B1 paper 1 biology notes

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cells Clarger St= faster diffusion) • used to get ions from soil ige (B1) (Microscopes 8 Magnification) (62) light microscopes mag = [mag of eyepiece X mag of objective lens transmission electronmicroscope 2D images - 1 8 resolution high mag nitosis. Scanning electron microscope-5. 3D images. low mag resolving power - effects detail can resolution: ability to distinguish M CHRO (STAGES OF CELL CYCLE) gains Sub-cellular structure & growth grows in size Ona replicates to form 2 copies of each chromosome one set of chromosomes pulled to opposite end of cell nucleus divides 9 V split cytoplasm + cell membrane divide, creates 2 identical daughter cells CHROMOSOMES are long coiled strands of Dna, paired up during mitosis to be MA show mag between 2 points image Size actual Size (STEM CELLS) cells that aren't specialised yet EMBRYONIC turn into any cell, used in theraputic cloning, won't be rejected ADULT STEM CELLS only make cell from tissive it's from turn into blood cells, can cure Chrons, Strokes, diabetes Found in bone marrow risk of spreading viral infections. STEM CELLS X issues aborted embrgos, expensive, could cause cancer, happened to the mice it was tested on & slow progress ✓ divide $ grow rapidly, won't be rejected much discovered w/ them Conly 20 more (dore). yesurs B1:Infection and Response Communicable = infectious diseases Animals and plants can catch infectious diseases from Viruses Bacteria Fungi- Protists Pathogen = disease causing microorganism. Ways you can catch diseases: Direct contact (touching) Droplets (in the air) Infected water The Human Immune System Your first line of defence against infection are your Skin, nose, trachea and bronchia and stomach. Your trachea is lined with mucus to trap dirt and bacteria and has microscopic hairs called cilia to 'waft' this back up and out of the body. If a pathogen gets inside, your white blood cells help you. They produce antibodies that are specific for certain pathogens, antitoxins and they can 'eat' pathogens by phagocytosis. If being infected for the first time, it takes a while for your body to make antibodies but if you have been infected before, the antibodies can be produced much faster. Viruses cause colds, flu, HIV, measles and tobacco mosaic virus in plants. They get inside cells and grow then damage cells. This is why they are hard to treat. Measles is caught through the air through coughs and sneezes. HIV is caught through contact with infected blood or semen. Condoms help reduce spread. Antiretroviral medicines help treat HIV but can't kill it. Tobacco mosaic virus makes plants not able to photosynthesis on parts of the leaves. Bacteria reproduce rapidly and produce toxins that make us feel ill and damage body tissues. Antibiotics kill bacteria. Salmonella is a bacterial infection that is caught from infected food like meat and eggs and causes fever, vomiting and diarrhoea. Cooking food thoroughly and washing hands after going to the toilet reduces spread. Gonorrhoea is an STD that causes yellow discharge from the penis or vagina and pain when urinating. Safe sex (using condoms) reduces spread of STDs. Some new strains of gonorrhoea are resistant to antibiotics. Fungal diseases are spread by fungi. Rose black spot is a plant fungal disease spread by water and wind between plants. It reduces photosynthesis which reduces growth of plants that are infected. It can be treated using fungicides or removing affected leaves. Protists are single celled microbes that can cause infection usually through a vector. Malaria is a protest infection that uses the mosquito as a vector. It causes fever that can recur and can be fatal. Methods of prevention involve killing the mosquito or preventing mosquito bites by using nets. Vaccination A dead or inactive form of the disease is injected White blood cells make specific antibodies If the same disease enters the body the antibodies can be made quickly, stopping infection. Vaccinating populations reduces the spread of diseases! Antibiotics are drugs that only kill bacteria. Painkillers only treat symptoms of disease. Drug discovery and development 1. PRECLINICAL testing = New medicines are tested on cells, tissues and animals 2. CLINICAL testing = first on healthy volunteers then patients. 