Reproduce via spores, not seeds. - Typically small, flat plants with a thallus (leaf-like structure). - Have structures called rhizoids to anchor themselves to surfaces. - Found in environments such as damp forests, riverbanks, and wetlands. 2. Hornworts - Non-vascular plants. - Named for their horn-like sporophyte (reproductive structure). - Thrive in damp, humid conditions. - Like liverworts, they lack true roots, stems, and leaves. - Use rhizoids for attachment and water absorption. - Reproduce via spores produced in horn-shaped structures. - Often found in tropical and temperate regions. 3. Mosses - Non-vascular plants that rely on direct water absorption. - Have small leaf-like structures surrounding a central stem. - Grow in dense mats in moist, shaded areas. - Use rhizoids to anchor themselves but lack true roots. - Reproduce via spores produced in capsules at the tips of stalks. - Help prevent soil erosion by covering large areas of ground. - Common in forests, wetlands, and on rocky surfaces. 4. Ferns - Vascular plants (have true roots, stems, and leaves). - Reproduce via spores, not seeds. - Have large fronds (leaves) that are often divided into smaller leaflets. - Typically grow in moist, shady environments like forests. - Ferns have a distinct life cycle that includes both sporophyte and gametophyte stages. - Often found in both temperate and tropical regions. 5. Conifers - Vascular plants; part of the gymnosperm group. - Produce cones (both male and female) instead of flowers. - Seeds are not enclosed in a fruit; they are exposed on scales of the cones. - Have needle-like or scale-like leaves.  - Often evergreen, retaining their leaves throughout the year. - Include species like pines, spruces, firs, cedars, and redwoods. - Adapted to survive in colder, harsher environments. 6. Cycads - Ancient seed plants with a long fossil history (gymnosperms). - Have large, compound leaves and grow in a crown formation. - Often mistaken for palms due to similar appearance. - Primarily found in tropical and subtropical regions. - Produce large cones for reproduction. - Many cycads are endangered due to habitat loss. 7. Ginkgo - Only one living species remains: *Ginkgo biloba*. - Classified as a gymnosperm. - Known for its fan-shaped, lobed leaves that turn yellow in the fall. - Ginkgo trees are resistant to pollution and can live for hundreds of years. - Reproduces via seeds, but not enclosed in fruits. - Ginkgo seeds have a fleshy outer layer, often mistaken for fruit. - Native to China and widely planted in urban areas worldwide. 8. Angiosperms - The largest and most diverse plant group, also known as flowering plants. (250,000 species) - Produce flowers for reproduction. - Seeds are enclosed within a fruit, which develops from the ovary. - Divided into two major groups: monocots (one seed leaf) and dicots (two seed leaves). - Can be herbaceous or woody and grow in a variety of habitats. - Dominant plant group in most ecosystems, including forests, grasslands, and gardens. - Includes crops, fruits, ornamental plants, and trees. - Highly specialized pollination mechanisms involving insects, wind, or animals. Key Terms and Definitions: 1. **Systematics** - The scientific study of the diversity and relationships among organisms, encompassing the classification and naming of plants. 2. **Identification** - The process of associating an unknown plant with a known entity through various methods, including specimen comparison, taxonomic keys, and expert determination. 3. **Taxonomy** - The branch of science concerned with classification, especially of organisms; systematic biology. 4. **Taxonomic Key** - A tool used to identify organisms based on a series of choices between two characteristics (a dichotomous key). Each step in the key narrows down the possible species until an identification is made. 5. **Cladogram** - A simplified version of a phylogenetic tree that emphasizes the branching patterns of evolution, without necessarily representing the time or genetic distance between species. 6. **Phylogenetic Tree (Cladogram)** - A branching diagram that represents the evolutionary relationships among different species or groups. It shows how species are related through common ancestry, based on shared characteristics. 7. **Couplet** - A pair of contrasting statements or questions in a taxonomic key that lead to different groups or outcomes. Each couplet helps to classify specimens into smaller and more specific categories. 8. **Dichotomous Key** - A step-by-step key that presents two choices at each step, guiding the user toward the identification of an organism. The word "dichotomous" means "divided into two parts," which is the essence of this key's structure. 