Basics of Digestion
Why do animals need to digest their food?
To break large food molecules into small absorbable units.
What does the soft palate do during swallowing?
It rises to block food from entering the nasal cavity.
What enzyme in the mouth begins carbohydrate digestion?
Salivary amylase.
Where do simple sugars and amino acids go after absorption?
Into the bloodstream.
What is the function of the crop in animals like birds?
Food Storage.
What is one advantage of extracellular digestion compared to intracellular digestion?
It allows digestion of larger food items outside the cell.
What does the epiglottis do during swallowing?
It covers the glottis to prevent food from entering the trachea.
What enzyme in the stomach begins protein digestion?
Pepsin.
Where do fatty acids and glycerol go after absorption?
Into the lymphatic system.
What is the function of the gizzard?
Mechanical grinding of food.
Why is intracellular digestion alone not sufficient for most animals?
It can only process tiny particles and cannot handle large food items.
What is the main function of the esophagus?
To move food from the pharynx to the stomach using peristalsis.
Which organ produces most digestive enzymes used in the small intestine?
The pancreas.
Why is surface area important for digestion and absorption?
More surface area allows more contact for enzymes and nutrient absorption.
Why don’t all animals have crops or gizzards?
Many animals use teeth for mechanical digestion instead.
Why do animals with incomplete guts rely on both extracellular and intracellular digestion?
Because extracellular digestion cannot fully break down food, so cells must finish digestion internally.
Why doesn’t much nutrient absorption occur in the stomach?
It lacks villi and microvilli and has thick protective epithelium.
What does bile do to fats during digestion?
It emulsifies them.
What adaptations increase surface area in the mammalian small intestine?
Length, folds, villi, and microvilli.
What long‑term effect can gallbladder removal have on digestion?
Less efficient fat digestion.
What is one major advantage of having a complete gut instead of an incomplete gut?
Food moves in one direction, allowing specialized regions and more efficient digestion.
Why is hydrochloric acid produced in the stomach?
To denature proteins, activate pepsin, and kill microbes.
Which enzymes in the small intestine complete digestion of carbohydrates and proteins?
Brush‑border enzymes.
Why is the pig intestine more coiled than the shark intestine?
Pigs need more surface area to digest complex, plant‑rich diets.
After gallbladder removal, where does bile come from?
It drips continuously from the liver.