Edexcel IGCSE Biology Definitions

• Nutrition

  Provide living organisms with energy and raw material for growth and repair.
• Respire

  Living organisms release energy from their food.
• Excretion

  The removal of waste products such as carbon dioxide and urine carried out by the skin, the lungs and the kidneys.
• Response

  Nerve coordination and reaction to stimuli.
• Reproduction

  To produce offsprings for their species to survive.
• Cells

  Tiny building blocks of living organisms.
• Multicellular

  Organisms that contain a lot of cells and therefore need organisation.
• Organelles

  Tiny structures within cells.
• Nucleus

  Contains genetic materials that control the cell's activities.
• Cell membrane

  Outer surface of the cell and control movement of substances in and out.
• Cytoplasm

  Place of most chemical reactions and contain enzymes.
• Chloroplasts

  Contain chlorophyll and carry out photosynthesis.
• Cell wall

  Rigid structure made of cellulose that supports and strengthens cells.
• Vacuole

  Large organelle that contains cell sap.
• Cell sap

  A weak solution of sugars and salts.
• Tissue

  A group of similar cells that work together to carry out particular function.
• Xylem tissue

  For transporting water and mineral salts in plants.
• Phloem tissue

  For transporting sucrose and amino acids in plants.
• Organ

  A group of different tissues that work together to perform a function.
• Organ system

  A group of organs that does a particular job.
• Cereals

  Example: maize
• Herbaceous legumes

  Example: beans and peas
• Mycelium

  A structure of fungi.

  
• Hyphae

  Thread like structure that make up mycelium.
• Saprotrophic nutrition

  Fungi that secret extracellular enzymes into the area outside their body to dissolve their food, so they can then absorb the nutrients.
• Yeast

  A single-celled fungus.
• Mucor

  Multicellular fungus and has a mycelium and hyphae.
• Chlorella

  Protoctists, plant-cell-like
• Amoeba

  Protoctists, animal-cell-like
• Lactobacillus bulgaricus

  Bacteria, can be used to make milk go sour and turn into yoghurt.
• Pneumococcus

  Bacteria, spherical in shape, causes pneumonia.
• Viruses

  Particles and smaller than bacteria
• Parasites

  Organisms that depend on other organisms to live.
• Tobacco mosaic virus

  Makes the leaves of tobacco plants discoloured by stopping them from producing chloroplasts.
• Pathogens

  Organisms that cause disease. (include fungi, protoctists, bacteria and viruses)
• Plasmodium

  Protoctists, causes malaria
• Influenza virus

  Viruses, causes flu and HIV which causes AIDS.
• Enzymes

  A substance that speeds up the speed of a reaction without being changed or used up in the reaction. Made up of chains of amino acids.
• Metabolic reactions

  Useful chemical reactions inside the body.
• Substrate

  A molecules that is changed in the reaction.