biology revision notes

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be carried out. to replace blood cells that are damaged or destroyed. due to an intensive cancer treatment. infection thesponse Health is a description of an individual's physical and mental well being. Disease is a major contributor to ill health. Disease can be divided into two categories: •communicable diseases, which can be spread between organisms. For example: HIV, influenza, measles, Covid-19 • non-communicable, which cannot be spread between organisms For example: Cancer, heart disease, chronic lung disease. TYPES OF PATHOGEN Type of Description Pathogen Bacteria Single celled organisms. without a nucleus non-living particles that Aids, measles, flu, can only reproduce within common cold, rubella a living cell. Viruses fungi Single-celled organism Protozoa, with a nucleus Simple organisms, including mushroomst yeast grow as single cells. that Examples of diseases, Salmonella, pruemonia, Tuberculosis, chlamydia. How do they infect you?". Bacteria: They damage your. cells by producing ham ful toxins. They are more infectious as 。 they are able to rapidly reproduce. Protazoa: They are transfered to forhost organisms by a vector and usually enters through bites or penetrating tissues Athletes foot, ringworm. yeast infection, rose black spot Malaria, giardia. toxoplasmosis fungi: They can penetrate human tissues, like skin or the surface of a plant and produce harmful spores. Virus: They infect a host cell after entering the body through the nose, mouth eyes or skin. It copies itself in the cell and bursts the cell to spread around the body. Human Defence System. The human body has non-specific defences. They are to prevent any pathogens from entering the body and causing ham Some examples: Mucus! designed • mucus is produced in the respiratory system and traps the particles and bactera entering our our ways ♥ • Skin is a waterproof banner that pathogens cannot pass through. Good bactena live on the surface of our stein permantly s preventing pathogens from growing. • Glands in the stomach wall produce hydrochoric acid, which destroys any pathogens that enter the stomach. • Tears contain enzymes that destroy any pathogens that make our eye. contact with If a pathogen passes the non specific defences the immune. system is activated. The immune system is made up of different white blood cells which have different functions. For example: Antitoxins • Some bacteria produce toxins that can damage cells and tissues. • The immune system responds to this by producing antitoxing, which neutralise the toxins and prevent them causing any harm. Phagocytosis • A white blood cell Finds the pathogen and engulfs it by changing its shape. •The white blood cell digests the pathogen, destroying it. Antibodies White blood cell recogruse foreign antigens on the surface of pathogens. and produce protein molecules called antibodies. Antibodies are specific to particular pathogens. •They have a complimentry shape to each and gen and lock onto the pathogen tagging them •This causes the microorganisms to cluster, allowing other white blood. cells to come and in gest them.. VACCINATION Vaccination is the main technique for helping the immune system recognise and destroy pathogens. Immunising (making immune) a large proportion of the population will make it very hard for the pathogen to spread. The process of Vaccination is: Inject a dead pathogen. • A vaccination inject's a dead or inactive form of pathogen into the blood. Immune System recognition •White blood cells recognise that antigens are foreign and produce antibodies against them. Memory Cells • Some of these white blood cells remain in the blood as memory cells. If the same pathogen invades the body again, a the memory cells are able to: • produce antibodies faster - •produce more antibodies meaning that the antibody concentration remains in the bloody for longer Immiority • next time the same pathogen infects the vaccinated person, it will be destroyed by the immune system before it can cause illness. herd Immunity If we immunise a large population for percentage), this will make it very hard for the pathogen to be spread. This is called herd immunity. Antibiotics antibioties, such as penicillin, are drugs developed to aire infections caused by bacteria. bacteria so they cant replicate. some antibiotics work by destroying the cell way of of the Antibiotics do not affect viruses. • antibiotics do not destroy viruses because viruses stay inside host cells and