State a word equation for anaerobic cell respiration in humans (1).
pyruvate/pyruvic acid → lactate/lactic acid;
glucose → (pyruvate/pyruvic acid) → lactate/lactic acid;
Accept correct chemical equation with formulae.
Outline the role of oxygen in cellular respiration (2).
SL STUFF
Oxygen is used during aerobic respiration.
Oxygen is used in the mitochondria during aerobic respiration.
HL STUFF
In the electron transport chain in the mitochondria;
I
it is the final electron/hydrogen acceptor;
Oxygen combines with H+ (and electrons) to produce water; (c)
Compare how pyruvate is used in human cells when oxygen is available and when oxygen is not
available.(5)
1. aerobic cell respiration occurs if oxygen available and anaerobic respiration occurs if
oxygen is
unavailable;
2. If oxygen is available pyruvate enters mitochondrion for aerobic respiration;
3. Whereas if oxygen is not available, pyruvate stays in the cytoplasm for processing under
anaerobic
conditions;
4. In the mitochondria, pyruvate converted aerobically into carbon dioxide and water;
5. Whereas in the cytoplasm, pyruvate converted anaerobically to lactate;
6. A large ATP yield when oxygen available/from aerobic cell
respiration;
7. There is no (further) ATP yield without oxygen;
5 max
IB Questionbank Biology
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(b) Outline anaerobic cell respiration in plant cells.(5)
1. anaerobic (cell) respiration occurs in the absence of oxygen;
2. Glycolysis is the first step in anaerobic respiration. Glycolysis is the breakdown of
glucose molecules;
3. Glycolysis leads to the production of pyruvate;
4. Anaerobic respiration is also known as fermentation;
5. Fermentation/ anaerobic respiration produces of small yield/two ATP (molecules
per molecule of
glucose respired) during glycolysis ;
6. Alcoholic fermentation produces ethanol;
7. Alcoholic fermentation produces carbon dioxide;
8. All fermentation occurs in cytoplasm;
9. An example of anaerobic respiration in plants (e.g. waterlogged roots when there is no
oxygen available to plant roots);
(5)
(a)
90 (minutes) – UNITS REQUIRED
(b)
Outline the relationship – summarize the general trend
as temperature increases activity increases/positive correlation
(c)
1
Suggest – use previous knowledge from other topics or personal experience to come up with a
reason for observation
avoid predators / less competition for food
(d)
1
1
State the relationship – make a concise observation/ statement about the overall trend/
relationship observed in data
as temperature increases metabolic rate decreases/negative correlation
(accept converse)1
(e)
Compare the results for the single mice at 15 °C with those for the group mice at 15 °C
1. metabolic rate of group mice is always less than single mice;
(accept converse)
2. both follow similar pattern of increases/decreases/fluctuations at
same time of day;
3. fluctuations greater in group mice;
4. both most active/higher metabolic rate during evening/21:00;
(accept any reference to times between 18:00 and 00:00)
(f)
Suggest one reason - use previous knowledge from other topics or personal experience to come
up with a reason for observation
single mice need to produce more heat/have greater heat loss
because of greater surface exposed to air /
group mice huddle
together to reduce the surface exposed to air1
Allow any other reasonable
answer.
IB Questionbank Biology
2
(g) Explain why – discuss a reason/ justification
1. oxygen is required for (aerobic) respiration and thus oxygen consumption would indirectly show
respiration rate;
2. respiration is a fundamental metabolic reaction, because it produces ATP/releases energy/heat in the
mice;
3. metabolic rate is a measure of total energy released/consumed in
the body / oxygen consumption is
proportional to energy released/
consumed in body/proportional to metabolic rate;
(h)
Using the data from both graphs, evaluate the hypothesis
1. metabolic activity high when mice more active supports the hypothesis;
2. activity is normally correlated with energy consumption;
3. However, another factor may be causing both to increase at the same time /
correlation does not
always establish cause and effect;
4. Another factor that could be influencing results is grouping/environmental temperature
also affect metabolic rate;
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IB Questionbank Biology
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