IGCSE biology revision- quick

• What are the five main topics covered in Edexcel International GCSE Biology?

  The five main topics are the nature and variety of living organisms, structures and functions in living organisms, reproduction and inheritance, ecology in the environment, and use of biological resources.
• Why is it important to pause the video during the Edexcel International GCSE Biology review?

  To allow time to understand the material being presented.
• What is the basic unit of life?


  Cells.
• What is the difference between a light microscope and an electron microscope?

  An electron microscope allows us to see finer details than a light microscope.
• How can we calculate the actual size of a cell using a microscope?

  By dividing the size of the image by the magnification.
• What are the two main groups of cells?

  Eukaryotic cells and prokaryotic cells.
• What is the function of the cell membrane?


  It keeps everything inside the cell and is semi-permeable.
• What is the role of the cytoplasm in a cell?


  The cytoplasm is the liquid where most chemical reactions take place.
• Where does respiration take place in a cell?


  In the mitochondria.
• What is the function of ribosomes?

  Ribosomes are where proteins are assembled or synthesized.
• What do chloroplasts contain and what is their function?

  Chloroplasts contain chlorophyll and are where photosynthesis takes place.
• What is a permanent vacuole and its function in plant cells?

  A permanent vacuole stores sap in plant cells.
• What are stem cells and where are they found?

  Stem cells are unspecialized cells found in human and animal embryos and the meristem of plants.
• How can stem cells be used in medicine?

  They can be used to combat conditions like diabetes and paralysis.
• What ethical considerations are associated with cloning?

  Cloning raises ethical arguments regarding the implications of creating and using clones for medical purposes.
• What is diffusion?

  Diffusion is the movement of molecules from an area of high concentration to an area of low concentration.
• What is osmosis specifically defined as?

  Osmosis is the diffusion of water across a semi-permeable membrane.
• How does the concentration of glucose outside a cell affect osmosis?

  If there is a higher concentration of glucose outside a cell, water moves out of the cell, decreasing its mass.
• What factors can increase the rate of diffusion and osmosis?

  Increasing the difference in concentrations, temperature, or surface area can increase the rate.
• What is the practical procedure for investigating osmosis using potato cylinders?

  1. Cut equal size cylinders from a potato.
  2. Weigh them and place in test tubes with varying concentrations of sugar solution.
  3. After a day, remove and dab excess water off.
  4. Reweigh and calculate percentage change in mass using:

  $\text{Percentage Change} =$$\frac{\text{Final Mass} - \text{Initial Mass}}{\text{Initial Mass}} \times 100$

  1. Plot percentages against sugar concentration and draw a line of best fit.
• What is active transport in cells?


  Active transport is the movement of substances through a membrane against a concentration gradient using energy.
• What is the relationship between cells, tissues, organs, and organ systems?

  Cells group together to form tissues, tissues form organs, and organs work together in organ systems.
• What is the function of bile in digestion?

  Bile neutralizes stomach acid and emulsifies fats to increase their surface area for enzyme action.
• What are enzymes and their role in biological processes?

  Enzymes are biological catalysts that break down larger molecules into smaller ones.
• What is the lock and key principle in enzyme activity?

  The lock and key principle states that the substrate must fit the enzyme's active site to form a complex.
• What happens to an enzyme when it denatures?

  When an enzyme denatures, its active site changes shape, preventing the substrate from binding.
• What is the practical procedure for investigating enzyme activity using amylase and starch?

  1. Mix amylase with starch at different temperatures or pH levels.
  2. Start timing and remove drops every 10 seconds.
  3. Place drops in iodine solution; initially, it will turn black if starch is present.
  4. Record the time when it stays orange, indicating starch breakdown.
  5. Plot times against pH or temperature to find optimum conditions.
• What are the main components of a balanced diet?

  A balanced diet includes carbohydrates, fats, proteins, vitamins, minerals, fiber, and water.
• What is the role of carbohydrates in the diet?

  Carbohydrates provide energy and are found in foods like bread, cereal, pasta, and potatoes.
• What can happen if there is a deficiency of vitamin C?

  A deficiency of vitamin C can lead to scurvy, affecting gums and hair.
• What is the function of calcium in the body?

  Calcium is needed for healthy bones; a deficiency can lead to osteoporosis.
• What is the function of the respiratory system?

  The respiratory system is responsible for breathing and gas exchange.
• How does oxygen enter the blood during respiration?

  Oxygen diffuses from the alveoli into the blood vessels surrounding them.
• What is the role of hemoglobin in red blood cells?

  Hemoglobin binds to oxygen and transports it to cells for respiration.
• What is the structure of the heart in relation to blood flow?

  The heart has a right side for deoxygenated blood and a left side for oxygenated blood, with valves to prevent backflow.
• What is the difference between arteries and veins?

  Arteries carry oxygenated blood away from the heart, while veins carry deoxygenated blood back to the heart.
• What is coronary heart disease (CHD)?

  Coronary heart disease occurs when coronary arteries are blocked by fatty deposits, leading to heart attacks.
• What is the function of stents in the cardiovascular system?

  Stents are inserted into blood vessels to keep them open for blood flow.
• What is the role of white blood cells?

  White blood cells combat infections in the body.
• What is the function of leaves in plants?

  Leaves are where photosynthesis takes place and water is lost through transpiration.