Looking for MCAT biology practice questions and answers? You have come to the right place! Your MCAT test prep must involve more than review of biology content. You must be able to apply your MCAT biology knowledge in practice questions and tests. Since biology is such a huge part of MCAT prep, we recommend doing as many practice quizzes and tests as possible. Now, let’s get to some MCAT biology sample passages, questions, and expert analysis!

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Article Contents
6 min read

MCAT Biology Practice Passage 1 MCAT Biology Practice Passage 2 MCAT Biology Practice Passage 3 FAQs

MCAT Biology Practice Passage 1:

In the human body, immunity can be acquired in either an active or passive fashion. An example of immunity being acquired actively would be when a microorganism (an antigen) enters the human body and begins to spread throughout the body. The body responds to this threat by producing antibodies as well as activating lymphocyte populations which work together to eliminate the threat. Memory lymphocytes are produced by this exposure that will re-engage with the antigen should the microorganism attack again in the future.

In contrast, an example of immunity being acquired passively would be when an individual receives pre-formed antibodies from another individual. An example of this would be IgG antibodies that are transferred from a mother to a fetus via the placenta. Additionally, IgA and IgG antibodies are often transferred from a mother to child when the child is breast fed.

Immunity can be acquired either naturally or artificially. An example of immunity being acquired naturally would be if an individual were to become sick with measles. The body will produce antibodies against this disease allowing for the individual to have acquired their immunity naturally. Alternatively, individuals can acquire immunity from measles artificially by undergoing vaccination. The body will produce antibodies in response to the vaccination, allowing the individual to have artificially acquired active immunity against this disease. Vaccinations allow for the acquisition of artificially acquired active immunity as they contain microorganisms (antigen) that are considered dead or attenuated (weakened) which allow for the body to create a memory response that can be engaged should the individual be infected later in their lifetime.


Question 1: Which of the following answers is most likely? A neonate is kissed by their father who is contagious with rubella. Why does the child remain healthy?

A.     The child quickly made antibodies in response to the viral infection.

B.     The father provided antibodies to the child by kissing the child. These antibodies then eliminated the virus.

C.     Maternal antibodies provided immunity to the virus.

D.    The child had formed antibodies to this condition prior to birth.

Question 2: If a neonate is orphaned at birth, which of the following would provide the child with the most antibodies?

I.       Vaccinate the child immediately to all childhood diseases. 

II.     Feed the child breast milk from another nursing mother.

III.   Seclude the child in a sterile hospital unit.

A.     I only

B.     II and III only

C.     II only

D.    I and III only

E.     I, II and III 

Question 3: An adult received pre-formed antibodies that were isolated from the serum of an immune individual. What type of acquired immunity is this?

A.     Artificially acquired passive immunity

B.     Artificially acquired active immunity

C.     Naturally acquired passive immunity

D.    Naturally acquired active immunity

Question 4: Which of the following antibodies is produced first following a primary infection with a microorganism? 

A.     IgD

B.     IgA

C.     IgM

D.    IgG

MCAT Biology Practice Passage 2:

Approximately 20% of the human body is comprised of protein of animal origin and because of this our bodies require multiple safety mechanisms to avoid the digestion of our own tissue. One of these well-known safety mechanisms are mucopolysaccharides (a core component of mucus) which line the epithelial tissue of the digestive tract. Mucus cannot be digested which allows for it to protect the tissues from digestive acids and enzymes. Additionally, the pancreas houses proteolytic enzymes in their inactive form (zymogens) which spares the pancreatic cells from being digested.

One safety mechanism that can be found in the GI tract is the rapid turnover of cells. Specifically, the endothelial lining of the GI tract is replaced every 5-7 days which allows for the maintenance of a protective barrier between the digestive acids and enzymes of the GI tract and the rest of the body’s tissues.

A final safety mechanism that can be found in the digestive tract is bicarbonate that is released by the pancreas. While the stomach is primarily responsible for acidifying a bolus of food so that it can be broken down, the pancreas will release bicarbonate after this breakdown in order to neutralize the pH of the duodenum.


Question 1: What is the approximate pH of the stomach?

A.     9.3

B.     2.1

C.     0.4

D.    6.9

Question 2: Chemotherapy works by targeting rapidly proliferating cells. While this therapy may be beneficial for ridding the body of cancer, it can also affect other cell populations within the body. Which of the following cell populations would be most adversely affected by a chemotherapy regimen?

