Biology: Diversity of Life Essay

: Diversity Of Life Fungi Fungi: are multi-cellular heterotrophs that use external digestion, and often grow out of sight, underground > fungi have nothing in common with plants other then the fact that they are stationary, and grow in the ground. They are not photosynthetic, and they do not produce their own food.

Characteristics/ Cell Structure: * Mesh like bodies, composed of branching networks of filaments called mycelium * Mycelium: a branched mass of hyphae Hyphae are thin filaments that make up the body of a fungus, they consist of long tubes of cytoplasm containing many nuclei * Cytoplasm is contained in a cell wall made of chitin Life Cycle Haploid: a single set of unpaired chromosomes Diploid: two complete sets of chromosomes from each parent Dikaryotic: a cell containing two separate nuclei * The life cycle of most fungi involve the haploid individuals that reproduce both sexually and asexually . Spores produce hyphae with haploid nuclei 2. Hyphae fuse together to form Dikaryotic cell 3.

Hyphae grow into large mycelium 4. Mycelium matures into mushroom cap with gills 5. Basidium on gills produces spores 6. Haploid nuclei fuse to form diploid zygote 7.

Zygotes produce new haploid nuclei which becomes basidiospores (released as spores) Zygote: formed by the fusion of two different sex cells, such as sperm and an egg Importance Fungi, along with bacteria are the major decomposers on Earth, they are responsible for the cycling of nutrients throughout the biosphere * Fungi as well engage in symbiotic relationships with plants * Plants rely on fungi to help obtain nutrients from the soil * Without the help of fungi, the plant growth and productivity would decrease severely Environment Impact * Fungi are responsible for some animal and plant diseases * Fungi can rot wood, and damage buildings The introduction of non-native fungi species have had serious consequences to the environment, in some cases it destroyed a forest of trees Plants Plants: All plants are multi-cellular eukaryotes and obtain their food from the process of photosynthesis; plants support virtually all-terrestrial food webs. History * Plants appeared on land about 400 million years ago * They adapted from aquatic to terrestrial environments as they had the advantages of a greater availability of light and a more rapid diffusion of carbon dioxide/oxygen in and out of their cells * Evolved from a green group of algaeCharacteristics * All plants have cell walls made up of cellulous * Just as fungi, plants are stationary and cannot move * They obtain their energy by the process of photosynthesis * The three main parts of the plant are: the root, stem and leaf systems, the root secures the plant, the stem provides height and acts as a transport tube and the leaf is a surface area to collect light * All plant types look differently and are very diverse Alterations of Generations The plant life cycle has diploid and haploid states, the diploid generation produces spores and the haploid generation produces gametes * A plant in the diploid stage is called a sporophyte, the diploid cells in this plant divide by meiosis to produce haploid cells * In plants haploid cells produce asexual spores * As the haploid generation is in process, the spores grow into gametophyte individuals * The gametophytes mature and produce haploid sex cells- gametes * These gametes undergo fertilization to form diploid zygotes, zygotes then grow into sporophyte individuals and the cycle continues there are 4 major groups of plants: 1. Bryophytes 2. Lycophytes and Pterophytes 3. Gymnosperms 4. Angiosperms Bryophytes * Are the simplest of land plants, they include mosses, liverworts and hornworts * Bryophytes have a protective cuticle and stomata for gas exchange, they don’t however have vascular tissue, leaves, roots, or seeds * Gametophyte generations of bryophytes produce swimming sperm in structures called antheridia and eggs in structures called archegonia * Live in places with at least occasional wet conditions Lycophytes & Pterophytes * Seedless vascular plants (ferns) * Reproduce sexually using sperm and eggs Photosynthetic unlike bryophytes, and have simple root and stem systems * Have developed symbiotic mycorrhizal relationships that help them obtain water and other nutrients from the soil Gymnosperms* Vascular seeded plants that reproduce with specialized cones that produce pollen grains and ovules * Cones are the reproductive structures, male cones produce and release pollen and female cones produce eggs * Many gymnosperms are woody trees, with needle like leaves * Have large shallow root systems that from a mycorrhizal relationship with symbiotic fungi Angiosperm * A vascular seeded plant that produces flowers/fruit Flowers replace the role of cones in these plants, except in the female flower parts, the eggs are protected in an enclosed ovary, after fertilization seeds from within the ovary and outer tissues of the ovary to become a fruit * Angiosperms are furthermore split into 2 groups, Monocot and Dicot * Monocot: angiosperm seed with one embryonic seed leaf * Dicot: angiosperm seed with two embryonic seed leaves Animals Animals: are multi-cellular, heterotrophic, eukaryotic, complex organisms. Unlike plants and fungi they are mobile, have amazing sensory ability and are capable of very complex behaviours. Characteristics Multi-cellular * Heterotrophic * Use oxygen for aerobic respiration * No cell walls * Feed on plants, fungi, protists and each other * Animals also have symbiotic relationships with Autotrophs that provide a supplementary source of food Germ Layers: are the layers of the cell in a developing embryo that give rise to specialized tissues.

There are 3 germ layers: 1. Ectoderm: the outer layer that, gives rise to the skin and nervous system. In complex animals this layer produces feathers, hair, shells, and nails 2. Endoderm: the inner lining of the gut and, in some organisms the respiratory system 3.Mesoderm: the middle layer, it gives rise to the circulatory, reproductive, excretory, and muscular system Protostome: an animal with bilateral symmetry; during embryonic development, the mouth forms before the anus Deuterostome: an animal with bilateral symmetry; during embryonic development, the anus develops before the mouth Vertebrate: an animal with a backbone or notochord (tail) Notochord: a flexible rod found in some chordates; in most modern chordates the vertebrae replaces it during embryonic development Invertebrate: an animal that does not have a backbone Coelomates: an animal that has a body cavityPseudocoelomates: an invertebrate that has a fluid filled cavity, apposed to a hollow body cavity Acoelomates: animal that doesn’t have a coelom Invertebrates Phylum| Examples| Key Features| Arthropoda| Insects, Spiders, Crabs, Shrimps, Lobsters| -Segmented-Joint appendages| Nematoda| Pinworms, Dog Heartworms| -unsegmented-parasites| Annelida| Earthworm, Feather Duster Worms| -segemnted-gills| Platyhelminthes| Tape worms| -unsegmented-no coelom-parasites| Mollusca| Snails, Clams, Squid, Octopus| -unsegmented-have shells| Radial Symmetry: symmetry around a central axisBilateral Symmetry: symmetry around a midline Vertebrates Phylum| Examples| Key Features| Agnathans| Lamprey| -no jaws-made of cartilage-gills| Chrondrichthyes| Sharks, Rays, Skates| -made of cartilage-internal fertlization| Actinopterygii| Bass, Tuna, Trout, Salmon| -bony skeleton-external fertilization| Amphibia| Frogs, Salamanders| -external fertilization-adult tetrapods| Reptilia| Snakes, Lizards, Crocodilians| -tetrapods-internal fertilization| Aves| Birds| -tetrapods-internal fertilization| Mammalia| -mammals| -tetrapods with hair-live birth, internal fertilization|