MCAT Biology Practice 2025 Latest
Exam set with Questions and simplified
Answers that are correct
Glucose typically enters the cell through which mechanism?
A. Simple diffusion through the cell membrane
B. Facilitated diffusion through a carrier protein
C. Pinocytosis through a channel protein
D. Active transport by a glucose transport protein - correct answer-Facilitated diffusion through a carrier
protein
Glucose is too large and polar to move quickly through the cell membrane by simple diffusion.
Typically the concentration of glucose outside the cell is higher than inside the cell.
Since glucose is moving down a concentration gradient by entering the cell, the process does not require
ATP.
Glucose typically enters cells by facilitated diffusion through a carrier protein.
Which type of membrane protein is most likely to be a hormone?
A. Lipid-bound protein
B. Peripheral protein
C. Integral protein
D. Steroid - correct answer-Peripheral protein
Hormones move through the circulatory system, acting as signaling molecules to specific organs/cells.
A steroid is not a membrane protein.
,An integral protein can not easily leave the cell membrane and would therefore be a poor signaling
molecule.
Lipid-bound proteins remain within the phospholipid bilayer by the fatty acid tails of phospholipids. They
would also be poor signaling molecules.
Peptide hormones like insulin and growth hormone interact with integral protein receptors in cell
membranes. These hormones can be considered peripheral membrane proteins.
Pulmonary edema occurs when fluid builds up in the interstitium between the pulmonary capillaries and
the alveoli, and eventually enters the alveoli. How do you decrease the risk of pulmonary edema?
A. Decrease hydrostatic pressure and increase osmotic pressure
B. Decrease hydrostatic pressure and decrease osmotic pressure
C. Increase hydrostatic pressure and decrease osmotic pressure
D. Increase hydrostatic pressure and increase osmotic pressure - correct answer-Decrease hydrostatic
pressure and increase osmotic pressure
Hydrostatic pressure is the pressure a liquid exerts on its container, and reflects the volume of liquid in a
space.
Osmotic pressure is the pressure required to prevent movement across a semipermeable membrane,
and reflects the protein content of the blood.
To decrease the risk of pulmonary edema, hydrostatic pressure exerted by the fluid must decrease, and
osmotic pressure exerted on the fluid must increase.
At what point does crossing over between sister chromatids occur?
A. During anaphase I of meiosis
B. During prophase I of meiosis
C. During anaphase II of meiosis
D. During prophase II of meiosis - correct answer-During prophase I of meiosis
, Crossing over is a form of genetic recombination in which homologous chromosomes pair up and
exchange pieces of their genetic material. Crossing over occurs in prophase I of meiosis, and is often
referred to as synapsis. However, crossing over occurs between homologous chromosomes, and not
between the sister chromatids of an individual chromosome. Sister chromatids are identical pieces of
DNA joined at the centromere to make up one chromosome.
Your trachea have short hair-like cell process that move the mucus. What is the name of these hair like
structures and which cytoskeletal elements form them?
A. Cilia, microfilaments
B. Villi, microfilaments
C. Villi, microtubules
D. Cilia, microtubules - correct answer-Cilia, microtubules
Villi are macroscopic foldings of tissue
Microvilli are foldings of the cell membrane that increase the surface area of cell but are not responsible
for movement
Cilia are eyelash like structures derived from microtubules, they are responsible for creating motion
outside the cell.
An organic molecule has been isolated from the nucleus of a human cell. Nuclear magnetic resonance
studies reveal the core structure of the molecule to be a six-membered ring containing carbon and
nitrogen. The ring also expresses an amine group and a keto group, and is attached to a five carbon sugar
moiety. No phosphate groups are noted. What is the most likely identity of the molecule?
A. Cytosine
B. Guanosine
C. Guanine
D. Cytidine - correct answer-Cytidine
First, realize that this question is asking you to identify a likely molecular component of the nucleus,
DNA. DNA is largely made up of the nucleobases Adenine, Guanine, Cytosine, and Thymine.
