bio

• What is the definition of a pathogen?

  A microorganism that causes infectious communicable diseases.
• How are pathogens spread?

  - Through direct contact.

  - Through water or air.

  - Through vectors (organisms that carry and pass the pathogen on without being infected themselves e.g mosquitos)
• Why are viruses so damaging?

  They reproduce rapidly inside body cells causing damage.
• Give three statements about measles.

  - Symptoms include red skin rash and fever.

  - It is spread by breathing in droplets from sneezes and coughs.

  - Measles can be fatal if complications occur and therefore many children are vacinated against it.
• Give 5 statements about Human Immunodeficiency Virus.

  - Spread by sexual contact/exchange of body fluids such as using the same needle for drugs.

  - Causes a flu-like illness.

  - After a while of not being treated, the virus enters the lymph nodes and attacks the body's immune cells.

  - Late stage HIV means that the body's cells cannot fight infections or cancers.

  - Therefore it is not HIV that kills the patient, it is the infections that the body would normally be able to survive (such as pneumonia).
• What do bacterial diseases do?

  Damage cells directly or release toxins that damage tissues.
• Give two statements about salmonella.

  - The bacteria is ingested through food; which was not prepared properly.

  - The bacteria release toxins which cause fever, abdominal cramps, vomiting and diaorreah.
• Give four statements about gonnoreah.

  - Spread by sexual contact.

  - Symptoms are a thick, yellor or green discharge from the penis or vagina as well as pain when urinating.

  - Used to be treated with pennicilin, but resistant strands have become more frequent.

  - Stopped by barrier forms of contraception such as condoms.
• What are protists?

  Single celled organisms, but are eukaryotic unlike bacterial cells.
• How is malaria spread?

  Malaria is a protist that is transferred by a vector (a moquito) and is caused when the mosquito bits the person.
• What does malaria do?

  Cause severe fever, which reocurrs.

  
  

  Can be fatal.
• How can you stop malaria?

  Stop people being bitten; either by killing the vectors or isolating the vectors.
• Give an example of a fungal disease and describe it.

  Rose black spot is spread by spores being carried from plant to plant by wind or water.

  
  

  Causes black or purple spots on leaves - causing them to turn yellow and drop early.

  
  

  This causes a reduced rate of photosynthesis; stunting plant development and growth.

  
  

  It is treated by using fungicides and destroying the already affected leaves.
• What are non-specific defences?

  Defences that attempt to stop all pathogens from entering the body.
• How are tears an example of a non-specific defense?

  The tears contain enzymes that destroy microorganisms.
• How is the nose and example of a non-specific defense?

  The nose traps particles that may contain pathogens.
• How is the skin a non-specific defense?

  Tough, outer layer stops pathogens from entering unless there is a open wound.

  
  

  The skin contains a sebaceaous gland which releases sebum, killing bacteria and fungi.
• How is the stomach a non-specific defense?

  The stomach lining contains gland that release hydrochloric acid which kills bacteria in food.
• What is the cilia and how is it a non-specific defense?

  The cilia features a sheet of mucus, which traps particles and bacteria - which are passed on by the cilia creating a wave motion.
• How do white blood cells protect against pathogens?

  Through a process called phagocytosis, where the pathogen is surrounded, engulfed and digested.

  
  

  They also create specific protein molecules called antibodies, attaching to antigen molecules on the pathogen.

  
  

  Finally, they create antitoxins which neutralise the poisonous toxins and their effects.
• What happens when a pathogen re-enters the body?

  The white blood cells respond more quickly to produce the antibodies or antitoxins.

  
  

  This quick response is called immunity.
• What happens when a person has a vaccination?

  A small quantity of dead or inactive pathogens are injected into the body.

  
  

  This stimulates the white blood cells to produce antibodies and antitoxins and to develop immunity.
• What is crowd-immunity?

  When a large amount of the population is vaccinated against a disease, it is very difficult for the pathogen or disease to spread.
• What do antibiotics do?

  To kill bacteria inside the body (not viruses).
• What is the main negative of antibiotics?

  They are over-prescribed or the person that has been prescribed does not complete the full course.

  
  

  This evolves a antibiotic-resistant disease which cannot be killed by antibiotics.
• How would you investigate the effect of different antibiotics on bacterial growth?

  - Inoculate a petri dish with a culture of specific bacteria.

  - Soak small discs with specific antibiotics.

  - Using forceps, place the small discs on the culture.

  - Incubate the sealed petri dish upside down for several days.
• Give three traditional drugs that were extracted from plants or microorganisms.

  - Digitalis is a heart drug that originates from foxgloves.

  - Aspirin is a pain killer that originated from willow.

  - Penicillin was discovered by Alexander Fleming from the Penicillium Mould.
• How does a double-blind trial work?

  - Some patients are given the real drug; however, some are given a placebo (a fake alternative that does not contain any of the drug).

  - Neither the patient nor the doctor knows whether they are prescribing a placebo or the real drug.
• What do painkillers do?

  They treat the symptoms of diseases, but do not kill the pathogen.
• What do antiviral drugs do?

  Kill viruses without damaging the internal body tissues.
• What is the process for producing single target antibodies?

  - Vaccinate a mouse, so it begins producing antibodies.

  - Collect the antibodies and fuse it with tumour cells to produce hybridoma cells.

  - Grow the hybriddoma cells in tissue culture and select the cells that produce the antibodies.

  - Collect the monoclonal antibodies.
• What are the signs that a plant may be diseased?

  - Stunted Growth.

  - Spots on leaves.

  - Areas of decay (rot)

  - Growths

  - Malformed (abnormal) stems or leaves.

  - Discoloring

  - Presence of pests.
• How can you identify the disease?

  - Consulting a gardening manual, or website.

  - Taking infected plants to a laboratory where it can be tested.

  - Using testing kits, which contain monoclonal antibodies.
• What does the Tobacco Mosaic Virus do?

  - Infects tobacco plants and many other plant.

  - Produces a distinctive "mosaic" pattern of discoloring on the leaves.

  - This discoloring reduces chlorophyll content and affects photosynthesis, meaning stunted growth as there is less photosynthesis.
• What are deficiency diseases?

  Non-communicable deficiency diseases caused by a lack of minerals in the soil.
• Give two examples of deficiency diseases.

  - Stunted growth due to a nitrate deficiency, since nitrates are needed for protein synthesis.

  - Chlorosis (caused by magnesium deficiency) as magnesium ions are needed to produce chlorophyll.
• Give three physical defences that plants have to stop organisms entering.

  - Cellulose cell walls.

  - Tough waxy cuticle on leaves.

  - Layers of dead cells around stems, which fall and take pathogens with them.
• Give two chemical defenses that some plants have.

  - Antibacterial chemicals, which are made by plants such as mint and witch hazel.

  - Poisons to deter herbivores (produced by tobacco, foxgloves and nightshade).
• Give three mechanical adaptions plant have evolved to have.

  - Physical thorns & hairs to deter animals from eating or touching them.

  - Leaves that droop or curls when touched.

  - Mimicry (tricking animals to not eating/laying eggs on them by copying a different plant e.g the white deadnettle looks very similar to a stinging nettle but does not sting).