9 Science Revision Topics PDF

**Immune System** 1. Virus/bacterial/antibody/pathogen definitions (glossary) Virus - microscopic infectious agent made of genetic material and proteins Chickenpox is caused by a virus that reproduces inside cells and can spread from skin sores. Bacteria- A simple, single-ce...

**Immune System** 1. Virus/bacterial/antibody/pathogen definitions (glossary) Virus - microscopic infectious agent made of genetic material and proteins Chickenpox is caused by a virus that reproduces inside cells and can spread from skin sores. Bacteria- A simple, single-celled microbe without a nucleus *E. coli* is a type of bacteria that causes disease by attaching to cells and releasing toxins. Antibody -- A protein that can identify and fight a specific pathogen Antibodies are produced by B cells and are specialized to fight one type of pathogen. Pathogen - A microscopic organism or agent that causes disease Pathogens include *E. coli* bacteria and the measles virus. 2. What is virus made of? Genetic material in a layer of protein or fat 3. Lines of defence First line of defense-before pathogen enters the body, skin, cilia, eye lids etc protect the body Second Line of defence -- general immune system fights back, white blood cells react, fever, inflammation are signs that body is fighting infection. Third line of defence -- vaccination create memory cells 4. How vaccines work- **Vaccines teach the immune system how to recognize and remember the pathogen and fight off specific disease-causing germs**.  5. Signs of infection -- inflammation, fever, redness 6. Define immune system -- body's defence against infection by invading pathogens. 7. Physical vs chemical barriers First line of defence has chemical and physical barriers. **Physical Barriers** 1. **Skin**: Acts as a tough barrier to prevent pathogens from entering the body. 2. **Mucous Membranes**: Line the respiratory, digestive, and urogenital tracts, trapping pathogens. 3. **Cilia**: Hair-like structures in the respiratory tract that move mucus and trapped particles out of the lungs. **Chemical Barriers** 1. **Stomach Acid**: Destroys pathogens that are ingested with food. 2. Tears and Saliva: Help wash away pathogens from the eyes and mouth. 3. **Urine Flow**: Flushes out pathogens from the urinary tract. 4. **Lysozyme**: An enzyme found in tears, saliva, and other secretions that breaks down bacterial cell walls. 5. **Sebum**: An oily substance produced by the skin that has antimicrobial properties. 6. **Mucus**: Contains antimicrobial peptides and enzymes that trap and neutralize pathogens. 7. **Acidic pH of Skin**: Creates an environment that is inhospitable to many pathogens. 8. Compare Vaccination vs not vaccination A vaccinated person has memory cells with antibodies ready to fight invading pathogens so they won't get so sick while the body is producing more antibodies. However, non-vaccinated person won't have antibodies in the system to start fighting when pathogens invade the body. This could make the non-vaccinated person really sick while their body is making antibodies from scratch. Nervous System 1. Revision sheet labelling neuron- dendrites 1  2. Role of nervous system -- Endocrine System 1. 1.1 Hormones -- receptors label diagram in revision sheet (gland cell 2. Endocrine -- adrenal gland and ? hormone adrenalin 3. Homeostasis -- positive and negative feedback systems 4. Homeostasis -- mammals vs reptiles mammals maintain their temperature through homeostasis 5. Insulin/glucagon cycle Q13 1.2 Homeostasis.  6. Compare endocrine vs nervous system Ecosystem 1. Predator/prey and competition relationships Compete because of lack of resources, compete for food, shelter, mates Predator/prey-predator kills, prey gets killed. If prey numbers decrease, predator would die. 2. Amount of energy transfer and energy losses Energy loss through Cellular respiration, waste, heat Energy amount decreases from producer to consumers at each step. 3. Energy transfer Explain why energy is lost by the rabbits in the middle step of this food chain. The rabbits gain energy from the grass and other foods they eat. But they lose energy in various ways: Rabbits carry out cellular respiration to support their life processes, such as movement and digestion. This uses up the stored energy in sugars obtained from their food. They also generate body heat, which is continually lost to their environment through heat transfer. Rabbits also lose energy to their environment by getting rid of waste products, such as faeces and fur. 4. Photosynthesis -- chemical energy Photosynthesis produces chemical energy using the sunlight, water and carbon dioxide and respiration **releases** the energy for consumers to use. 5. Symbiotic relationship types -- why  6. Predator/prey graphs