characteristics and classificatioon.pdf

CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM...

CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES CONTENTS: 1.1 CHARACTERISTICS 1.2 CLASSIFICATION 1.3 FEATURES OF ORGANISMS 1.4 CLASSIFYING ANIMALS 1.5 CLASSIFYING PLANTS (EXTENDED ONLY) 1.6 VIRUSES (EXTENDED ONLY) 1.7 DICHOTOMOUS KEYS VIEW EXAM QUESTIONS 1.1 CHARACTERISTICS Characteristics of Living Organisms: Basics Movement: an action by an organism causing a change of position or place Respiration: the chemical reactions that break down nutrient molecules in living cells to release energy Sensitivity: the ability to detect and respond to changes in the environment Growth: a permanent increase in size Reproduction: the processes that make more of the same kind of organism Excretion: the removal from organisms of toxic materials and substances in excess of requirements Nutrition: the taking in of materials for energy, growth and development CIE IGCSE Biology Resources © copyright Save My Exams Page 1 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.1 CHARACTERISTICS cont... EXTENDED ONLY Characteristics of Living Organisms Movement: an action by an organism or part of an organism causing a change of position or place Respiration: the chemical reactions that break down nutrient molecules in living cells to release energy for metabolism Sensitivity: the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses Growth: a permanent increase in size and dry mass by an increase in cell number or cell size or both Reproduction: the processes that make more of the same kind of organism. Excretion: the removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements Nutrition: the taking in of materials for energy, growth and development; plants require light, carbon dioxide, water and ions; animals need organic compounds, ions and usually need water EXAM TIP Use this mnemonic to help you remember these processes: MRS. H. GREN Movement Respiration Sensitivity Homeostasis Growth and development Reproduction Excretion Nutrition CIE IGCSE Biology Resources © copyright Save My Exams Page 2 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.2 CLASSIFICATION How Organisms are Classified: Basics There are millions of species of organisms on Earth A species is defined as a group of organisms that can reproduce to produce fertile offspring 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 specialised groups The species in these groups have more and more features in common the more subdivided they get 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 CIE IGCSE Biology Resources © copyright Save My Exams Page 3 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.2 CLASSIFICATION cont... EXAM TIP The order of classification can be remembered by using this mnemonic: King Philip Came Over For Gran’s Spaghetti EXTENDED ONLY How Organisms are Classified Organisms share features because they originally descend from a common ancestor Example: all mammals have bodies covered in hair, feed young from mammary glands and have external ears (pinnas) Originally, organisms were classified using morphology (the overall form and shape of the organism, e.g. whether it had wings or legs) and anatomy (the detailed body structure as determined by dissection) As technology advanced, microscopes, knowledge of biochemistry and eventually DNA sequencing allowed us to classify organisms using a more scientific approach Studies of DNA sequences of different species show that the more similar the base sequences in the DNA of two species, the more closely related those two species are (and the more recent in time their common ancestor is) This means that the base sequences in a mammal’s DNA are more closely related to all other mammals than to any other vertebrate groups DNA sequences can show how closely related different species are The sequences above show that Brachinus armiger and Brachinus hirsutus are more closely related than any other species in the list as their DNA sequences are identical except for the last-but-one base (B.armiger has a T in that position whereas B.hirsutus has an A) As DNA base sequences are used to code for amino acid sequences in proteins, the similarities in amino acid sequences can also be used to determine how closely related organisms are CIE IGCSE Biology Resources © copyright Save My Exams Page 4 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.3 FEATURES