3. In double blind trials the patient and doctor don't know who has had the drug or the placebo (fake drug). This helps avoid bias. Cancer is caused by uncontrolled division (mitosis) of cells. Benign in 1 area and not harmful, malignant = spread to different areas and harmful. Drugs need to be safe and effective (work) so they use low doses first before increasing the dose to find the best dose to use. The earliest drugs came from plants. Digitalis for heart comes from foxgloves, aspirin from willow tree bark and the antibiotic penicillin from mould grown by Alexander Fleming. B1:Bioenergetics Photosynthesis Photosynthesis is represented by the equation: carbon dioxide + water light glucose + oxygen 6CO2+ 6H₂O-C6H12O6 +602 Photosynthesis is an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light. Rate of photosynthesis Light intensity, carbon dioxide and temperature are LIMITING factors. They can increase the rate of photosynthesis. These limiting factors can interact, so you have to decide which one might be 'limiting' the rate. For temperatures above the optimum, enzymes denaturing prevents higher rates of photosynthesis. Farmers use these factors to control growth. They have to consider costs vs profits. Light Intensity Carbon dioxide concentration Temperature . . T ● Cuticle (wase layer) green chloroplasts -air space stoma (pore) guard cet Leaves are adapted for photosynthesis. Transparent cuticle to let light through Palisade layer packed with chloroplasts • Air spaces for gas exchange in the spongy mesophyll Stomatal pores control water and gases palisade layer spongy mesophyl lover Investigating photosynthesis: You can measure rate by counting bubbles or collecting gas in an amount of time. This would be your dependent variable. HT: The inverse square law states that: original'. This is because intensity = 1/d², where d= distance. 'if you move the light source double the distance, the intensity will be one-quarter of the The glucose produced in photosynthesis may be: used for respiration converted into insoluble starch for storage used to produce fat or oil for storage used to produce cellulose, which strengthens the cell wall used to produce amino acids for protein synthesis. To produce proteins, plants also use nitrate ions that are absorbed from the soil. You can test for starch using iodine. This turns from ORANGE to BLACK if starch is present, proving photosynthesis happens. Pondweed Water- Bubble of gas Lamp Ruler Aerobic Respiration Respiration is represented by the equation: glucose + oxygen carbon dioxide + water C6H12O6 + 602 6CO2 + 6H₂O Respiration is an exothermic reaction which is continuously occurring in the mitochondria of living cells. The energy transferred supplies all the energy needed for living processes, e.g. chemical reactions, movement, warmth. Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy. Anaerobic Respiration Anaerobic respiration in us is represented by the equation: glucose lactic acid in plant and yeast cells: glucose ethanol + carbon dioxide Anaerobic respiration in yeast cells is called fermentation and is used in the making of bread and alcoholic drinks. *Much less energy is transferred than in aerobic respiration. Exercise: if the human body needs more energy, heart rate, breathing rate and breath volume increase. This gives muscles more oxygenated blood. • The incomplete oxidation of glucose causes a build up of lactic acid and makes an oxygen debt. Muscles become fatigued and stop contracting efficiently. HT: Lactic acid is converted to glucose in the liver. HT: Oxygen debt is oxygen to break down lactic acid. . Metabolism Metabolism is the sum of all the reactions in a cell or the body. Energy from respiration in cells is used by the organism for the enzyme controlled processes that happen all the time. These produce new molecules, convert glucose to starch in plants, glucose to glycogen for storage in muscles, they form lipid (fats) molecules from a molecule of glycerol and three molecules of fatty acids, use glucose and nit £iide which are then are used to make proteins for respiration. breakdown of excess proteins to form urea for Biology Knowledge Organiser B1-Cell structure and transport Exchange and Transport To stay alive, all organisms must exchange substances with their environment. This means they must transport into cells the substances they need from the environment and transport out waste products to the environment. Substances can be transported into or out of cells by: diffusion, osmosis or active transport. Diffusion Diffusion allows many substances to move into or out of cells. Thanks to the random motion of particles in liquids and gases, particles will spread out until the concentration is equal throughout. If there is a cell membrane that lets the substance through (is permeable) in the way, it doesn't matter. Overall, the net movement of the substance will be from higher to lower concentration, as the diagram shows. Diffusion is the process by which oxygen is transported into the bloodstream, and carbon dioxide is transported out (in the lungs, or gills of fish). It is also how the waste product urea moves from cells into the bloodstream, before removal in the urine. The rate of diffusion is affected by: 1. the steepness of the concentration gradient 