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IGCSE BIOLOGY GENERAL REVIEW Ch. 1-5

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  • How would you test the presence of PROTEINS?
    Add BIURET REAGENT, it turns PURPLE in the presence of proteins.
  • Name the characteristics of all living organisms.
    Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition
  • Explain what happens to the cells in each case due to Osmosis:
    1. No change in size / 2. Cell shrinks (plasmolysis) / 3. Cell swells up (turgid in plants, bursts in animals)
  • Name the principal clases of the following groups: VERTEBRATES, ARTHROPODS, MOLLUSCS
    VERTEBRATES: Mammals, Reptiles, Fish, Amphibians, Birds / ARTHROPODS: Crustaceans, Arachnids, Myriapods, Insects / MOLLUSCS: Bivalves, Gastropods, Cephalopods
  • The image represents 3 biological molecules. Name them and identify each structure of the diagrams.
    1. Fat molecule / 2. Protein molecule/ 3. Carbohydrate molecule
  • Define the term OSMOSIS and name 1 example
    NET MOVEMENT of WATER MOLECULES from a region of HIGHER WATER POTENTIAL (diluted) to a region of LOWER WATER POTENTIAL (concentrated) through a SEMIPERMEABLE ME
  • How would you test for STARCH?
    Add some drops of IODINE SOLUTION (orange), in the presence of starch it turns DARK BLUE.
  • Explain how ENZYMES work and give 2 examples.
    Biological catalists, lock-key model, enzyme-substrate complex, optimum ph and T°... Brewing, washing powders, digestion, photosynthesis, etc.
  • Name the 4 factors that affect the RATE of ENZYME ACTION.
    Temperature, pH, concentration of enzyme, concentration of substrate.
  • How would you test the presence of VITAMIN C?
    Add a few drops of DCPIP (blue dye) and in the presence of Vitamin C, it turns COLOURLESS.
  • How would you test the presence of FATS?
    EMULSION test: alcohol + water. MILKY-WHITE emulsion.
  • The picture shows and ANIMAL cell and a PALLISADE cell. Identify them and name their components.
    Animal: Cell membrane, nucleous, mitochondria, cytoplasm. Plant: the same as animal PLUS cell wall, chloroplasts and big vacuole.
  • How would you test the presence of REDUCING SUGARS? (simple sugars)
    Add BENNEDICT'S REAGENT (blue), mix, heat in a water bath for 3min. In the presence of sugar a RED PRECIPITATED appears.
  • Use all your knowledge about ENZYMES to explain the following image:
    The rate of reaction is affected by pH, not all enzymes work at the same pH, there's an optimum pH, denaturalisation, etc.
  • Why viruses are not considered living organisms and why aren't destroyed by antibiotics?
    They can't live without a host (no MRS GREN). Antibiotics attack bacterial structures that viruses don't have (cell wall, cell membreane)
  • Biologists compare the s_________ of the b______in the ____ of organisms from different species to see how related they are.
    sequences - bases
  • Explain what is the BINOMIAL SYSTEM and how it is used.
    A system of naming species in which the scientific name of an organism is made up of two parts showing the GENUS and the SPECIES. Eg. Homo sapiens
  • With all the info from the picture classify each solution depending on its tonicity
    1. Hypertonic solution / 2. Isotonic solution / 3.Hypotonic solution
  • Explain how to calculate the MAGNIFICATION of an image.
    M= I/A Magnification = Observed size of the IMAGE (or drawing) / ACTUAL size of the specimen
  • Define the term SPECIES
    A group of organisms that can reproduce to produce fertile offspring.
  • Flowering plants can be classified into Monocotyledons and Dicotyledonds. Explain their 4 main differences.
    Leaf shape (long and narrow vs braod), leaf veins (parallel vs branching), number of cotyledons (1 vs 2), grouping of flower parts (3 vs 5)
  • Name the 3 factors that may affect the rate of diffusion.
    1. Temperature, 2. Concentration gradient, 3. Surface area
  • Define the term DIFUSSION and name 2 examples.
    NET MOVEMENT of molecules and ions from a region of their HIGHER CONCENTRATION to a region of their LOWER CONCENTRATION down a CONCENTRATION GRADIENT (random)
  • Explain the difference between PASSIVE and ACTIVE transport.
    Active transport: movement of particles AGAINST a concentration gradient and using energy from cellular respiration.
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