TOPIC 4 - BIOENERGETICS

Why did all the air have to be removed from the leaf discs before putting them in water?

so that the discs would sink; any gas produces is from PS

Why did the leaves rise after a while?

oxygen was produced from PS; the gas is trapped around the disc so floated

Instead of just water, to release CO2, what substance are the leaves kept in?

sodium hydrogencarbonate

Give uses of the energy released from respiration

• movement/ muscle contraction
• keeping warm
• active transport
• building larger molecules

What are the differences between aerobic and anaerobic respiration?

• anaerobic produces lactic acid/ A doesn't
• A produces CO2; AN doesn't
• A produces water; AN doesn't
• A occurs in mitochondria mainly; An doesn't (in the cytoplasm only)
• AN releases less energy than aerobic

What are the two products of anaerobic respiration in plants?

Ethanol + CO2

Suggest ways the method (of putting pondweed in water with a bulb to see oxygen produced) could be improved so the results would be more valid?

• repeat + calculate a mean, eliminate anomalies
• control the water temperature
• control the con of carbon dioxide
• control the distance of the bulb from the pondweed
• control the length, mass and psecies of pondweed
• give the pondweed time to acclimatised

How would you investigate the effect of light intensity on the rate of photosynthesis? (with a lamp, pondweed, beaker and ruler)

• weed in water in beaker
• light shining on beaker at different distances
• use the same pond weed each time
• use a water bath to control the temperature
• use a con sol of sodium hydrocarbonate each time so access to CO2
• leave sufficient time at each new light intensity before measurement 
• counting bubbles or collect gas and measuring volume in a syringe
• measure rate of PS by counting bubble for a set period of time
• repeats

Why does the bell jar model not accurately present our breathin system?

• only one air space per ballong
• alveoli not represent
• blood vessels not shown
• glass tube is flexible like the trachea
• the bell jar doesn't move during breathing like the ribs
• the ribs have gaps between them with muscles

Why does the air you inhale not turn lime water cloudy?

atmospheric air contains less CO2 than exhaled air

What is the purpose of a control?

for comparison; to check that not other factor is influencing the results

Why can't exercised be sustained with anaerobic respiration?

muscles become fatigued and stop contracting; because not enough energy is transferred

What are the uses of fermentation in industry?

brewing/ bread making