2. the temperature (a higher temperature increases the rate of diffusion as particles have more kinetic energy) 3. The surface area of the membrane (a larger surface area of cell membrane increases the rate of diffusion into/out of a cell). Cell Exterior Higher Concentration Cell Interior Cell high water concentration Lower Concentration solute o water Osmosis Osmosis is the movement of water from a more dilute solution (more 'watery') to a more concentrated solution (less 'watery') across a partially permeable membrane, such as a cell membrane. Osmosis causes cells to swell up if they are placed in a dilute solution, or shrivel up if they are placed in a concentrated solution (a solution of salt, for instance, or sugar). low water concentration Key Terms Diffusion Concentration gradient Surface area to volume ratio Exchange surface Diffusion pathway Osmosis Partially permeable membrane. Active transport Definitions The net (overall) movement of particles from a higher concentration to a lower concentration, simply due to the random motion of particles in a liquid or gas. Diffusion happens across cell membranes, from higher to lower concentration. It does not require any energy from the cell. The difference in concentration of a substance between two places. A 'steeper concentration gradient means there is a bigger difference in concentration. The surface area divided by the volume of an organism, organ or cell. Generally, the smaller something is, the larger the surface area to volume ratio. A place, such as the walls of the small intestine, where exchange of substances takes place e.g. by diffusion across it. The distance over which a substance must diffuse. A thin wall or membrane is a short diffusion pathway. Osmosis only describes the movement of water. It is the diffusion of water from a dilute solution to a more concentrated solution across a partially permeable membrane. A membrane that only allows some substances through - others are prevented from travelling through. The movement of substances against the concentration gradient - from lower to higher concentration. This requires energy from respiration. Active transport Active transport is so-named because it requires energy. A good example of where it happens is in plant roots. Root hair cells (see specialised cells topic) absorb mineral ions (like magnesium ions and nitrate ions) from the very dilute solution in the soil by active transport. They need ions like these for healthy growth. An example in animals is absorption of sugar from the intestine into the blood-the blood has a higher sugar concentration so active transport is needed. The sugar is needed by all cells in the body for respiration. Biology Knowledge Organiser B1-Cell structure and transport Adaptations for efficient exchange and transport Unicellular organisms have a very large surface area to volume ratio compared to multicellular organisms. This means that they simply exchange substances through their cell membrane directly with their environment. They are carbon dioxide small enough that diffusion is sufficient to meet their needs (see diagram). oxygen maximum distance is 0.1 mm However in multicellular organisms, cells that are not at the surface wouldn't be able to directly exchange substances with the environment. This is why organs with specialised exchange surfaces have evolved. Without lungs, gills, or leaves, for example, multicellular organisms wouldn't be able to obtain all the substances they need to survive, or be able to get rid of waste products efficiently. Specialised exchange surfaces To be effective at exchanging substances with the environment, any exchange surface must have a large surface area, and a thin wall/membrane for a short diffusion pathway. In animals, a constant blood supply also increases effectiveness, and in the lungs, ventilation (breathing in and out) increases effectiveness by refreshing the concentration gradient with each breath. Exchange in animals and plants Gas exchange in many animals, including us, happens in the lungs. The structures in the lungs where it happens are the alveoli. There are millions of these tiny air sacs, so in total their surface area is gigantic. They also have a short diffusion pathway, a good blood supply and air supply due to ventilation. (look at the diagram of one alveolus) In fish, gills are where gas exchange takes place (see diagram). Again, a huge surface area increases the efficiency of gas exchange, along with a short diffusion pathway and good blood supply. The huge surface area comes from the division of gills into very thin plates of tissue called lamellae. This also creates the short diffusion pathway. In plants, the roots absorb water and mineral ions. The root hair cells have long projections that increase the surface area of this exchange