biology paper 1 cell biology and organisation

• why do electron microscopes have a greater resolution and magnification?

  uses beams of electrons with shorter wavelength than photons of light
• define magnification

  number of times bigger an image appears compared to size of real object
• how in plants is the xylem cell adapted to its function?

  no upper/lower margins between cells - continuous route for water to flow

  thick/ woody side walls strengthen structure and prevent collapse
• describe how the muscle cell is adapted to its function

  arrangement of protein filaments slide over each other to produce muscle contraction. mitochondria provides energy for muscle contraction
• describe the process of active transport in root hair cells of plants

  takes soluble substances against concentration gradient. through a membrane. energy from mitochondria
• plant roots obtain some of their mineral ions/ salts from soil via active transport. what is involved in active transport?

  molecules move across cell membrane against a concentration gradient by a series of chemical reactions because diffusion cannot occur. energy via respiration is required and oxygen is required for respiration to occur
• when a plant cell is placed in distilled water it becomes turgid. why does the cell swell and name the process involved

  water molecules enter cell through partially permeable membrane by osmosis because the concentration of water is greater outside the cell
• where are stem cells found in adults?

  bone marrow
• reasons for not using adult stem cells

  difficult for them to differentiate
• true or false? in therapeutic cloning, there is a risk of donor stem cells being rejected by the patients body? (explain answer)

  false. therapeutic cloning produces stem cells with the same genetic makeup as the patient so no risk of stem cells being rejected by patients body
• what are 2 ways to culture bacteria?

  nutrient broth solution, or as colonies on agar gel plate
• what is the risk when transferring stem cells in medical treatments

  infection
• true or false? during diffusion, substances enter a cell against the concentration gradient

  false
• another name for cells in plants and animals is...

  eukaryotes
• what is the effect of increasing temp on enzyme?

  enzyme and substrate move faster so there are more collisions per second between substrate and active site. at optimum temp, enzyme works at fastest possible rate as theres max frequency of successful collisions between substrate and active site ( 37 degrees celcius ). temp increase past optimum = enzyme activity decreases to 0. active site is denatured substrate no longer fits. enzyme no longer catalyses reaction
• how is the small intestine adapted for absorbing products of digestion?

  long length means large sa : vol ratio

  good blood supply bloodstream removes products of digestion increasing concentration gradient

  thin membrane = short diffusion path

  interior of small intestine covered in villi and microvilli increasing sa for absorption of molecules
• what type of circulatory system do fish have and what is the issue with this?

  single circulatory system - blood uses a lot of pressure passing through gills before reaching organs so blood travels to organs relatively slowly. cant deal a great amount of oxygen
• describe the structure of the heart

  right atrium and left atrium at top, right ventricle and left ventricle at the bottom. the atria are separated from ventricles by valves, when atria contract, blood is forced into ventricles.

  first blood vessel - vena cava carries deoxygenated blood from body. blood goes from heart to lungs via pulmonary artery.

  oxygenated blood from lungs carried back via pulmonary vein (farthest on the right). Blood from heart carried to body by aorta
• name a feature on the left ventricle and atrium and why we have it?

  thicker muscular wall. left ventricle pumps blood all around body needing a greater force. right ventricle only pumps blood to lungs
• purpose of coronary artery

  provides oxygen to muscle cells in heart, oxygen used in respiration provides energy for contraction
• where is the natural pacemaker found in the body?

  right atrium
• adaptations of artery

  thick muscular walls withstand high pressure

  elastic fibres = when surge of blood beats, they recoil to keep blood moving
• describe transportation of substances via capillaries

  glucose and oxygen diffuse out of blood into cells

  carbon dioxide diffuses into blood
• adaptations of veins

  thin wall as blood pressure is low

  valves stop blood flow backwards
• job of placelet

  helps blood clot
• what is another type of cardiovascular disease, other than coronary heart disease?

  some heart valves wont fully open causing heart enlargement. heart has to pump extra hard for blood passage
• 2 treatments to reduce risk of coronary heart disease. advantage and disadvantage?

  • statins - lower levels of cholesterol in blood. this slows down the rate in which fatty acids build up in the arteries. ADV = effective treatment. DISADV = unwanted side effects like liver problems
  • stent = a tube inserted into coronary artery to keep it open. ADV = blood flows normally in artery. DISADV = wont prevent other regions of coronary artery from narrowing. doesnt treat underlying cause.