Question

question 1
cellulose is a residue of digestion that comes from:
carbohydrates.
meat proteins.
undigested fats.
undigested connective tissue.
question 2
which of the following is not one of the openings that must be blocked when food moves from the pharynx into the esophagus?
oropharynx
nasopharynx
larynx
mouth
question 3
which of these is not an example of mechanical digestion?
moistening the food
changing food from large to small particles
propelling food through the digestive tract
all of the above are examples of mechanical digestion.

Explanation:

Question 1

Cellulose is a type of carbohydrate (a polysaccharide) that is indigestible by humans. Meat proteins, undigested fats, and undigested connective tissue do not relate to cellulose's origin. So the correct option is the one about carbohydrates.

When food moves from pharynx to esophagus, the nasopharynx (to prevent food from going to nose), larynx (to prevent aspiration into lungs), and the mouth (since food is moving down, the mouth opening needs to be blocked in terms of backflow, but the oropharynx is part of the pharynx pathway. Wait, actually, the openings to block are nasopharynx (via soft palate), larynx (via epiglottis), and the mouth is already the entry point, but the oropharynx is the middle part. Wait, the question is which is NOT one. The mouth is the initial entry, and when moving to esophagus, the oropharynx is part of the pharynx, but the nasopharynx (blocked by soft palate), larynx (blocked by epiglottis), and the mouth is not an opening that needs to be blocked in the same way (or maybe the key is that the mouth is the source, not an opening to block. Wait, the options: Oropharynx is part of the pharynx, nasopharynx is above, larynx is the voice box. The mouth is the opening we chew in, and when swallowing, we block nasopharynx (soft palate), larynx (epiglottis), and the oropharynx is part of the path. Wait, actually, the correct answer is Mouth, because the other three (oropharynx? Wait no, maybe I got it wrong. Wait, the pharynx has three parts: nasopharynx, oropharynx, laryngopharynx. When swallowing, the nasopharynx is blocked by soft palate, larynx is blocked by epiglottis, and the oropharynx is the passage. So the opening that is not blocked is Mouth? Wait, the question is "which is not one of the openings that must be blocked when food moves from pharynx into esophagus". So the openings to block are nasopharynx (so food doesn't go to nose), larynx (so food doesn't go to lungs), and maybe oropharynx? No, the mouth is not an opening of the pharynx. Wait, the pharynx connects to nasopharynx (nose), oropharynx (mouth), and larynx (voice box). So when food moves from pharynx (oropharynx) to esophagus, we block nasopharynx (soft palate up), larynx (epiglottis down), and the mouth is already the place the food came from, so the mouth is not an opening of the pharynx that needs to be blocked. So the answer is Mouth.

Mechanical digestion involves physical breakdown of food. Changing food from large to small particles (chewing) and propelling food (peristalsis) are mechanical. Moistening food is part of chemical or preparatory, not mechanical breakdown. So "Moistening the food" is not mechanical digestion.

Answer:

A. carbohydrates.

Question 2