surface, and shorten the diffusion pathway. The leaves are responsible for gas exchange, including oxygen out and water vapour out, and carbon dioxide in. Being flat and broad increases the effectiveness of the leaves as exchange surfaces, by increasing the surface area and shortening the diffusion pathway. In leaves, exchange happens through microscopic holes called stomata. Key Terms Small intestine Lungs Gills Leaves Ventilation Blood In Definitions Water The organ in the digestive system where products of digestion are absorbed into the bloodstream. Alveoli Co, Out O, in Root hair cell Root hair The organs were gas exchange takes place. The air sacs where gases are actually exchanged are called alveoli. Soil particle The organs in fish where gas exchange takes place. Oxygen is absorbed from the water into the blood, and carbon dioxide is transferred to the water. The plant organs responsible for gas exchange. Technical term for breathing in and out. Breathing in brings fresh air, with a relatively high oxygen concentration, into the lungs, and breathing out removes the air with a relatively high concentration of carbon dioxide (and low concentration of oxygen). Gas exchange in lungs Substance exchange in roots Blood Out TIH tttt dearygensted Mond asygenated bod Gas exchange in gills Upper epidems Palisade mesophy Spangy mosophyll epidermis Gas exchange in leaves Sunlight 1000000 Guard cells with chloroplants Whay cuticle apace Wexy Exchange of gass Card culls with chloroplasts through stoma Define Prokaryotic 8 Eukaryotic cells & their differences. what are the 3 stages of the cell cycle? what does Biurets test for? what do sylem 8 phloem cells do? Define active transport. what is active transport used for? Prokaryotic bacterial cell-free flow DNA + plasmids 0.2-2um no mitochondrial ribosomes but has flagella ● Eukaryotic animal I plant cell - much larger 10-100μm (CELL CYCLE) 1 DNA replication + sub-cellular gro -with 2. nuclei split in 2=3.2 genetically identical dooteer cells Biurets= protein purplev blue x ethanol water = lipids cloudy ✓ clear * ocylems carries water from roots dies makes tubes. Phloem carries food cell walls break: sieve plates active transport = movement of ions against the concentration gradient using energy from respiration transports glucose animal) into blood ensures enough amino acids are in blood used in microvilli in the small intestine in root hair cells plant) langer SA= faster diffusion get ions from soit needed for growth, storage B1:Organs Organisation Cells are the basic building blocks of all living organisms. A tissue is a group of cells with a similar structure and function. Organs are groups of tissues performing specific functions. Organs are organised into organ systems, which work together to form organisms. Human digestive system Salivary glands Mouth Oesophagus Liver Stomach Gall bladder Pancreas Large intestine Appendix Small intestine Rectum Anus Digestion is breaking down the complex nutrients in the food we eat to useful molecules. The organs and substances involved are: Amylase is a carbohydrase enzyme that digests starch to simple sugars (glucose) for use in respiration. It is produced in the salivary glands, pancreas and small intestine. Proteases are enzymes made in the pancreas, stomach and small intestine and break down proteins into amino acids. Lipases are enzymes made in the pancreas and small intestine and break down fats (lipids) into glycerol and fatty acids. Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream. The products of digestion are used to build new carbohydrates, lipids and proteins for use in the body. Some glucose is used in respiration. Bile is an alkaline substance made in the liver and stored in the gall bladder. It neutralises hydrochloric acid from the stomach. It also emulsifies fat which means to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase. Enzymes have a specific shaped active site for their substrate like a key only fits a certain lock. 'Lock n key'. High temperatures and some pHs can denature the enzyme so the active site unravels, doesn't fit anymore and can't work. The features that make the intestine AND lungs good at absorption/.diffusion are: having a large surface area • a membrane that is thin, to provide a short diffusion path Food tests The digestive system is adapted for efficient absorption of nutrients like glucose, fats and amino acids by diffusion. Villi are finger like projections on the inner surface of the small intestine. (in animals) having an efficient blood supply (in animals, for gaseous exchange) being ventilated. Digestive system adaptations Food group Starch Sugars (Glucose) Proteins Fat (Lipids) Vena.cava (voin) Right atrium Tricuspid valve Septum Right ventricle Pleural cavity (filled with fid) Ethanol The Heart, Circulatory