Biology paper 1 answers i got wrong

• How to convert cm-mm

  x10
• How do the eyes prevent pathogens from entering the body?


  produce tears, containing enzymes to kill bacteria. Tears are antiseptic
• How does the skin prevent pathogens from entering the body?


  • tough / dry / dead outer layer

  • skin acts as a barrier

  • sebum / oil on (surface of) skin

  • sebum / oil repels pathogens

  • scabs form over cuts or scabs form a barrier

  • platelets are involved in forming clots / scab
• How does the breathing system prevent pathogens from entering the body?



  • trachea / bronchi / nose produce mucus

  • mucus is sticky • (mucus) traps bacteria

  • (mucus) carried away by cilia
• What are the benefits/negatives of mechanical valves?


  -patient has to take anti-clotting medication (for the rest of their lives)

  -some patients say they can hear the valves opening and closing

  -if medication not taken (correctly), clots can lead to blood clots on brain / heart attack
• What are the benefits/negatives of biological valves?

  no additional medication required and little waiting time

  • ethical issues surrounding use of animal tissue

  • valve may harden

  • more likely to need further operation or another new valve

  • more likely to be rejected • more likely to need (immuno-suppressant) medication
• Explain how diabetes can cause the body cells to lose more water?


  The blood is more concentrated, so water moves out of cells by osmosis water moves through a partially permeable membrane.
• How can monoclonal antibodies be used to track how molecules move in a plant?


  monoclonal antibodies are specific to molecule a fluorescent dye is attached to the monoclonal antibody the antibody binds to the molecule an the fluorescent dye allows you to see where the molecule is in the tissue.
• Name two substances that travel from respiring cells into the blood.

  Urea

  carbon dioxide
• Glucose is a substance that moves from the blood to cells.

  Explain how glucose moves from the blood into muscle cells.

  by diffusion, because there is a higher concentration of

  glucose.
• Describe the process that produces new skin cells.


  • By mitosis

  • DNA/ chromosomes is

  replicated/duplicated / copied

  • chromosomes separate, one set of

  chromosomes is pulled / moved to each

  end of the cell

  • the cytoplasm and cell membrane

  divides/cytokinesis

  • forming two genetically identical daughter

  cells
• Anaerobic respiration in yeast cells is important for the food industry.

  Explain why yeast cells are important to the brewing and baking

  industries.

  Baking:

  -produces carbon dioxide

  -CO2 makes bread rise

  Brewing:

  1. Produces ethanol

  2. CO2 can make alcoholic drinks fizzy

  3. Ethanol is the alcohol in alcoholic drinks
• Explain how these two molecules are used and removed from the

  body through metabolic processes. Your answer should include:

  • The metabolic reactions these molecules are used for

  • Glucose is converted to glycogen

  • Glucose is broken down in respiration
• Explain how these two molecules are used and removed from the

  body through metabolic processes. Your answer should include:

  • The importance of each molecule to the functioning of the body

  • Glycogen acts as a store of glucose in

  muscles for respiration

  • Energy transferred/released from

  respiration in cells is used by the

  organism for further metabolic reactions

  • Link to uses of energy from respiration:

  Need energy to synthesise new

  molecules, carry out active transport,

  heat energy – maintain body temp
• Explain how these two molecules are used and removed from the

  body through metabolic processes. Your answer should include:

  • How the products of the breakdown of these molecules are

  removed from the body.

  • Water from breakdown of glucose/

  respiration is removed by the lungs

  during exhalation, as sweat from skin,

  and in urine via the kidney