What plants need to grow well
Biology · Key Stage 1 · The School
The water highway
Water goes in through root hairs, up tiny tubes in the stem, and out of the leaves as vapour. That escape at the top is what PULLS the next drop up — like sucking through a straw, but powered by evaporation. Put a white flower in coloured water overnight and the petals show you the route in colour.
Leaves are food factories
Leaves are flat and wide to catch as much light as possible, and green because of chlorophyll, the substance that captures light energy. Using light, water and a gas from the air, a leaf builds sugar. Plants make their own food — animals cannot, which is why every food chain starts with a plant.
Recording properly
Measure the same way each time: same ruler, same day of the week, from soil to tip. Put results in a table with units in the heading (Height in cm), then draw a line graph. A table you can read a month later is worth more than a careful experiment you cannot remember the results of.
Put a white carnation or a stick of celery into a glass of water with red food colouring. Come back after a few hours: red streaks are visible in the petals or in the celery's stringy tubes. Cut across the stem and you can see the coloured tubes. Nothing pumped it — the leaves lost water to the air and pulled the rest up behind it. Cut the leaves off and the colour stops rising.