The Nature and Variety of Living Organisms 1.1 Characteristics of living organisms Movement: can change position Respiration: can produce energy aerobically or anaerobically Sensitivity: can detect and respond to stimuli, such as light Control: can keep their internal environment constant/controlled Growth: can increase mass or number of cells Reproduction: can have offspring sexually or asexually Excretion: can remove waste products from the body Viruses are not living organisms because they can not grow or excrete and can only reproduce inside another organism. 1.2-1.4 Variety of living organisms Eukaryotes are organisms that have a nucleus and organelles within a membrane. Prokaryotes do not have a nucleus or organelles within a membrane. Saprotrophic nutrition is the extracellular secretion of digestive enzymes onto food material and absorption of the small nutrients. Animals: multicellular, cannot photosynthesize, no cell walls, nervous coordination, store carbohydrates as glycogen (mammals + insects) Plants: multicellular, contain chloroplasts so photosynthesize, cellulose cell walls, store carbohydrates as starch or sucrose (flowering plants + herbaceous legume) Fungi: multicellular/unicellular, mycelium containing thread-like hyphae, chitin cell walls, saprotrophic nutrition, store carbohydrates as glycogen (mucor + yeast) Protoctista: unicellular, Chlorella contain chloroplasts so photosynthesize, Amoeba consume other organisms for energy, plasmodium causes malaria Bacteria: unicellular, cell wall, membrane, cytoplasm, plasmids, no nucleus, circular chromosome, feed off other organisms, pneumococcus causes pneumonia Viruses: tiny particles, not living, parasites, protein coat, DNA or RNA, influenza causes flu, tobacco mosaic virus causes discolouring of leave of tobacco plants

Structures and Functions in Living Organisms 2.1 Level of organisation Organelle (e.g. cytoplasm): subcellular structures found within living cells Cell (e.g. muscle cell / palisade cell): basic structural unit of a living organism Tissue (e.g. muscle tissue / palisade tissue): group of similar cells working together to carry out a particular function Organ (e.g. stomach / leaf): group of different tissues working together to carry out a particular function Organ system (e.g. digestive system / shoot system): group of organs working together to carry out a particular function Organism (e.g. human / sunflower): a form of life 2.2-2.6 Cell Structure Nucleus: stores genetic material Cytoplasm - where chemical reactions take place Cell membrane: controls which substances can pass in and out of the cell Mitochondria: provides energy for the cell through respiration Ribosomes: site of protein synthesis Rigid cell wall (plants): provides support and structure Chloroplasts (plants): carry out photosynthesis with chlorophyll absorbing light from the sun Permanent vacuole (plants): contains cell sap (sugars, salts, water) 2.7-2.14 Biological molecules Carbohydrates: carbon, hydrogen, oxygen, starch and glycogen from simple sugars (e.g. glucose, fructose) Proteins: carbon, hydrogen, oxygen, nitrogen, proteins from amino acids Lipids: carbon, oxygen, hydrogen, lipids from 3 fatty acids + glycerol Glucose test: benedict's solution + water bath, blue to brick-red Starch test: iodine, brown to blue-black Protein test: biuret A + biuret B, blue to purple Fat test: ethanol + distilled water, colourless to milky white emulsion Enzyme: biological catalysts which increase the rate of reaction Enzymes + temperature: rate increases as temperature increases (particles have more kinetic energy so move faster and higher chances of collision), optimum 37 Enzymes + high temperature: bonds are broken, active site changes shape, enzyme cannot bind with the substrate, enzyme is denatured Enzyme + temperature exp: heat starch to set temperature, add amylase, add iodine to each well after a minute, measure time till iodine stops turning blue-black Enzyme  + temperature exp: independent - temperature, dependent - rate of starch breakdown, control - volume of starch, concentration of starch Enzymes + pH: rate increases as neutrality increases (particles have more kinetic energy so move faster and higher chances of collision), optimum 7 Enzymes + high pH: bonds are broken, active site changes shape, enzyme cannot bind with the substrate, enzyme is denatured Enzyme + pH exp: heat starch + amylase + pH solution, add a drop of the solution to each well with iodine after 10 seconds, measure time till solution turns orange Enzyme + pH exp: independent - pH, dependent - rate of starch breakdown, control - temperature, volume of starch, concentration of starch 2.15-2.17 Movement of substances into and out of cells Diffusion: the net movement of particles from an area of high concentration to an area of low concentration Diffusion example: single-celled organisms use diffusion to transport molecules into the body from the air as they have a large surface area : volume ratio Diffusion + concentration gradient: the greater the difference in concentration, the quicker the rate of diffusion (more particles are moving down the gradient) Diffusion + temperature: the greater the temperature, the quicker the rate of diffusion (particles have more kinetic energy so move faster and collide frequently) Diffusion + surface area : volume ratio: the greater the surface area, the quicker the rate of diffusion (particles have more space to move through) Diffusion + distance: the lower the distance particles need to travel, the quicker the rate of diffusion Active transport: the movement of particles from an area of low concentration to an area of high concentration