Leaf structure
| English | Chinese | Pinyin |
|---|---|---|
| adaptation | 适应 | shì yìng |
| palisade | 栅栏组织 | zhà lán zǔ zhī |
| chloroplasts | 叶绿体 | yè lǜ tǐ |
| veins | 静脉 | jìng mài |
| xylem | 木质部 | mù zhì bù |
| phloem | 韧皮部 | rèn pí bù |
| stomata | 气孔 | qì kǒng |
| guard cells | 保卫细胞 | bǎo wèi xì bāo |
The perfect solar panel
- A leaf looks simple, but it's beautifully built to capture light and make food.
- Almost every feature is an adaptation 适应 for photosynthesis.
A leaf is broad and flat mainly to:
Large surface area maximises light capture.
A leaf is ______ so that gases can diffuse in and out over short distances.
Thinness shortens the diffusion distance.
Built for light
- A leaf is broad and flat for a large surface area to catch light.
- It is thin, so gases diffuse in and out quickly.
A leaf in cross-section: each tissue is adapted for photosynthesis and gas exchange
Inside a leaf
Tap each layer of a leaf cross-section to see how its structure is built for photosynthesis and gas exchange.
Which leaf layer contains the most chloroplasts?
The palisade layer near the top absorbs the most light.
Inside the leaf
- The upper palisade 栅栏组织 layer is packed with chloroplasts 叶绿体 to absorb the most light.
- A network of veins 静脉 (xylem 木质部 and phloem 韧皮部) brings water and carries away sugars.
Stomata 气孔 in the lower surface of a leaf
Stomata are pores that allow:
Stomata let CO₂ in and O₂ out.
Guard cells open and close the stomata.
They control gas exchange and water loss.
Gas exchange
- Tiny pores called stomata (on the underside) let carbon dioxide in and oxygen out.
- Guard cells 保卫细胞 open and close the stomata to control gas exchange and water loss.
Worked example. A leaf's broad, thin shape gives a large surface area and short diffusion distance — letting it absorb plenty of light and exchange gases quickly. Form fits function.
What a plant does with the glucose it makes
You've got it
- a leaf is broad and flat (large surface area) and thin (fast diffusion)
- the palisade layer holds the most chloroplasts; veins carry water and sugar
- stomata (controlled by guard cells) let CO₂ in and O₂ out