system and disease Pulmonary artery Left atrium The heart is a pump. It is a muscle. It has its own pacemaker in the right atrium keeping the heart rate steady. The right side pumps blood to the Pulmonary vein lungs to collect oxygen and remove CO, and the left pumps blood around Bicuspid valve the whole body to deliver oxygen to cells and get rid of waste CO₂ from respiration. When you exercise you need MORE oxygen and glucose for respiration, so heart rate increases. Arteries have thick walls and are The heart muscle has its own blood supply stretchy to cope with high pressure from the coronary artery. If this gets but veins are thinner and have valves blocked by fat then this can starve the to stop backwards flow of blood. muscle cells of oxygen and glucose and they Capillaries are very thin vessels that die, causing a heart attack. Statins are drugs branch from As& Vs that deliver to help stop this. substances to cells. Nasal cavity Intercostal muscles Ribs Food test chemical Diaphragra lodine Bendicts Biuret solution Aorta (artery) Left ventricle Trachea Lung Bronchus Bronchiole Result Alveol Orange liquid turns black Blue liquid when heated turns brick red Colourless liquid turns purple/lilac When shaken goes cloudy. Blood contains plasma containing dissolved substances, platelets for clotting, red blood cells to carry oxygen and white blood cells for immunity. BIO BI OSMOSIS. paper 1 is the movement of water particles down the concentration gradient across a partially permeable membrane: (THE REQUIRED PRACTICAL) effect of sugar solutions on potato tissue V water potato if the final mass of the potato increased, has been drawn in by osmosis-. (less sugar out than in) if final mass decreased. water was drawn out by osmosis (more sugar in than out) •ACTIVE TRANSPORT is the movement of ions against the concentration gradient using energy from transpiration res used in microvilli diffuses naturally in the small intestine ✓ ensures enough glucose 8 amino acids are in the ANIMALS) blood. used for respiration pure water transports glucose into blood sugar Solution (concentrated) ((USES) OF AT) in root hair cells lots of root hairs = larger SA= faster diffusion PLANTS ↓ used to get ions from soil needed for growth storage BIO B1 cell structure RIBOSOME = protein synthesis where all CYTOPLASM= MITOCHONDRIA=0 animal / Eukaryotic Cell (Nucleus) paper 1 chemical reactions happen (vacuole) -contains salts+ cell sap -keeps cell turgid Electron microscopes have higher magnification + resolution (ribosome)-contains DNA -controls cell's activity • protein synt -hesis (cytoplasm - where all cells chemical reactions happ -en (chloroplast) -contains chlorophy!! - site of photosynthesis (cell membrane) -Controls what comes in & out ~(cell wall) 10-100vm in length -made of cellwose - Provides strength & support Eukaryotic -animal & plant cells -much larger mitochondria -releases energy via transpiration using iodine stain Examining onion tissue under microscope coverslip & drop of water Mitrochondria : 0-2-2um in length Prokaryotic bacterial cell -Free Flowing DNA S plasmids - no mitrochondria or ribosomes flagella ÷ AH X B1 CELL DIFFRENTIATION specialization in animal cells NERVE CELLS)-carry electrical impulses around body allow rapid communication • long axons · . (MUSCLE CELLS) ● Contract 8 relax Special proteins contained that slide over each other to make the fibres contract • lots of mitochondria + protein filaments (SPERM CELLS) reproduction - lots of mitochondria for energy flagelium - to help swim . . • Contains digestive enzymes for breaking down outer layer of the egg • large nucleus w/ genetic energy to be passed on (ROOT HAIR CELLS) • mineral ions are moved into cell by active transport • large surface area (PHOTOSYNTHETIC CEL contain Chloroplasts con the light needed for ph •harge permanent vaci (XYLEM CELLS) • Carries water from t • alive when Ist forme hollow tubes allowir spirals of lignin Su . PHO(PHLOEM CEL • a transport tissue t • cell walls break d (PHOTOSYNTHETIC CELLS) •contain Chloroplasts containing Chlorophyll that trap the light needed for photosynthesis •harge permanent vacuole er to (XYLEM CELLS) • carries water from the roots, around plants alive when Ist formed, the cells die & form long hollow tubes allowing water s mineral ions to travel spirals of lignin support plant outer sed on ● PHO(PHLOEM CELLS) • a transport tissue that carries food • cell walls break down to form sieve plates ve transport MICROSCOPES to find the magnification of the magnification of the a light microscope, multiply eyepiece, objective lens, stage. slide, light, fine focus, coarse focus eyepiece by the magnifical -tion of the objective lens (TRANSMISSION ELECTRON) •2D images high magnification resolution (SCANNING ELECTRON) • 30 images low magnification