9. **Indented Key** - A type of taxonomic key where the options are indented and organized in a clear hierarchy. This makes it easier to follow the choices down to a final identification. 10. **Lineage/Clade** - A group of organisms that includes a single common ancestor and all of its descendants. This shows the evolutionary path of a group from a common point. 11. **Common Ancestor** - The most recent species from which two or more species have evolved. It represents a point on the phylogenetic tree where the paths of descendant species diverge. 12. **Divergence** - Refers to the process by which two or more species evolve different traits or characteristics after they branch off from a common ancestor. 13. **Speciation** - The evolutionary process where one species splits into two or more distinct species, usually due to genetic isolation or differing environments or the formation of new and distinct species in the course of evolution. 14. **Monophyletic** - A group on a phylogenetic tree that includes an ancestor and **all** of its descendants, making it a complete branch. 15. **Paraphyletic** - A group that includes an ancestor and **some** but not all of its descendants. This means that some branches of descendants are excluded from the group. 16. **Polyphyletic** - A group that includes species from different branches of the tree without their most recent common ancestor, often due to convergent evolution (where unrelated species evolve similar traits independently). 17. **Character** - A specific trait or feature of an organism that can be used to distinguish it from other organisms (e.g., leaf arrangement, flower color). 18. **Character State** - The specific manifestation of a character in a specimen. For example, if "leaf type" is the character, "pinnately compound" and "opposite" could be two possible character states. 19. **Leaf Arrangement** - The way leaves are positioned on the stem of a plant. Examples mentioned include: - **Opposite** - Leaves are paired at each node, directly across from each other. - **Pinnately Compound** - A type of compound leaf where leaflets are arranged along both sides of a central stem. 20. **Final Key** - The complete taxonomic key that is constructed through the series of couplets. The final key should accurately identify all species under study. 21. **Apomorphy** - A derived or new characteristic that is unique to a particular group or species. 22. **Polythetic Key** - A key that uses multiple characters for identification instead of just one or two. This contrasts with a dichotomous key and may be more flexible but potentially more complex. 23. **Advantages of a Dichotomous Key** - It is simple, easy to follow, and provides clear, step-by-step instructions to identify organisms by presenting only two choices at each step. 24. **Advantages of a Polythetic Key** - It allows for more flexibility in identifying organisms because it doesn't rely on a single distinguishing feature. Multiple characters can be considered simultaneously, which may provide more accurate results in some cases. TABLE 1.3 1. Root Fibrous: - *Allium cepa* - *Bambusa vulgaris* - *Zea mays* Taproot: - *Daucus carota* Tuberous:  - *Ipomoea batatas* 2. Stem Herbaceous: - *Daucus carota* Perennial rhizomes, hollow: - *Bambusa vulgaris* Compressed: - *Allium cepa Monocot, fibrous: - *Zea mays* 3. Leaf Simple, palmately lobed: - *Ipomoea batatas* Alternate, hollow: - *Allium cepa* Hollow, alternating: - *Bambusa vulgaris* Alternate, fibrous: - *Zea mays* 4. Flower Flat-topped umbel: - *Daucus carota* Cypsela/syngin: - *Bambusa vulgaris* 5. Fruit Fleshy orange: - *Ipomoea batatas* Capsule: - *Allium cepa* Seed: - *Zea mays* 6. Dispersal Wind: - *Zea mays* Man: - *Ipomoea batatas* DICHOTOMOUS KEY Terminalia catappa- Talisay Swietenia macrophylla- mahogany Plumeria- Calachuchi Muntingia calabura- manzanitas Azadirachta indica- neem tree FLOWERS Gumamela (Hibiscus rosa-sinensis)  Kingdom: Plantae Phylum: Tracheophyta Class: Magnoliopsida Order: Malvales Family: Malvaceae Genus: Hibiscus Species:rosa-sinensis Calachuchi (Plumeria rubra) Kingdom: Plantae Phylum: Tracheophyta Class: Magnoliopsida Order: Caryophyllales Family: Apocynaceae Genus: Plumeria Species: rubra Santan (Ixora sp.) Kingdom: Plantae Phylum: Tracheophyta Class: Magnoliopsida Order: Rubiales Family: Rubiaceae Genus: Ixora Species: sp. Anthurium (Anthurium andraeanum) Kingdom: Plantae Phylum: Tracheophyta Class: Magnoliopsida Order: Alismatales Family: Araceae Genus: Anthurium Species: There are many species of Anthurium, including Anthurium andreanum and Anthurium scherzerianum. African Daisy (Osteospermum) Kingdom: Plantae  Phylum: Tracheophyta Class: Magnoliopsida Order: Asterales Family: Asteraceae Genus: Osteospermum Species: ecklonis Rose (Rosa) Kingdom: Plantae Phylum: Tracheophyta Class: Magnoliopsida Order: Rosales Family: Rosaceae Genus: Rosa Species: There are many species of roses, including Rosa gallica, Rosa canina, and Rosa centifolia. WORKSHEET 2 Etymology: The study of the origin of words and the way their meanings have changed throughout history. TABLE 1.1 1. Ipomoea batatas (Sweet Potato) ○ Etymology: Genus: Ipomoea (Greek words meaning "worm" and referring to its creeping habit) Species epithet: batatas (Derived from the Taino language, referring to sweet potato) ○ Family: Convolvulaceae Family ○ Distribution: Cultivated in many tropical and subtropical countries. 