Some useful websites to help with your understanding:

Molecular Biology Web Book
Great Cell Biology Website!!
Lots of information and worksheets for most Unit 3 and 4 Biology topics
Biology Colouring worksheets
Additional Biology Class notes
Science quizzes for revision
Podcasts and Videos
Khan Academy
Biology Oracle (Douchy Biology)
Bozeman Biology
For Biology, Chemistry and Physics
Educator Vids (Biology/Chemistry/Physics/Maths)
Interactive Biology
Savage's Science Tutorials
YouTube Search: mahalodotcom - Learn Biology

YouTube videos:

Chapter 1: Introducing Biomacromolecules
Chemical Bonds: Covalent or Ionic?
Polar and Non-Polar Covalent Bonds
Dissociation of salt
Dissolving Salt
The Basics of Biology (Cell Biology - 12 mini-videos)
Basic Cell Biology video and explanation
Basic Molecular Biology
Water Molecules (Part 1) Water Molecules (Part 2)
Properties of Water, Acids and Bases (Part 1) Properties of Water, Acids and Bases (Part 2)
Water: A Polar Molecule

Chapter 2: Membranes and Cell Organelles
Apoptosis: Cell Death
Apoptosis animation
Apoptosis under the microscope
Cell Membrane Composition and Structure
Active and Passive Transport
The Plasma Membrane
Endocytosis and Exocytosis
Tour of a Cell
Cell Organelles and Their Functions
Mitochondria ATP Synthesis
Cell Biochemistry (12 mini-videos on protein synthesis and ATP Synthesis)
Ribosome and Endoplasmic Reticulum
Endoplasmic Reticulum and Golgi Apparatus
Cytoskeleton (1) Cytoskeleton (2)
Communication between cells
Differences between Plant and Animal Cell

Chapter 3: Biochemical processes in Cells
Enzymes and their substrates
Cellular Metabolism, Enzymes
Enzyme Action, Induced-fit model
Lock and Key Theory of Enzyme Action
Enzyme Catalysis
Photosynthesis lesson on You Tube
The Photosynthesis Song
Photosynthesis Rap
Images of photosynthesis process
You Tube video of the Process of Photosynthesis
Photosynthesis - in depth
Light Reaction in Photosynthesis
Calvin Cycle or Dark Reactions
The Process of Photosynthesis (5 mini videos)
Introduction to Cellular Respiration
Video of Respiration
Celluar Respiration song (more complex than we need!)
In depth video of Glycolysis
Krebs Cycle
Krebs Cycle song
Cellular Respiration (original) song
Cellular Respiration Rap
Cell Respiration (no sound but good explanations)
Cellular Respiration (From video 4 onwards)

Chapter 4: Molecular Biology in Medicine
18 things to know about genetics (simple intro to genes)
General Molecular Genetics (57 mini videos....)
Beginner's Guide to Molecular Biology
Gene Technology (Part 1 of 6) Gene Technology (Part 2 of 6) Gene Technology (Part 3 of 6) Gene Technology (Part 4 of 6) Gene Technology (Part 5 of 6) Gene Technology (Part 6 of 6)
Gene Therapy

Chapter 5: Coordination and Regulation: Endocrine Systems
The Endocrine System (49 mini videos)
Positive and Negative Feedback
Intro to cell communication
Cell Signalling Pathways (Part 1) Cell Signalling Pathways (Part 2)
Plant Hormones (1 of 3) Plant Hormones (2 of 3) Plant Hormones (3 of 3)

Chapter 6: Coordination and Regulation: Nervous Systems
Animal Nervous System
Divisions of the Nervous System
Brains and Things Related (25 videos)
Introduction to Neurons
The Release of Neurotransmitters
Central Nervous System
Peripheral Nervous System
The Human Nervous System (Part 1) The Human Nervous System (Part 2)
Pinky and the Brain - Parts of the Brain song

Chapter 7: Infection and Disease and Chapter 8: Immunity: Defence Against Disease
Pathogens (1 of 4) Pathogens (2 of 4) Pathogens (3 of 4) Pathogens (4 of 4)
Overview of Immune System
Cells of the Immune System
Cells and Organs of the Immune System
Immune Response - Toll Like Receptors
Antibody Immune Response (22 videos)
The Process of Phagocytosis
Blood Types: ABO and Rhesus
Immunology (75 videos)

Worksheets and other stuff

Revision Questions

Chapter 1: The Chemical Nature of Cells
Organic Compounds Concept Map

Organic Macromolecules Slideshow
Organic Macromolecule Worksheet
Biochemistry Worksheet (with answers)

Chapter 2: Membranes and Cell Organelles
Images of Cells
Cell Structures and Functions
Cell Membrane Functions
Organelles Worksheet (with answers)
Cell Structure and Functions Webpage (Worksheets, revision, powerpoints)

Distance Education Unit 3 Notes