paper 1

• what are xylem cells


  Dead, hollow, continuous tubes that carry water in the transpiration system
• how are xylem cells adapted for their function


  no cytoplasm-more room for water

  -walls contain lignin for strength

  -dead cells joined end to end to form continuous tube
• what are phloem cells


  living cells that carry products of photosynthesis such as sugars up and down the plant
• how are phloem cells adapted for their function?


  -made up of tube like living cells joined end to end

  -no nucleus for more space

  -sieve tube has sieve plates which connect them
• what makes phloem cells living but not xylem cells?


  -xylem consists of dead cells with no cytoplasm whereas phloem cells do have cytoplasm
• how can you show that a plant gives of oxygen during photosynthesis?


  -use water plant

  -collect gas bubbles made during photosynthesis

  -gas will relight glowing splint as it contains oxygen
• how can you calculate the rate of photosynthesis by measuring oxygen production?


  -set up bubble potometer apparatus

  -oxygen gas produced will cause the bubble in capillary tube to move

  -distance moved by bubble is used to calculate volume of oxygen produced
• what are features of animals?

  heterotrophic

  multicellular

  reproduce sexually
• what are features of plants?

  multicellular

  autotrophs
• what is saprotrophic nutrition?


  -Extracellular secretion of digestive enzymes onto food material

  -enzymes break down and digest the food

  -then they absorb the organic products
• are viruses cells?


  no
• give a example of a specialised exchange surface and what it does

  alveoli

  exchanges carbon dioxide and oxygen with the bloodstream
• how does the upper epidermis help the palisade mesophyll receive light

  it is transparent so light can get through it
• what happens if there is lots of water in th leaf?

  guard cells become turgid which opens the stomata so C02 can enter but water can escape
• where is meristem tissue found?

  tips of roots and shoots
• is glucose a monomer or polymer?

  monomer
• where are proteins broken down?


  stomach and small intestine
• what are lipids made of?

  glycerol and fatty acids
• how does bile help with lipids digestion

  emulsifies the lipids

  so there is a increased surface area for the enzymes to work on
• why do we need carbs


  for energy in chemical reactions
• what are the two roles of the digestive system?


  -digestion-break down large food molecules into smaller one

  absorption-absorb the small food molecules into body
• what is pepsin?


  type of protease enzyme which breaks down protein into amino acids in the stomach
• what does hydrochloric acid do in the digestive system?


  kills microorganisms

  provides right PH for pepsin to work
• Which organs produce amylase?

  Salivary glands, pancreas, small intestine
• describe the effects of coronary heart disease

  -coronary arteries provide oxygenated blood to the heart

  -in coronary disease layers of fatty material build up in arteries causing the lumen to get narrower

  -this reduces blood flow to the heart which reduces the amount of oxygen and other nutrients the heart is getting to function properly

  -this can cause chest pain as the heart is starved of oxygen and in severe cases a heart attack
• what are benefits of stents?


  • Surgery is quick

  • Last a long time

  .almost immediate effect
• what are disadvantages of statins?


  -They are a long-term drug that must be taken regularly

  - could be forgotten to be taken

  -They can have some negative side effects e.g. headaches, kidney failure, liver damage and memory loss

  -It takes time for them to kick in
• describe the stages of phagocytosis


  1-phagocyte locates and binds to pathogen

  2-phagocyte membrane surrounds and engulfs pathogen

  3-enzymes inside phagocyte break down the pathogen and destroy it
• what is transpiration?

  evaporation of water from plant leaves
• why does the rate of transpiration increase when its windy?


  -wind blows away water vapour as soon as it diffuses out of the leaf

  -this maintains a strong concentration gradient which increases diffusion rate
• how do viruses spread and multiply?


  As they can't reproduce themselves, viruses have to enter one of our cells, and then use it to create multiple copies of the virus itself.

  Once there are lots of copies, the viruses cause the cell to burst, and then go on to infect neighbouring cells.
• can vaccines be used against bacterial and viral diseases?

  yes
• how do vaccines work?

  they expose you to the antigens of the pathogens so we can develop immunity to it
• what is the pathway of light through a microscope?

  Light source ➔ stage ➔ microscope slide ➔ object ➔ objective lens ➔ body tube ➔ eyepiece lens
• Is unicellular or multicellular

  unicellular
• what kind of stem cell can only differentiate into different blood cells?

  adult stem cells
• what do plants use magnesium ions to make?

  chlorophyll
• what is active transport


  movement of molecules into or out of a cell against a concentration gradient
• What does active transport require?

  Energy from respiration (ATP)
• what is diffusion


  The movement of particles from an area of high concentration to an area of low concentration.