B3

• why does bacteria make you feel ill?

  They produce toxins that damage specific cells or prevent them from functioning
• why do viruses make you feel ill

  >destroy cells, through invasion when they reproduce

  >this kills cells and causes damage with living tissue
• how can we control the spread of communicable diseases?

  >hygiene- hand washing, disinfecting...

  >isolation- isolating infected individuals

  >controlling vectors- If a vector spread a disease destroying or controlling the population of the vector can limit the spread of disease

  >vaccination
• what are pathogens


  > microorganisms that cause infectious disease

  >may be viruses, bacteria, protists or fungi.

  >may infect plants or animals

  >can be spread by direct contact, by water or by air.
• how are measles spread

  inhalation of droplets produced by infected people when sneezing and coughing
• what is measles

  >viral disease showing symptoms of fever and a red skin rash. >Measles is a serious illness that can be fatal if complications arise.

  >For this reason most young children are vaccinated against measles
• what is hiv

  >viral disease

  >HIV initially causes a flu-like illness.

  > Unless successfully controlled with antiretroviral drugs the virus attacks the body's immune cells.

  > Late stage HIV infection, or AIDS, occurs when the body's immune system becomes so badly damaged it can no longer deal with other infections or cancers.
• how is HIV spread

  > HIV is spread by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles.
• what is TMV

  >viral disease

  >is a widespread plant pathogen affecting many species of plants including tomatoes.

  >It gives a distinctive 'mosaic' pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis.
• how is TMV spread

  >direct contact between diseased plant material

  >animal and plant vectors

  >soil: pathogen can remain in soils for decades
• how do TMV/Rose black Spot lead to a lower crop yirld

  >leads to less chlorophyll, so less light absorbed so less glucose produced

  >reduces the plants ability to photosynthesis

  >damages lead
• how is salmonella spread

  Salmonellafood poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions.
• What is salmonella


  >bacterial disease>In the UK, poultry are vaccinated againstSalmonellato control the spread.>Fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete.
• What is gonorrhoea


  >bacterial disease

  > sexually transmitted disease (STD) with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating.

  >It is caused by a bacterium and was easily treated with the antibiotic penicillin until many resistant strains appeared.
• how is gonorrhoea spread and how can it be controlled?

  >Gonorrhoea is spread by sexual contact.

  >The spread can be controlled by treatment with antibiotics or the use of a barrier method of contraception such as a condom.
• what is rose black spot?

  > a fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early.

  >It affects the growth of the plant as photosynthesis is reduced.
• how is rose black spot spread and how can it be treated?

  >It is spread in the environment by water or wind.

  >Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves.
• what is malaria

  >protist disease caused by pathogens

  > malarial protist has a life cycle that includes the mosquito. >Malaria causes recurrent episodes of fever and can be fatal. n.
• how is malaria spread + controlled ?

  >mosquitoes feed on the blood of infected people and spread their protest pathogen when they feed on another person

  >The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten + avoid having stagnant pools of water since malaria mosquitos breed there
• how is the skin a non-specific defence system?

  >Physical barrier to infection

  >produces anti-microbial secretions

  >microorganisms that normally live on the skin prevent pathogens growing
• how is the nose a non-specific defence system?

  >Cilia and mucus trap particles in the air preventing them from entering the lungs

  > trachea and bronchi produce mucus which is moved away from the lungs to the back of the throat by cilia, where it is expelled
• how is the stomach a non-specific defense system

  >Produces strong acid (pH2) that destroys pathogens in mucus, food and drinks
• how does the immunse system defend against disease

  if a pathogen eneters the body, the immune systen tries to destry the pathogen
• what are the two types of white blood cells

  lymphocytes and phagocytes
• how do phagocytes help to defend against pathogens?

  >phagocytes are attracted to an area of infection

  >phagocyte surrounds the pathogen and engulfs it

  >enzymes that digest and destroyed the pathogen of released
• how do lymphocytes fight pathogens?

