Question 1

During the last trimester of pregnancy, the BMR increases approximately 15% to 30%. The amount of energy necessary to produce milk for lactation can increase the BMR 40%.

Accepted Answer

Basal metabolic rate indicates the energy required for involuntary physiological functions to maintain life. Lactation requires extra energy, which is reflected in a higher BMR. A naturally higher BMR is why pregnant women do not feel as cold as adults under the same weather conditions.

Question 2

During oxidation of triglycerides, 1 lb of fat results in 1000 kcal of energy. Ketones are formed when excessive amounts of fat are oxidized for energy.

Accepted Answer

During oxidation of triglycerides, 1 lb of fat results in 3500 kcal of energy. Ketones are formed when the liver becomes overwhelmed because of excessive amounts of fat being oxidized for energy. Ketones are acidic metabolic products that are not oxidized in the liver, but they are carried to the skeletal and cardiac muscle, where under normal circumstances, they are rapidly metabolized. Note that production of 3500 kcal is more energy than most individuals use in a 24-hour period.

Question 3

The major waste product of protein catabolism is ammonia. The liver converts ammonia to urea to be excreted by the kidneys.

Accepted Answer

The roles of urea and ammonia are reversed in the question. Urea is the major waste product of protein catabolism (breakdown of a compound into simpler substance). The liver converts urea to ammonia to be excreted by the kidneys. The levels of urea and ammonia vary directly with dietary protein levels.

Question 4

In addition to producing excessive water within cells, ketoacidosis is a dangerous condition because the brain and nerve cells use ketones for some of their fuel requirements when glucose levels remain low for several days.

Accepted Answer

Ketoacidosis is an extension of a condition known as ketosis. Dangerous dehydration can occur because an accumulation of ketone bodies upsets the acid-base balance. This condition, called acidosis, results in loss of large amounts of water and sodium ions and a disruption in the glucose balance. When blood glucose levels remain low for several days, brain and nerve cells adapt to use ketones for some of their fuel requirements. Ketoacidosis frequently occurs in patients with uncontrolled diabetes mellitus or individuals who are not eating because they are burning fat rather than carbohydrate because of illness or weight reduction.

Question 5

Thyroxine, produced by the thyroid gland, has a greater influence on the basal metabolic rate (BMR) than secretions from any other gland. The pituitary gland accounts for a 15% to 20% increase in the BMR during growth of children and adolescents.

Accepted Answer

The iodine-containing hormone thyroxin has a greater influence on the rate of metabolic processes than secretions from any other gland. Adrenal glands affect metabolism to a lesser degree. The pituitary gland accounts for about a 15% to 20% increase in the BMR during growth of children and adults.

Question 6

Hormones stimulate, but do not retard, the functions of other cells. Hormones act as messengers that principally control metabolic functions that affect the skeletal muscular and nervous systems.

Accepted Answer

Hormones are "messengers" produced by a group of cells that stimulate or retard the functions of other cells. Hormones principally control different metabolic functions that affect growth and secretions.

Question 7

During which period of life is the basal metabolic rate (BMR) the highest?

Accepted Answer

From birth through age 2 years, growth results in the highest BMR. This rate then decreases until the puberty growth spurt, and is followed by a gradual decline for the rest of the life cycle.

Question 8

During times of low caloric intake, high-protein diets successfully build muscle mass because this type of diet utilizes the amino acid metabolic pool to stimulate anabolism of muscle.

Accepted Answer

High-protein diets are neither safe nor effective as a means to increase (anabolize) muscle mass. The amino acid metabolic pool, a small reservoir containing approximately 70 g of amino acids, is not intended for this purpose. This pool contains less amino acid than most Americans consume in a day and is not intended to supplement proper nutrition, nor is it capable of building muscle mass in the absence of caloric intake and exercise.

Question 9

Each of the following is a function of the liver except one. Which one is the exception?

Accepted Answer

The liver converts monosaccharides to glucose to provide energy for utilization by the cells. Its major role is regulatory; it controls the kinds of quantities of nutrients within the bloodstream. The polysaccharide glycogen is stored in the liver (and muscle) and converted to glucose. In this form, glucose can be supplied to the bloodstream and delivered to the cells as needed. Other end products of digestion can be oxidized to be converted to glucose, protein, fat, or other substances as needed by the cells and tissues of the body.

Question 10

The macronutrients supplying physiologic energy are carbohydrate, protein, fat, and alcohol. After conversion to glycogen and glycerol, these basic nutrient units are delivered to the cells.

