Biochemistry - Module 12 2026 Ratio

C. The activated G proteins would remain locked in the "on" position, transmitting signal even in the absence of signaling molecule

The cholera toxin does not allow GTP to be hydrolyzed to GDP. What effects would you expect to see in the cell?

A. The inactivation of G-protein linked signaling pathways

B. All of the cAMP would be used up

C. The activated G proteins would remain locked in the "on" position, transmitting signal even in the absence of signaling molecule

D. The inactivation of ligand-gated ion channels

B. Insulin

Glycolysis, glycogenesis and lipogenesis are stimulated by this hormone:

A. Cortisol

B. Insulin

C. Glucagon

D. Epinephrine

B. Tyrosine

The thyroid hormone thyroxine (T4) is derived from which amino acid?

A. Threonine

B. Tyrosine

C. Thiamine

D. Tryptophan

C. Insulin

Of the following hormones, which one is an essential requirement for triacyglycerol synthesis in the adipose tissue?

A. Thyroxine

B. Cortisol

C. Insulin

D. Glucagon

C. They stimulate adenylate cyclase upon binding the ligand

Signal transduction occurs when a ligand binds to a cell surface receptor. Which of the following is TRUE of the G-protein coupled receptors?

A. They cause opening of the calcium channel when bound to the ligand

B. They must produce a second messenger upon binding the ligand

C. They stimulate adenylate cyclase upon binding the ligand

D. They dimerize when bound to a ligand

A. It inhibits the conversion of cyclic GMP to GMP

Sildenafil (Viagra) is a drug used to treat erectile dysfunction.Which of the following is its mechanism of action?

A. It inhibits the conversion of cyclic GMP to GMP

B. It inhibits the conversion of cyclic AMP to AMP

C. It activates guanylate cyclase

D. It increases the rate of synthesis of cyclic GMP

B. Activation of a stimulatory G protein

A 12-yr-old boy went to the beach with his family and ate clams and oysters for dinner, but shortly thereafter developed severe diarrhea, vomiting and leg cramps. The molecular basis of his disorder is which of the following?

A. Inhibition of a stimulatory G protein

B. Activation of a stimulatory G protein

C. Activation of an inhibitory G protein

D. Inhibition of an inhibitory G protein

C. inhibition of NF-κB

Glucocorticoids are very useful agents for the treatment of many inflammatory and immune disease partly due to which of the following mechanisms?

A. inhibition of Gi PR

B. stimulation of protein kinase C

C. inhibition of NF-κB

D. stimulation of NF-κB

D. They enhance transcription when bound to receptors

Which of the following statements accurately describes sex hormones such as estrogen?

A. They inhibit translation through specific cytoplasmic proteins

B. They bind specific membrane receptors

C. They interact with DNA directly

D. They enhance transcription when bound to receptors

A. Terminates the signal

The GTPase activity is crucial to the proper functioning of the cell because it:

A. Terminates the signal

B. Amplifies the signal

C. Propagates the signal

D. Signifies the presence of a receptor

A. Bind to cell-surface receptors, which transmit signal to the interior of the cell

Hydrophilic hormones are best described by which of the following statements? They

A. Bind to cell-surface receptors, which transmit signal to the interior of the cell

B. Bind to G proteins in the cell membrane

C. Include thyroid and steroid hormones

D. Enter the cell, bind to intracellular receptors, the complex of which alter gene expression

B. breaks down into nitric oxide, which increases blood flow to the heart.

Isosorbide dinitrate is effective in treating chest pains because it

A. mimics the action of signal receptors

B. breaks down into nitric oxide, which increases blood flow to the heart.

C. interferes with chemical cascades that trigger contraction of heart muscle

D. is broken down into hormones that affect the heart

B. Its ability to interact with a specific receptor

Each hormone’s organ specificity is determined by:

A. Whether it is lipophilic or lipophobic

B. Its ability to interact with a specific receptor

C. Whether it is a corticosteroid or a gonadotropic hormone

D. The signaling cascade it initiates

C. Amplification

Number of affected molecules increases geometrically in an enzyme cascade. This is:

A. Integration

B. Adaptation

C. Amplification

D. Specificity

D. Ketogenesis

The liver is a central player in metabolism.Which of the following is the liver’s most important function during prolonged starvation?

A. Glycogenolysis

B. Gluconeogenesis

C. Proteolysis

D. Ketogenesis

A. Lipids

After glycogen has been used up in the postabsorptive state, which of the following is usually used as the next source of energy?