2. Daucus carota (Carrot) ○ Etymology: Genus: Daucus (Greek for "parsnip") Species epithet: carota (Latin, meaning carrot, referring to the plant's edible root) ○ Family: Apiaceae Family ○ Distribution: Commonly found in Britain, Ireland, and especially in coastal areas. 3. Allium cepa (Onion) ○ Etymology: Genus: Allium (Latin for garlic)  Species epithet: cepa (Latin word meaning onion) ○ Family: Amaryllidaceae Family ○ Distribution: Found in Iran, Turkmenistan, and Uzbekistan. 4. Bambusa vulgaris (Bamboo) ○ Etymology: Genus: Bambusa (Malay/Indian origin meaning bamboo) Species epithet: vulgaris (Latin word meaning common) ○ Family: Poaceae Family ○ Distribution: Distributed globally except Europe and Antarctica. 5. Zea mays (Corn) ○ Etymology: Genus: Zea (Greek word meaning grain) Species epithet: mays (Native American origin, referring to corn) ○ Family: Poaceae Family ○ Distribution: Southern Mexico, especially in valley areas. Additional Notes: - **Convolvulaceae Family**: A family of flowering plants commonly known as bindweed or morning glory family, includes species like sweet potato (*Ipomoea batatas*). - **Apiaceae Family**: Also known as the carrot or parsley family, this group includes carrots, celery, and parsley. - **Amaryllidaceae Family**: The family that includes onions, garlic, and other bulbous plants. - **Poaceae Family**: Also known as the grass family, it includes economically significant species like rice, wheat, maize, and bamboo. 1.Nomenclature: The system or set of names used in a particular field of study or community, especially in science. In biology, it refers to the formal naming of organisms using a standardized system, typically binomial nomenclature, where each species is given a two-part name (genus and species). 2. Epithet: In biological nomenclature, an epithet refers to the second part of a species' scientific name in binomial nomenclature. It is used to distinguish the species within a genus. For example, in Homo sapiens, "sapiens" is the specific epithet, which, together with the genus "Homo", forms the full species name. 3.Phylogenetic Systematics: The study of evolutionary relationships among species, often represented through a branching diagram called a phylogenetic tree or cladogram. 4.Phylogeny: The evolutionary history and relationship of an organism or group of organisms, often depicted in tree-like diagrams showing common ancestors and divergence points. 5.Character: A trait or feature of an organism (e.g., physical structure, genetic sequence) used to determine evolutionary relationships. 6.Taxon (plural: Taxa): A group of one or more populations of an organism, seen as a unit in biological classification (e.g., species, genus, family). 7.Synapomorphy: A derived character or trait shared by two or more taxa that is inherited from their most recent common ancestor. 8.Apomorphy: A derived or new characteristic that is different from the ancestral form, used to distinguish evolutionary relationships. 9.Cladogram: A diagram that shows the evolutionary relationships between species based on shared characteristics, representing the branching patterns of evolution. 10.Monophyletic Group: A group of organisms that includes a common ancestor and all of its descendants, forming a single branch on the tree of life. 11.Hypothesis of Relationship: A proposed explanation for the evolutionary relationships among a group of organisms, typically based on shared characteristics or genetic information. 12.Ingroup: In phylogenetic analysis, this refers to the group of species being studied, usually assumed to share a common ancestor. 13.Matrix: In phylogenetics, a matrix is a table used to organize data, where rows often represent species (taxa) and columns represent different characters or traits. This matrix helps in analyzing evolutionary relationships. 14.Dichotomous: Refers to something that is divided into two distinct parts or branches, often used to describe branching patterns in a cladogram where each node splits into two groups. 