BIO101 – Topic 24: Cell Transport Mechanisms and
Their Importance
Course Code: BIO 101
Course Name: General Biology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism-Free | A4 Format)
24.1 Introduction
Cells constantly exchange substances with their environment to maintain homeostasis. This
exchange of materials such as nutrients, gases, and waste occurs through the cell membrane in a
process called cell transport.
24.2 Definition of Cell Transport
Cell transport is the biological process that enables the movement of substances across the cell
membrane, either into or out of the cell. It maintains homeostasis and supports cellular functions.
24.3 The Cell Membrane and Its Role
The cell membrane is semi-permeable and regulates the movement of substances. It is composed
of phospholipids and proteins (fluid mosaic model) and maintains the cell’s internal environment.
24.4 Types of Cell Transport
1. Passive Transport – Movement without energy (ATP).
2. Active Transport – Movement against the concentration gradient using energy (ATP).
24.5 Passive Transport
Movement from high to low concentration without using energy.
Types:
1. Diffusion – Movement of molecules like oxygen and CO■.
2. Osmosis – Movement of water molecules across a semi-permeable membrane.
3. Facilitated Diffusion – Movement through carrier or channel proteins.
24.6 Active Transport
Movement of molecules from low to high concentration using ATP.
Examples:
Their Importance
Course Code: BIO 101
Course Name: General Biology
© Lesuyai Organic Guides 2025
(Original | Educational | Professional | Plagiarism-Free | A4 Format)
24.1 Introduction
Cells constantly exchange substances with their environment to maintain homeostasis. This
exchange of materials such as nutrients, gases, and waste occurs through the cell membrane in a
process called cell transport.
24.2 Definition of Cell Transport
Cell transport is the biological process that enables the movement of substances across the cell
membrane, either into or out of the cell. It maintains homeostasis and supports cellular functions.
24.3 The Cell Membrane and Its Role
The cell membrane is semi-permeable and regulates the movement of substances. It is composed
of phospholipids and proteins (fluid mosaic model) and maintains the cell’s internal environment.
24.4 Types of Cell Transport
1. Passive Transport – Movement without energy (ATP).
2. Active Transport – Movement against the concentration gradient using energy (ATP).
24.5 Passive Transport
Movement from high to low concentration without using energy.
Types:
1. Diffusion – Movement of molecules like oxygen and CO■.
2. Osmosis – Movement of water molecules across a semi-permeable membrane.
3. Facilitated Diffusion – Movement through carrier or channel proteins.
24.6 Active Transport
Movement of molecules from low to high concentration using ATP.
Examples:
