Classification and Diversity of Living Organisms
Concept and Use of a Classificatory System
Binomial System
A system of naming species in which the scientific name of an organism is made up of two parts showing the genus (starting with a capital letter) and species (starting with a lower case letter), written in italics when printed (therefore underlined when handwritten) e.g. Homo sapiens
Classes of Animals
Class Fish
Moist skin, fins, gills, scaly skin, poikilothermic (cold-blooded), lays eggs with jelly coat.
Class Amphibia
Poikilothermic (cold-blooded), smooth moist skin, lay eggs in water, larva (gills) live in water, adult (lungs) live on land.
Class Reptilia
Poikilothermic (cold-blooded), dry scaly skin, have lungs, lay eggs on land with hard shell.
Class Birds
Homeothermic (warm-blooded), feathers, beaks, lay eggs on land with hard shell.
Class Mammalia
Homeothermic (warm-blooded), fur or hair, have placenta, lungs, give birth.
Phyla of Animals
Phylum Annelida
Round segmented worms, no legs, bristles for movement. Ex: Earthworms
Phylum Nematoda
Round unsegmented worms, have separated sexes, two pointed ends. Ex: Ascaris
Phylum Mollusca
Soft unsegmented body, may have shell, have muscular foot. Ex: Snail, octopus
Phylum Cnidaria
Soft body, one opening, made of 2 layers of cells, ring of tentacles around mouth. Ex: Jellyfish
Phylum Arthropoda
Segmented body, jointed legs, hard waterproof exoskeleton made up of chitin.
Classes of Arthropoda
Class Insecta
3 body parts, 3 pairs of legs, 1 or 2 pairs of wings, 1 pair antenna. Ex: Bee, ant
Class Crustacea
Has claws, more than 4 pairs of legs, 2 pairs of antenna, body is 2 parts, compound eye. Ex: Crab, shrimp
Class Arachnida
2 body parts, 4 pairs of legs, no antenna, 8 simple eyes, legs with claws to catch preys. Ex: Spider
Class Chilopoda (Myriapods)
Segmented body with pair of legs on each segment, 1 pair of antenna.
Kingdom Plants
Contain chlorophyll, feed by photosynthesis, have cell wall, have nucleus.
Monocots
Seed contain one cotyledon, fibrous roots, petals are 3 or multiples, veins are parallel, vascular bundle scattered, long narrow leaves.
Dicots
Seed contains 2 cotyledons, short broad leaves, veins are net like, vascular bundle arranged in a ring, petals 4 or 5 or their multiples.
Fungi
Multicellular organisms, except for yeast which is a unicellular fungus. Some fungi are not made of cells, but rather of microscopic threads called hyphae.
Types of Hyphae
- Reproductive hyphae: They form spores which carry out reproduction.
- Feeding hyphae: They form a network which grows over or through the food materials, they are called mycelium.
Hyphae are tube-like, microscopic structures. It contains a cytoplasm which contains glycogen granules, and several nuclei. It doesn’t contain chloroplasts neither starch granules. In the center there is a vacuole, and the hyphae is surrounded by a hyphae wall which is sometimes made of chitin. Large numbers of hyphae grow together through whatever the fungus is feeding on making a branching network called mycelium.
How Do Fungi Eat?
Fungi use a process called saprotrophic nutrition to feed itself. The hyphae secretes enzymes which digests dead organic matter or animal waste which is then absorbed by the hyphae to be used by the fungi.
Reproduction of Fungi
At some point the fungi produce a reproductive structure, mushrooms for example, which produces thousands of tiny spores, these are then dispersed to other areas and grow into a new mycelium.
Adaptations of Fungi
Fungi are adapted to perform their functions easily by the following ways:
- They grow long mycelium of hyphae on whatever they feed on, these secret enzymes which digests what the fungi feeds on.
- They are able to grow tall mushrooms of toadstools so the spores could be widely dispersed by wind or insects, thus they reproduce quickly.
Why Fungi Are Not Plants
Long ago, fungi were classified as plants, but in details, fungi are actually different to plants, firstly, they do not contain chloroplasts and they do not undergo photosynthesis. Secondly, their cell walls (hyphae walls) are made of chitin not cellulose as in plants. Thirdly, their extra supplies of sugar is stored as glycogen not starch. And lastly, they are heterotrophic eaters not autotrophic like plants.