BIOLOGY 240-Golden_rules_AQA_Biology_paper

BIOLOGY 240-Golden_rules_AQA_Biology_paper GCSE AQA BIOLOGY 9-1 PAPER 1 CELLS, TISSUES AND ORGANS 1. When a question asks you about MITOCHONDRIA, always discuss  Respiration  Energy RELEASE  Oxygen and glucose Muscle cells will have the most mitochondria as they need the most energy! Root hair cells will also have a lot as they need ‘Energy from respiration for Active Transport’ 2. Structure of an organelle = what does it look like. Function = what does it do. Learn this for each organelle in animal and plant cells 3. REMEMBER: Bacteria have no nucleus! (Prokaryotes) Have their DNA as a loop. May also have one or more ring/s of DNA called a Plasmid/s. 4. Model answer for diffusion:  What is moving? (i.e. glucose)  How is it moving? (i.e. diffusion)  Where does it move from and why? (i.e from inside gut because concentration is high there)  Where does it move to and why? (i.e. to the intestine cells because concentration is low there)  What does it move across? (i.e. partially permeable cell membrane) When discussing active transport you must mention the following:  Mitochondria  (use up) glucose and oxygen  (to carry out) respiration  ATP/energy released from respiration!!!  (used by) carrier proteins  (to move particles) against concentration gradient In plants, ions/minerals are ACTIVELY TRANSPORTED into the roots. Water moves in by OSMOSIS. OSMOSIS Water moves from a HYPOTONIC solution to a HYPERTONIC solution. IF A QUESTION MENTIONS SUGAR BEING PRESENT, WATER WILL MOVE IN THAT DIRECTION PARTIALLY PERMEABLE MEMBRANE A high water potential means solution is watery/dilute. A low water potential mean solution is concentrated/full of salts or sugars. CELL DIVISION AND STEM CELLS . Mitosis 1. DNA replicates, cell organelles increase in number (mitochondria, ribosomes and chloroplasts) 2. Replicated chromosomes are pulled to each end of the cell and then nucleus divides 3. Cytoplasm and cell membrane divide to form 2 GENETICALLY IDENTICAL BODY CELLS Meiosis = DNA replicates, cell divides TWICE, 4 different GAMETES (sex cells) are formed with HALF the n