Bonds in cellulose that make it resistant to digestion is:
**Core Concept**
Cellulose is a complex carbohydrate, specifically a polysaccharide, composed of glucose molecules. Its resistance to digestion is due to the unique chemical bonds between these glucose units.
**Why the Correct Answer is Right**
The correct answer is beta-glycosidic bonds. These bonds are formed between glucose molecules through a condensation reaction, resulting in a long chain of glucose units. The beta-glycosidic bond is resistant to hydrolysis by human digestive enzymes, making cellulose indigestible in the human small intestine. The presence of beta-glycosidic bonds also explains why cellulose is not broken down by pancreatic amylase, which targets alpha-glycosidic bonds.
**Why Each Wrong Option is Incorrect**
**Option A:** Beta-glycosidic bonds are indeed the correct answer, so it's not possible to explain why it's incorrect.
**Option B:** Alpha-glycosidic bonds are indeed broken down by pancreatic amylase, but they are not the primary bonds in cellulose.
**Option C:** Hydrogen bonds are weak intermolecular forces that do not contribute to the resistance of cellulose to digestion.
**Option D:** Glycogen is a polysaccharide composed of glucose molecules, but it is broken down by human digestive enzymes and is not resistant to digestion.
**Clinical Pearl / High-Yield Fact**
The human gut microbiome contains bacteria capable of breaking down cellulose, such as Ruminococcus and Clostridium. These bacteria can ferment cellulose to produce short-chain fatty acids, which provide energy to the host.
**Correct Answer: B. Beta-glycosidic bonds**