bio topic 1

• an electron microscope has a higher magnification and a higher resolution than a light microscope
• plant cells have some features like a cell wall and chloroplasts that are absent in animal cells
• the function of the cell wall is to support and keep the cell in place
• the cell membrane controls what enters and leaves the cell and is made of phospholipids and proteins
• the vacuole stores cell sap
• the cytoplasm is a watery jelly where most of the cells activities take place
• the nucleus contains the genetic material of the cell and controls the cell
• chloroplast has chlorophyll that traps energy transferred by the sun to be used during photosynthesis
• mitochondria is a jelly bean structure in which aerobic respiration takes place
• ribosomes make protein
• the acrosome is a vacuole that contains enzymes that break down the substances in the eggs jelly coat
• the mitochondria in a sperm cell is spiral shaped and is alot to provide energy for the sperm
• the tail waves from side to side to swim
• the cell membrane in the egg hardens after fertilization to ensure no other sperm can enter
• the cytoplasm in the egg is packed with nutrients to give out energy for the growth of the embryo
• the jelly coat protects the egg and hardens after fertilisation
• the small intestine is adapted by having membranes with may tiny folds called microvilli which increases the surface area. its one cell thick and surrounded by a variety of capillaries. the villi is surrounded by a thin layer of cells for short diffusion. it also has a rich blood supply which produces a steep concentration gradient for faster diffusion
• enzymes are biological catalysts that increases the rate of reactions
• the enzyme proteases breaks down protein into amino acids
• the enzyme amylase breaks down starch into glucose
• the enzyme lipase breaks down lipids into glycerol and fatty acid
• the active site of an enzyme has a very specific shape which only the substrate which has the complementary shape can bind in
• if an enzyme is exposed to very high temperatures and pH then the active site changes causing the enzyme to denature
• in order to test for starch you need to take a food sample and put 2 drops of iodine solution. if the sample turns into the blue/black colour then starch is present
• to test for reducing sugar, add benedict's solution to your sample. then place it in a hot water bath. If it turns brick red or orange then reducing sugars are present.
• to test for protein, use biuret solution. if the sample turns blue/black, then protein is present
• to test for fats, mix the sample with ethanol and shake. If the mixture forms a cloudy emulsion then there are fats present
• diffusion is the movement of particles from a higher concentration to a lower concentration. it doesnt require energy
• osmosis is when water moves from a lower concentration to a higher concentration through a semi permeable membrane
• active transport is when particles move from a low to a high concentration. it requires alot of energy
• a hypotonic solution is when the concentration is higher in the solvent than in the solute
• a hypertonic solution is when the concentration is higher in the solute than the solvent