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Ch. 3 The Cellular Level of Organization
Martini - Fundamentals of Anatomy and Physiology 12th Edition
Martini, Nath, Bartholomew12th EditionFundamentals of Anatomy and PhysiologyISBN: 9780137854011Not the one you use?Change textbook
All textbooksMartini, Nath, Bartholomew 12th EditionCh. 3 The Cellular Level of OrganizationProblem 3
Chapter 3, Problem 3

Plasma membranes are said to be
(a) Impermeable
(b) Freely permeable
(c) Selectively permeable
(d) Actively permeable
(e) Slightly permeable

Verified step by step guidance
1
Understand the concept of permeability in the context of plasma membranes. Permeability refers to the ability of substances to pass through the membrane.
Recall that plasma membranes control the movement of substances in and out of the cell, allowing some molecules to pass while restricting others.
Recognize that 'impermeable' means no substances can pass through, which is not true for plasma membranes since they allow selective passage.
Note that 'freely permeable' means all substances can pass without restriction, which is also incorrect for plasma membranes.
Conclude that plasma membranes are best described as 'selectively permeable' because they regulate the entry and exit of specific molecules based on size, charge, and solubility.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Plasma Membrane Structure

The plasma membrane is a biological barrier composed mainly of a phospholipid bilayer with embedded proteins. This structure provides fluidity and flexibility, allowing it to control the movement of substances in and out of the cell.
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Biological Membranes

Selective Permeability

Selective permeability refers to the plasma membrane's ability to allow certain molecules or ions to pass through while blocking others. This property is essential for maintaining cellular homeostasis by regulating nutrient intake and waste removal.
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Clonal Selection

Transport Mechanisms Across Membranes

Transport across the plasma membrane occurs via passive methods like diffusion and osmosis, or active methods requiring energy. These mechanisms enable the cell to control internal conditions by selectively moving substances based on size, charge, and concentration.
Recommended video:
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Introduction to Membrane Transport
Related Practice
Textbook Question

____ ion concentration is high in extracellular fluids, and____ion concentration is high in the cytoplasm.

(a) Calcium; magnesium

(b) Chloride; sodium

(c) Potassium; sodium

(d) Sodium; potassium

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Textbook Question

At resting membrane potential, the cytoplasmic side of the membrane surface of the cell is___, and the cell extracellular membrane surface is___.

(a) slightly negative; slightly positive

(b) slightly positive; slightly negative

(c) slightly positive; neutral

(d) slightly negative; neutral

Textbook Question

In the following diagram, identify the type of solution (hypertonic, hypotonic, or isotonic) in which the red blood cells are immersed.

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Textbook Question

The organelle responsible for a variety of functions centering on the synthesis of lipids and carbohydrates is

(a) The Golgi apparatus

(b) The rough endoplasmic reticulum

(c) The smooth endoplasmic reticulum

(d) Mitochondria

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Textbook Question

The process that transports solid objects such as bacteria into the cell is called

(a) Pinocytosis

(b) Phagocytosis

(c) Exocytosis

(d) Receptor-mediated endocytosis

(e) Channel-mediated transport

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