using energy Active transport example: root hair cells use diffusion to take mineral ions from the soil using energy as cells have a higher concentration of mineral ions Diffusion exp: cut out 1cm cubed agar cube, place in HCl, remove + wash the cube, cut cube in half, measure diffusion distance, use different concentrations of HCl 2.18-2.33 Nutrition Carbohydrates: bread, pasta, potatoes, for energy Proteins: meat, fish, eggs, for growth and repair Lipids: butter, oil, cheese, for energy and insulation Fibre: vegetables, bran, for pushing food down the gut + preventing constipation Vitamin A: carrots, for vision Vitamin C: citrus fruits, for absorbing iron + preventing scurvy Vitamin D: margarine, for absorbing calcium Calcium: milk, for bone and teeth strength + preventing rickets Iron: red meat, for haemoglobin + preventing anaemia Water: water, juice, milk, for cell reactions to take place Age: energy requirements increase when approaching adulthood then decreases as adults age Activity levels: energy requirements increase because you need energy for movement Pregnancy: energy requirements increase to support growth of the foetus Mouth: mechanical when teeth break down food pieces, chemical when amylase breaks down starch, salivary glands produce saliva to lubricate the food bolus Oesophagus: tube from mouth to stomach, bolus moves down due to wave-like contractions (peristalsis) which squeeze the food down Pancreas: produces carbohydrates, protease and lipase and secretes these enzymes into the stomach and small intestine Stomach: pepsin breaks down proteins, hydrochloric acid kills bacteria, muscular walls churn food Liver: produces bile (alkaline) to neutralize HCl and to emulsify fat which increases surface area and it is broken down quicker, stored in gall bladder Small intestine: enzymes break down food, molecules diffuse into the bloodstream via the villi, bile enters via the bile duct Villi: thin walls decreases diffusion distance, rich capillary network to carry digested food, microvilli to increase surface area, small intestine is long Large intestine: absorbs water, produces faeces, faeces are stored in the rectum, faeces are removed through the anus Carbohydrates: starch to maltose by amylase, maltose to glucose by maltase, broken down in mouth + small intestine Proteins: proteins to amino acids by proteases, broken down in stomach + small intestine Lipids: lipids to glycerol + 3 fatty acids by lipases, broken down in small intestine Energy exp: measure temperature of cold water, measure mass of food sample, heat food till it catches fire, put sample under water, measure temperature of water Energy exp: independent - food sample, dependent - temperature rise, control - volume of water, distance from food to calorimeter Energy equation: Energy transferred (J) = Temperature increase (degrees C) x Mass (g) x 4.2 (J/g/degrees C) 2.34-2.39 Respiration Respiration: release of energy within the cell either aerobically or anaerobically Aerobic: Glucose + Oxygen > Water + Carbon Dioxide (C6 H12 O6 + O2 > CO2 + H2O), uses oxygen, full breakdown of glucose, releases energy used to make ATP Anaerobic (animals): Glucose > Lactic acid, very low energy release, partial breakdown of glucose, very less ATP produced Anaerobic (plants + fungi): Glucose > Ethanol + Carbon Dioxide (C6 H12 O6 > C2 H5 OH + CO2), low energy release, partial breakdown of glucose, less ATP produced Energy: ATP is used for other processes in the cell (e.g. active transport, protein synthesis, muscle contraction) Evolution of CO2 exp: flask 1 limewater, flask 2 germinating seeds, flask 3 limewater, connect flasks with capillary tubes Evolution of CO2 exp: flask 1 remains clear - air doesn't have enough CO2 to affect limewater, flask 3 goes cloudy - organisms are respiring + producing CO2 Evolution of CO2 exp: independent - living or not living, dependent - colour of limewater in flask 3, control - temperature, volume and concentration of limewater Evolution of heat exp: flask 1 germinating seeds, flask 2 dead seeds, measure initial temperature, leave for few days, measure end temperature Evolution of heat exp: temperature will increase for live germinating seeds as they release heat from aerobic temperature Evolution of heat exp: independent - living or not living, dependent - temperature, control - number of seeds 2.40-2.50 Gas Exchange Ribs: bone cage surrounding the lungs to provide protection of internal organs Intercostal muscles: muscles found between the ribs that control inhalation and exhalation Diaphragm: dome at the bottom of the thorax that changes the pressure to control inhalation and exhalation Trachea: the windpipe where air enters the thorax and flows to the lungs Bronchi: two tubes to each lung Bronchioles: smaller tubes that connect to the alveoli Alveoli: tiny air sacs that are the place of gas exchange Pleural membranes: found on the outside of the lungs to lubricate them (reduce friction while breathing) Inhalation: intercostal muscles contract, the ribcage moves up and out, the diaphragm contracts downwards, pressure decreases, air moves in Exhalation: intercostal muscles relax, the ribcage moves down and in, the diaphragm relaxes upwards, pressure increases, air moves out Alveoli: thin walls so short diffusion distance, large surface area so more space for molecules to travel through, good blood supply so maintains the concentration Exercise exp: We'll change whether the student has exercised or not. The students will be of the same age, gender, size and general fitness. We'll repeat the investigation several times to ensure our results are reliable. We'll measure the change in breathing rate. Immediately after exercise and each minute for the subsequent 5 minutes. We'll control the type of exercise carried out, the temperature of the environment, the food intake of the students prior to the investigation. 2.51-2.69 Transport Unicellular organisms: diffusion to transport molecules, high surface area to volume ratio, more space for molecules to travel at once + short diffusion distance Multicellular organisms: transport system to transport molecules, low surface area to volume ratio, less space for molecules to travel at once + larger distance

