set a Flashcards
Sunflower oil is used to make biodiesel, which contains methyl esters. The fatty acids in the
triglyceride molecule are reacted with methanol in a process called transesterification. After the reaction, two liquid products form which naturally separate from each other. The methyl esters float on top of a more dense liquid. Name the part of the molecule seen in Fig. 22 that forms this more dense liquid.
- glycerol
Living organisms have many uses for triglycerides, one of which is the production of
phospholipids.Name three other functions of triglycerides in living organisms
- energy storage
- energy source for respiration
- thermal insulation
- electrical insulation
Phospholipid molecules also contain fatty acids.
Explain how the fatty acids in phospholipids allow the formation of membranes
- hydrophillic heads that face outwards and hydrophobic tails that face inwards this form the bilayer
Describe how you could make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope.
- Add drop of water to (glass) slide;
- Obtain thin section and place on
slide on drop of water; - Stain with iodine in potassium iodide;
- Lower cover slip using mounted needle;
what is the function of the chloroplast and the nucleus?
- chloroplast, photosynthesis
- nucleus, contains dna
State what assumption is made when using this apparatus to measure the rate of transpiration.
- water loss equals uptake
There must be no air in the apparatus in Fig. 4.1 for it to work correctly.
Describe and explain the precautions that need to be taken when setting up and using
the apparatus in Fig. 4.1 to ensure that no air is present.
- cut stem under water so no air can enter the apparatus
- insert stem under water as air could block the xylem
- do not allow the bubble to move too far so that it doesn’t enter the xylem
Suggest why it might be considered better to use a capillary tube rather than a calibrated
pipette to measure water uptake
- capillary tube measures smaller volumes
The student wanted to compare the rates of transpiration of the two leafy shoots shown in
Fig. 4.3. Describe how the student could ensure that a valid comparison could be made between the
two leafy shoots.
- find leaf area
- calculate transpiration rate per unit area
Give two safety precautions that should be followed when dissecting a heart.
- wash hands
- cover any cuts
- use a sharp scalpel
Explain how the atrioventricular valve maintains a unidirectional flow of blood.
- Pressure in (left) atrium is higher than in
ventricle causing valve to open - Pressure in (left) ventricle is higher than in
atrium causing valve to close
Caffeine affects the autonomic nervous system.
Suggest how caffeine could account for the results of Group I in Figure 3 at
60 minutes.
- More impulses along sympathetic nervous system pathway
- To SAN increasing the heart rate
The increase seen in Group I could be due to the combination of caffeine and sugar.
Suggest one drink to be given to an additional group that should be investigated to
find out if this is true.
Give a reason for your answer.
- A drink with sugar (and no caffeine)
- To show that sugar (alone) is not causing
the increases (in HR)
What is meant by ‘species richness’?
- the amount of different species in a ecosystem
Three of the bee species collected in the farmland areas were Peponapis pruinosa,
Andrena chlorogaster and Andrena piperi.
What do these names suggest about the evolutionary relationships between these
bee species?
- A. chlorogaster and A.piperi are more closely related (share common ancestor) than to P.prumosa
- because they are in the same genus