Accepted Answer

The macronutrients responsible for physiologic energy are carbohydrate, protein, fat, and alcohol. These substances are converted to glucose, fatty acids, and amino acids and delivered to the cells for utilization. Glycogen is a carbohydrate derived from glucose that is stored in the muscles and liver. Glycerol is a portion of the chemical structure of triglycerides.

Question 11

Each of the following accurately describes aspects of lipid metabolism except one. Which one is the exception?

Accepted Answer

An important concept is that the liver is the principal regulator of fat metabolism and lipoprotein synthesis (building of new substances). Fatty acids are an important component of this function, and they can be modified in many ways before they are released from the liver into the circulations. Modification, also known as hydrolysis, of fatty acids can be by shortening, lengthening, or adding double bonds.

Question 12

The best source for assuring optimal glycogen stores is:

Accepted Answer

Adequate carbohydrates must be consumed to assure optimal glycogen stores. In fact, glycogen stores are depleted with a carbohydrate-poor diet even when high levels of fat and protein are eaten. A patient who ingests a carbohydrate-poor diet has decreased energy reserves and is prone to having prolonged healing periods and fatigue.

Question 13

For adults of all ages, one to two alcoholic drinks daily results in the lowest mortality rate because moderate alcohol consumption provides protective effects on the cardiovascular system.

Accepted Answer

The Dietary Guidelines for Americans advise moderation in alcohol consumption. Specifically, its recommendation of one to two drinks daily applies to middle-aged and older adults only. Alcohol consumption seems to provide little, if any, health benefit for younger individuals. Alcoholic beverages should be avoided by women who may become pregnant or are pregnant or breastfeeding.

Question 14

Metabolic rate is lowest:

Accepted Answer

Metabolic rate is lowest after a few hours of sleep because muscles are more relaxed. Approximately 10% less energy is needed for the basal metabolic rate during this relaxed state.

Question 15

Each of the following is true of metabolic interrelationships except one. Which one is the exception?

Accepted Answer

There are many interrelationships between macronutrients and micronutrients responsible for metabolism. In some situations, one nutrient can be substituted for another because of their interrelationship. Proteins, carbohydrates, and fats contribute to anabolism and catabolism (buildup and breakdown) of products, but glucose is not converted to fatty acids or amino acids. Rather, fatty acids and some amino acids can be converted to glucose.

Question 16

The liver performs each of the following actions upon cholesterol except one. Which one is the exception?

Accepted Answer

The liver does not convert cholesterol to urea. Instead, the liver converts urea to ammonia, which is then excreted by the kidneys. Urea is the major waste product of the breakdown (catabolism) of protein.

Question 17

Many patients gain weight after age 25 because the BMR decreases and previous eating habits are maintained without increasing activity.

Accepted Answer

BMR is highest from birth through age 2 years. It decreases until the puberty growth spurt, then is followed by a gradual decline for the rest of the life-cycle. At age 25 not only is the BMR becoming lower, many young adults no longer have the time for physical exercise.

Question 18

Catabolism is also called the Krebs cycle. During the Krebs cycle glucose, fatty acids, and amino acids are converted to a usable form of energy.

Accepted Answer

Catabolism, one of the two major chemical reactions, splits complex substances into simpler substances. Its counterpart, anabolism, builds or synthesizes more complex compounds. The Krebs cycle, also called the citrus acid cycle, utilizes enzymes to convert glucose, fatty acids, and amino acids into usable forms of energy.

Question 19

Symptoms of hypoglycemia include all of the following except one. Which one is the exception?

Accepted Answer

During hypoglycemia, the patient's coloring fades and is pale. It is also possible for the patient to have no symptoms but have low blood glucose levels.

Question 20

Regardless of whether excessive food intake is in the form of protein, carbohydrate, alcohol, or fat, most excess energy intake is stored in the liver. Fat is a good source of energy, but protein is the preferred fuel.

Accepted Answer

Regardless of the source of excessive food intake, most excess energy intake is stored in adipose tissue. Fat is a good source of energy, but the preferred fuel is carbohydrate. Note that in the absence of adequate carbohydrates, the body cannot metabolize excessive amounts of fat without some side effects-ketoacidosis, hyperlipidemia, and accumulation of fat in the liver. Glycogen is another storage form of energy; however, the amount of glycogen stored in the body is limited.

Quiz 7: Use of the Energy Nutrients: Metabolism and Balance