Nutrition And Digestion

1. Digestion is the

Absorption of nutrients suspended in water.

Conversion of glycogen to glucose.

Chemical and mechanical breakdown of food for absorption into the body.

Churning of food in the stomach and intestine.

Digestion is the process of breaking down food into smaller molecules that can be absorbed by the body. This involves both chemical and mechanical processes. The chemical breakdown includes the action of enzymes that break down large molecules into smaller ones, while the mechanical breakdown involves the physical grinding and churning of food in the stomach and intestine. The end goal of digestion is to release nutrients from food so that they can be absorbed and used by the body for energy and other functions.

Explanation

Digestion is the process of breaking down food into smaller molecules that can be absorbed by the body. This involves both chemical and mechanical processes. The chemical breakdown includes the action of enzymes that break down large molecules into smaller ones, while the mechanical breakdown involves the physical grinding and churning of food in the stomach and intestine. The end goal of digestion is to release nutrients from food so that they can be absorbed and used by the body for energy and other functions.

2. Mary asked the doctor to recommend a plan so that she can minimize her risk of developing cardiovascular disease. The following are a few of the doctor's recommendations: quit smoking, exercise for at least 30 minutes per day, reduce saturated fats and trans fats in his diet, and increase the number of fruits and vegetables in his diet. Which of the following would match his doctor's recommendations?

Eat less of foods that contain partially hydrogenated vegetable oils

Eat less of foods that contain antioxidants

Avoid cooking with olive oil

Consume more beef and less fish

The doctor's recommendations include reducing saturated fats and trans fats in the diet. Partially hydrogenated vegetable oils are a source of trans fats, so eating less of foods that contain these oils aligns with the doctor's advice.

Explanation

The doctor's recommendations include reducing saturated fats and trans fats in the diet. Partially hydrogenated vegetable oils are a source of trans fats, so eating less of foods that contain these oils aligns with the doctor's advice.

3. Which of the following is associated with a reduced risk of cardiovascular disease?

High blood pressure

High levels of HDL

High levels of LDL

High consumption of trans fats

High levels of HDL (high-density lipoprotein) are associated with a reduced risk of cardiovascular disease. HDL is often referred to as "good" cholesterol because it helps remove excess cholesterol from the bloodstream and carries it back to the liver for processing. This helps prevent the buildup of plaque in the arteries, reducing the risk of heart disease and stroke. Conversely, high blood pressure, high levels of LDL (low-density lipoprotein or "bad" cholesterol), and high consumption of trans fats are all associated with an increased risk of cardiovascular disease.

Explanation

High levels of HDL (high-density lipoprotein) are associated with a reduced risk of cardiovascular disease. HDL is often referred to as "good" cholesterol because it helps remove excess cholesterol from the bloodstream and carries it back to the liver for processing. This helps prevent the buildup of plaque in the arteries, reducing the risk of heart disease and stroke. Conversely, high blood pressure, high levels of LDL (low-density lipoprotein or "bad" cholesterol), and high consumption of trans fats are all associated with an increased risk of cardiovascular disease.

4. What happens to nutrient macromolecules in an animal's digestive tract?

They are absorbed whole and are broken down into monomers in cells that ultimately use them.

Proteins and nucleic acids are digested into monomers before absorption; energy-storage macromolecules (starch and fat) are absorbed whole.

The digestive breakdown of macromolecules is keyed to the body's need for monomers; only the monomers that are immediately needed are produced.

Nutrient macromolecules are digested into monomers before absorption.

Nutrient macromolecules, such as proteins and nucleic acids, need to be broken down into their monomers (amino acids and nucleotides) before they can be absorbed by the cells in the digestive tract. This allows the body to utilize these monomers for various cellular processes. Energy-storage macromolecules like starch and fat, on the other hand, are absorbed whole without being broken down into monomers. The breakdown of macromolecules is regulated based on the body's immediate need for monomers, ensuring that only the necessary monomers are produced.

Explanation

Nutrient macromolecules, such as proteins and nucleic acids, need to be broken down into their monomers (amino acids and nucleotides) before they can be absorbed by the cells in the digestive tract. This allows the body to utilize these monomers for various cellular processes. Energy-storage macromolecules like starch and fat, on the other hand, are absorbed whole without being broken down into monomers. The breakdown of macromolecules is regulated based on the body's immediate need for monomers, ensuring that only the necessary monomers are produced.

5. Digestion takes place in specialized compartments for all of the following reasons except that

The environment of digestion must favor the action of digestive enzymes.

The environment of digestion must protect the food.

The environment of digestion must be contained.

The animal's body must be protected from its own digestive enzymes.

Digestion takes place in specialized compartments for the reasons that the environment of digestion must favor the action of digestive enzymes, the environment of digestion must be contained, and the animal's body must be protected from its own digestive enzymes. However, the environment of digestion does not need to protect the food itself as the purpose of digestion is to break down the food into smaller molecules that can be absorbed by the body.

Explanation

Digestion takes place in specialized compartments for the reasons that the environment of digestion must favor the action of digestive enzymes, the environment of digestion must be contained, and the animal's body must be protected from its own digestive enzymes. However, the environment of digestion does not need to protect the food itself as the purpose of digestion is to break down the food into smaller molecules that can be absorbed by the body.

6. Interestingly, most herbivorous animals do not have the ability to digest the cellulose in plants. However, in the absence of this ability, they have evolved a mechanism that allows them to survive despite eating only plant matter, namely

Digestion by symbiotic microorganisms.

Production of saliva containing amylase.

Avoidance of plants containing cellulose.

Converting cellulose to other carbohydrates.

Herbivorous animals have evolved a mechanism of digestion by symbiotic microorganisms to survive despite their inability to digest cellulose in plants. These microorganisms reside in the digestive system of these animals and break down cellulose into simpler carbohydrates that can be absorbed and utilized by the animal for energy. This symbiotic relationship allows herbivorous animals to extract nutrients from plant matter and thrive on a plant-based diet.

Explanation

Herbivorous animals have evolved a mechanism of digestion by symbiotic microorganisms to survive despite their inability to digest cellulose in plants. These microorganisms reside in the digestive system of these animals and break down cellulose into simpler carbohydrates that can be absorbed and utilized by the animal for energy. This symbiotic relationship allows herbivorous animals to extract nutrients from plant matter and thrive on a plant-based diet.