Ecology and the Environment 4.1-4.5 The Organism in the Environment Population: all the organisms of one species living in the same habitat Community: all the populations of organisms that live in an area or ecosystem Habitat: a small part of an ecosystem where a species lives Ecosystem: a system in which organisms interact with each other and their environment Biodiversity: a measure of the variety of organisms in an area Population exp: random number generator for grid coordinates to place quadrat, count how many in each quadrat, find number per square metre, multiply by area Distribution exp: tape measure, place a quadrat at equal lengths along the transect, count how many in each quadrat Abiotic: light intensity - light required for photosynthesis, temperature - affects the rate of photosynthesis, water levels - needed to survive Biotic: food availability - organisms can breed successfully, pathogens - can kill organisms, competition - some animals can't get food or water 4.6-4.9 Feeding Relationships Producer: an organism that produces its own food Primary: an animal that eats plants (a herbivore) Secondary: an animal that eats primary consumers Tertiary: an animal that eats secondary consumers Decomposer: an organism that causes decay of dead material (fungi and bacteria) Food chain: shows the feeding relationships between organisms Food web: shows many interdependent food chains Pyramid of number: shows the population at each trophic level, often a pyramid shape, for a large plant the bar size is small as 1 tree feeds many insects Pyramid of biomass: shows the biomass at each trophic level, often a pyramid shape, not all the food consumed is converted into biomass Pyramid of energy: shows the energy content at each trophic level, always a pyramid shape Energy loss: 10% transferred as organisms don't normally eat every part, bits they eat might not be absorbed, biomass gets released as waste products 4.10-4.11 Cycles within Ecosystems Combustion: burning of fossil fuels which releases carbon back into the atmosphere Decomposition (Carbon cycle): dead plants and animals are broken down by decomposers and carbon returns to the atmosphere Respiration: plants and animals respire which releases carbon dioxide into the atmosphere Photosynthesis: plants remove carbon dioxide from the atmosphere through photosynthesis Fossil fuels: fuels formed organic material, such as peat, coal, oil, and natural gas Nitrogen fixing: nitrogen fixing bacteria convert nitrogen in the atmosphere into nitrates in the soil Nitrification: nitrifying bacteria convert ammonia into nitrates in the soil Decomposition (Nitrogen cycle): decomposers convert decaying matter into ammonia Denitrification: denitrifying bacteria convert nitrates in the soil into nitrogen in the atmosphere 4.12-4.8 Human Influences on the Environment Sulphur dioxide: releases when fossil fuels are burnt, dissolves in water, falls as acid rain, low pH in lakes so fish die, corrodes limestone in buildings Carbon monoxide: released when fossil fuels are burnt through incomplete combustion, binds with haemoglobin, no O2 can bind, less O2 transported, people die Methane (greenhouse gas): comes from cattle farming and causes global warming Water vapour (greenhouse gas): comes from combustion and causes global warming CFC (greenhouse gas): comes from refrigerators and affects the ozone layer Carbon dioxide (greenhouse gas): comes from burning fossil fuels and causes global warming Nitrous oxide (greenhouse gas): comes from burning fossil fuels and causes acid rain Greenhouse effect: greenhouse gases absorb sun's heat, trap it above the Earth's surface, which leads to higher temperatures and global warming Global warming effects: glaciers melt, water levels rise, loss of habitats, changes om weather patterns Eutrophication: nutrients allow rapid growth of algae, algal bloom stops light reaching aquatic plants, oxygen depletion means other aquatic organisms die Deforestation: the clearing of an area of trees on a mass scale Leaching: without trees nutrients and minerals from the soil run into rivers and lakes Soil erosion: without tree roots the soil will be washed away by the rain Disturbance: transpiration releases water vapour affecting the water and carbon cycle Imbalance of atmospheric gases: removal of trees causes more CO2 levels and lower O2 levels

Use of Biological Resources 5.1-5.9 Food Production: Maintaining water quality: filter water to remove waste and harmful bacteria to prevent disease Controlling intraspecific predation: stops competition within the same species, as fish are separated by size and age to prevent competition Controlling interspecific predation: stops competition between species, as different species are separated by nets or tanks Controlling disease: antibiotics are given to increase chances of survival Removal of waste products: water is filtered to remove waste faeces Controlling feeding quality + frequency: fish are fed frequently in small amounts so they don't overeat and to avoid food wastage Selective breeding: reproduce fish with desired characteristics