Biology

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

  The five 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 an electron microscope preferred over a light microscope for viewing cells?

  An electron microscope allows us to see finer details and subcellular structures that are not visible with a light microscope.
• How can you calculate the actual size of a cell using a microscope's magnification?

  By rearranging the formula magnification = image size / object size to find object size = image size / magnification.
• What are the two main groups of cells?

  Eukaryotic cells and prokaryotic cells.
• What distinguishes eukaryotic cells from prokaryotic cells?

  Eukaryotic cells have a nucleus where their DNA is found, while prokaryotic cells do not have a nucleus and their DNA is found in a plasmid.
• What is the function of the cell membrane?


  The cell membrane keeps everything inside the cell and is semi-permeable, allowing certain substances to pass through.
• What is the role of mitochondria in a cell?

  Mitochondria are where respiration takes place, releasing energy for the cell to function.
• What do ribosomes do in a cell?

  Ribosomes are where proteins are assembled or synthesized.
• What is the function of chloroplasts in plant cells?

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

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

  Stem cells are undifferentiated cells that can specialize into different cell types, found in human and animal embryos and the meristem of plants.
• How can stem cells be used in medicine?

  Stem cells 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 clones and the potential for misuse of technology.
• What is diffusion?

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

  Osmosis is the diffusion of water across a semi-permeable membrane.
• How does the concentration gradient affect the rate of diffusion and osmosis?

  The rate of diffusion and osmosis increases with a greater difference in concentrations.
• What is the practical procedure for investigating osmosis using potato cylinders?

  Cut equal size cylinders from a potato, weigh them, place them in varying concentrations of sugar solution, and measure the change in mass after a day.
• How do you calculate percentage change in mass?

  Percentage change in mass is calculated by the formula: \(\frac{\text{final mass} - \text{initial mass}}{\text{initial mass}} \times 100\).
• What does it indicate if a potato cylinder is lighter after the osmosis experiment?

  If a potato cylinder is lighter, it indicates a negative change in mass due to water moving out of the cell.
• What is active transport in cells?


  Active transport is the movement of substances through a membrane against a concentration gradient using energy from carrier proteins.
• 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 role of bile in digestion?

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

  Enzymes are biological catalysts that break down larger molecules into smaller ones for absorption.
• How does temperature affect enzyme activity?

  The rate of enzyme activity increases with temperature until the enzyme denatures at high temperatures.
• What is the practical procedure for investigating enzyme activity using amylase and starch?

  Mix amylase with starch at different temperatures or pH levels, then time how long it takes for the starch to be broken down.
• What is the optimum temperature or pH for enzyme activity?

  The optimum temperature or pH is the point at which the enzyme works the fastest, determined by plotting times against temperature or pH.
• 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 you have too little vitamin C?

  Too little vitamin C can lead to scurvy, which affects gums and hair.
• What is the function of calcium in the body?

  Calcium is needed for healthy bones, and a deficiency can lead to osteoporosis.
• What is the role of water in the body?

  Water is needed by every cell in the body.
• What is the difference between breathing and respiration?

  Breathing is the process of taking in oxygen and expelling carbon dioxide, while respiration is the chemical process that uses oxygen to release energy from food.
• What is the pathway of air during breathing?

  Air moves down the trachea into the bronchi, then bronchioles, and ends up in the alveoli.
• How does oxygen enter the blood from the alveoli?

  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 in red blood cells and transports it to cells throughout the body.
• What happens to carbon dioxide produced during respiration?


  Carbon dioxide diffuses into the plasma of the blood and is exhaled through the lungs.
• 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 preventing backflow.
• What is the function of the coronary artery?

  The coronary artery supplies oxygenated blood to the heart muscle.
• What can happen if coronary arteries are blocked?

  Blocked coronary arteries can lead to a heart attack due to insufficient blood supply to the heart muscle.
• What is the role of valves in veins?


  Valves in veins prevent backflow of blood as it returns to the heart.