15.Annotated: Providing additional notes or explanations, often used in phylogenetics to add information or clarification about certain traits or relationships in a cladogram. 16.Non-monophyletic Groups: Groups that do not contain all descendants of a common ancestor, meaning the group is not a true reflection of evolutionary history. WORKSHEET #3 Chloroplasts & Cell Wall Elodea (Hydrocharitaceae): A common aquatic plant used for observing live plant cells. In this lab, a wet mount is prepared to examine its cells under a microscope. Cell Wall: The rigid, outermost layer of plant cells made primarily of cellulose, providing structure and protection. It appears as a thin whitish line under the microscope. Cellulose: A complex carbohydrate (polysaccharide) that forms the main component of plant cell walls. It helps maintain the structure and shape of the plant cell. Chloroplasts: Organelles in plant cells responsible for photosynthesis. Chloroplasts contain chlorophyll pigments that give plants their green color. In Elodea, they are pushed to the edges of the cell due to the large central vacuole. Chlorophyll a + b : The main pigments in chloroplasts that absorb light energy for photosynthesis. They reflect green light, giving the plants their green appearance. Cytoplasmic Streaming (Cytosis): A process in which the cytoplasm moves inside the cell, causing organelles, like chloroplasts, to circulate within the cell. Thylakoids: Membrane-bound structures within chloroplasts where the light-dependent reactions of photosynthesis occur. Thylakoids are organized into stacks called *grana*. Grana: Stacks of thylakoids inside the chloroplast. These structures increase the surface area for photosynthetic reactions. Apomorphy: A derived characteristic that is unique to a particular group of organisms, distinguishing them from others. For green plants, apomorphies include chloroplasts containing chlorophyll b, grana, and starch. Oogamy and Antheridia Oogamy: A type of sexual reproduction where the female gamete (egg) is larger and non-motile, and the male gamete (sperm) is smaller and motile. This form of reproduction is common in many plants and algae. Chara: A genus of green algae used in plant studies to observe reproductive structures like oogonia and antheridia Oogonium: The female reproductive organ in Chara. It contains the egg cell and is surrounded by helical cells that protect the egg. This structure represents a major apomorphy for green plants such as Chlorobionta. Antheridium: The male reproductive structure in Chara, producing sperm cells. The antheridium is enclosed by a sterile “jacket” layer of cells, which protects the sperm during development. Sterile Jacket: A protective layer of non-reproductive cells that surrounds reproductive organs like the antheridium in Chara. Egg Cell: A large, non-motile female gamete involved in sexual reproduction. In oogamy, it remains stationary while being fertilized by motile sperm. Sperm Cells: Small, motile male gametes that move towards the egg for fertilization in oogamy. Apomorphy: A derived feature that is characteristic of a particular lineage. In this context, the development of reproductive structures like the oogonium and antheridium are apomorphies for plants like Chara and land plants. Key Definitions: -Cellulose: The main component of plant cell walls, made up of glucose units. It provides rigidity and strength to plant cells. Chlorophyll a + b: Pigments in plants that are crucial for photosynthesis. They absorb light and convert it into chemical energy. Thylakoid: A membrane structure inside the chloroplast where the light-dependent reactions of photosynthesis take place. Grana: Stacks of thylakoids in the chloroplast that increase the surface area for photosynthesis. Cytoplasmic Streaming: The directed flow of the cytoplasm within cells that helps transport nutrients, organelles, and other cellular materials. Oogonium: The female reproductive organ in algae and some plants, containing the egg cell. Antheridium: The male reproductive organ in algae and some plants, producing sperm cells. Oogamy: A form of sexual reproduction in which one gamete (egg) is larger and non-motile, while the other (sperm) is smaller and motile. TAXONOMIC ACTIVITY Definitions of Terms in the Biology Worksheet Taxonomy and Classification Taxonomy: The scientific classification of organisms into hierarchical groups based on shared characteristics. Classification: The process of grouping organisms into categories based on their similarities and differences. Kingdoms of Life Animalia: Kingdom of multicellular eukaryotic organisms that can move, consume food, and reproduce sexually. Plantae: Kingdom of multicellular eukaryotic organisms that produce their own food through photosynthesis. Fungi: Kingdom of eukaryotic