BIOLOGY P1

• Eukaryotic cell


  • Plant
  • Animal
  • Fungi
• Organelles found only in plant cells


  • Chloroplasts
  • Vacuole
  • Cell wall
• Mitochondria


  Release energy for cells by Aerobic respiration
• Ribosomes


  Make proteins
• Cell membrane


  Controls what enters and leaves the cell
• Similarities between Eukaryotic and Prokaryotic cells


  • Genetic material
  • Ribosomes
  • Cytoplasm
  • Cell membrane
  • Cell walls
• Differences between Eukaryotic and Prokaryotic cells

  • Nucleus (E) and no nucleus (P)
  • Mitochondria (E)
  • Plasmid DNA (P)
  • Asexual reproduction only (P)
• Mitosis


  • Cell growth
  • Cell repair
• Cancer


  Uncontrollable cellular division
• Differences between malignant and benign cancer


  • Malignant- Can spread through the blood
  • Benign- forms a tumour but does not spread
• Disadvantages of using Embryonic stem cells

  • They can be rejected
  • They can turn into cancer cells
  • Unethical- killing an embryo to use
• Aerobic respiration


  Glucose + Oxygen -> Carbon Dioxide + Water
• C6H12O6 + 6O2 -> 6CO2 + 6H2O
• Products of anaerobic respiration


  • Animal: Lactic acid
  • Plant (Fermentation): Ethanol and CO2
• Oxygen debt


  Amount of oxygen required to remove the lactic acid and replace the body's reserves of oxygen
• Humans have 46 chromosomes
• Cell division


  1. DNA replication/sub-cellular growth

  2. The nuclei must disappear and chromosomes aligned centrally by spindle fibres
• Mitosis


  TWO genetically identical daughter cells
• Stages of Mitosis

  • Chromosomes centrally align and are split apart by spindle fibres
  • New nuclei form
  • Cell membranes/cytoplasm's split into two new cells
• Cell division in bacteria

  Binary Fission
• Stem cells in plants

  • Meristems
  • Found throughout their life
  • Found in tips of roots and shoots
• Function of stem cells in adult animals

  Make RBC's, WBC's and Bone marrow
• Function of sperm cells

  To carry the male DNA to the female DNA / fertilise female egg
• Function of muscle cells

  To contract and relax
• Why muscle cells have a lot of mitochondria

  Mitochondria release energy into the cell via aerobic respiration. Muscles contract which requires energy. The mitochondria together with extra blood supply provide the muscle with energy it needs.
• A bacteria cell is 0.02µm wide and a Mitochondrion is 0.08µm. The bacteria does not contain a mitochondria because the mitochondrion is too big and would not fit into a bacteria.
• Highest magnification of a light microscope


  X400 (X40 Objective lens x x10 eyepiece lens)
• Why electron microscopes are better than light microscopes


  They have higher magnification and higher resolution
• Resolution


  • The ability to distinguish between two points
  • Turn the fine coarse focusing wheel to improve the clarity (Resolution) of a specimen
• Diffusion


  Movement of particles from an area of high concentration to an area of low concentration (down a concentration gradient)
• Adaptations of alveoli for gas exchange

  • Millions of alveoli in lungs means huge surface area
  • Very thin walls so diffusion path is very short
  • Very good blood supply.
  • Once oxygen rapidly diffuses into blood, it is rapidly removed. This ensures conc. gradient is steep as possible.
• Adaptations of small intestines for faster diffusion

  • Millions of villi cover interior of SI, massively increases surface area for absorption of molecules
  • Microvilli (surface of villi) increase large surface area further
  • Villi has thin cell membrane- shorter diffusion pathway
  • Large supply of blood capillaries- Good blood supply. rapidly removes products of digestion - increases conc. gradient
  • Many Mitochondria in microvilli - More energy for active transport
• Osmosis


  Movement of water particles from a dilute to a concentrated solution through a partially permeable membrane
• Active transport


  Movement of molecules / ions from low to high (Against conc gradient) using energy from aerobic respiration
• Why plants wilt if the soil they are growing in is flooded with salty water


  The sea water has a high concentration of salt, so the water concentration in the soil will be lower than that in the plant. This means the water would move by osmosis from the plant to the soil (high to low conc), causing the plant to lose water and wilt.
• Why active transport is important for glucose absorption in the gut


  Sometimes the conc of glucose in the gut is lower than the conc of glucose in the blood, so cells must use active transport to absorb glucose into the bloodstream.
• Heart

  Made up of cardiac muscle
• Function of the heart

  To pump blood around the body
• Part of the heart that sends blood to the body

  Left ventricle
• Part of the heart with pacemaker cells

  Right Atrium