Untitled

• Characteristics of living organisms (MRS GREN)

  • Movement
  • Respiration
  • Sensitivity
  • Growth
  • Reproduction
  • Excretion
  • Nutrition
• Movement


  An action by an organism causing a change of position or place
• Respiration


  The chemical reactions in cells that break down nutrient molecules and release energy for metabolism
• Sensitivity


  The ability to detect and respond to changes in the environment
• Growth


  The permanent increase in size
• Reproduction


  The process that make more of the same kind of organism
• Excretion


  The removal from organisms of toxic materials and substances in excess of requirements
• Nutrition


  Taking in of materials for energy, growth and development
• Magnification


  Image size / actual size
• Actual size


  Image size / magnification
• Living organisms are made of cells
• Active transport


  The movement of particles through a cell membrane from a region of lower concentration to a region of higher concentration using energy from respiration
• Passive transport


  The movement of particles through a cell membrane from a region of higher concentration to a region of lower concentration (Does not require energy)
• Functions of cell structures

  • Nucleus: controls the cell's activities and contains genetic material (DNA)
  • Cytoplasm (jelly like): Most biochemical reactions take place here. Controlled by enzymes
  • Chloroplast: contains chlorophyll, which absorbs light energy for photosynthesis which produces sugars using light energy
  • Vacuole: creates a pressure to maintain the shape of the cell. store food, mineral, water and waste product
  • Cell Membrane: control the movement of substances into and out of the cell, acts as a barrier
  • Cell Wall: protect and withstand the internal pressure of the cell
  • Mitochondria: Site for aerobic respiration. Produces energy
  • Ribosome: site of protein synthesis
• Specialised cell features and functions

  • Ciliated Cell: Tiny hair cells called cilia which can sweep the mucus up and out of the trachea and into your mouth
  • Goblet cell: secrete mucus which trap bacteria and dust particle
  • Root Hair Cell: Elongated shape- gives a large surface area for absorption, Thin walls- fast diffusion, No chloroplast which increases efficiency for absorption, Absorbs water by osmosis and mineral ions by active transport
  • Palisade Mesophyll Cell: Tightly packed with chloroplast and positioned near surface of the leaf to maximise absorption of sunlight, Carry out photosynthesis
  • Red Blood Cell: Have no nucleus, Biconcave shape, Contain haemoglobin to transport oxygen around the body
  • Sperm Cell: Tail- provides movement so it can swim and find an egg cells, Head-contain the genetic materials in haploid nucleus, Head- contain enzyme that help the sperm penetrate the egg, To carry out genetic information and fertilise the egg
  • Egg Cell: Has jelly coating, Haploid nucleus for fertilisation, To carry genetic information and to be fertilised by the spam
• Diffusion


  The net movement of particles from a region of higher concentration to a region of lower concentration. Particles move down a concentration gradient, as a result of their random movement
• Factors affecting diffusion


  • Surface area
  • Temperature
  • Concentration gradient
  • Diffusion distance
• Substances move into and out of cells by diffusion through the cell membrane
• Osmosis


  The net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane
• Effects of immersing plant tissues in solutions of different concentrations

  • Hypertonic solution: Water diffuses out of the cell by osmosis, causing the cytoplasm to shrink and the cell membrane to be ripped away from the cell wall (plasmolysis)
  • Isotonic solution: No net movement of water, so the volume or shape of the plant cell is unlikely to change
  • Hypotonic solution: Water diffuses into the cell by osmosis, causing the cytoplasm to enlarge and push outwards on the cell wall, making the cell turgid
• Turgor pressure


  The pressure that water applies in plants (i.e. the water pressure)
• Turgid


  Swollen, especially due to high fluid content
• Plasmolysis


  Cells lose water by osmosis, causing the cytoplasm to shrink and the cell membrane to be ripped away from the cell wall
• Flaccid


  Wilts because not enough water
• Hypertonic


  Water moves out by osmosis, cell shrinking
• Isotonic


  Water moves in and out at equal rate, no change in size and shape
• Hypotonic


  Water moves into the cell by osmosis, cell expands and bursts
• In the uptake of water by plants, the soil around the plant must contain water that is more dilute than the water in root hair cells, allowing water to diffuse in by osmosis
• Unlike plant cells, animal cells do not have a cell wall to support them, so if immersed in a hypertonic solution, the cell will shrivel up, and if immersed in a hypotonic solution, the cell will burst (undergo lysis)
• Chemical elements that make up biological molecules

  • Carbohydrates: Carbon, Hydrogen, and Oxygen
  • Fats: Carbon, Hydrogen, and Oxygen
  • Protein: Carbon, Hydrogen, Oxygen, and Nitrogen
• Biological molecules and their components

  • Starch and glycogen made from glucose
  • Protein from amino acids
  • Fats from fatty acids and glycerol
• Food tests


  • Iodine solution: Tests for starch (Positive-blue-black, Negative-orangey brown)
  • Benedict's Solution: Tests for reducing sugar (glucose) (Positive- green,yellow,orange,brick red, Negative- blue)
  • Biuret Solution: Tests for protein (Positive-purple, Negative-blue)
  • Ethanol: Tests for fats (Positive- milky white, Negative- clear)
• Water is extremely important as a solvent. All reactions in our body occur in water, our cells are 70% water on average, and substances are transported around our body after being dissolved in water
• Uses of water in a plant

  • Photosynthesis
  • Transport
  • Solvent
• Enzyme


  Proteins that function as biological catalysts
• Substrate must be complementary to the enzyme
• Optimum temperature


  The temperature an enzyme works best at
• Optimum pH


  The pH an enzyme works best at
• Catalyst


  A substance which speeds up the rate of a reaction without themselves being altered in the reaction
• Factors affecting enzymes


  • Temperature
  • pH