Plant and Animal Kingdom: Characteristics and Anatomy
Plant Groups and Their Characteristics
Bryophytes: Nonvascular plants (mosses, liverworts, hornworts)
- Lack true roots and vascular tissues
- Small size, restricted to moist environments
Seedless Vascular/Monilophyta: Ferns, horsetails
- Have vascular tissues but lack seeds
- Reproduce via spores
- Larger size and more complex structures than bryophytes
Gymnosperms: Seed plants with naked seeds (conifers, cycads, ginkgos)
- Produce seeds in cones
- Most have woody stems
Angiosperms: Flowering plants
- Produce flowers and fruits
- Seeds are enclosed in fruits
- More diverse and widespread than other plant groups
Plant Anatomy
- Root: Anchors, absorbs.
- Stem: Supports, transports.
- Leaves: Photosynthesis, gas exchange.
- Dermal tissues: Epidermis (outer), cuticle, guard cells.
- Vascular tissues: Xylem (water), phloem (nutrients).
- Ground tissues: Parenchyma (storage), collenchyma (support), sclerenchyma (support).
- Meristems: Apical (length), lateral (width).
Lignin: Provides support in plants; makes wood woody
Sexual Reproduction
Vascular Plants (e.g., ferns, gymnosperms, angiosperms)
- Sporophyte (diploid) stage: Produces spores through meiosis.
- Spore dispersal: Spores are released into the environment.
- Gametophyte (haploid) stage: Spores germinate into gametophytes, which produce gametes (sperm and egg).
- Fertilization: Sperm and egg cells fuse to form a zygote.
- Zygote development: Zygote develops into a new sporophyte, completing the life cycle.
Nonvascular Plants (e.g., mosses, liverworts)
- Gametophyte (haploid) stage: Dominant stage, produces gametes.
- Fertilization: Sperm and egg cells fuse in a moist environment.
- Sporophyte (diploid) stage: Zygote develops into a sporophyte, which produces spores.
- Spore dispersal: Spores are released into the environment.
Fungi
- Hyphae: Thread-like structures.
- Mycelium: Network of hyphae.
- Chitin: Cell wall material.
- Septa: Cross-walls in hyphae.
- Mycorrhizae: Symbiotic relationship with plants.
- Fruiting Bodies: The reproductive structures of fungi
- Alteration of Generations: Plants alternate between a sexual phase (gametophyte) and an asexual phase (sporophyte).
- Spores: Haploid reproductive cells produced by sporophytes.
- Sporangia: Structures that produce spores.
- Sporophyte: Diploid generation that produces spores.
- Gametophyte: Haploid generation that produces gametes (sperm and egg).
- Antheridia: Male reproductive structures that produce sperm.
- Archegonia: Female reproductive structures that contain eggs.
- Plasmogamy: The fusion of the cytoplasm of two fungal cells. This results in a cell with two distinct nuclei, one from each parent fungus. This fused cell is called a dikaryon.
- Karyogamy: The fusion of the two nuclei within the dikaryon. This results in the formation of a diploid zygote, which contains genetic material from both parent fungi.
- Lichens: Symbiotic relationships between a fungus (mycobiont) and an alga or cyanobacterium (photobiont) (fungus provides structure and protection, while alga or cyanobacterium produces food through photosynthesis)
Fungi Reproduction
- Hyphal fusion: Two hyphae (filamentous structures) from different fungi come into contact and fuse.
- Plasmogamy: The cytoplasm of the two hyphae fuses, forming a dikaryon.
- Dikaryotic stage: The dikaryon may persist for a long period of time, during which it can grow and develop.
- Karyogamy: Under certain conditions, the two nuclei in the dikaryon fuse to form a diploid zygote.
- Meiosis: The diploid zygote undergoes meiosis to produce haploid spores.
- Spore germination: The spores germinate and develop into new haploid hyphae, starting the cycle anew.
Animals
Ecdysozoans
Characteristics: Molting of exoskeleton, segmented bodies, bilateral symmetry.
Examples: Arthropods (insects, crustaceans, spiders), nematodes (roundworms).
Arthropods
Characteristics: Jointed appendages, exoskeleton, segmented bodies, three tagmata (head, thorax, abdomen).
Examples: Insects, spiders, crustaceans, millipedes, centipedes.
Lophotrochozoans
Characteristics: Lophophore (crown of ciliated tentacles) or trochophore larva.
Examples: Annelids (segmented worms), mollusks (snails, clams, squid), flatworms (tapeworms, flukes).
Mollusca
Characteristics: Muscular foot, visceral mass, mantle, shell (often present).
Examples: Snails, clams, squid, octopuses.
Deuterostomes
Characteristics: Radial cleavage, blastopore becomes anus, coelom forms from mesoderm.
Examples: Chordates (vertebrates, tunicates), echinoderms (starfish, sea urchins).
Key Comparisons
- Ecdysozoans vs. Lophotrochozoans: Ecdysozoans molt, while Lophotrochozoans have lophophores or trochophores.
- Arthropods vs. Mollusks: Arthropods have jointed appendages and exoskeletons, while mollusks have a muscular foot and mantle.
- Deuterostomes vs. Protostomes: Deuterostomes have radial cleavage and a blastopore that becomes the anus, while protostomes have spiral cleavage and a blastopore that becomes the mouth.
Body Plans and Characteristics
- Diploblastic: Two germ layers (ectoderm, endoderm).
- Triploblastic: Three germ layers (ectoderm, mesoderm, endoderm).
- Body cavity: Acoelomate (no cavity), pseudocoelomate (partially lined), coelomate (completely lined).
- Symmetry: Radial (can be divided into equal halves along any plane), bilateral (can be divided into left and right halves).
- Circulatory system: Open (blood flows freely through cavities), closed (blood flows through vessels).
- Segmentation: Body divided into repeating segments.
Animal Phyla and Their Characteristics
Porifera (Sponges)
Characteristics: Filter feeders, lack true tissues, have spongocoel (central cavity) and osculum (exit pore), contain choanocytes (flagellated cells).
Example: Bath sponges
Cnidarians
Characteristics: Radial symmetry, gastrovascular cavity, cnidocytes (stinging cells), two body forms (polyp and medusa).
Examples: Jellyfish, corals, sea anemones.
Platyhelminthes (Flatworms)
Characteristics: Bilateral symmetry, acoelomate (no body cavity), dorsoventrally flattened.
Examples: Tapeworms, flukes, planarians.
Nematodes (Roundworms)
Characteristics: Cylindrical body, pseudocoelomate, unsegmented.
Examples: Ascaris (intestinal roundworm), hookworms.
Annelids (Segmented Worms)
Characteristics: Segmented body, closed circulatory system, parapodia (locomotion).
Examples: Earthworms, leeches, marine worms.
Mollusca
Characteristics: Muscular foot, visceral mass, mantle, often have shells.
Examples: Snails, clams, squid, octopuses.
Arthropods
Characteristics: Jointed appendages, exoskeleton, segmented body.
Examples: Insects, crustaceans, spiders, millipedes, centipedes.
Echinoderms
Characteristics: Radial symmetry as adults, water vascular system, spiny skin.
Examples: Starfish, sea urchins, sea cucumbers, brittle stars.
Chordates
Characteristics: Notochord (flexible rod), dorsal hollow nerve cord, pharyngeal slits, post-anal tail.
Examples: Vertebrates (fish, amphibians, reptiles, birds, mammals), tunicates, lancelets.