are not living cells Antibiotics are specific. • Specific antibiotic's are prescribed by medical doctors for specific diseases • The use of antibiotics has greatly reduced the number of deaths from infectious bacterial diseases. Antibiotic Resistance. •Some strains of bacteria are resistant to certain antibiotics. That means antibiotics cannot kill them. •MRSA is often called a "superbug" because it is resistant to many antibiotics. How to stop antibiotic resistance? • To prevent strains of resistant bacteria from developing: • Doctors should only prescribe antibiotics if they! are needed and not for minor of Gral infections as over use of antibiotics is a main cause. • Patents should finish their whole eycle of course of antibiotics to ensure all bactera are filled. Enzymes Enzymes increase the speed of reactions. They are often called bidogical catalysts. The active site of an enzyme important. is very enzyme site ално Active Site To catalyse (speed up) a reaction, the reacting chemical (substrate) must bind to the enzyme's active site. •The active site will only fit specific substrates. Substrate Lock and key The active site is like a lock and the substrate is the key usually • In the same way there is one senzyme for every substrate (or one key for each lock) Factors effecting the rate of enzyme action. PH (measure of acidity) • enzymes •If the pH changes away activity decreases. have a optimum pH. enzyme substrate from the optimum pH, then the enzyme • If the pH is too lowor too high, then the will not Function. enzyme is denatured and Temperature • increasing the temperature of a working enzyme intially i the reacting activity. • enzymes have an optimum temperature. once this temperature is reached the activity decreases J •past a certain temperature, the active site changes shape, and enzyme is denatured (looses its catalyctic activity) the increases. Enzymes in digestion Digestive enzymes are made by specialised cells in the glands and lining of the gut. They are then secreted (released) out of the body cells and into the cavity of the digestive system. Digestive enzymes are used to: Breakdown Large Food molecules. •The digestive enzymes catalyse (speed up) the breakdown of large. insoluable food molecules into smaller, soluable (can be dissolved) molecules that are small enough to be absorbed into the blood stream Digested molecules can be used to construct new, " proteins and lipids in the body. • Some glucose produced by digestion is used for respiration. Enzymes in digestion The 3 main digestive enzymes are: •Anylase P •Protease •Lipase. Amylase = Amylase is a type of carbohydrase that breaks down starch in our bodies. Starch → maltose (tother sugars). Protease= Protease are 1 carbohydrates; digestive enzymes that break down proteins into amino acids. Protein Amino Acids... Lipase- Lipase are digestive errzymes that break down fats into glyreed or other alcohols fats → 7 glyrecol (t other alcohols) Respiration cellular respiration is an exothermic reaction which occurs in the mitochondria of all living cells. The transferred to energy needed for the human body to supplies all the function as it should. energy There are 2 types Respiration= of respiration : Aerobic Respiration Aerobic respiration releases. alot more energy in cells when food is broken down in prescence. OF the oxygen. Aerobic (with (₂) •Anaerobic (without (₂) مه EQUATIONS glucose +oxygen- carbon dioxidet water.. C6H12O6 +6026CO₂ + 6H₂O Anaerobic Respiration Anaerobic respiration releases less. than Aerobic Respiration. energy the oxidation of glucose is uncomplete. When humans are exercising, they would benifit from aerobic respiration as they are redeasing more However as energy. they are the oxygen levels. decrease, humans would then switch to Anaerobic Respiration. Glucose → Lactic Acid+ Water. (in humans) Anaerobic Respiration can also take place in yeast cells, where glucose is broken down to create ethand, carbon dioxide and energy. This is called fermentation. Glucose Ethanol + Carton Dioxide. Bread Beer Protosynthesis. Sun 111 water Light energy glucose охудел (0₂ During Photosynthesis. radiant energy from the sun is absorber by groen plants. The energy is used to convert carbon dioxide, water and minerals the plants take in from their guroundings into sugar/glucose and gaseous oxygen. Photosynthesis is is an endothermic reaction, meaning that is taken from the surroundings, and the temperature of the Surroundings decrease. 600₂ + 6H₂O →→ C6H12O6 +602 Photosynthesis Respiration. energy