8. Raoul ate a meal of oats before seeing his doctor. Oats are made of mostly starch molecules. Raoul feels tired, so his doctor gave him a test and found that Raoul’s cells contained glucose molecules, but they did not contain enough oxygen molecules. Does this explain why Raoul feels tired? a
No, something else must be wrong because his cells have all the molecules they need.

b
Yes, his digestive system is breaking down starch molecules, but his respiratory system may not be working properly.

c
Yes, his respiratory system is working, but his digestive system is not getting energy from combining glucose molecules.

d
Yes, his digestive system is working, but his respiratory system is not breaking down oxygen, so his body stopped making energy.