Practice Test Review: Chapters 1–4

1. Metabolism

Metabolism refers to all chemical reactions occurring within the body. These reactions are essential for maintaining life and are broadly categorized into two types: catabolism and anabolism.

• Definition: Metabolism encompasses both catabolism (breaking down molecules to release energy) and anabolism (building up molecules, requiring energy).

• Key Point: Every physiological process in the body depends on metabolic reactions.

• Example: Digestion (catabolic) and protein synthesis (anabolic).

2. Feedback Mechanisms

Feedback mechanisms regulate physiological processes to maintain homeostasis. There are two main types: positive and negative feedback.

• Positive Feedback: Enhances and amplifies the initial stimulus, leading to an even greater response.

• Negative Feedback: Works to reverse a change and restore balance (homeostasis).

• Comparison: Unlike negative feedback, which stabilizes systems, positive feedback intensifies the original change.

• Example: Blood clotting (positive feedback); body temperature regulation (negative feedback).

3. Serous Membranes: Visceral Serosa

Serous membranes line body cavities and cover organs. The visceral serosa is a specific layer of these membranes.

• Visceral Serosa: Covers the outer surfaces of organs within body cavities.

• Parietal Serosa: Lines the cavity walls (not directly mentioned but important for context).

• Function: Reduces friction between organs and cavity walls.

• Example: The visceral pericardium covers the heart.

4. Covalent Bond Polarity

Covalent bonds involve the sharing of electrons between atoms. The polarity of a covalent bond depends on how equally the electrons are shared.

• Electron Distribution: Uneven sharing of electrons due to differences in electronegativity leads to a polar bond.

• Nonpolar Bond: Even sharing of electrons results in a nonpolar bond.

• Key Term: Electronegativity is the ability of an atom to attract electrons in a bond.

• Example: Water (H2O) has polar covalent bonds; O2 (oxygen gas) has nonpolar covalent bonds.

5. Synthesis Reactions

Synthesis reactions are fundamental chemical processes in which new chemical bonds are formed, resulting in the creation of larger, more complex molecules from smaller ones.

• Key Event: Chemical bonds form during synthesis reactions.

• General Equation:

• Example: Formation of proteins from amino acids.

• Application: Synthesis reactions are essential for growth, repair, and maintenance in living organisms.