- Understand the significance of photosynthesis.
- Relate the structures of leaves and chloroplasts to their functions in photosynthesis.
Photosynthesis 🌿
- 🔆Light energy ➡️🧪Chemical energy
- Light energy from sun is captured and utilised in the conversion of carbon dioxide, water and minerals into oxygen and organic compounds.
👆🏻This photo showing the process of photosynthesis.
Significance of photosynthesis 🌿
- Photosynthesis supporting the oxygen provision in the atmosphere.
- Photosynthesis contributes to the carbon cycle among the earth, oceans and organism.
- Carbon cycle ➡️Circulation of carbon atoms in the biosphere.
- Photosynthesis act as the primary energy process for plants.
In HKDSE Biology examination, students have to memorize the importance of photosynthesis ❗️ ❕NO photosynthesis ▶️ No organism can survive.
Leaves 🌿
👆🏻This photo showing the structure of leaf.
Students have to link up the structure of leaf to the function in photosynthesis in HKDSE Biology examination❗️ ❕
1. Large surface area
- Allows leaves to absorb more light.
2. The epidermis is thin and transparent
- Allows more light to reach the palisade mesophyll cells.
3. Palisade mesophyll cells are located at the top of the leaf
- Allows the rapid absorption of light which leads to an increment on the rate of photosynthesis.
4. Palisade mesophyll cells containing numerous chlorophyll
- Allows the absorption of all available light.
Chlorophyll 🌿
👆🏻This photo showing the structure of chloroplast.
Students have to link up the structure of chloroplast to the function in photosynthesis in HKDSE Biology examination❗️ ❕
1. Thylakoid system
- Thylakoid is a flattened sac-like membrane structure where light energy converts into chemical energy.
2. Grana
- Grana consisting 10 to 20 thylakoid where light energy converts into chemical energy.
3. Stroma
- Stroma is dense fluid enclosed in the membrane envelope and outside thylakoid membrane where carbon dioxide converts into carbohydrates.
4. Chlorophyll
- Chlorophyll is the green photosynthetic pigment inside grana and having the role of absorbing light energy.
That's the end of this topic 👏🏻
References
- Bassham, J. A., & Lambers, H. (2020, March 17). Carbon fixation in C4 plants. Encyclopædia Britannica. https://www.britannica.com/science/photosynthesis/Carbon-fixation-in-C4-plants.
- Brenner, L. (2019, November 22). Why Is Photosynthesis Important for All Organisms? Sciencing. https://sciencing.com/photosynthesis-important-organisms-6389083.html.
- BBC. Adaptations of the leaf for photosynthesis and gaseous exchange - Plant organisation - Edexcel - GCSE Biology (Single Science) Revision - Edexcel - BBC Bitesize. BBC News. https://www.bbc.co.uk/bitesize/guides/z2jydxs/revision/1.
Bailey, R. (2019, July 1). How Chloroplasts Make Plant Photosynthesis Possible. ThoughtCo. https://www.thoughtco.com/chloroplast-373614.