Question 1

Which of the following types of proteins provides physical support to tissues?
A) receptors
B) structural proteins
C) immunoglobulins
D) transport proteins
E) dietary proteins

Accepted Answer

Structural proteins, such as collagen and elastin, provide physical support to tissues by forming a framework for cells to attach and form tissues. Receptors, immunoglobulins, and transport proteins have different functions in the body, while dietary proteins refer to the source of protein rather than their function.

Question 2

Which of the following is NOT one of the four categories of biomolecules?
A) proteins
B) vitamins
C) lipids
D) carbohydrates
E) nucleic acids

Accepted Answer

The four categories of biomolecules are proteins, lipids, carbohydrates, and nucleic acids. Vitamins are not a category of biomolecules but rather organic compounds that are essential nutrients for various functions in the body.

Question 3

An amino acid zwitterion has
A) a net positive charge.
B) a net negative charge.
C) a net neutral charge.
D) any non-neutral charge.
E) Zwitterions can have any charge.

Accepted Answer

A zwitterion has both a positive charge and a negative charge, but they cancel out each other, resulting in a net neutral charge.

Question 4

In which of the following structures is the box ONLY around the amino acid side chain? 
A)a
B)b
C)c
D)d
E)e

Accepted Answer

The answer of In which of the following structures is...

Question 5

Physiological pH is a pH of approximately
A) 5.7.
B) 7.3.
C) 8.1.
D) 9.1.
E) 0.

Accepted Answer

Physiological pH refers to the pH at which most biological systems operate optimally, which is around 7.3-7.4. Therefore, the correct choice is B.

Question 6

Which type of protein signals cellular events?
A) receptors
B) structural proteins
C) immunoglobulins
D) transport proteins
E) dietary proteins

Accepted Answer

Receptors are proteins that bind to specific signaling molecules and trigger cellular responses. Examples include receptors for hormones or neurotransmitters. Structural proteins provide support, immunoglobulins are involved in the immune response, transport proteins move molecules across membranes, and dietary proteins provide amino acids for protein synthesis but do not necessarily signal cellular events.

Question 7

What percentage of amino acids in sickle cell hemoglobin is different from normal hemoglobin?
A) 100%
B) 50%
C) 25%
D) 10%
E) <1%

Accepted Answer

Sickle-cell hemoglobin differs from normal hemoglobin due to a single amino acid substitution out of the total 146 amino acids in the beta chain, which is less than 1% difference.

Question 8

Which of the following structures illustrates how an amino acid reacts in a low pH solution? 
A) 
B)
C)
D)
E)All of these reactions occur to the same extent in a solution with a pH less than 7 .

Accepted Answer

Option B shows the amino acid in a low pH solution where the amino group (-NH2) is protonated and becomes NH3+. This results in the overall charge of the amino acid becoming positive, making it polar and water-soluble. This is called the protonated form of the amino acid. The other options do not show this protonation of the amino group and therefore do not represent an amino acid in a low pH solution. Option E is incorrect because the other options do not represent the same reaction occurring to the same extent.

Question 9

Which of the following choices are the best labels for this amino acid? 
A)a
B)b
C)c
D)d
E)e

Accepted Answer

The answer of Which of the following choices are the...

Question 10

How many naturally occurring amino acids are there?
A) 1
B) 5
C) 10
D) 20
E) hundreds

Accepted Answer

There are 20 naturally occurring amino acids, which are the building blocks of proteins. These include 9 essential amino acids that cannot be produced by the human body and must be obtained through diet.

Question 11

Which of the following choices is NOT a problem associated with sickle-cell anemia?
A) People with sickle-cell anemia are prone to severe headaches.
B) People with sickle-cell anemia are prone to episodes of infection.
C) Organs can be damaged because of sickled red blood cells.
D) Sickle-cell anemia can cause anemia.
E) The sickle cells can aggregate and clog blood vessels.

Accepted Answer

While people with sickle-cell anemia may experience pain, headache is not a common symptom or problem associated with the condition.

Question 12

At low pH, the amino acid zwitterion reacts with hydronium (H₃O⁺). What is the product of this acid-base reaction? A)a B)b C)c D)d E)e

Accepted Answer

The answer of At low pH, the amino acid zwitterion...

