bio p1

• VACCINES

  Small amount of dead/inactive pathogen

  The antigens on them trigger lymphocytes

  Antibodies to attack pathogens since they are complementary

  white blood cells rapidly produce later = immunity
•  bacteria and viruses are pathogens 

  they reproduce rapidly inside the body 

  bacteria may produce toxins (that make us feel ill) 

  viruses live +  reproduce  inside cells

  white blood cells help to defend against pathogens by

   destroying pathogen

  producing antibodies 

   producing antitoxins 

  to counteract toxins
• pre-clinical trials of the new drug on cells / tissues

  to test toxicity, dosage and efficacy 

  clinical trials / test on healthy volunteers and Ebola patients at very low doses 

  so that you can monitor for side effects 

  and only then do trials to find the optimum dosage and test for efficacy 

  double blind trial / use of placebo 

  peer review of data 

   to help prevent false claims
• monoclonal antibodies

  They are produced by stimulating mouse lymphocytes to make a particular antibody

  by injecting them with an antigen (e.g. one that attaches to HCG pregnancy hormone for

  pregnancy tests).

  The lymphocytes are combined with a tumour cell to make a hybridoma cell

  The hybridoma cell can both divide and produce the antibody

  Single hybridoma cells are cloned, resulting in many divisions, making high quantities of

  identical cells that all produce the same antibody

  A large amount of the antibody can be collected and purified ready for use
• advantages/disadvantages

  monoclonal antibodies are cheaper to develop than conventional drugs because it is based on tested technology.

  There can be many side effects. Side effects can be treated and reduced by using mice-human hybrid cells or by using

  fractions of antibodies.

  They bind to specific diseased or damaged cells needing treatment.

  They treat a wide range of conditions.
• HIV / antigen / protein injected into mouse extract / collect (mouse)

   lymphocytes that make a specific antibody to HIV / antigen / protein 

  lymphocytes are combined with a tumour cell to create a hybridoma 

  (hybridoma) cloned to create many cells that produce the antibody
• Sperm cells have a tail to help them swim.

  They have mitochondria in the middle section which allows for respiration so that energy

  generated so the cell has energy to swim.

  They have a nucleus which contains genetic material.

  The sperm cell also has an acrosome which contains digestive enzymes

  to digest through the egg cell.

  They have a streamlined head to help them manoeuvre faster.
• glucose

   

  Converted into insoluble starch for storage in the stems, leaves and roots

  Used to produce fat or oil for storage (especially in seeds)

  Used to produce cellulose, which strengthens the cell wall

  Combined with nitrate ions absorbed from the soil to produce amino acids for protein

  synthesis
• aphids

  Aphids have long sharp mouthpieces that pierce the surface of the stem and

  into the phloem so that they can feed on the sugar filled sap.

  They can infest a plant in large numbers and remove large quantities of the phloem sap

  This can weaken the plant

  Aphids can also act as a vector for the transfer of diseases
• defences

  The cellulose cell wall not only provides support for the plant but also protection from microorganisms

  The waxy cuticle of the leaf is a barrier to microbes from entering the plant.

  Bark provides a tough layer around the stem to prevent pathogens from entering 

  As deciduous trees lose leaves in the winter the infection can be taken with them.

  chemicals that have antimicrobial properties
• State two roles that these bacteria play.

  Break down foods.

  Make vitamins.

  Break down toxins.

  Protect against pathogens.

  Break down foods.
• lactic acid

  Lactic acid can be oxidised (reacted with oxygen) to form carbon dioxide

  and water.

  Lactic acid can be transported to the liver by the blood where it can be

  converted back to glucose
• Smoking - chemicals in cigarette smoke such as tar and nicotine damage alveoli

  in the lungs and endothelial lining of arteries and can cause lung disease/cancer. Obesity (poor diet) - excess consumption of sugar reduces body's sensitivity to insulin and can cause type 2 diabetes.

  Alcohol - the breakdown of alcohol by liver produces substances which can be toxic

  to liver cells and even brain cells leading to liver disease and impaired brain function.
• metabolic reactions

  respiration

  formation of proteins

  breakdown of (excess) protein/ formation of urea

  photosynthesis or formation of glucose / starch (in plants)
• blood plasma

  carbon dioxide

  water

  glucose

  amino acids

  lactic acid

  hormones

  antibodies
• Different parts of the human digestive system help to break down molecules of fat so that they can be absorbed into the body.

  Describe how.

  • mechanical breakdown in mouth

  Chemical digestion with lipase:

  • lipase breaks down fats
  • fats are broken down into fatty acids and glycerol
  • lipase is produced by the pancreas and small intestine

  Chemical digestion with bile:

  • bile is produced by the liver
  • bile neutralises the acid from the stomach
  • bile produces alkaline conditions in the small intestine
  • bile emulsifies fats  OR  increases surface area of fats
• epidermal tissues form the outer layer of the plant/  provide protection

  palisade mesophyll is where most photosynthesis occurs

  spongy mesophyll (contains air spaces to) facilitate gas exchange

  xylem is involved in the transport of water and mineral ions

  phloem is involved in the transport of sugars

  meristem tissue (is found at the growing tips of shoots and roots and) is responsible for plant growth
• changes that happen during + after exercise

  • breathing rate + breath volume increases to take in more oxygen for aerobic + remove carbon dioxide
  • heart rate increases to increase blood flow so theres more oxygen for respiring cells + removing carbon dioxide
  • more glycogen converted to glucose to meet demands for respiration
  • anaerobic resp occurs which creates oxygen debt + lactic acid build up
  • after exercise, heart/breathing rate stays high to pay back oxygen debt, lactic acid may be converted to glucose or transported to liver
• enzymes are protein molecules that have a 3D strructure

  active site had a specific shape which will only match shape of substrate

  at pH values above/below optimum, shape of active site changed = substrate can no longer fit active site

  can lead to rate of digestion decreasing
• tumours

  • result from changes in dna
  • uncontrolled cell growth
  • can form a lump of cells
  • made up of abnormal cells
  • MALIGNANT - cancer cells, usually grow faster, invade neighburing tissues, cells can travel in the blood
• light in = 1/distance sqr