Biology Paper 1

• What type of cells have a nucleus and include animal and plant cells?


  Eukaryotic cells
• What is the function of the cell membrane?


  It controls the movement of substances into and out of a cell
• What is the cytoplasm and its role in a cell?


  Cytoplasm is a jelly-like substance where reactions take place inside a cell
• Where does respiration take place in cells and what does it release?


  Respiration takes place inside mitochondria and releases energy
• Where are proteins made in cells?


  Inside ribosomes
• What are cell walls made of and what is their function?


  Cell walls are made of cellulose and give a cell structure
• What is the function of a vacuole in a cell?


  A vacuole stores cell sap and gives a cell structure
• What do chloroplasts contain and what is their role?


  Chloroplasts contain chlorophyll used for photosynthesis
• What is the role of chlorophyll in photosynthesis?


  Chlorophyll absorbs light for photosynthesis
• Where is genetic material stored in a cell?


  On chromosomes held in the nucleus
• What type of cells are prokaryotic cells and what do they lack?


  Prokaryotic cells are bacteria cells that lack a nucleus
• What happens as a cell differentiates?


  • It develops different sub-cellular structures
  • Enables it to carry out a particular function
  • Becomes a specialised cell
• What are sperm cells specialised for?


  Sperm cells are specialised for energy production with a large number of mitochondria
• What are mesophyll cells specialised for?


  Mesophyll cells are specialised for photosynthesis with a large number of chloroplasts
• When do animal cells differentiate?


  Animal cells differentiate at an early stage of life
• When can plant cells differentiate?


  Plant cells can differentiate throughout their life
• What is the formula for magnification?


  Magnification = image size ÷ actual size
• What do µm and nm stand for?


  µm stands for micrometre, nm stands for nanometre
• How many micrometres are in a millimetre?


  1 mm = 1000 µm
• Which type of microscope was developed first?


  Light microscopes were developed first
• What advantages do electron microscopes have over light microscopes?


  Electron microscopes give greater magnification and resolution
• How do electron microscopes contribute to our understanding of cells?


  Electron microscopes allow people to see more subcellular structures
• What is the purpose of mitosis?

  Mitosis allows cells to divide for growth, repair, and development of an embryo
• What are the stages of the cell cycle during mitosis?


  1. Stage 1: DNA is copied & number of subcellular structures, mitochondria & ribosomes are increased
  2. Stage 2: Chromosomes are pulled to either end of the cell and nucleus divides
  3. Stage 3: Cytoplasm and cell membranes divide to form 2 genetically identical cells
• What are stem cells?


  Stem cells are undifferentiated cells found in embryos, adult animals, and meristems in plants
• How can stem cells from human embryos be used?


  They can be cloned and made to differentiate into most different types of human cells
• What medical treatments can stem cells help with?


  Treatment with stem cells can be used to help diabetes and paralysis
• What are some risks associated with the use of stem cells?


  Risks include transfer of viral infection and ethical objections about killing a potential human life
• How can stem cells in plants be utilized?


  Stem cells in plants can be used to produce clones of plants quickly and economically
• What is diffusion?


  Diffusion is the passive movement of particles from a high concentration to a low concentration.
• What factors can change the rate of diffusion?


  The rate of diffusion can be changed by altering concentration gradient, temperature, and surface area.
• Why are surfaces and organ systems in multicellular organisms specialised?


  Surfaces and organ systems are specialised for exchanging materials.
• What increases the effectiveness of an exchange surface?


  • Having a large surface area
  • Thin membrane
  • Efficient blood supply (in animals)
  • Being ventilated (in animals for gas exchange)
• What is osmosis?


  Osmosis is the passive movement of water from an area of higher water concentration to an area of lower water concentration, across a partially permeable membrane.
• What causes mass changes in plant cells?


  Mass changes are caused by the movement of water across a plant cell membrane.
• What is active transport?


  Active transport uses energy from respiration to transport substances across a membrane from low concentration to high concentration.
• Where is active transport used in the body?


  Active transport is used in root hair cells and the small intestine for the absorption of nutrients.
• What are cells in living organisms?


  Cells are the basic building blocks of all living organisms.
• What is a tissue?


  A tissue is a group of similar cells working together.
• What is an organ?


  An organ is a group of different tissues working together.