Question 13

Which of the following structures illustrates an amino acid at physiological pH? 
A)a
B)b
C)c
D)d
E)e

Accepted Answer

At physiological pH (around 7.4), the amino group (-NH2) on the amino acid will be protonated (+NH3+) and the carboxyl group (-COOH) will be deprotonated (-COO-). Option B shows an amino acid with a protonated amino group and a deprotonated carboxyl group, making it the correct choice.

Question 14

Hemoglobin is an example of this type of protein.
A) receptors
B) structural proteins
C) immunoglobulins
D) transport proteins
E) dietary proteins

Accepted Answer

Hemoglobin is a transport protein that carries oxygen from the lungs to the body's tissues and carbon dioxide from the tissues back to the lungs for removal.

Question 15

Which of the following structures illustrates an amino acid in a solution with a high pH? 
A)a
B)b
C)c
D)d
E)e

Accepted Answer

The answer of Which of the following structures illustrates an...

Question 16

Which of the following structures illustrates an amino acid as a zwitterion? 
A)a
B)b
C)c
D)d
E)e

Accepted Answer

The answer of Which of the following structures illustrates an...

Question 17

Which type of protein can be used for energy when necessary?
A) receptors
B) structural proteins
C) immunoglobulins
D) transport proteins
E) dietary proteins

Accepted Answer

Dietary proteins can be broken down and used for energy when necessary, through a process called gluconeogenesis. Receptors, structural proteins, immunoglobulins, and transport proteins have other specialized functions in the body and are not typically used for energy.

Question 18

Which of the following biomolecules has the most diverse functions in the body?
A) carbohydrates
B) proteins
C) nucleic acids
D) lipids
E) These have equally diverse functions.

Accepted Answer

Proteins have the most diverse functions in the body, as they are involved in enzymatic reactions, structural support, cell signaling, transport, muscle contraction, and immune function, among others. While the other biomolecules also have important functions, they are not as versatile as proteins.

Question 19

Sickle-cell anemia is caused by
A) an abnormal form of acetylcholine.
B) an abnormal form of iron.
C) too little iron.
D) an abnormal form of hemoglobin.
E) Actually, the cause of this disease is unknown.

Accepted Answer

Sickle-cell anemia is caused by an abnormal form of hemoglobin, specifically hemoglobin S. This results in the production of sickle-shaped red blood cells, which can block blood flow and cause a range of health complications.

Question 20

Which of the following types of proteins defend the body against infectious agents?
A) receptors
B) structural proteins
C) immunoglobulins
D) transport proteins
E) dietary proteins

Accepted Answer

Immunoglobulins, also known as antibodies, are proteins produced by B cells in response to an infectious agent. They recognize and bind to specific antigens on the surface of the infectious agent, marking it for destruction by other immune cells. This is a key role in defending the body against infectious agents. Receptors, structural proteins, transport proteins, and dietary proteins do not have a primary function in defending the body against infectious agents.

Quiz 13: Proteins: Structure and Function

Which of the following types of proteins provides physical support to tissues?

Which of the following is NOT one of the four categories of biomolecules?

An amino acid zwitterion has

In which of the following structures is the box ONLY around the amino acid side chain?

Physiological pH is a pH of approximately

Which type of protein signals cellular events?

What percentage of amino acids in sickle cell hemoglobin is different from normal hemoglobin?

Which of the following structures illustrates how an amino acid reacts in a low pH solution?

Which of the following choices are the best labels for this amino acid?

How many naturally occurring amino acids are there?

Which of the following choices is NOT a problem associated with sickle-cell anemia?

At low pH, the amino acid zwitterion reacts with hydronium (H₃O⁺) . What is the product of this acid-base reaction?

Which of the following structures illustrates an amino acid at physiological pH?

Hemoglobin is an example of this type of protein.

Which of the following structures illustrates an amino acid in a solution with a high pH?

Which of the following structures illustrates an amino acid as a zwitterion?

Which type of protein can be used for energy when necessary?

Which of the following biomolecules has the most diverse functions in the body?

Sickle-cell anemia is caused by

Which of the following types of proteins defend the body against infectious agents?