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      Observing the structure and distribution of stomata: practical

      Lesson details

      Learning outcome

      I can use a light microscope to observe imprints of stomata and investigate their distribution on leaves.

      Key learning points

      1. The parts of a light microscope and their functions.
      2. The sequence of steps for setting up a microscope to observe specimens, including changing the magnification and focus.
      3. The steps of applying nail varnish and clear sticky tape to a leaf surface, then observing imprints of stomata.
      4. Light microscopy can be used to observe and compare the density and distribution of stomata on different leaf surfaces.
      5. Explaining observations of stomatal density using ideas about transpiration and water loss.

      Keywords

      • Light microscope - an instrument that uses visible light and lenses to magnify a viewed specimen

      • Lens - a glass or plastic disc that refracts light to increase magnification

      • Focus - to make an image sharper and clearer

      • Magnification - the number of times greater in size the viewed object is compared to its actual size

      • Stomata - pores in the leaf through which water, oxygen and carbon dioxide can diffuse

      Common misconception

      Thinking that plants have stomata in equal numbers on every surface of their leaves.

      Through practical work and data analysis, pupils explore the distribution of stomata on the top and bottom surfaces of leaves.

      Teacher tip

      The first learning cycle can be omitted if pupils are already secure in their knowledge of how to set up and use a light microscope to view a specimen on a slide. The third learning cycle could be taught while pupils wait for nail varnish to dry on their leaves.

      Equipment

      light microscope, leaf, nail varnish and brush, clear sticky tape, microscope slide

      Content guidance

      Risk assessment required - equipment

      Supervision

      Adult supervision required

      Licence

      This content is © Oak National Academy Limited (2026), licensed on Open Government Licence version 3.0
      except where otherwise stated. See Oak's terms & conditions
      (Collection 2).

      Lesson video

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      Prior knowledge starter quiz

      6 Questions

      Q1.
      Which process occurs in the chloroplasts of plant cells?

      Correct Answer: photosynthesis

      Q2.
      A light is used to magnify small objects in the lab.

      Correct Answer: microscope

      Q3.
      Which part of the plant cell is responsible for water loss regulation?

      chloroplast
      mitochondria
      nucleus
      Correct answer: stomata

      Q4.
      What is transpiration in plants?

      the process of nitrogen fixation
      the process of photosynthesis
      the process of respiration
      Correct answer: the process of water loss through stomata

      Q5.
      Why is it important for stomata to be able to open and close?

      to absorb nutrients
      to produce food
      Correct answer: to regulate gas exchange and water loss
      to transport water

      Q6.
      Which gas is released by plants during photosynthesis?

      Correct Answer: oxygen, O2

      6 Questions

      Q1.
      What does the term 'magnification' mean in microscopy?

      the brightness of the light source
      the clarity of the image
      Correct answer: how many times larger the viewed object is than its actual size
      the size of the lens

      Q2.
      What is the purpose of using nail varnish in the stomata experiment?

      to colour the leaf
      Correct answer: to create an imprint of the stomata
      to make the leaf waterproof
      to protect the leaf

      Q3.
      Where are stomata more commonly found on a leaf?

      equally on both surfaces
      on the edges
      Correct answer: on the lower surface
      on the upper surface

      Q4.
      How does stomatal density relate to a plant's environment?

      Correct answer: Plants in dry environments have fewer stomata to conserve water.
      Plants in dry environments have more stomata for increased gas exchange.
      Stomatal density is higher in humid environments.
      Stomatal density is the same regardless of environment.

      Q5.
      Calculate the stomatal density if 20 stomata are found in an area of 0.1 mm².

      2000 stomata per mm²
      Correct answer: 200 stomata per mm²
      20 stomata per mm²
      2 stomata per mm²

      Q6.
      If a plant has a stomatal density of 100 stomata per mm² and the leaf area is 10 mm², how many stomata are on the leaf?

      Correct Answer: 1000

      To help you plan your 11 biology lesson on: Observing the structure and distribution of stomata: practical, download all teaching resources for free and adapt to suit your pupils' needs...