Every card in Cells and organisation, Year 7: microscopes and photosynthesis
The whole deck, in order — so you can read it through before your child ever sees it.
← Back to Cells and organisation, Year 7: microscopes and photosynthesis
- When you first look at a slide under a light microscope, which objective lens should you start with?
The lowest-power lens
HintPick the one that gives the widest view, so the specimen is easy to find.
WhyLow magnification shows a wide area and is easy to focus. Once the specimen is centred and sharp, you switch up to a higher magnification to see detail.
- Which knob on a light microscope do you turn first to bring a specimen roughly into view?
The coarse focus knob
HintIt moves the stage in big steps; the other one is only for sharpening.
WhyThe coarse knob makes large movements to find the image on low power. The fine knob then makes tiny adjustments to sharpen it.
- Why is a stain such as iodine or methylene blue added to cells before they are viewed under a microscope?
It makes the cell parts easier to see
HintThink about what an unstained specimen looks like against a bright light.
WhyLight passes straight through unstained cells, so there is little contrast. A stain is taken up more strongly by some parts, such as the nucleus, which then stand out.
- A pupil looking at onion cells adds green chloroplasts to the drawing because 'plant cells have them'. Which rule of microscope drawing has been broken?
Draw only what you actually see
HintOnion bulbs grow underground, so their cells are not green.
WhyA scientific drawing is a record of an observation, not a copy of a textbook diagram. Onion bulb cells have no chloroplasts, so none should appear.
- Under a microscope, a cell has a clear box-like outline and a large central space filled with sap. Is it a plant cell or an animal cell?
A plant cell
HintThink about which kind has a rigid wall and a permanent vacuole.
WhyThe box-like outline is the cell wall and the central space is the vacuole. Animal cells have neither, so they look rounder and less regular.
- Photosynthesis: carbon dioxide + water → ____ + oxygen
glucose
HintThe name of one particular sugar, beginning with 'gl'.
WhyThe plant builds this sugar from two simple raw materials, using energy from light. Oxygen is the other product.
- Which gas do plants take in from the air to make food by photosynthesis?
Carbon dioxide
HintYou breathe out more of this gas than you breathe in.
WhyIt enters the leaf through tiny pores and is one of the two raw materials. The other, water, comes up from the roots.
- Which gas is released by a plant as a product of photosynthesis?
Oxygen
HintAnimals need this gas for respiration.
WhyIt is made alongside glucose and leaves through the pores of the leaf. Almost all the oxygen in the air was made this way.
- Where does the energy for photosynthesis come from?
Light
HintA plant kept in a dark cupboard cannot do it.
WhyLight is absorbed by the green chlorophyll in the leaf and is used to join carbon dioxide and water into glucose.
- A tree gains hundreds of kilograms as it grows. Does most of that new material come from the soil, or from the air and water?
From the air and water
HintLook at the left-hand side of the word equation for photosynthesis.
WhyThe glucose a plant builds its body from is made out of carbon dioxide and water. Only a small amount of minerals comes from the soil.
1★ KS3-BIOL-CEL-0013
2★ KS3-BIOL-CEL-0014
3★ KS3-BIOL-CEL-0015
4★ KS3-BIOL-CEL-0016
5★ KS3-BIOL-CEL-0017
6★ KS3-BIOL-CEL-0018
7★ KS3-BIOL-CEL-0019
8★ KS3-BIOL-CEL-0020
9★ KS3-BIOL-CEL-0021
10★ KS3-BIOL-CEL-0022
Keep what you learn
Here, nothing is saved. In your child’s own sky every card is scheduled — it comes back just before they’d forget it — and the professor who wrote it is one tap away.