P6 Photosynthesis (Concept Map)
Primary 6 Science — Concept Map
Created by Miss Clarissa Ng · www.clartutors.com
Photosynthesis
plants make their own food using light energy from the Sun
needs
Light energytrapped by chlorophyll
CO₂ Carbon dioxideenters via stomata
H₂O Waterabsorbed by roots
produces
Sugar (food)excess → starch
O₂ Oxygenreleased via stomata
Stored as starchexcess sugar is turned into starch and stored in roots, stems and fruits
rate affected by
Light intensity↑ then plateaus
Chlorophyllthe green pigment in the chloroplasts that traps light energy — in the leaves, and in the stem of a cactus
CO₂ amount↑ then plateaus
Temperature↑ to 30 °C, then ↓
trapping the light
Chlorophyllthe green pigment in the chloroplasts that traps light energy — in the leaves, and in the stem of a cactus
Coloured leavesgreen, red and purple parts contain chlorophyll; yellow and white parts do not, so they cannot photosynthesise
how animals get energy
No chlorophyllanimals cannot make their own food, so they eat food for the energy their life processes need
Three groupsherbivores eat only plants · carnivores eat only animals · omnivores eat both
testing for it
Destarch firstleave the plant in the dark for at least 48 hours so no starch is present at the start
Starch testiodine solution (yellowish-brown) turns dark blue where starch is present
Other waysa data logger in a closed system, or an indicator solution that changes colour with CO₂ or O₂
Removing the chlorophyllboil the leaf in alcohol so the green colour is gone and the iodine colour change can be seen
gases and the limit
Stomatatiny openings in the leaf: carbon dioxide enters and oxygen leaves through them
The limitmore light or more carbon dioxide cannot raise the rate past a point — the plant has reached its maximum
moving water and food
Water-carrying tubeswater absorbed by the roots travels up through the water-carrying tubes
Food-carrying tubesthe sugar made in the leaves is carried away through the food-carrying tubes
Water from the rootswater is absorbed by the roots and transported up to the leaves
The word equation: carbon dioxide + water → sugar + oxygen, with light energy trapped by chlorophyll in the leaves. Excess sugar is stored as starch.