GCSE SCIENCE TRILOGY

• What is cell specialization?


  Cells may be specialized to carry out a particular function.
• Can you name three types of specialized animal cells?

  Sperm cells, nerve cells, and muscle cells.
• Can you name three types of specialized plant cells?


  Root hair cells, xylem, and phloem cells.
• What is the importance of cell differentiation?


  It allows cells to form different types necessary for various functions.
• When do most types of animal cells differentiate?


  At an early stage of development.
• Do many types of plant cells retain the ability to differentiate throughout life?


  Yes, many types of plant cells can differentiate throughout their life.
• What happens in mature animals regarding cell division?


  Cell division is mainly restricted to repair and replacement.
• What does a cell acquire as it differentiates?


  Different sub-cellular structures to carry out a specific function.
• What is the role of microscopy in biology?


  It helps to understand sub-cellular structures.
• How has electron microscopy improved our understanding of cells?


  It has much higher magnification and resolving power than light microscopy.
• What is the formula for magnification?


  Magnification = size of image / size of real object.
• If the size of the image is 10 cm and the size of the real object is 2 cm, what is the magnification?


  Magnification = $\frac{10 \text{ cm}}{2 \text{ cm}} =$$5$
• What do chromosomes contain?


  Chromosomes contain DNA molecules that carry genes.
• How are chromosomes typically found in body cells?


  Chromosomes are normally found in pairs.
• What is the cell cycle?


  The series of stages through which a cell divides.
• What happens to genetic material during the cell cycle?


  It is doubled and then divided into two identical cells.
• What must a cell do before it can divide?


  It needs to grow and increase the number of sub-cellular structures.
• What occurs during mitosis?


  One set of chromosomes is pulled to each end of the cell and the nucleus divides.
• What is the final step of cell division?


  The cytoplasm and cell membranes divide to form two identical cells.
• Why is cell division by mitosis important?


  It is important for the growth and development of multicellular organisms.
• What is a stem cell?


  An undifferentiated cell capable of giving rise to many more cells of the same type.
• What is therapeutic cloning?


  It produces an embryo with the same genes as the patient for stem cell treatment.
• What are some potential risks of using stem cells?


  Transfer of viral infection and ethical objections.
• How can stem cells from meristems be used in agriculture?


  To produce clones of plants quickly and economically.
• What is diffusion?


  The spreading out of particles resulting in net movement from higher to lower concentration.
• What substances are commonly transported by diffusion in cells?


  Oxygen, carbon dioxide, and urea.
• What factors affect the rate of diffusion?


  Concentration gradient, temperature, and surface area of the membrane.
• Why do single-celled organisms have a large surface area to volume ratio?


  To allow sufficient transport of molecules into and out of the cell.
• Why do multicellular organisms need exchange surfaces?


  To allow sufficient transport of molecules into and out of cells.
• What adaptations do the small intestine and lungs have for exchanging materials?


  They have a large surface area and thin membranes.
• What is osmosis?


  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
• What should students be able to calculate regarding plant tissue?

  Percentage gain and loss of mass of plant tissue.
• What is active transport?


  Movement of substances from a dilute solution to a concentrated solution against a concentration gradient, requiring energy.
• Why is active transport important for plants?


  It allows mineral ions to be absorbed from dilute solutions in the soil.
• How does active transport relate to sugar absorption in the gut?


  It allows sugar molecules to be absorbed from lower concentrations into the blood.
• What are the basic building blocks of all living organisms?

  Cells.
• What is a tissue?


  A group of cells with a similar structure and function.
• What are organs?


  Aggregations of tissues performing specific functions.
• What are organ systems?


  Groups of organs that work together to form organisms.
• What is the digestive system?


  An organ system where several organs work together to digest and absorb food.