biology paper 1 questions

• compare the function of the xylem tissue and the phloem tissue.

  xylem transports mineral ions/ water whilst phloem transports dissolved sugars

  xylem is involved in transpiration whereas phloem is involved in translocation

  xylem transports unidirectionally while phloem transports bidirectionally

  both transport liquids / substances through stem / leaves / roots / plant
• what happens when muscles are supplied with insufficient oxygen?

  anaerobic respiration > oxidation of glucose is incomplete causing a build up of lactic acid which causes:

  oxygen debt

  muscles becoming fatigued and stopping contracting efficiently if activity is long / vigorous
• what is the role of the liver in recovery from vigorous exercise

  blood flowing through muscles transports lactic acid to the liver

  where it is converted back to glucose
• describe the term metabolism

  metabolism is the sum of chemical reactions in a cell or body
• what is made when an enzyme and substrate combine?

  an enzyme substrate complex
• name 5 examples of metabolism

  glucose molecules can be joined together to form starch and cellulose in plant cells, or glycogen in animal cells

  glycerol + fatty acids join to form a lipid

  excess protein can be broken down to form urea

  amino acids are made from glucose and nitrate irons that join together to make proteins

  respiration happens in all cells - chemical reactions release anergy from glucose
• what is glycogen 


  the storage form of glucose in humans
• what is starch


  the storage form of glucose in plants
• what is the definition of a eukaryotic cell

  a cell that contains their genetic material enclosed in a nucleus
• give an example of a prokaryotic cell

  a bacteria cell
• what is the definition of a prokaryotic cell

  a cell where the genetic material is not enclosed in a nucleus
• where is the genetic material stored in bacterial cell

  a single loop of DNA and in some cases small rings of DNA called plasmids
• what happens to an enzyme when it denatures?

  the enzyme active site changes so it now no longer fits the substrate so an enzyme substrate complex can not be formed
• what reagent is used to test for starch?

  iodine
• what reagent is used to test for sugar?

  bennedicts
• what reagent is used to test for fats?

  sudan III
• what reagent is used to test for protein?

  biuret
• what is osmosis?

  the diffusion of water molecules from a high concentration to a low concentration with the concentration gradient so it does not require energy
• why is iodine used when preparing onion cell slides?

  staining in order to see parts of the cell more clearly
• • Electron microscopes have a better resolving power and a higher resolution than light microscopes, allowing us to see finer details of the organelles.
• name 5 structures that are found in both plant and animal cells

  cytoplasm, ribosomes, cell membrane, nucleus, mitochondria
• what is the name of the first antibiotic developed?

  penecillin
• suggest why doctors do not give antibiotics to patients with minor infections

  to prevent resistant strains of bacteria developing and to reduce antibiotic resistance
• what component in the blood starts the clotting process?

  platelets
• give two ways that cell division by mitosis is important in fully grown animals

  repair of tissues, replacement of cells
• which organs in the digestive system produce amylase

  salivary glands, pancreas, small intestine
• during a food test describe how a student would know if all the starch had been digested.

  iodine solution would not turn black and would stay orange
• explain how the structure of enzyme molecules is related to the effect of ph on the activity of amylase.

  > enzymes are protein molecules so have a 3D structure

  >lock and key theory - enzymes have an active site which has a specific shape

  >shape of active site will only match shape of substrate > starch is substrate for amylase

  > at pH values above or below the optimum the shape of active site is changed so substrate can no longer fit the active site

  > at extreme pH values enzyme is denatured

  > so amylase can no longer digest starch

  > so rate of digestion decreases
• why are xylem cells dead

  cell walls are sealed with lignin
• what is the equation for photosynthesis?

  6CO2 + 6H2O → C6H12O6 + 6O2
• Measuring the rate of photosynthesis

  1. Leave the pondweed in the light (for a few minutes) before taking measurements

  2. Use a gas syringe to collect and measure gas produced

  3. Measure time oxygen is collected for using a stopwatch

  4. Repeat the measurements and calculate a mean
• Experimental setup

  • Use pondweed in water
  • Use different colours of light (red, blue, green)
  • Ensure light intensity is the same for each colour
• the trachea has rings of cartilage to prevent the trachea collapsing and allowing air to pass through
• the trachea splits into two smaller tubes called bronchi, one passing to each lung
• further into the lungs the bronchi subdivide into many smaller tubes called bronchioles
• bronchioles end in tiny air sacs called alveoli
• alveoli is where gases diffuse in and out of the blood stream
• millions of alveoli mean that the lungs have a huge surface area which increases the rate of gas exchange
• alveoli have very thin walls so the diffusion path is very short
• alveoli have a very good blood supply