1. a) Lipid test
Positive: Butter, cupcake (not shown)
b) Starch test
Positive: Cupcake, bread, pancake
c) Simple sugars test
Positive: Apple, butter, cheese, pancake, orange
2. Here's a starch molecule (...why is this picture rotated correctly and not the others):
The building blocks of starch are glucose.
3. Carbohydrate molecules are hard to break down. The two test tubes that had not reacted until further heating took a longer time to break down, so we can infer that the carbohydrate molecules were longer/larger, thus taking more time.
4. The cupcake enters the body. The mouth begins its assault. The teeth mash down on the enemy, effectively breaking it down using physical digestion. The salivary glands secrete salivary amylase, breaking down the enemy further until it becomes a bolus. The starch in the cupcake is broken down as well, as peristalsis moves the bolus down the esophagus. As it reaches the stomach, it is immersed in the body's second phase of attack- being immersed in gastric juice. The hydrochloric acid and pepsin burn through the bolus, melting it down. Any proteins present in the enemy bolus are then turned into peptides.
The enemy changes form- the body begins it's next phase of assault. Now a substance called chyme, it is expelled from the stomach through the pyloric sphincter, In the duodenum, enzymes and chemicals excreted by the pancreas attack. Since the enemy cupcake's composition was mainly starch, pancreatic amylase attacks, changing the starch into maltose. As the chyme moves down the small intestine, the maltose is further broken down by a chemical called maltase, changing the maltose to glucose, which can be absorbed.
Absorption continues to occur throughout the large intestine, and the chyme soon collects in the rectum as feces. It is expelled from the body through the anus, giving the digestive system another win against the enemy.
