Amylase breaks down starch by cutting the alpha-1,4 glycosidic bonds, producing smaller glucose units. The main immediate product of this action is maltose, a disaccharide of two glucose units, with some other small glucose-containing units like maltotriose and dextrins also formed. In the digestive tract, enzymes at the brush border (such as maltase) then convert maltose into glucose. So maltose and glucose together represent the primary carbohydrate products you get when amylase acts on starch. Fructose, galactose, sucrose, and lactose are not produced from starch by amylase digestion.

The key idea is that fat digestion by lipase needs the enzyme itself in addition to the oil substrate. Bile salts don’t hydrolyze fats; they emulsify the oil to increase the surface area available for lipase. So, if a tube contains oil and bile salts but no lipase, there will be no triglyceride breakdown and no fatty acid production, regardless of the emulsification. That tube shows no enzyme activity because the essential catalyst (lipase) is missing. The other tubes either contain lipase (and thus show activity by converting triglycerides into fatty acids and glycerol) or have conditions where the enzyme can act, but without the enzyme being present, activity cannot occur.

Stroke volume is the amount the ventricle pumps with each beat. In a healthy adult at rest, this is about 70 mL. This comes from typical volumes: end-diastolic around 120 mL minus end-systolic around 50 mL gives roughly 70 mL per beat. If heart rate is about 70 beats per minute, cardiac output is about 5 L per minute (70 mL × 70/min), which fits resting values. Values around 50 mL are a bit low for rest, around 90 mL can occur with higher demand or conditioning, and about 110 mL is generally seen with greater exercise load. So the best approximate resting ejected volume per beat is 70 mL.

Residual volume is the air left in the lungs after you exhale as forcefully as possible. This amount cannot be removed even with maximal effort, so a small quantity of air remains in the airways and alveoli to keep the lungs from collapsing and to allow a minimal level of gas exchange between breaths. It’s not the air you breathe in or out during normal breathing, and standard spirometry can’t measure it directly because you can’t fully empty the lungs with typical tests. This leftover air helps define total lung capacity when added to the volumes you can exhale.