CALCULATING - Light Microscopes - -developed in mid-17th century -2000x magnification (Light Microscope) - Electron microscopes - - developed in 1930s 7 - uses beam of electrons 2,000,000 x magnification - MAGNIFICATION magnification of eyepiece X magn -ification of objective lens Size of an object, use the formula (RESOLVING POWER) - affects how much detail it can show (RESOLUTION)- ability to disiguish magnification Image size MA between 2 seperate points magnification actual Size BICell Biology Eukaryotes and Prokaryotes Eukaryotic cells (eukaryotes) have a cell membrane cytoplasm and genetic material inside a nucleus. Prokaryotic cells also have a cell wall surrounding the cell membrane. The genetic material is not in a nucleus but free in the cytoplasm. It can be as a large loop or small loops called plasmids. Cell part Nucleus Cytoplasm Cell membrane Ribosomes Mitochondria Chloroplasts Function Permanent vacuole Animal cell Controls the cell. Contains DNA as chromosomes usually in pairs. Chemical reactions occur here www 109 10- 103 102 Cytoplasm 0.001 0.01 Ribosome Guardian of the cell- controls what enters and leaves Nucleus Mitochondrion Stores fluid and keeps the cell turgid Cell wall Strengthens cell, made of cellulose Orders of magnitudes you need to know (of m) 0.000 000 001 Nano n 0.000 001 Micro Milli m Centi c Cell membrane Protein synthesis (making enzymes, hormones etc) Respiration (energy release from glucose) Photosynthesis (Glucose made from light) Plant cell Bacterial cell Pilus Ribosomes Chloroplast Vacuole Cell wall Bacterial flagellum Found in plant cells Cell differentiation Cell wall Plasma membrane DNA Capsule Cytoplasm Differentiation is when cells become specialised to certain jobs or roles. Most animal cells differentiate at an early stage in life but plant cells can differentiate at any point in life. In mature animals cells only divide for repair and replacement. Uncontrolled growth is what causes cancer. Benign = not harmful, malignant = harmful. Stem Cells These are undifferentiated cells that could make many more cells of the certain types. In embryos: stem cells can be cloned and grown into most cell types. In adults: bone marrow stem cells can form blood cells and some other cell types. In meristems of plants: stem cells can differentiate into any plant cell type throughout life of the plant. Stem cell treatments could be used for diabetes or paralysis. Plasmids Microscopy Early microscopes were simple lenses. Light microscopes were first developed in 1590 just made from lenses and tubes. Improved quality of lenses enable better magnification. In the 1830s the nucleus was discovered. In 1930s the electron microscope was made and let us see smaller structures inside cells. Magnification how many times bigger an object is. Resolution (resolving power) = ability to see two points clearly. magnification = size of image size of real object use this formula for microscope images. Mitosis and the Cell Cycle The cell cycle is how cells divide. During the cycle, genetic material is doubled, the cell grows new mitochondria and ribosomes and copies chromosomes and then the cell splits into two new identical cells. The chromosomes are pulled apart to two ends of the cell, then the cell membrane and cytoplasm split. This process is important in growth and development. In therapeutic cloning an embryo is grown with the same genes as the patient. This means that any cells would not be rejected by the patient's immune system. There are risks such as passing on viruses. Some people disagree with the use of stem cells due to religious or ethical reasons. Meristem cells from plants can be used to clone rare species to preserve them or to produce dicenco recictant crons for farmors Transport of substances Diffusion: This is the spreading out of particles from an area of high to low concentration. Substances that move this way are oxygen, carbon dioxide and urea. High concentrations, high temperature and a large surface area make this proce faster. Small organisms tend have large surface area to volume ratios. Osmosis: Water moves from dilute (lots water) to concentrated (little water) through a semi-permeable membrane. Active Transport: Uses energy to move from low-➜ high. Ilead for sugar and minerals. Cell Biology Knowledge Organiser - Foundation and Higher Required Practical Specialised Cells Microscopy Required Practical When a cell changes to become a specialised cell, it is called differentiation. . Includes preparing a slide, using a light microscope, drawing any observations - use a pencil and label important observations. stage light eyepiece stage clips Secondary focussing wheels Osmosis and Potato Practical . Independent variable - concentration. . Dependent variable - change in mass. . Control variable-volume of