Biology - Neurons, Hormones, and Circulation - MCAT Practice Questions

What is the term for plasmids that integrate into the bacterial host genome?

A. Virions
B. Prophages
C. Episomes
D. Lysogens

In which bacteriophage life cycle is the viral DNA embedded into the host DNA, allowing the virus to remain dormant?

A. Lytic
B. Lysogenic
C. Productive
D. Endosomal

The ovaries, the primary female reproductive organs, are controlled by which pair of hormones released by the anterior pituitary?

A. GnRH and Progesterone
B. Estrogen and Prolactin
C. ACTH and TSH
D. FSH and LH

Gonadotropin-Releasing Hormone (GnRH) is produced by the:

A. Anterior pituitary
B. Adrenal cortex
C. Hypothalamus
D. Posterior pituitary

After production in the hypothalamus, GnRH is released and travels to which gland for the secretion of FSH and LH?

A. Posterior pituitary
B. Adrenal medulla
C. Thyroid
D. Anterior pituitary

During the repolarization phase of an action potential, K⁺ ions primarily leave the cell through which two types of channels?

A. Na⁺ leak channels and voltage-gated Na⁺ channels
B. Cl⁻ channels and Na⁺/K⁺ pump
C. Voltage-gated K⁺ channels and K⁺ leak channels
D. Voltage-gated Ca²⁺ channels and K⁺ leak channels

The negative resting potential of a cell membrane is primarily maintained because there are:

A. Fewer K⁺ leak channels than Na⁺ leak channels.
B. Equal numbers of K⁺ and Na⁺ leak channels.
C. Na⁺/K⁺ pumps that move only K⁺ out of the cell.
D. More K⁺ leak channels than Na⁺ leak channels.

A synapse where there is a direct physical connection (gap junctions) between the presynaptic and postsynaptic neurons is called a/an:

A. Chemical synapse
B. Neuromuscular junction
C. Electrical synapse
D. Axo-axonic synapse

The somatic nervous system is associated with the control of skeletal muscles, making its control over body movements:

A. Autonomic
B. Involuntary
C. Reflexive
D. Voluntary

Aldosterone, a hormone that acts on the kidney, increases the reabsorption of which ion, leading to increased blood osmolarity and ultimately raising blood pressure?

A. Potassium (K⁺)
B. Calcium (Ca²⁺)
C. Chloride (Cl⁻)
D. Sodium (Na⁺)

Antidiuretic Hormone (ADH), or vasopressin, primarily functions to:

A. Decrease blood pressure by increasing urine output.
B. Decrease heart rate and cardiac output.
C. Increase blood pressure by increasing water reabsorption.
D. Increase glomerular filtration rate (GFR).

Where are red blood cells (erythrocytes) primarily formed in a healthy adult?

A. Spleen
B. Liver
C. Lymph nodes
D. Bone marrow

The primary function of red blood cells is to:

A. Phagocytize foreign material.
B. Initiate the clotting cascade.
C. Carry oxygen.
D. Produce antibodies.

Which blood cell type has no nucleus, mitochondria, or organelles at maturity, allowing it to maximize its capacity for oxygen transport?

A. Platelets
B. White blood cells (Leukocytes)
C. Red blood cells (Erythrocytes)
D. Lymphocytes

Leukocytes (white blood cells) are divided into two main groups based on the appearance of their cytoplasm under a microscope. These groups are:

A. Monocytes and Lymphocytes
B. T-cells and B-cells
C. Granulocytes and Agranulocytes
D. Phagocytes and Immunocytes

Each of the four polypeptide chains in a hemoglobin molecule is combined with a heme group that contains an atom of which element?

A. Calcium
B. Copper
C. Magnesium
D. Iron

The hemoglobin dissociation curve is described as having what shape, reflecting the cooperative binding of oxygen?

A. Hyperbolic
B. Parabolic
C. Linear
D. Sigmoidal

Fetal hemoglobin (HbF) has a higher affinity for oxygen compared to adult hemoglobin, which results in:

A. A higher P₅₀ value.
B. A shift of the dissociation curve to the right.
C. A lower P₅₀ value.
D. More susceptibility to the effects of 2,3-BPG.

Myoglobin is a protein found in muscle tissue that stores oxygen. Unlike hemoglobin, myoglobin contains how many heme groups?

A. Four
B. Two
C. One
D. Eight

What is the shape of the myoglobin dissociation curve?

A. Sigmoidal
B. Hyperbolic
C. Linear
D. Bell-shaped

Which molecule displays endogenous antigen (antigen from inside the cell, like from a viral infection) to cytotoxic CD8⁺ T-cells?

A. MHC-II
B. Toll-like receptors (TLR)
C. TCR (T-cell receptor)
D. MHC-I

The highly specific part of an antibody that directly binds to a specific antigen is located at the:

A. Fc region (constant region)
B. Heavy chain constant region
C. Tip of the variable region
D. Disulfide bond linkage

Activated B cells mature into which type of cell that is responsible for actively secreting large amounts of antibodies?

A. Macrophages
B. Memory B cells
C. Suppressor B cells
D. Plasma cells

The blood pathway requires the passage of blood from the right atrium to the right ventricle through the:

A. Pulmonary valve
B. Aortic valve
C. Mitral valve
D. Tricuspid valve

The liver performs many metabolic and detoxification functions, including the conversion of the highly toxic waste product NH₃ to the less toxic compound:

A. Creatinine
B. Bilirubin
C. Glucose
D. Urea