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UNIT 2 CELLS AND SYSTEMS Topic 1 Living Organisms What do all living things have in common? 1) need energy 2) respond and adapt to their environment 3) reproduce 4) grow 5) produce wastes 6) made of cells Topic 2 Microscopes and Cells Microscopes – compound light microscopes – use more than one lens – magnify up to 2000 x - electron microscopes up to 2000000 x How to calculate magnification : magnification of objective lens x magnification of eyepiece lens. How to calculate field of view. 1) Measure the diameter of the field of view on low power. 2) for medium-power = low-power field of view x low-power lens Medium-power lens Topic 3 The Cell and Its Structures Parts of an animal cell cell membrane – surrounds cell and controls the passage of materials into and out of the cell cytoplasm – acts like blood in our bodies, moving materials such as oxygen and food to the organelles and supports other organelles in cell nucleus – contains genetic material that controls growth and reproduction – surrounded by nuclear membrane vacuoles – storage for food, wastes etc. – surrounded by a membrane mitochondria – break down food particles to produce energy for the cell Parts of a plant cell membrane, cytoplasm, nucleus, vacuoles cell wall – thick and rigid to give cell support chloroplasts – where photosynthesis takes place Topic 4 Fluid Movement in Cells Diffusion in cells: ex. carbon dioxide passes through the cell membrane of an amoeba – inside the cell CO2 is being produced, so there is a higher concentration of CO2 in the cell – therefore, by diffusion, CO2 moves out of the cell until the concentration of CO2 is equal on both sides of the cell membrane Osmosis in cells: water is important to cells because it dissolves many substances the cell needs – when a cell loses water the solution inside the cell becomes more concentrated – water will move from a more dilute solution to a more concentrated solution to even out the concentrations of the solutions on both sides of the cell Fluid movement in plants – phloem carries food from leaves – xylem carries water and minerals from the roots when there is more water outside a root hair cell than inside water moves into the cell by osmosis – it moves from cell to cell by osmosis to xylem tissue, which are like straws – as more water enters the root hairs pressure is created pushing the water upwards to stems and leaves water is used in leaves for photosynthesis – leaves flat and thin to provide surface area for sunlight and to diffuse gases into and out of cell through stomata – guard cells open and close the stomata as transpiration occurs through stomata this provides force to draw water up the plant plants use a pushing force from the roots and a pulling force from the leaves to transport water up the plant Topic 5 Cell Specialization and Organization Humans have about 100 different types of cells, each with its own function and structure – ex. nerve cells have long fibres to carry signals, muscle cells are long so they can contract to do work, blood cells are hollow disc shaped to increase surface area to pick up oxygen Advantage of being unicellular – reproduce quickly advantages of being multicellular – can grow large – don’t have to live in watery, food-rich environment – can obtain energy from wide variety of foods – cells specialize and can do jobs more effectively Cells of organisms are organized into tissues – main types in animals – muscle – epithelial (skin and also covers internal structures such as intestines) – connective (connects and supports ex. bone, blood – some are fibrous) - nerve in plants – epidermal (skin) – xylem – phloem several tissues working together form organs – ex. stomach, brain, eyes, lungs, heart, kidneys – in plants (roots, stem, leaves) organs work together to form systems – ex. circulatory, respiratory, digestive – in plants (root system, shoot system and reproductive system) RECENT ADDITION TO NOTES: 1. why does the body need oxygen? - oxygen is used in each of our cells to burn our fuel (food) to produce energy 2. the pathway taken for carbon dioxide to exit the body from a cell in our hand - the CO2 diffuses from the cell into a capillary, and then moves into a vein - the vein leads to the heart from there the CO2 moves into an artery to the lungs and again into a capillary so it can diffuse into the alveoli - it moves into a bronchiole, a bronchus, the trachea and out through your nose or mouth Topic 7 Body Systems and Your Health High blood pressure (hypertension) heart attacks, strokes -test blood pressure to find: blood volume heart rate – if high builds blood pressure artery size – if clogged harder for blood to move through artery elasticity – if flexible can expand to let blood through – hardening of arteries produces high blood pressure blood viscosity – if thick flows less easily disorders of circulatory system cigarettes constrict vessels and CO competes with oxygen poor diet – high salt raises blood pressure _ cholesterol builds on walls of arteries, narrowing or blocking them – tiny tears in walls cause blood clots – if travel to brain have stroke – restricted flow to heart, heart attack to avoid above - eat properly, exercise, don’t smoke digestive system carbohydrates – provide energy – sugar and starch – fruit, grains, beans, peas fats – energy and cushion for internal organs – can be stored (great when we were– cilia cells may die, mucus nomadic and did not have reliable food source; not so great now) proteins – growth and repair – meat, fish, eggs, certain plants disorders of digestive system low fibre diet – takes longer for colon to process – irritates colon wall – colon cancer stress, smoking, excessive alcohol – peptic ulcer disorders of respiratory system cigarette smoke and pollutants irritate cilia causing build-up of mucus on them – cough to remove – lead to bronchitis - mucus producing cells multiply – narrow and block airways – lead to emphysema lung cancer – smoke damages lung tissue and causes cells to grow out of control