A.     Cardiomyocytes

B.     Neurons

C.     Gastric Epithelia

D.    Skeletal myocytes

Question 3: Which parts of the digestive tract are lined with mucus?

I.     Mouth

II.     Duodenum

III. Colon

A.     I only

B.     I and II only

C.     II and III only

D.    I, II, and III

Question 4: Which class of molecules do mucopolysaccharides belong to?

A.     Nucleic acids

B.     Lipids

C.     Proteins

D.    Carbohydrates 

Want to learn how to ace the MCAT with a 528 score? Check out our video:

MCAT Biology Practice Passage 3:

Circulatory shock is essentially when there is not enough blood flowing through the circulatory system to meet the oxygen demands of the body’s tissues. If this shock is not remedied quickly it can lead to the death of the patient.

One type of circulatory shock is hypovolemic shock which occurs when the body’s blood volume is too low. This low amount of blood volume results in a decrease of the patient’s blood pressure and an overall decrease in the patient’s cardiac output. The body’s arterial blood pressure is proportional to blood flow, therefore, if the patient is in hypovolemic shock there will be an inadequate amount of blood flow to the body’s organs and tissues.

In the human body, baroreceptors can sense a drop in a person’s blood pressure. When baroreceptors sense this drop, these receptors will stimulate the sympathetic nervous system which will help correct the patient’s low blood pressure in hypovolemic shock. Specifically, the sympathetic nervous system will enable a cascade of events to occur which will cause vasoconstriction of the arterioles allowing for an increase in the patient’s blood pressure.

To calculate a patient’s blood pressure, one can use the equation below:


Blood pressure (BP) is related to the patient’s cardiac output (CO) and total peripheral resistance (TPR). It is important to note that resistance to blood flow is inversely proportional to the radius of the blood vessel raised to the fourth power. Cardia output is equivalent to the heart rate times the stroke volume of the ventricles of the heart.


Question 1: Which of the following would most likely result in hypovolemic shock?

A.     Heart failure

B.     Severe hemorrhaging

C.     Sepsis

D.    Amyotrophic Lateral Sclerosis (ALS) 

Question 2: Which of the following responses represents a likely physiological compensation for the body being in hypovolemic shock?

A.     Increased heart rate

B.     Decreased stroke volume

C.     Dilation of the arterioles leading to the dermis

D.    Increase parasympathetic output

Question 3: In patients with hypovolemic shock, the production of ADH and Aldosterone is increased. What are these hormones primarily responsible for?

A.     Inhibiting sympathetic output

B.     Inhibiting parasympathetic output

C.     Increasing blood pressure

D.    Decreasing salt reabsorption 

Question 4: Which of the following treatments would be most effective in treating hypovolemic shock?

A.     Administer a diuretic to the patient

B.     Administer an antibiotic to the patient

C.     Administer a transfusion of blood plasma to the patient

D.    Administer an acetylcholine antagonist to the patient 


1. How much biology is on the MCAT?

If added up, biology makes up about 75% of the content covered on the MCAT.

2. What kind of biology knowledge is tested on the exam?

MCAT tests content usually covered in introductory science classes and medical school prerequisites that are offered in most universities in the US and Canada.

3. What are the best MCAT study strategies I can implement?

Firstly, you must be comfortable with the content covered in the exam. The first phase of your MCAT study schedule should include active study strategies to help you absorb the necessary knowledge. Once you are comfortable with the content, use sample passages and questions, quizzes, and full-length tests to apply your knowledge.

4. How long is the test?

The test lasts for 7.5 hours, including breaks.

5. How much time do I have for each MCAT section?

You have 95 minutes for 3 of the 4 sections: BBLS, CPBS, and PSBB. For CARS, you only have 90 minutes.

6. Who can help me prepare for the MCAT?

You can always join an MCAT prep course or hire an MCAT tutor. Not only can they help you with studying biology, but they can also help you prepare for the test format and length.

7. Are there going to be graphs present in MCAT biology questions?

You have to learn how to read MCAT graphs because they can be implemented in the BBLS, CPBS, and PSBB sections of the test.

8. What’s the hardest section of the MCAT?

Many consider MCAT CARS the hardest because it’s impossible to prepare for using content review. However, by designing a great MCAT CARS strategy, you can tackle this section without a problem.

To your success,

Your friends at BeMo

BeMo Academic Consulting

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