Cells, microscopy and transport
Everything a body does happens in cells. Structure explains function, and three transport processes explain how substances get in and out.
Lesson overview
What you'll learn in this lesson
Explain cell structure, transport, enzyme action and bioenergetics at GCSE standard.
Key learning points
- • Cell types and structures
- • Microscopy and magnification
- • Diffusion, osmosis and active transport
This lesson at a glance
- 30 minutes
- 20 parts to scroll through
- 4 quick checks
- Marked quiz at the end
- Gentle pace: short sittings with pauses
Words to know
Scroll down — the lesson carries on below
Watch & discover
Part 1 of 20
Visual introductionPicture this
Cells, microscopy and transport
Everything a body does happens in cells. Structure explains function, and three transport processes explain how substances get in and out.
In a nutshell
Explain cell structure, transport, enzyme action and bioenergetics at GCSE standard.
Learning cycle
Part 2 of 20
Learning cycle 1 of 2
Part 1 · Cell types and structures
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 3 of 20
Learn
Cell types and structures
Eukaryotic cells have a nucleus containing DNA; prokaryotic cells such as bacteria have DNA free in the cytoplasm plus plasmids, and are much smaller. Plant cells add a cellulose cell wall, permanent vacuole and chloroplasts. Specialised cells, such as sperm, root hair and nerve cells, show structure matched to function.
Reset break
Part 4 of 20
Pause
That's sitting 1 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Explore the idea
Part 5 of 20
Learn
Microscopy and magnification
Magnification = image size ÷ real size, so real size = image ÷ magnification. Electron microscopes have far higher resolution than light microscopes, revealing sub-cellular structures such as ribosomes. Convert all measurements into the same unit before calculating: 1 mm = 1,000 µm.
Quick check
Part 6 of 20
Quick check
Part 7 of 20
Reset break
Part 8 of 20
Pause
That's sitting 2 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Learning cycle
Part 9 of 20
Learning cycle 2 of 2
Part 2 · Diffusion, osmosis and active transport
A short piece of teaching, then a check to make sure it has landed.
Explore the idea
Part 10 of 20
Learn
Diffusion, osmosis and active transport
Diffusion moves particles down a concentration gradient, passively. Osmosis is the movement of water across a partially permeable membrane from dilute to concentrated solution. Active transport moves substances against the gradient and therefore requires energy from respiration, which is why root hair cells are packed with mitochondria.
Quick check
Part 11 of 20
Reset break
Part 12 of 20
Pause
That's sitting 3 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Quick check
Part 13 of 20
Explore the idea
Part 14 of 20
Worked example
Worked answer: potato pieces in concentrated sugar solution lose mass. Explain (3 marks)
The solution outside the cells is more concentrated, so it has a lower water potential than the cell contents (1). Water moves out of the cells by osmosis, across the partially permeable cell membrane, down the water potential gradient (1). Losing water reduces the mass of each potato piece and makes the cells flaccid (1). Saying 'sugar moves in' is incorrect: sugar molecules are too large to cross freely.
Challenge round
Part 15 of 20
Game · Sort it
Which of these are true?
Drag each card into the right column. Tap a card first if dragging is fiddly.
True
Not true
Reset break
Part 16 of 20
Pause
That's sitting 4 of 5 done
Stretch, get a drink, look out of the window. There is no timer and nothing is counting down — your place is saved, so you can come back in five minutes or tomorrow.
Challenge round
Part 17 of 20
Game · Fill the gaps
Finish the sentences
Choose the word that belongs in each gap.
Specialised cells, such as sperm, root hair and nerve cells, show ____ matched to function.
Active ____ moves substances against the gradient and therefore requires energy from respiration, which is why root hair cells are packed with mitochondria.
Challenge round
Part 18 of 20
Game · Recall cards
Prokaryotic cells differ from eukaryotic cells because they
Card 1 of 4
Mastery quiz
Part 19 of 20
Marked quiz
End of lesson quiz: Cells, microscopy and transport
4 questions, marked with the reasoning shown. No timer.
1. Prokaryotic cells differ from eukaryotic cells because they
2. Real size equals
3. Osmosis is the movement of
4. Active transport requires energy because it moves substances
Lesson round-up
Part 20 of 20
Lesson round-up
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