Biology

• Eukaryotic cells


  • Animal and plant cells have genetic material (DNA) that forms Chromosomes and is contained in a nucleus
• Animal cell structures


  • Cell membrane
  • Nucleus
  • Mitochondria
  • Cytoplasm
• Plant cell structures


  • Cell wall
  • Chloroplasts
  • Permanent vacuole
• Prokaryotic cells (Bacteria)


  • Single-celled
  • No nucleus
  • Have a single loop of DNA
  • Have small rings of DNA called plasmids
  • Smaller than eukaryotic cells
• Cell differentiation


  Cells in animals and plants differentiate to form different types of cells. Most animal cells differentiate at an early stage of development, whereas a plant's cells differentiate throughout life.
• Specialised animal cells


  • Red blood cell
  • Muscle cell
  • Neuron
• Specialised plant cells


  • Palisade cell
• Diffusion


  The spreading out of particles, resulting in movement from an area of higher concentration to an area of lower concentration. Particles move down the concentration gradient from an area of high concentration to an area of low concentration.
• Diffusion


  • Nutrients in the small intestine diffusing into capillaries
  • Oxygen from water passing over fish gills diffusing into the blood
  • Carbon dioxide used for photosynthesis diffusing into leaves through stomata
• Osmosis


  The diffusion of water through a partially permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
• Osmosis


  • Water moving from a dilute solution in the soil to a concentrated solution in the root hair cell
• Active transport


  The movement of particles from a more dilute solution to a more concentrated solution using energy from respiration. Particles move against the concentration gradient from an area of low concentration to an area of high concentration.
• Chromosomes


  The structures in the nucleus that contain the genetic material (DNA)
• Cell cycle


  1. Cell growth

  2. DNA replication

  3. Increase in sub-cellular structures

  4. Chromosome separation

  5. Nuclear division

  6. Cytoplasm and cell membrane division
• Mitosis


  Cell division to form two identical daughter cells, important for growth and repair
• Heart


  The organ that pumps blood around the body
• Heart


  • Made from cardiac muscle tissue
  • Supplied with oxygen by the coronary artery
• Blood flow through the heart

  1. Deoxygenated blood enters right atrium

  2. Right ventricle pumps blood to the lungs

  3. Oxygenated blood from lungs enters left atrium

  4. Left ventricle pumps blood around the body
• Pacemaker


  Group of cells in the right atrium that generate electrical impulses to control heart rate
• Artificial pacemaker


  Can be used to control irregular heartbeats
• Levels of organisation in living organisms

  • Cells
  • Tissues
  • Organs
  • Organ systems
  • Organisms
• Cells


  Basic building blocks of living organisms
• Tissues


  Groups of cells that have similar structures and functions
• Organs


  Groups of tissues working together to perform a specific function
• Organ systems


  Groups of organs working together
• Organisms


  Organ systems work together, forming an organism
• The Cell Cycle


  Growth and repair, cells Mitosis
• Cell division by mitosis

  1. Body cells divide to form two identical daughter cells

  2. Going through a series of stages known as the cell cycle
• Cell division by mitosis


  • Important for the replacement of skin
  • Used for asexual reproduction
• Cell cycle


  1. Stage 1: Cell grows bigger, DNA replicates (chromosomes are duplicated), increase in number of sub-cellular structures

  2. Stage 2 (mitosis): A complete set of chromosomes is pulled to each end of the cell, the nucleus divides to form two nuclei

  3. Stage 3: Cytoplasm and cell membrane divide to form two identical daughter cells