Exam set with Questions and simplified
Answers that are correct
Glucose typically enters the cell through which mechanism?
A. Simple diffusion through the cell membrane
B. Facilitated diffusion through a carrier protein
C. Pinocytosis through a channel protein
D. Active transport by a glucose transport protein - correct answer-Facilitated diffusion through a carrier
protein
Glucose is too large and polar to move quickly through the cell membrane by simple diffusion.
Typically the concentration of glucose outside the cell is higher than inside the cell.
Since glucose is moving down a concentration gradient by entering the cell, the process does not require
ATP.
Glucose typically enters cells by facilitated diffusion through a carrier protein.
Which type of membrane protein is most likely to be a hormone?
A. Lipid-bound protein
B. Peripheral protein
C. Integral protein
D. Steroid - correct answer-Peripheral protein
Hormones move through the circulatory system, acting as signaling molecules to specific organs/cells.
A steroid is not a membrane protein.
,An integral protein can not easily leave the cell membrane and would therefore be a poor signaling
molecule.
Lipid-bound proteins remain within the phospholipid bilayer by the fatty acid tails of phospholipids. They
would also be poor signaling molecules.
Peptide hormones like insulin and growth hormone interact with integral protein receptors in cell
membranes. These hormones can be considered peripheral membrane proteins.
Pulmonary edema occurs when fluid builds up in the interstitium between the pulmonary capillaries and
the alveoli, and eventually enters the alveoli. How do you decrease the risk of pulmonary edema?
A. Decrease hydrostatic pressure and increase osmotic pressure
B. Decrease hydrostatic pressure and decrease osmotic pressure
C. Increase hydrostatic pressure and decrease osmotic pressure
D. Increase hydrostatic pressure and increase osmotic pressure - correct answer-Decrease hydrostatic
pressure and increase osmotic pressure
Hydrostatic pressure is the pressure a liquid exerts on its container, and reflects the volume of liquid in a
space.
Osmotic pressure is the pressure required to prevent movement across a semipermeable membrane,
and reflects the protein content of the blood.
To decrease the risk of pulmonary edema, hydrostatic pressure exerted by the fluid must decrease, and
osmotic pressure exerted on the fluid must increase.
At what point does crossing over between sister chromatids occur?
A. During anaphase I of meiosis
B. During prophase I of meiosis
C. During anaphase II of meiosis
D. During prophase II of meiosis - correct answer-During prophase I of meiosis
, Crossing over is a form of genetic recombination in which homologous chromosomes pair up and
exchange pieces of their genetic material. Crossing over occurs in prophase I of meiosis, and is often
referred to as synapsis. However, crossing over occurs between homologous chromosomes, and not
between the sister chromatids of an individual chromosome. Sister chromatids are identical pieces of
DNA joined at the centromere to make up one chromosome.
Your trachea have short hair-like cell process that move the mucus. What is the name of these hair like
structures and which cytoskeletal elements form them?
A. Cilia, microfilaments
B. Villi, microfilaments
C. Villi, microtubules
D. Cilia, microtubules - correct answer-Cilia, microtubules
Villi are macroscopic foldings of tissue
Microvilli are foldings of the cell membrane that increase the surface area of cell but are not responsible
for movement
Cilia are eyelash like structures derived from microtubules, they are responsible for creating motion
outside the cell.
An organic molecule has been isolated from the nucleus of a human cell. Nuclear magnetic resonance
studies reveal the core structure of the molecule to be a six-membered ring containing carbon and
nitrogen. The ring also expresses an amine group and a keto group, and is attached to a five carbon sugar
moiety. No phosphate groups are noted. What is the most likely identity of the molecule?
A. Cytosine
B. Guanosine
C. Guanine
D. Cytidine - correct answer-Cytidine
First, realize that this question is asking you to identify a likely molecular component of the nucleus,
DNA. DNA is largely made up of the nucleobases Adenine, Guanine, Cytosine, and Thymine.
