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Diffusion

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eMusic Study Pack • Biology
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📖 Comprehensive Note

Diffusion is the passive movement of molecules or ions from a region of higher concentration to lower concentration until equilibrium is reached. It does not require energy. Simple diffusion happens directly through the membrane or medium (e.g., O2, CO2), while facilitated diffusion uses carrier or channel proteins to help larger or polar molecules (e.g., glucose, amino acids) cross membranes down their gradient.

Key points: direction = high → low, passive (no ATP), simple vs. facilitated depends on membrane permeability and protein assistance.

🎤 Lyrics + Audio

Verse 1 Simple diffusion occurs when molecules move directly across a membrane or through a medium uh! from a region of high concentration to low concentration. Oxygen in, carbon out — that’s respiration’s route! Chorus Diffusion is the movement of molecules or ions from a region of higher concentration to a region of lower concentration ha ha hauh until they are evenly distributed, without the use of energy. ye eeee...! Verse 2 Facilitated diffusion occurs with the help of carrier proteins or channel proteins in a cell membrane. hmmmmhmmm It still moves from high to low concentration but needs protein assistance. Glucose and amino glide with care — carrier proteins take them there! Diffusion is the movement of molecules or ions from a region of higher concentration to a region of lower concentration ha ha hauh until they are evenly distributed, without the use of energy. ye eeee...!
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📊 Line-by-Line Study Guide

Lyric LineExplanation
Simple diffusion — molecules move directlySmall nonpolar molecules (O2, CO2) cross the lipid bilayer unaided.
From high to low concentrationThe concentration gradient is the driving force; net movement continues until equilibrium.
Oxygen in, carbon outGas exchange in respiration relies on diffusion across membranes (alveoli, cell membranes).
Facilitated diffusion uses proteinsChannel proteins (pores) or carrier proteins undergo conformational change to move molecules like glucose across membranes.
No energy requiredBoth simple and facilitated diffusion are passive processes — movement down the gradient without ATP.

💡 Mnemonic

"DIFFUSE = DOWN" — remember diffusion moves down the concentration gradient; FACILITATE = PROTEIN (needs protein help).

❓ Quiz

1. Simple diffusion requires:

2. Facilitated diffusion differs because it:

3. Direction of diffusion:

4. Which molecule commonly uses simple diffusion?

5. Energy (ATP) is required?

🃏 Flashcards

Q1: Define diffusion.
Passive movement of molecules from high to low concentration until equilibrium.
Q2: What is facilitated diffusion?
Passive transport using carrier/channel proteins for molecules that cannot cross the lipid bilayer directly.
Q3: Example of simple diffusion in organisms?
Gas exchange: O2 and CO2 across alveolar and cell membranes.
Q4: Do facilitated and simple diffusion use ATP?
No — both are passive and do not use cellular energy.

🎯 Drag & Drop

Drag items into the matching category box.

Simple Diffusion
Facilitated Diffusion
General
Oxygen movement
Channel/carrier proteins
High → Low concentration
Glucose transport
No ATP required

📌 Summary

  • Diffusion = passive movement from high → low concentration until equilibrium.
  • Simple diffusion: direct across membrane/medium (gases, small nonpolar molecules).
  • Facilitated diffusion: needs channel/carrier proteins for larger or polar molecules (glucose, ions); still passive.
  • Neither process consumes ATP; both are driven by concentration gradients.