Topic 2- Cells and Control

• What does the cornea do?

  The transparent outer layer of the eye helps to refract light onto the retina.
• What does the lens do?

  Allows light rays to focus
• What does the iris do?

  Controls the size of the pupil and regulates the amount of light entering the eye.
• What are rod cells?

  In the retina, they are responsible for vision at low light levels.
• What are cone cells?

  Photoreceptor cells in the retina that detect colour.
• What are cataracts?

  Clouding of the lens in the eye due to a build up of proteins.
• How can you treat cataracts?

  Surgery to replace the lens
• What is myopia?

  Short sightedness caused by the eyeball being elongated or the lens being too thick/curved
• What is hyperopia?

  Long sightedness caused by the eyeball being too short or loss of elasticity in the lens.
• How can short sightedness be corrected?

  A concave lens causing the light rays to diverge
• How can long sightedness be corrected?

  A convex lens causing the light rays to converge
• What does the cerebellum control?

  Balance movement and moscular activity.
• What does the cerebral hemisphere control?

  Senses, intelligence, thought, personality and high level functions.
• What does the medulla oblongata control?

  Unconscious activities like the heart rate and breathing rate
• What does the hypothalamus regulate?

  Temperature and water balance.
• What is mitosis?

  Process of cell division in which a single cell divides into two identical daughter cells with each having identical sets of chromosomes forming diploid body cells.
• What are the stages of mitosis?

  Interphase, prophase, metaphase, anaphase, telophase and cytokinesis.
• What is cancer?

  The uncontrollable division of diseased cells
• Why is mitosis so important in growth and repair?

  It replaces damaged cells
• Why is mitosis important in asexual reproduction?

  This happens in one organism so the offspring is produced by replication of cells.
• How does growth occur in animals?

  Cell division and differentiation.
• How does growth occur in plants?

  Cell division, elongation and differentiation