organisms that obtain nutrients by absorbing organic matter from their surroundings. Eubacteria: Kingdom of prokaryotic organisms that have cell walls made of peptidoglycan. Archaea: Kingdom of prokaryotic organisms that have unique cell walls and live in extreme environments. Protista: Kingdom of mostly unicellular eukaryotic organisms that are not classified as animals, plants, or fungi. Cell Types Unicellular: Organisms composed of a single cell. Multicellular: Organisms composed of multiple cells. Prokaryotes: Cells that lack a nucleus and membrane-bound organelles. Eukaryotes: Cells that have a nucleus and membrane-bound organelles. Autotrophic: Organisms that can produce their own food. Heterotrophic: Organisms that obtain food from other organisms. Taxonomic Ranks Kingdom: The highest level of classification. Phylum: A major division within a kingdom. Class: A group of related orders within a phylum. Order: A group of related families within a class. Family: A group of related genera within an order.  Genus: A group of closely related species. Species: The basic unit of classification, representing a group of organisms that can interbreed and produce fertile offspring. MORE INFORMATION Taxonomy and Classification Taxonomy is the science of classifying organisms, while classification is the process of grouping organisms into categories. Taxonomy is based on shared characteristics, while classification can be based on any number of criteria, such as physical appearance, genetic similarity, or ecological niche. The levels of classification are kingdom, phylum, class, order, family, genus, and species. Each level is more specific than the one above it. For example, all animals belong to the kingdom Animalia, and all mammals belong to the class Mammalia. Kingdoms of Life The six kingdoms of life are Animalia, Plantae, Fungi, Eubacteria, Archaea, and Protista. Animals are multicellular eukaryotes that can move, consume food, and reproduce sexually. Plants are multicellular eukaryotes that produce their own food through photosynthesis. Fungi are multicellular eukaryotes that obtain nutrients by absorbing organic matter from their surroundings. Eubacteria and Archaea are prokaryotes, which are unicellular organisms that lack a nucleus and membrane-bound organelles. Protista is a catch-all kingdom for eukaryotic organisms that are not classified as animals, plants, or fungi. Cell Types Eukaryotic cells have a nucleus and membrane-bound organelles, such as mitochondria and chloroplasts. Prokaryotic cells lack a nucleus and membrane-bound organelles. Autotrophic organisms can produce their own food, while heterotrophic organisms obtain food from other organisms. Taxonomic Ranks The seven levels of classification are kingdom, phylum, class, order, family, genus, and species.  The highest level of classification is the kingdom, and the lowest level is the species. Each level is more specific than the one above it. For example, all animals belong to the kingdom Animalia, and all mammals belong to the class Mammalia. QUIZ 2_9.18.24 SYSTEMATICS LABORATORY GUIDE/REFERENCE_FOR REVIEW 1. What are the two parts of a scientific name in binomial nomenclature? GENUS & SPECIES 2. The classification of organisms can change as new scientific information becomes available. TRUE 3. The branches of a phylogenetic tree indicate the genetic distance between species. TRUE 4. Phylogenetic trees only show the relationships between living species. FALSE(They can show relationships between both living and extinct species.) 5. The discipline of naming, classifying, and organizing organisms into hierarchical categories such as kingdom, phylum, and class. TAXONOMY 6. A taxonomic rank that groups together organisms sharing the closest common ancestor, placed just above genus. FAMILY 7. The fewer shared traits two species have, the closer they are related in a phylogenetic tree. FALSE (The more traits they share, especially from a common ancestor, the closer they are related.) 8-10. Enumerate the major domains used in modern taxonomy. Bacteria, Archaea, and Eukarya 11. The person who developed the binomial nomenclature system. Carl Linnaeus 12. Give one example of a binomial nomenclature. 