Question 1

The biosynthesis of amino acids takes place mostly in the liver.

Accepted Answer

The liver plays a central role in the biosynthesis of amino acids, as it is the primary site for the metabolism and synthesis of various biochemical compounds, including amino acids.

Question 2

Chylomicrons are aggregates of triglycerides, phosphoglycerides, and cholesterol complexed with proteins.

Accepted Answer

Chylomicrons are lipoprotein particles that consist of triglycerides, phospholipids, cholesterol, and proteins, which transport dietary lipids from the intestines to other locations in the body.

Question 3

Nutritionists suggest that a healthy diet be low in fats and high in carbohydrates.

Accepted Answer

Nutritionists recommend a balanced diet that includes a moderate amount of healthy fats and emphasizes complex carbohydrates (like whole grains and vegetables) over simple carbohydrates (like sugar and white flour). The focus is on nutrient-dense foods rather than strictly categorizing foods as high or low in specific macronutrients.

Question 4

If there is an excessive intake of fatty acids and\or carbohydrates, the energy is stored as triglycerides for later use.

Accepted Answer

Excessive intake of fatty acids and carbohydrates leads to the storage of excess energy as triglycerides in adipose tissue for later use, as the body converts excess calories into fat for energy storage.

Question 5

Consider the diagram of a mitochondrion shown below.  Which of the numbered locations is where β -oxidation occurs?

Accepted Answer

The answer of Consider the diagram of a mitochondrion shown...

Question 6

Consider the simplified diagram of the urea cycle shown below. Which species, numbered 1 through 4, is synthesized in the mitochondria?

Accepted Answer

The answer of Consider the simplified diagram of the urea...

Question 7

Glycogen that is required by brain tissue leaves the liver and is transported to the brain by means of large blood vessels used specifically for this purpose.

Accepted Answer

Glycogen is not directly transported to the brain. Instead, the liver breaks down glycogen into glucose, which is then released into the bloodstream and transported to the brain and other tissues.

Question 8

The processes of fatty acid degradation and fatty acid synthesis are the chemical reverse of each other and respond to stress as predicted by Le Châtelier's principle.

Accepted Answer

Although fatty acid degradation and synthesis involve similar substrates and products, they occur through different pathways and mechanisms. Fatty acid degradation (beta-oxidation) takes place in the mitochondria, while fatty acid synthesis occurs in the cytosol and involves a different set of enzymes. The regulation of these processes is complex and does not simply respond to stress based on Le Châtelier's principle, which applies to chemical equilibria, not to enzyme-catalyzed metabolic pathways.

Question 9

Amino acids that the body does not synthesize are termed nonessential.

Accepted Answer

Amino acids that the body cannot synthesize and must be obtained from the diet are termed essential amino acids. Nonessential amino acids are those that the body can synthesize.

Question 10

Glycerol that is liberated from fats is digested by passing through glycolysis.

Accepted Answer

Glycerol is a byproduct of fat digestion and is converted into glucose through glycolysis.

Question 11

Some amino acids are synthesized from α -keto acids.

Accepted Answer

Amino acids can be synthesized through transamination reactions where α-keto acids serve as precursors, with the amino group being transferred from another amino acid, typically glutamate, to the α-keto acid, forming a new amino acid.

Question 12

Given the chance, a few long exercise periods will burn off more fat than will many short periods.

Accepted Answer

Longer exercise periods allow for a greater energy expenditure, leading to more fat burn.

Question 13

If an individual does not have a sufficient level of insulin in the blood, the uptake of glucose by the cells is inhibited.

Accepted Answer

Insulin is a hormone that facilitates the uptake of glucose by the cells. Without sufficient insulin, cells cannot effectively take in glucose from the blood, leading to elevated blood glucose levels.

Question 14

Phenylalanine is derived from tyrosine by oxidation.

Accepted Answer

Phenylalanine is converted into tyrosine, not the other way around. This process is a hydroxylation reaction, where phenylalanine is hydroxylated to form tyrosine.

Question 15

The synthesis of amino acids and the intake of amino acids are both important in order to replace cells lost from cellular death caused by either old age of the cells or disease.

Accepted Answer

The body requires amino acids for various functions including the synthesis of new proteins, which are essential for replacing cells lost due to cellular death from old age or disease. Some amino acids can be synthesized by the body, while others must be obtained from the diet.

Question 16

Phenenylketonuria (PKU)is a genetic disorder where an individual is unable to produce the enzyme phenylalanine hydroxylase.  This results in the inability of the body to convert phenylalanine to what substance?

Accepted Answer

Phenylalanine hydroxylase is responsible for converting phenylalanine into tyrosine. In individuals with Phenylketonuria (PKU), this conversion is impaired, leading to a buildup of phenylalanine and a deficiency in tyrosine.

Question 17

Fatty acid chains are built up of uneven numbers of carbons, but are degraded in carbon pairs.

Accepted Answer

Fatty acid chains can be made up of both even and odd numbers of carbons, but they are typically degraded two carbons at a time through the process of beta-oxidation.

Question 18

The body can prepare asparagine from aspartic acid.

Accepted Answer

The body can convert aspartic acid into asparagine through a process called amination, where an amine group is added to aspartic acid, forming asparagine.

Question 19

The liver is the most important site for the biosynthesis of fatty acids and triglycerides.

Accepted Answer

The liver is a central organ for lipid metabolism, including the biosynthesis of fatty acids and triglycerides, which are crucial for energy storage and cell structure.

Question 20

Consider the simplified diagram of the urea cycle shown below.  What is the identity of the species numbered with a 3?

Accepted Answer