Question

1. a student thinks that the human body only works properly when cells are getting molecules from food and molecules from air. is the student correct?

yes, the body only works when cells get molecules from food and molecules from air.
no, the body only works when cells are getting molecules from different types of food.
no, the body only works when the lungs get molecules from air, and the stomach gets molecules from food.
no, the body works as long as cells are making all the molecules they need.

1. stellas respiratory system is not working well. why is this a problem for her ability to exercise?

her respiratory system will not be able to break down molecules from air into oxygen.
her cells will not work well when they have low levels of oxygen.
her digestive system will have to work twice as hard to get the same amount of energy from glucose molecules.
her cells will not work because molecules from air will be too large for her body to use.

Explanation:

Question 7

The human body's cells need molecules from food (for energy, building blocks) and from air (like oxygen for respiration). The first option correctly states that the body functions when cells get these molecules. The other options are incorrect: cells need both food - derived and air - derived molecules, not just food of different types, not just lungs/stomach getting molecules, and cells can't make all needed molecules on their own.

The respiratory system's role is to get oxygen (from air) to cells. During exercise, cells need more energy, which requires more oxygen for cellular respiration. If the respiratory system isn't working well, cells get low oxygen levels, so they don't work well. The first option is wrong (respiratory system doesn't break down air into oxygen in that way), the third is wrong (digestive system isn't related here), the fourth is wrong (air molecules like oxygen are small enough).

Answer:

Yes, the body only works when cells get molecules from food and molecules from air.

Question 8