BIOLOGY PAPER 1

• a eukayotic cell are complex and include all animal and plant cells
• a prokayotic cell has no nucleus and is smaller an example being bacteria
• the main function of the egg cell is to carry female dna and nourish the development of the embryo
• it contains nutrients in the cytoplasm to feed the embryo
• it contains a hapliod nucleus
• the sperm cell carries male DNA and fertilises the egg cell
• the sperm has a acrosome at the front of the head where it stores enzymes needed to digest its way through the membrane of the egg cell
• epithelial cells line the surface of our organs
• some of them have cilia (hair like stuructures) on top surface of the cell
• the fuction of ciliaed epithelial cells is to move substances
• calculating magnification: magnification=image size/actual size
• milimeters into micrometers is times by 1000
• micro to nanometeres is times by 1000
• nano to picometers is times by 1000
• enzymes have special shapes so that they can catalyse reactions
• tempreture ,ph and substrate conc affect the rate of reaction
• if the ph is too high or too low the ph interferes with the bonds holding the enzyme together , this changes the shape of the active site
• enzymes have an optimum ph its often ph 7 but not always as pepsin is an enzyme that breaks down protienin the stomarch , optimum ph is ph2 meaning its sutiable for acidic conditions
• enzymes called carbohydrates convert carbohydrates into simple sugares such as amylase is an example of a carbohydrate that breaks down into starch
• starch is broken down by the enzyme amylase into maltose and sugars
• proteins are broken down by protease into amino acids
• lipids are broken down by lipase into glycerol and fatty acids
• proteins are made by joining amino acids together
• diffusion is simply the gradual movement of particles
• diffusion is the net overall movement of particles from an area of high concentration to an area of lower concentration
• Osmosis is the net movment of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower
• active transport is the movement of particles across a membrane against a concentration gradient for example from an area of low conc to an area of high
• once you've got all your results , you need to calculate the precentage change in mass for each group of cylinders before and after
• you can plot a graph and analyse your results , where there is no chnage in mass (where the curve crosses the x-axsis)the fluid inside the cylinders and surcose solutionare know as isotonic as they have the same water conc
• interphase - the subcellular sturctures increase
• prophase- chromosomes condense the membrane around the nucleus breaks down and the chromosomes lie free in cytoplasm
• metaphase- the chromosomes line up in the centre
• anaphase- spindle fibers pull the chromosomes apart and the chromatids are pulled to either side of the cell
• telophase- membranes form around each set of chromosomes these become the nuclei of the 2 new cells , the nucleus divides
• cytokinesis- cytoplasm and cell membrane divide to form two new genetically identical daughter cells
• growth involves cell division,differentiation and elongation
• cell differentiation- the process by which a cell changes to become specialised for its job
• cell division- by mitosis
• plants also grow by cell elongation this is where plant cell expands
• adult stem cells are found in bone marrow and blood they only produce certain types of cells