A. Lipids

B. Glucose

C. Proteins

D. amino acids

C. hypoxia-inducible factor 1α

Most cancers have exceptional capacity for generation of ATP because of the presence of which of the following:

A. interleukin 6

B. tumor necrosis factor alpha

C. hypoxia-inducible factor 1α

D. interleukin I

D. Muscle wasting occurs because of excessive protein breakdown

Which of the following occurs during stress and injury?

A. Catecholamines are inhibited because insulin receptors are down-regulated

B. Hypothermia is a hallmark because of the release of cytokines

C. There is hypoglycemia because glucose is utilized for lipogenesis

D. Muscle wasting occurs because of excessive protein breakdown

C. Osmotic imbalance due to increased glucose levels in the urine

The polyuria that occurs in type 1 diabetics is due to which one of the following?

A. Insulin stimulation of urea production

B. Osmotic imbalance due to elevated ketones in the blood

C. Osmotic imbalance due to increased glucose levels in the urine

D. Insulin stimulation of glucose reabsorption in the kidney

A. Gluconeogenesis

After 30 hours of fasting,which of the following is most important for the maintenance of normal blood glucose levels?

A. Gluconeogenesis

B. Triacylglycerol synthesis

C. Increased insulin release

D. Glycogenolysis

A. increased free fatty acids in the circulation

Which of the following is the biochemical abnormality seen in patients with insulin resistance?

A. increased free fatty acids in the circulation

B. excessive vasodilatation

C. Inhibition of insulin release from the pancreas

D. decreased glucose release from the liver

B. Low insulin/glucagon ratio activates lipolysis in adipocytes.

Which of the following statements about the integration of fat and carbohydrate metabolism control is correct?

A. Insulin-dependent glucose transporters are recruited to their functional membrane site when insulin levels are low

B. Low insulin/glucagon ratio activates lipolysis in adipocytes.

C. High insulin/glucagon ratio inhibits lipogenesis in liver.

D. High insulin/glucagon ratio activates lipolysis in muscle

A. activation of CPT I (B. increased glucagon/Insulin)

Accelerated ketogenesis occurs in which situation?

A. activation of CPT I

B. increased glucagon/Insulin

C. activation of acetyl CoA carboxylase

D. increased malonyl CoA

A. Adiponectin

The only known adipocyte secreting factor that increases tissue sensitivity to insulin:

A. Adiponectin

B. interleukin 6

C. tumor necrosis factor alpha

D. interleukin I

C. Plasma glucose is maintained by gluconeogenesis and ketogenesis.

Which one of following statements occurs during prolonged fasting?

A. There is an increase in metabolic rate in the fasting state.

B. The muscle can take up glucose for use as a metabolic fuel because glucose transport in muscle is stimulated in response to glucagon.

C. Plasma glucose is maintained by gluconeogenesis and ketogenesis.

D. There is decreased secretion of glucagon in response to increased glucose in the portal blood.

D. The liver is always in gluconeogenic and ketogenic state because the insulin/glucagon ratio cannot increase.

Which of the following biochemical reactions is occurring in an uncontrolled type 1 diabetic patient?

A. Ketoacidosis develops due to accumulation of fatty acids in the kidneys

B. There is increased protein synthesis in the muscle because of increased GLUT 4 activity.

C. The insulin production from the pancreas is not enough to meet the demands of the peripheral tissues.

D. The liver is always in gluconeogenic and ketogenic state because the insulin/glucagon ratio cannot increase.

A. The main metabolic fuel for most tissues comes from fatty acids released from adipose tissue.

Which of the following statements is TRUE during fasting?

A. The main metabolic fuel for most tissues comes from fatty acids released from adipose tissue.

B. Fatty acids and triacylglycerol are synthesized in the liver

C. Plasma glucose is maintained by gluconeogenesis in adipose tissue from the glycerol released from triacylglycerol.

D. The main fuel for the central nervous system is fatty acids released from adipose tissue

B. Methionine (D. Lysine)

The following amino acids are both glucogenic and ketogenic, EXCEPT, which one?

A. Phenylalanine

B. Methionine

C. Isoleucine

D. Lysine

D. Pyruvate

The end product of glycolysis in the liver and kidneys is:

A. Glycerol

B. Lactate

C. Oxaloacetate

D. Pyruvate