HURDCO International School Subject- Biology Chapter-1 Classification Characteristics of Living Organisms • Movement • Respiration • Sensitivity • Growth • Reproduction • Excretion • Nutrition: How Organisms are Classified: Basics • These species can be classified into groups by the features that they share e.g. all mammals have bodies covered in hair, feed young from mammary glands and have external ears (pinnas) The Binomial System • Organisms were first classified by a Swedish naturalist called Linnaeus in a way that allows the subdivision of living organisms into smaller and more specialized groups • He named organisms in Latin using the binomial system where the scientific name of an organism is made up of two parts starting with the genus (always given a capital letter) and followed by the species (starting with a lower case letter) • When typed binomial names are always in italics (which indicates they are Latin) e.g. Homo sapiens • The sequence of classification is: Kingdom, Phylum, Class, Order, Family, Genus, Species Linnaeus’s system of classification The Five Kingdoms The first division of living things in the classification system is to put them into one of five kingdoms. They are: • Animals • Plants • Fungi • Protoctists • Prokaryotes Animalia all animals – animals are multicellular (eukaryotic lacking cell wall material, but have a chromosome containing nucleus), do not have cell walls, do not have chlorophyll, feed heterotrophically (heterotrophs can't make their own food) e.g. fish, insects, mammals, reptiles etc. Plantae All plants - are multicellular (eukaryotic), have cell walls (and a chromosome containing nucleus), have chlorophyll, feed autotrophically (autotrophs can make their own food from photosynthesis) e.g. grasses, flowers, trees etc. Fungi Usually multicellular (eukaryotic), have cell walls, do not have chlorophyll e.g. mushrooms, toadstools, yeasts. Fungi can (i) feed saprophytically - saprophytes/saprotrophs feed off dead organisms and decaying material, (ii) Parasite symbiont - feeding off another living organism (at its host's expense!) (iii) symbiosis, where both the fungus and host benefit each other. Fungi MUSHROOM YEAST MOLD Protoctista (protists) Usually unicellular (single celled eukaryotes), have a nucleus, protists include algae (can photosynthesize) and protozoa. Protoctista protozoa Protoctista SEAWEED BLUE-GREEN ALGAE ON WATER Prokaryotes Unicellular (single celled prokaryotic organisms), have no nucleus e.g. bacteria, cyanobacteria and archaea. Classification of Animals Animals Animals are divided into two categories: 1. Invertebrates: animals without a backbone or bone skeleton. 2. Vertebrates: animals with a backbone or bone skeleton. Mammalia • These organisms have mammary glands. They have two pairs of limb. Digits are provided with claws, nails or hooves. Skin is covered by hair and they have an external ear called pinnae. They are warmblooded animals. • Examples of Class Mammalia include monkeys, lions, bats, squirrels and humans. Vertebrates (continued) Mammals Birds • Birds have a streamlined body to offer low air resistance during flight. The forelimbs are modified into wings, with the power coming from breast muscles. Feathers play important roles, from flight, thermal insulation to water-proofing. • They are warm-blooded and can regulate their body temperature. • Aves have beaks, which are used for preening and feeding. • Examples of Class Aves are Parrot, Pigeon, Duck, etc. Vertebrates (continued) Birds Reptilia • Reptilia are ectothermic in nature (cold-blooded). They are characterized by osteoderms which form scales, bony plates or scutes on the skin. • Reptiles also lack an external ear and some reptiles such as snakes are actually “deaf” and instead, pick up vibrations through the ground. • Snakes possess Thermoception means that snakes can see infrared radiation emitted by objects or prey. • Examples of Class Reptilia are Tortoise, Wall lizard, Snake, etc. Vertebrates (continued) Reptiles Amphibia • Amphibia are cold-blooded and require an aquatic habitat to lay eggs. • These organisms are mainly characterized by the two pairs of limbs, smooth and moist skin for respiration. • They also possess protruding eyes which are protected by usually more than one pair of eyelids. (Frogs have 3). • Examples of Class Amphibia are frog, toad, and salamander. Vertebrates(continued) Amphibia Fishes • They are aquatic animals, having a streamlined body and a pair of fins which are used for propulsion and movement. Furthermore, fish are cold-blooded, but the discovery of a new species in 2015 has changed this perception. The opah or the moon-fish is a fully warmblooded fish capable of regulating its body temperature. • Endoskeleton may be cartilaginous or bony and respiration occurs through gills. They do not possess eyelids because the surface of the eye is to be kept moist all the time. • Examples of Class Pisces includes dogfish and Rohu. Vertebrates(continued) Bony fish Myriapods (Invertebrates- arthropods) • Body consists of many segments • Each segment contains at least 1 pair of jointed legs • 1 pair of antennae • E.g. Centipede Insects (Invertebrates- arthropods) • 3 part body – head, thorax and abdomen • 3 pairs of jointed legs • 2 pairs of wings (1 or both pairs may be vestigial- meaning nonfunctional and undeveloped • 1 pair of antennae • E.g. Butterfly (Invertebrates- arthropods) Insects Arachnids (Invertebrates- arthropods) • 2 part body – cephalothorax and abdomen • 4 pairs of jointed legs • No antennae • E.g. Spider Crustaceans (Invertebrates- arthropods) • More than 4 pairs of jointed legs • Chalky exoskeleton formed from calcium • Breath through gills • 2 pair of antennae • E.g. Crab Classifying Plants • Ferns & Flowering Plants • At least some parts of any plant are green, caused by the presence of the pigment chlorophyll which absorbs energy from sunlight for the process of photosynthesis • The plant kingdom includes organisms such as ferns and flowering plants Ferns • Have leaves called fronds • Do not produce flowers but instead reproduce by spores produced on the underside of fronds Flowering plants • Reproduce sexually by means of flowers and seeds • Seeds are produced inside the ovary found at the base of the flower • Can be divided into two groups – monocotyledons and dicotyledons How to distinguish between monocotyledons and dicotyledons 1) FLOWERS • Flowers from monocotyledons contain petals in multiples of 3 • Flowers from dicotyledons contain petals in multiples of 4 or 5 2) LEAVES • Leaves from monocotyledons have parallel leaf veins • Leaves from dicotyledons have reticulated leaf veins (meaning that they are all interconnected and form a web-like network throughout the leaf) Viruses Features of Viruses • Viruses are not part of any classification system as they are not considered living things • They do not carry out the seven life processes for themselves, instead they take over a host cell’s metabolic pathways in order to make multiple copies of themselves • Virus structure is simply genetic material (RNA or DNA) inside a protein coat Dichotomous Keys Constructing & Using a Key • Keys are used to identify organisms based on a series of questions about their features • Dichotomous means ‘branching into two’ and it leads the user through to the name of the organism by giving two descriptions at a time and asking them to choose • Each choice leads the user onto another two descriptions • In order to successfully navigate a key, you need to pick a single organism to start with and follow the statements from the beginning until you find the name • You then pick another organism and start at the beginning of the key again, repeating until all organisms are named Example of a dichotomous key THANK YOU