  >lymphocytes fight pathogens in two ways:

  > lymphocytes produce anti-toxins that bind to the toxins produced by some pathogens ( usually bacteria) . this neutralizes the toxins

  >lymphocytes produce antibodies that target and help to destroy specific pathogens by binding to antigens on the pathogens surface
• what is herd immunity?

  if a large portion of a population is vaccinated against the disease, the disease is unlikely to spread even if there are unvaccinated individuals
• describe the process of antibody production

  >Microbes with specific antigens invade and reproduce + lymphocytes with different specific anti-gen receptors respond >specific receptor, on lymphocytes; bind to antigens and stimulates the lymphocytes

  >lymphocytes divide (becoming plasma cells) by mitosis, and secrets specific antibodies

  >antibodies bind to antigen on bacteria/ viruses and clump it together

  >phagocytes engulf and destroy the microbes + some of the lymphocytes become memory cells and our stored in the lymph glands
• What is a vaccination and how does it work?

  >Vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies.

  >specific antigens stimulate specific lymphocytes to replicate and then produce specific antibodies

  >memory lymphocytes are formed- if the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies, preventing infection.

  >pathogen is destroyed before it can reproduce and cause damage
• what are anitbiotics?

  >Antibiotics, are medicines that help to cure bacterial disease by killing infective bacteria inside the body.

  (e.g penicillin)

  > It is important that specific bacteria should be treated by specific antibiotics.

  >The use of antibiotics has greatly reduced deaths from infectious bacterial diseases. However, antibiotic- resistant strains of bacteria are emerging
• Why can't antibiotics kill viruses?

  >Viruses have no cell wall or protein synthesis mechanisms to be disrupted by antibiotics- viruses use host cells to reproduce >viruses live and reproduce inside body cells and so antibodies cannot get to the virus
• How do we treat viral diseases?

  >Antibiotics cannot kill viral pathogens.

  >Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens.

  >It is difficult to develop drugs that kill viruses without also damaging the body's tissues.
• What makes responsive specific?

  >all cells have molecules usually proteins attached to the outside of the cell surface membrane- these are antigens

  >those that your lymphocyte to recognize as foreign will stimulate the lymphocytes to multiply and produce specific antibodies

  >different antigens have different shapes are different antibodies are needed for each antigens- and antigens are found on the surface of all cells that the immune system can recognize
• How does antibiotic resistance develop?

  1. antibiotics act as a selection pressure on the bacteria because they select one for ones that are resistant

  2. within any population of bacteria there is variation since bacteria reproduce quickly. some bacteria is naturally resistant to the antibiotic ( due to variation in DNA)

  3. if an antibiotic is used on a patient and some of their bacteria is resistant, the bacteria will have a selective advantage and won't be killed by the antibiotic.

  4. surviving bacteria would have less competition and will reproduce and pass on the gene that gave them resistance onto the next generation of bacteria

  5. if the same antibiotic is used against numerous times, you can continue select for the ones that are resitstant so that over time more of the bacteria are resisted to the antibiotic
• How can the strain of antibiotic resistant bacterium be reduced?

  >ensure patients take the full course of antibiotics- so all bacteria are killed and none survive to mutate and form resistant strains

  >doctors should prescribe antibiotics minor/viral infections ensure the correct dose is given
• how can plant disease be detected?

  Plant diseases can be detected by:

  • stunted growth

  • spots on leaves

  • areas of decay (rot)

  • growths

  • malformed stems or leaves

  • discolouration

  • the presence of pests.
• How can one identify plant disease?

  • reference to a gardening manual or website

  • taking infected plants to a laboratory to identify the pathogen

  • using testing kits that contain monoclonal antibodies.
• how can insects cause plant disease?

  Aphids are insects that sucks sap from the stems of plants

  this results in:

  > reduced rate of growth

  >wilting

  >discoloration of leaves
• how can aphid infestations be controlled

  > ladybirds can be used to control aphid infestations as ladybird larvae eat aphids
• what is stunted growth in plants caused by

  Nitrate deficiency, because nitrates are needed for protein synthesis, and therefore slower rate of growth