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SavannahYear 8
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ScienceGCSE biology: cells, organisation and bioenergetics30 min★★★ difficulty

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
  • 16 parts to scroll through
  • 4 quick checks
  • Marked quiz at the end
  • Gentle pace: short sittings with pauses

Words to know

structuretransportenzymeactionbioenergetics

Scroll down — the lesson carries on below

Part 1 of 16 · Discover6%
1

Watch & discover

Part 1 of 16

Watch first

Cells, microscopy and transport

An English teaching video on this topic from Cognito. Watch it, then scroll down for the lesson.

In a nutshell

Explain cell structure, transport, enzyme action and bioenergetics at GCSE standard.

2

Learning cycle

Part 2 of 16

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.

3

Explore the idea

Part 3 of 16

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.

4

Explore the idea

Part 4 of 16

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.

5

Quick check

Part 5 of 16

Quick check

Prokaryotic cells differ from eukaryotic cells because they

6

Quick check

Part 6 of 16

Quick check

Real size equals

7

Reset break

Part 7 of 16

Pause

That's sitting 1 of 2 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.

Stop here for now
8

Learning cycle

Part 8 of 16

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.

9

Explore the idea

Part 9 of 16

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.

10

Quick check

Part 10 of 16

Quick check

Osmosis is the movement of

11

Quick check

Part 11 of 16

Quick check

Active transport requires energy because it moves substances

12

Explore the idea

Part 12 of 16

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.

13

Challenge round

Part 13 of 16

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

14

Challenge round

Part 14 of 16

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.

15

Mastery quiz

Part 15 of 16

Marked quiz

End of lesson quiz: Cells, microscopy and transport

4 questions, marked with the reasoning shown. No timer.

  1. 1. Prokaryotic cells differ from eukaryotic cells because they

  2. 2. Real size equals

  3. 3. Osmosis is the movement of

  4. 4. Active transport requires energy because it moves substances

16

Lesson round-up

Part 16 of 16

Lesson round-up

Ready when you are

Quiz score

Not sat

Games

Not played

Points this lesson

0

Best run

0 in a row

Luna: 0 out of 4 on the practice checks. Only if you feel up to it — one more?

Ask Luna

Do the work

Your written work for this lesson

This is the part you'd do in your book at school. Pick the pieces below, write here or on paper, and photograph anything you draw or work out.

Case study

Why the school greenhouse failed

A science club grew tomato plants in the school greenhouse. In June the plants grew well: leaves were dark green and the fruit set quickly. In July the club went away for two weeks and left the greenhouse door shut. When they came back, the leaves were curled and pale and most of the fruit had dropped.

The club had a data logger inside. It showed the temperature reached 46 °C on several afternoons and the soil moisture fell close to zero. The club knew photosynthesis needs light, water and carbon dioxide, and that enzymes in a plant work best in a narrow range of temperature. Above that range the enzymes stop working properly.

The club repeated the summer with the door propped open and a water bottle drip on each pot. Temperature peaked at 31 °C and the plants survived.

Written for Good Learning Co.

Reading questions

  1. Name the variable the club changed the second time, and one variable they kept the same.
  2. Explain, using the words photosynthesis and enzymes, why the plants were damaged in July.
  3. Write a conclusion for the club's report, saying how far the evidence supports it.

  • Method and results

    Writing

    Write the aim, what you changed, what you measured and what you kept the same, then record your results in a table.

    1 page + results table

  • Conclusion

    Writing

    Explain what your results show and why, using the scientific words from the lesson. Say how you know you can trust them.

    6–8 sentences

  • Labelled diagram

    Diagram

    Draw the apparatus or the process in pencil, label it fully, and photograph it.

    1 labelled diagram

  • Reading and notes

    Reading

    Read the lesson text again and write the key ideas in your own words.

    Half a page of notes

Saved as you type.

Part 1 of 16 · Watch & discover

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