13. Identify the term for traits shared by species due to common ancestry. Homologous Traits 14. Identify the term for the point on a phylogenetic tree where two lineages diverge. Node 15. Identify this term for traits that have evolved after the last common ancestor of a group, making them unique to a specific group of descendants. Derived Traits (Apomorphies) LE 1 False 1. Once a species Is part of a lineage, it cannot branch off to form a new lineage. True 2, In-a cladogram, organisms that share a more recent common ancestor are placed closer together. True 3. Lineage represents a direct line of descent from an ancestor to its descendants. True 4.,A common ancestor is an organism from which two or more species have evolved. True 5. Divergence refers to the process by which two or more species evolve from a common ancestor. False 6. The greater the divergence between two species, the more genetically similar they are. False 7. Speciation always takes millions of years to occur. False 8. All apomorphies are ancestral traits shared by all members of a clade. False 9. An apomorphy that is unique to a single species is called a synapomorphy. True 10. Apomorphies are important for constructing cladograms and understanding evolutionary relationships. True 11. The only surviving species of Ginkgo is Ginkgo biloba. False 12. Ginkgo seeds are enclosed in fruits, similar to angiosperms, True 13. liverworts are part of the bryophyte group, which also includes mosses and hornworts. False 14. Mosses typically thrive in dry environments and are resistant to desiccation. True 15. Conifers are a group of gymnosperms that produce seeds in cones. Corn (Zea mays) Kingdom: Plantae Phylum: Tracheophyta Class: Magnoliopsida Order: Cyperales Family: Poaceae Genus: Zea Species: Zea mays Gumamela (Hibiscus rosa-sinensis) Kingdom: Plantae Phylum: Magnoliophyta Class: Magnoliopsida Order: Malvales Family: Malvaceae Genus: Hibiscus Species: rosa-sinensis Sweet Potato ( Ipomoea batatas) Kingdom: Plantae Phylum: Magnoliophyta Class: Magnoliopsida Order: Solanales Family: Convolvulaceae Genus: Ipomoea Species: batatas Carrot (Daucus carotas) Kingdom: Plantae Phylum: Magnoliophyta Class: Magnoliopsida Order: Apiales Family: Apiaceae Genus: Daucus  Species: carota Bamboo (Bambusa vulgaris) Kingdom: Plantae Phylum: Magnoliophyta Class: Liliopsida Order: Poales Family: Poaceae Genus: Bambusa Species: vulgaris Onion (Allium cepa) Kingdom: Plantae Phylum: Magnoliophyta Class: Liliopsida Order: Asparagales Family: Alliaceae Genus: Allium Species: cepa ACT #1 ACT #2 DICOT Azadirachta indica (NEEM TREE) OLD. YOUNG Dicot Anatomy: Key Tissues and Structures Dicots (dicotyledons) are a group of flowering plants characterized by having two cotyledons (seed leaves) in their embryos. They have a distinct vascular system, which is arranged in bundles. 1. Epidermis: * Function: The outermost layer of cells that forms a protective covering. * Characteristics: Often has a waxy cuticle to reduce water loss. May have specialized structures like trichomes (hairs) for various functions (e.g., defense, absorption). 2. Pericycle: * Function: A layer of cells just inside the endodermis. It gives rise to lateral roots and plays a role in secondary growth (e.g., formation of cork). * Characteristics: Often consists of a single layer of cells. 3. Cortex: * Function: A region between the epidermis and the vascular bundles. It consists of various cell types, often involved in storage and support. * Characteristics: May contain parenchyma cells, collenchyma cells, and sclerenchyma cells. 4. Vascular Bundle: * Function: The unit of vascular tissue that transports water, minerals, and sugars throughout the plant. * Structure: Typically consists of: * Xylem: Conducts water and minerals from roots to leaves. * Phloem: Transports sugars produced in photosynthesis from leaves to other parts of the plant. * Cambium: A layer of meristematic cells that produces new xylem and phloem tissue, leading to secondary growth. 5. Pith: * Function: A central tissue region, often composed of parenchyma cells. It can store food and water. * Characteristics: May be absent or reduced in some dicot stems, especially those with secondary growth. Note: The arrangement of these tissues can vary among different dicot species and stem structures. For example, in a young dicot stem, the vascular bundles are often arranged in a ring, while in a mature stem with secondary growth, they may form a solid cylinder. MONOCOT Zea mays (CORN) Monocot Anatomy: Key Tissues and Structures Monocots (monocotyledons) are another group of flowering plants characterized by having a single cotyledon in their embryos. Their vascular bundles are scattered throughout the ground tissue, rather than arranged in a ring. 1. Epidermis: * Similar to dicots: The outermost layer of cells, often with a waxy cuticle for water retention. * Differences: May have specialized structures like stomata (pores) for gas exchange and trichomes (hairs) for various functions. 2. Hypodermis: * Function: A layer of cells just beneath the epidermis, often composed of sclerenchyma cells.  * Characteristics: Provides mechanical support and protection. 