Understanding cellular respiration requires applying core concepts to real-world biological scenarios. For Class 10, numerical problems focus on comparing the energy efficiency (ATP yield) of aerobic versus anaerobic respiration, and analyzing physiological changes during physical activity.
- Aerobic Respiration: 1 molecule of glucose yields 38 ATP.
- Anaerobic Respiration (Muscle/Lactic Acid): 1 molecule of glucose yields 2 ATP.
- Anaerobic Respiration (Yeast/Alcoholic): 1 molecule of glucose yields 2 ATP.
Question:
A sprinter's muscle cells require 190 molecules of ATP to complete a short, intense sprint.
- If the muscle cells are well-oxygenated, how many molecules of glucose must be broken down aerobically to produce this ATP?
- If the muscle cells run out of oxygen and switch to anaerobic respiration, how many molecules of glucose would be needed to produce the exact same amount of ATP?
Step-by-step Solution:
-
Aerobic Glucose Requirement:
- In aerobic respiration, 1 glucose molecule yields 38 ATP.
- Glucose required=ATP per glucoseTotal ATP Needed
- Glucose required=38190=5 molecules.
-
Anaerobic Glucose Requirement:
- In anaerobic respiration in muscles, 1 glucose molecule yields only 2 ATP.
- Glucose required=2190=95 molecules.
Insight: This huge difference explains why our muscles run out of energy (glucose reserves) so quickly when we sprint and rely on anaerobic respiration!
Question:
While resting, an adult human takes 12 breaths per minute, inhaling 500 mL of air with each breath (this is called the Tidal Volume). During vigorous exercise, the breathing rate increases to 30 breaths per minute, and the volume of air taken in per breath increases to 1500 mL.
Calculate the percentage increase in the total volume of air inhaled per minute during exercise compared to resting.
Step-by-step Solution:
- Calculate Resting Air Intake:
- Resting Intake=12 breaths/min×500 mL/breath=6,000 mL/min.
- Calculate Exercise Air Intake:
- Exercise Intake=30 breaths/min×1500 mL/breath=45,000 mL/min.
- Calculate the Difference (Increase):
- Increase=45,000−6,000=39,000 mL/min.
- Calculate Percentage Increase:
- Percentage Increase=(Resting IntakeIncrease)×100
- Percentage Increase=(6,00039,000)×100=6.5×100=650%.
Answer: The volume of air inhaled per minute increases by 650% during vigorous exercise to meet the body's high oxygen demand.
Question:
A marathon runner's leg muscles require 380,000 molecules of ATP per minute to sustain their pace. For the first 30 minutes, the runner is breathing deeply and supplies enough oxygen to produce all this ATP aerobically.
However, during the final 5-minute uphill sprint, the oxygen supply drops, and the muscles can only produce 190,000 ATP aerobically per minute. The remaining ATP must be produced anaerobically by converting glucose into lactic acid.
Calculate the total number of glucose molecules converted into lactic acid during this 5-minute uphill sprint.
Step-by-step Solution:
- Determine the ATP Deficit per minute:
- Total ATP needed=380,000 ATP/min
- ATP produced aerobically=190,000 ATP/min
- ATP deficit (to be made anaerobically)=380,000−190,000=190,000 ATP/min.
- Calculate Anaerobic Glucose Required per minute:
- Anaerobic respiration yields 2 ATP per glucose molecule.
- Glucose required/min=2190,000=95,000 glucose molecules/min.
- Calculate Total Glucose for the 5-minute sprint:
- Total glucose=95,000 molecules/min×5 minutes
- Total glucose=475,000 molecules.
Answer: The runner's muscles broke down 475,000 glucose molecules into lactic acid during the 5-minute sprint, leading to a massive oxygen debt and muscle fatigue.
BioNotes