MCAT Boss Practice Problems - Biology and Biochemistry Section 3

Practice problems from section 3 of the Biology and Biochemistry on the MCAT!

Welcome to a deep dive into the MCAT Bio/Biochem section! In this video, I provide a comprehensive walkthrough of 27 practice questions covering the AAMC's Foundational Concept 3. This concept is all about how complex organ systems work together to sense the environment, maintain homeostasis, and keep the body in a stable, healthy equilibrium.

We'll break down everything from the nervous and endocrine systems to the nitty-gritty details of the circulatory, immune, and excretory systems. Let's get into it!

-MCAT Concepts Covered in This Set

-Nervous System (Q1, Q2, Q15, Q16, Q27):
We'll cover the action potential, neuromuscular junctions, saltatory conduction, the functions of different brain regions like the cerebellum, and the distinction between the somatic and autonomic nervous systems.
-Endocrine System (Q3, Q4, Q11, Q17, Q25):
This set hits hard on hormone function, comparing peptide and steroid hormones, explaining negative feedback loops (e.g., cortisol), and detailing the hormones involved in reproduction (FSH, LH) and calcium regulation (PTH).
Circulatory & Respiratory Systems (Q5, Q6, Q7, Q19, Q20):
We'll explore the Bohr effect for oxygen delivery, the cardiac cycle (systole/diastole), blood typing (ABO system), the mechanics of breathing (diaphragm contraction), and how baroreceptors regulate blood pressure.
Immune & Lymphatic Systems (Q8, Q18, Q24):
Learn the primary functions of the lymphatic system, the critical process of clonal selection, and the role of helper T cells (CD4+) as the "master regulators" of the adaptive immune response.
Digestive System (Q9, Q23):
Review the sources and functions of key digestive enzymes like trypsin and understand the essential role of bile in fat emulsification.
Excretory System (Q10, Q21):
These questions focus on the nephron, covering where the filtrate is most concentrated and the specific action of Antidiuretic Hormone (ADH) on the collecting duct to regulate water reabsorption.

*Musculoskeletal System (Q12, Q13, Q22):
A close look at the sliding filament model, including the role of ATP in myosin head detachment, the function of osteoclasts in bone resorption, and the definition of a sarcomere.
Integumentary (Skin) System (Q14):
We'll discuss how keratin provides the skin with its water-resistant barrier.
Cellular Signaling (Q26):
This question breaks down the initial activation steps of G protein-coupled receptors (GPCRs), a high-yield topic in cell communication.

About This Video

This MCAT practice session is designed to give you a review of Foundational Concept 3: Complex systems of tissues and organs sense the internal and external environments of multicellular organisms and, through integrated functioning, maintain a stable internal environment. By working through 27 standalone MCAT-inspired questions, you'll sharpen your ability to connect physiological processes and understand how different organ systems are integrated.

This video is perfect for students who want to test their knowledge of human physiology and endocrinology, identify weak spots, and learn how to approach complex, multi-system questions. No medical advice.

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