solution, temperature, time, surface area of the potato. The potato in the sugar solution will lose water and so will have less mass at the end; the potato in the pure water solution will gain water. Specialised Function Cell sperm nerve muscle root hair phloem xylem To get the male DNA to the female DNA. To send electrical impulses around the body. To contract quickly. To absorb water from the soil. Transports substances around the plant. Transports water through the plant. Equations and Maths Equation Adaptation Streamlined head, long tail, lots of mitochondria to provide energy. Standard Form: 0.0033 10³ 5.6 x 105 0.0056 Long to cover more distance. Has branched connections to connect in a network. Long and contain lots of mitochondria for energy. A large surface area to absorb more water. Pores to allow cell sap to flow. Cells are long and joined end- to-end. Hollow in the centre. Tubes are joined end-to-end. image size actual size magnification Maths Skills Conversions: Micrometres to millimetres: divide by 1000. Page 1 of 2 Prokaryotic and Eukaryotic Cells Animal Cells nucleus ribosomes mitochondria nucleus cytoplasm chloroplast chloroplasm Plant and animal cells have similarities and differences: cell membrane cell membrane cell wall cell membrane Animal permanent vacuole X mitochondria ribosomes ✓ ✓ ✓ cytoplasm X ✓ Plant Cells ribosomes nucleus X mitochondria Plant ✓ ✓ Bacterial Cells Bacterial cells do not have a true nucleus, they just have a single strand of DNA that floats in the cytoplasm. They contain a plasmid. chromosome -cell wall vacuole -flagella cell membrane cell wall -chloroplast visit twinkl.com twinkl Chromosomes and Mitosis In the nucleus of a human cell there are 23 pairs of chromosomes. Chromosomes contain a double helix of DNA. Chromosomes have a large number of genes. Finol The cell cycle makes new cells. Mitosis: DNA has to be copied/replicated before the cell carries out mitosis. Key Vocabulary active transport alveoli chromosome diffusion eukaryotic gas exchange mitosis multicellular osmosis prokaryotic undifferentiated replicated specialised villi Secondary Stem Cells Embryonic stem cells are undifferentiated cells, they have the potential to turn into any kind of cell. Adult stem cells are found in the bone marrow, they can only turn into some types of cells e.g. blood cells. Uses of stem cells: Replacing faulty blood cells; • making insulin producing cells; making nerve cells. Some people are against stem cell research. For Stem Cell Research Against Stem Cell Research Embryos are human life. Curing patients with stem cells more important than the rights of embryos. They are just using unwanted embryos from fertility clinics, which would normally be destroyed. Scientists should find other sources of stem cells. Stem Cells in Plants In plants, stem cells are found in the meristem. These stem cells are able to produce clones of the plant. They can be used to grow crops with specific features for a farmer, e.g. disease resistant. Cell Biology Knowledge Organiser - Foundation and Higher Exchange - Humans Key Processes Multicellular organisms have a large surface are to volume Diffusion is the spreading out of ratio so that all the substances can be exchanged. Gas exchange: Lungs particles from an area of higher concentration to an area of lower concentration. The alveoli are where gas exchange takes place. They have a large surface area, moist lining, thin walls and a good blood supply. SAN Villi: Small Intestine Millions of villi line the small intestine increasing the surface area to absorb more digested food. They are a single layer of cells with a good blood supply. Exchange in Plants 000000 oxygen CO₂ The surface of the leaf is flattened to increase the surface area for more gas exchange by diffusion. Page 2 of 2 Oxygen and water vapour diffuse out of the stomata. Guard cells open and close the stomata, controlling water loss. Cell membranes are semi-permeable, only small molecules can get through. Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher concentration to a region of lower concentration. Active transport is the movement of substances against the concentration gradient. This process requires energy from respiration. Cell Diffusion Active Transport in Cells Exchange in Fish Fish have a large surface area for gas exchange. These are called gills. Water enters the fish through the mouth and goes out through the gills. The oxygen is transported from the water to the blood by diffusion. Carbon dioxide diffuses from the blood to the water. Each gill has gill filaments which give the gills a large surface area. Lamellae cover each gill filament to further increase the surface area for more gas exchange. They have a thin surface layer and capillaries for good blood supply which helps with diffusion. visit twinkl.com twinkd