paper 2 Flashcards
state difference of anaerobic respiration animal v yeast
In animals, the pyruvate is converted into lactic acid (or lactate)
In plants and yeasts, the pyruvate is converted into ethanol and carbon dioxide
difference between anaroebic and aerobic respiration
Anaerobic respiration involves the partial breakdown of glucose in the cytosol for a small yield of ATP
Aerobic respiration utilises oxygen to completely break down glucose in the mitochondria for a larger ATP yield
APPLICATION: Lactate production in humans when anaerobic respiration is used to maximise the power of muscle contractions
Muscle contractions require the expenditure of high amounts of energy and thus require high levels of ATP
When exercising at high intensity, the cells’ energy demands will exceed what the available levels of O2 can supply aerobically
Hence the body will begin breaking down glucose anaerobically to maximise ATP production
This will result in an increase in the production of lactic acid, which leads to muscle fatigue
When the individual stops exercising, oxygen levels will increase and lactate will be converted back to pyruvate
Although carbohydrates, lipids and proteins can all be consumed as energy sources, only carbohydrates will typically undergo anaerobic respiration
define respirometer
respirometer is a device that determines an organism’s respiration rate by measuring the rate of exchange of O2 and CO2
limiting factors of photosynthesis - temperature
As temperature increases reaction rate will increase, as reactants have greater kinetic energy and more collisions result
Above a certain temperature the rate of photosynthesis will decrease as essential enzymes begin to denature
limiting factors of photosynthesis - light
Light is absorbed by chlorophyll, which convert the radiant energy into chemical energy (ATP)
As light intensity increases reaction rate will increase, as more chlorophyll are being photo-activated
At a certain light intensity photosynthetic rate will plateau, as all available chlorophyll are saturated with light
Different wavelengths of light will have different effects on the rate of photosynthesis (e.g. green light is reflected)
limiting factors of photosynthesis - co2 conc
Carbon dioxide is involved in the fixation of carbon atoms to form organic molecules
As carbon dioxide concentration increases reaction rate will increase, as more organic molecules are being produced
At a certain concentration of CO2 photosynthetic rate will plateau, as the enzymes responsible for carbon fixation are saturated
how to measure co2 uptake
Carbon dioxide uptake can be measured by placing leaf tissue in an enclosed space with water
Water free of dissolved carbon dioxide can initially be produced by boiling and cooling water
Carbon dioxide interacts with the water molecules, producing bicarbonate and hydrogen ions, which changes the pH (↑ acidity)
Increased uptake of CO2 by the plant will lower the concentration in solution and increase the alkalinity (measure with probe)
Alternatively, carbon dioxide levels may be monitored via a data logger
how to measure o2 production
Oxygen production can be measured by submerging a plant in an enclosed water-filled space attached to a sealed gas syringe
Any oxygen gas produced will bubble out of solution and can be measured by a change in meniscus level on the syringe
Alternatively, oxygen production could be measured by the time taken for submerged leaf discs to surface
Oxygen levels can also be measured with a data logger if the appropriate probe is available
how to measure biomass
Glucose production can be indirectly measured by a change in the plant’s biomass (weight)
This requires the plant tissue to be completely dehydrated prior to weighing to ensure the change in biomass represents organic matter and not water content
An alternative method for measuring glucose production is to determine the change in starch levels (glucose is stored as starch)
Starch can be identified via iodine staining (turns starch solution purple) and quantitated using a colorimeter
what causes non disjunction
refers to the chromosomes failing to separate correctly, resulting in gametes with one extra, or one missing, chromosome.
The failure of chromosomes to separate may occur via:
Failure of homologues to separate in Anaphase I (resulting in four affected daughter cells)
Failure of sister chromatids to separate in Anaphase II (resulting in only two daughter cells being affected)
This may be due to developing oocytes being arrested in prophase I until ovulation as part of the process of oogenesis
