Biology igcse

• MRSGREN


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


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


  the chemical reactions that break down nutrient molecules in living cells to release energy.
• Sensitivity


  the ability to detect or sense changes in the environment (stimuli) and to make responses.
• Growth


  a permanent increase in size and dry mass* by an increase in cell number or cell size or both
• Reproduction


  the process by which living organisms produce offspring
• Excreation


  the process of eliminating or expelling waste matter
• Nutrition


  taking in of nutrients which are organic substances and mineral ions containing raw materials or energy for growth and tissue repair, absorbing and assimilating them.
• Cells


  All living things are made of cells
• cell structure


  membrane, cytoplasm, nucleus, cell wall, vacuole, chloroplast
• animal cell


  does not have a cell wall, chloroplast or a vacuole

  
• Cytoplasm function


  Where the organelles reside

  
• cell membrane function


  Controls the movement of substances into and out of the cell

  
• Nucleus function


  Control center of the cell

  controls; cell division, cell action and cell developement

  
• cell wall function


  provides support and protection

  
• Vacuole function


  Store a variety of things such as water, nutrients, or waste products.

  
• Chloroplast function


  photosynthesis - convert solar energy to chemical energy

  
• Ciliated cells function


  movement of mucus in the trachea and bronchi

  
• Root hair cells function

  absorb water and minerals

  
• Palisade mesophyll cells function

  photosynthesis

  
• red blood cells function

  transportation of oxygen

  
• Egg cells/ovum function


  To carry the female DNA, to nourish the developing embryo in the early stages and reproduction

  
• Sperm cells function


  To fertilise the egg

  
• Magnification


  1- measure the image size by using a ruler (in millimeters)

  2- convert the millimeters into micrometers (x1000)

  3- devide the answer by the actual size

  
• Diffusion


  net movement of particles from an area of higher concentration to an area of lower concentration, due to the random movement of particles.

  
• factors that increase diffusion

  -Higher concentration gradient

  -Higher temperature

  -Larger surface area

  -Shorter distance
• Osmosis


  The net movement of water molecules from a region of higher water potential to a region of a lower water potential through a partially permeable membrane

  
• hypertonic solution/low water potential

  -water moves out of the cell and it becomes plasmolyzed

  -the cell becomes weak and limp

  
• isotonic solution


  -same water potential as the cell

  -water will move in and out of the cell at the same rate

  -flaccid

  
• hypotonic solution/high water potential

  -water moves into the cell and the cell starts to swell.

  -the cell becomes turgid due to turgor pressure caused by the cytoplasm and vacuole pushing against the cell wall .

  
• Chemical elements that make up carbohydrates, fats, and proteins

  carbohydrates: c,h,o

  fats: c,h,o

  proteins: c,h,o,n
• monomers of carbs


  Starch and glycogen

  
• monomers of fats


  glycerol and fatty acids

  
• monomers of proteins


  amino acids
• Test for starch


  Iodine solution

  -Posotive:Blue black

  -Negative:Orange yellow

  
• Test for protein


  Buriet solution

  -Positive:Purple

  -Negative:No change

  
• Test for glucose


  Benedict's solution

  Positive - brick red

  Negative - blue
• Test for fat


  Ethanol

  -Positive: Milk white emulsion

  -Negative: No change
• Enzymes


  proteins that act as biological catalysts
• enzyme action


  -Substrate approaches enzyme's active site

  -Molecules bind together forming enzyme-substrate complex

  -Enzyme-substrate specificity—lock and key

  -Enzyme releases reaction products

  -Enzyme unchanged and can repeat process