New
New
Year 11
Edexcel
Higher

Observing the structure and distribution of stomata: practical

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

New
New
Year 11
Edexcel
Higher

Observing the structure and distribution of stomata: practical

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

Lesson details

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.

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.

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

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.
Teacher tip

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 (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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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

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