OF ORGANISMS Common Cell Structures The cells of all living organisms contain the following: Cytoplasm Cell membrane DNA as genetic material (either found in the nucleus or free in the cytoplasm) General cell features A typical animal cell and plant cell A typical prokaryotic cell CIE IGCSE Biology Resources © copyright Save My Exams Page 5 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.3 FEATURES OF ORGANISMS cont... EXTENDED ONLY Cell Composition & Structure When viewed under an electron microscope (at a much higher magnification), all cells also contain the following: Ribosomes for protein synthesis Enzymes for respiration (in many, but not all types of cells, found in mitochondria) The Five Kingdoms Animals Plants Fungi Protoctists Prokaryotes Main features of all animals: They are multicellular Their cells contain a nucleus but no cell walls or chloroplasts They feed on organic substances made by other living things A typical animal cell CIE IGCSE Biology Resources © copyright Save My Exams Page 6 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.3 FEATURES OF ORGANISMS cont... Main features of all plants: They are multicellular Their cells contain a nucleus, chloroplasts and cellulose cell walls They all feed by photosynthesis A typical plant cell EXTENDED ONLY Fungi, Protoctists & Prokaryotes Main features of all fungi (e.g. moulds, mushrooms, yeast) usually multicellular cells have nuclei and cell walls not made from cellulose do not photosynthesize but feed by saprophytic (on dead or decaying material) or parasitic (on live material) nutrition A typical fungal cell CIE IGCSE Biology Resources © copyright Save My Exams Page 7 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.3 FEATURES OF ORGANISMS cont... EXTENDED ONLY cont... Main features of all Protoctists (e.g. Amoeba, Paramecium, Plasmodium) Most are unicellular but some are multicellular All have a nucleus, some may have cell walls and chloroplasts This means that some protoctists photosynthesise and some feed on organic substances made by other living things Two examples of protoctist cells Main features of all Prokaryotes (bacteria, blue-green algae) They are often unicellular Their cells have cell walls (not made of cellulose) and cytoplasm but no nucleus or mitochondria A typical bacterial cell CIE IGCSE Biology Resources © copyright Save My Exams Page 8 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.4 CLASSIFYING ANIMALS Vertebrates All vertebrates have a backbone. There are 5 classes of vertebrates: CLASS MAIN FEATURES EXAMPLES MAMMALS -- FUR/HAIR ON SKIN HORSE, DOG, -- HAVE A PLACENTA SQUIRREL, HUMAN -- YOUNG FEED ON MILK FROM MAMMARY GLANDS -- EXTERNAL EARS (PINNA) VISIBLE -- ENDOTHERMIC BIRDS -- SKIN COVERED IN FEATHERS PARROT, BLUE TIT, -- HAVE 2 LEGS AND 2 WINGS INSTEAD OF FORELIMBS EAGLE -- LAY EGGS WITH HARD SHELLS ON LAND -- HAVE A BEAK -- ENDOTHERMIC REPTILES -- DRY, FIXED SCALES ON SKIN SNAKE, TURTLE, -- LAY EGGS WITH RUBBERY SHELLS ON LAND IGUANA AMPHIBIANS -- SMOOTH, MOIST SKIN FROG, TOAD, NEWT -- ADULTS USUALLY LIVE ON LAND (SO HAVE LUNGS), LARVAE LIVE IN WATER (SO HAVE GILLS) -- LAY EGGS WITHOUT SHELLS IN WATER FISH -- LOOSE, WET SCALES ON SKIN FLOUNDER, -- GILLS TO BREATHE GROUPER -- LAY EGGS WITHOUT SHELLS IN WATER Vertebrate classification CIE IGCSE Biology Resources © copyright Save My Exams Page 9 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.4 CLASSIFYING ANIMALS cont... Invertebrates One of the morphological characteristics used to classify invertebrates is whether they have legs or not All invertebrates with jointed legs are part of the phylum Arthropods They are classified further into the following classes: CLASS MAIN FEATURES EXAMPLES MYRIAPODS --BODY CONSISTS OF MANY SEGMENTS CENTIPEDE --EACH SEGMENT CONTAINS AT LEAST 1 PAIR OF JOINTED LEGS --1 PAIR OF ANTENNAE INSECTS --3 PART BODY - HEAD, THORAX AND ABDOMEN BUTTERFLY --3 PAIRS OF JOINTED LEGS --2 PAIRS OF WINGS (1 OR BOTH PAIRS MAY BE VESTIGIAL - MEANING NON-FUNCTIONAL AND UNDEVELOPED) --1 PAIR OF ANTENNAE ARACHNIDS --2 PART BODY - CEPHALOTHORAX AND ABDOMEN SPIDER --4 PAIRS OF JOINTED LEGS --NO ANTENNAE CRUSTACEANS --MORE THAN 4 PAIRS OF JOINTED LEGS CRAB --CHALKY EXOSKELETON FORMED FROM CALCIUM --BREATHE THROUGH GILLS --2 PAIRS OF ANTENNAE Arthropod classification CIE IGCSE Biology Resources © copyright Save My Exams Page 10 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.5 CLASSIFYING PLANTS EXTENDED ONLY 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 Ferns Ferns reproduce by spores found in the underside of their fronds CIE IGCSE Biology Resources © copyright Save My Exams Page 11 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.5 CLASSIFYING PLANTS cont... EXTENDED ONLY cont... 