3. Ground Tissue: * Function: The bulk of the tissue that fills the spaces between the vascular bundles. It can be differentiated into various types based on cell structure and function. * Types: * Parenchyma: Thin-walled cells involved in storage, photosynthesis, and respiration. * Collenchyma: Thick-walled cells providing support and flexibility. * Sclerenchyma: Thick-walled, rigid cells providing mechanical support. 4. Vascular Bundles: * Similar to dicots: Consist of xylem, phloem, and cambium. * Differences: Scattered throughout the ground tissue, rather than arranged in a ring. * Types: * Collateral: Xylem and phloem are arranged side by side. * Radial: Xylem and phloem are arranged in a radial pattern. Note: The arrangement and composition of these tissues can vary among different monocot species and stem structures. However, the general characteristics and functions remain consistent. Videos First Video: How Tree Diagrams Work - Concept: Tree diagrams represent evolutionary relationships among organisms, descending from a common ancestor. - Branches: These show reproductive lineages and how they split over time, connecting organisms to their hypothetical common ancestors at different points (nodes). - Key Features: 1. Base: Represents a common ancestor. 2. Branches: Show the lineage and how traits evolve or split. 3. Nodes (Branch Points): Indicate the most recent shared ancestor between organisms. Important Details: - Relatedness can be inferred based on the number of shared traits. - The order of organisms across the top of the tree doesn't matter; what matters are the branching points. - Trees are hypotheses based on evidence from anatomy, fossils, embryonic development, and DNA sequences. -Implication: Organisms with more traits in common share a more recent common ancestor. --- Second Video: Taxonomy and Phylogenetic Trees Taxonomy: Not just about classification but understanding evolutionary relationships. Phylogenetic Tree (Tree of Life): Shows how all species are related through evolution, though it's an imperfect system. Carl Linnaeus: Introduced a classification system in the 18th century based on morphology (physical traits). Taxonomic Hierarchy: Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species. Domains: 1. Bacteria: Prokaryotes with simple cell structure. 2. Archaea: Prokaryotes with evolutionary traits closer to eukaryotes. 3. Eukarya: Includes organisms with a nucleus (protists, fungi, plants, animals). Kingdoms: 1. Plantae: Autotrophs that use photosynthesis. 2. Protista: A diverse group of mostly single-celled organisms.  3. Fungi: Have chitin in their cell walls and absorb food through enzymes. 4. Animalia: Multicellular heterotrophs that usually move and develop from multiple germ layers. - Examples: - Cats: Belong to Kingdom Animalia, Phylum Chordata, Class Mammalia, Order Carnivora, Family Felidae, Genus Felis, Species Catus. - Platypus: Lay eggs, sweat milk, and are part of a branch that split from other mammals long ago. Third Video: Phylogeny and Systematics - Phylogeny: The study of the evolutionary history of organisms. Phylogenetic trees show how species are related based on common ancestors. - Linnaean Taxonomy: Classification system grouping species based on observable traits. - Systematics: A more objective method than Linnaean taxonomy, relying on evolutionary history and genetic data. - Homologous Traits: Shared traits inherited from a common ancestor. - Example: Human, horse, and bat limbs are homologous structures, sharing a basic bone structure. - Analogous Traits: Traits that look similar but evolved independently (e.g., bird and dragonfly wings). - Molecular Clock: Hypothesis that DNA and proteins evolve at a roughly constant rate, allowing for genetic comparisons between species. - Neutral Theory: Proposed by Motoo Kimura, suggesting that most genetic changes are neutral (random, neither helpful nor harmful), rather than driven by natural selection. - Applications: Phylogeny helps answer evolutionary questions such as: - The origin of feathers in dinosaurs. - Relationships between species (e.g., crocodiles are closer to birds than to other reptiles). - Gene Flow: Even closely related species that have split can still interbreed, producing hybrids (e.g., polar and brown bears). Key Takeaways 1. Tree Diagrams: Show hypotheses of evolutionary relationships based on branching from a common ancestor. 2. Taxonomy: Linnaeus's classification is still used but has evolved with the inclusion of domains and more understanding of evolutionary histories. 3. Phylogeny: Helps explain how organisms evolved, using both physical traits and genetic similarities to map evolutionary trees. 4. Evolution: Driven by both natural selection and random genetic changes, with neutral theory playing a significant role in genetic evolution..