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 Wheat plants are monocotyledons Sunflowers are dicotyledons CIE IGCSE Biology Resources © copyright Save My Exams Page 12 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.5 CLASSIFYING PLANTS cont... EXTENDED ONLY cont... 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) Comparing Monocots and Dicots EXAM TIP Identification of monocotyledons and dicotyledons comes up fairly frequently in the multiple choice paper. So it is worth learning the two differences between their flowers and leaves. CIE IGCSE Biology Resources © copyright Save My Exams Page 13 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.6 VIRUSES EXTENDED ONLY 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 Structure of a typical virus 1.7 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 CIE IGCSE Biology Resources © copyright Save My Exams Page 14 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES 1.7 DICHOTOMOUS KEYS cont... Example of a dichotomous key #1 Example of a Dichotomous Key #2 CIE IGCSE Biology Resources © copyright Save My Exams Page 15 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES 1.7 DICHOTOMOUS KEYS cont... KEY 1 (a) BODY IS COMPLETELY OR PARTLY COVERED IN A SHELL GO TO 2 (b) BODY IS NOT COMPLETELY OR PARTLY COVERED IN A SHELL LIMAX FLAVUS 2 (a) SHELL IS ATTACHED TO ROCKS BY THIN THREADS MYTILUS EDULIS (b) SHELL IS NOT ATTACHED TO ROCKS BY THIN THREADS GO TO 3 3 (a) SHELL IS A SPIRE THAT COMES TO A POINT BUCCINUM UNDATUM (b) SHELL IS NOT A SPIRE THAT COMES TO A POINT GO TO 4 4 (a) ANIMAL HAS TENTACLES NAUTILUS POMPILIUS (b) ANIMAL HAS 2 TENTACLES PLANORBIS PLANORBIS EXAM TIP Simple dichotomous keys almost always come up in the multiple choice paper, so make sure you can use one. Very occasionally they show up in the theory paper When they do you almost always have to use one instead of constructing one: so focus on this rather than spending hours learning to construct them yourself! > NOW TRY SOME EXAM QUESTIONS CIE IGCSE Biology Resources © copyright Save My Exams Page 16 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES EXAM QUESTIONS cont... ? QUESTION 1 The image below shows a house mouse, whose scientific name is Mus musculus. Which genus does it belong to? A Mammal B musculus C Mus D Vertebrate ? QUESTION 2 The image below shows what occurs to a seed during and after germination, the seed has been planted in well-watered soil. Which characteristics of living things are demonstrated by this sequence? A Nutrition and reproduction B Reproduction and growth C Nutrition and sensitivity D Sensitivity and growth CIE IGCSE Biology Resources © copyright Save My Exams Page 17 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS & CLASSIFICATION OF LIVING ORGANISMS YOUR NOTES EXAM QUESTIONS cont... ? QUESTION 3 Which of the following would not be a characteristic seen in all living organisms? A Reproduction B Respiration C Excretion D Photosynthesis ? QUESTION 4 Four different descriptions about plants are given below. Which statement would apply to a plant that is a dicotyledon? A The veins in the leaf are reticulated. B Each flower has six petals. C The flowers are all wind-pollinated. D The leaves have parallel veins. ? QUESTION 5 Some of the processes carried out by living organisms are illustrated in the diagram below. CIE IGCSE Biology Resources © copyright Save My Exams Page 18 REVISION NOTES TOPIC QUESTIONS PAST PAPERS  CIE IGCSE Biology Revision Notes savemyexams.co.uk CHARACTERISTICS 2 ORGANISATION & CLASSIFICATION OF THE ORGANISM OF LIVING ORGANISMS YOUR NOTES EXAM QUESTIONS cont... ? QUESTION 5 cont... Which row of the following table correctly describes the characteristics shown by living organisms in the diagram above? W X Y A respiration photosynthesis respiration B respiration respiration nutrition C photosynthesis respiration excretion D respiration excretion nutrition > CHECK YOUR ANSWERS AT SAVEMY EXAMS.CO.UK Head to savemyexams.co.uk for more questions and revision notes CIE IGCSE Biology Resources © copyright Save My Exams Page 19 REVISION NOTES TOPIC QUESTIONS PAST PAPERS