🎯 What You'll LearnApa yang Anda Akan Pelajari
Explain the role of plant hormones (phytohormones)Menerangkan peranan hormon tumbuhan (fitohormon)
Describe different types of tropism — phototropism, geotropism, hydrotropism, thigmotropismMenerangkan pelbagai jenis tropisme — fototropisme, geotropisme, hidrotropisme, tigmotropisme
Explain auxin distribution and its effect on plant growthMenerangkan taburan auksin dan kesannya terhadap pertumbuhan tumbuhan
Describe the functions of ethylene, gibberellin, cytokinin, and abscisic acidMenerangkan fungsi etilena, giberelin, sitokinin, dan asid absisik
Relate plant hormone applications in agricultureMengaitkan aplikasi hormon tumbuhan dalam pertanian
🧪 PhytohormonesFitohormon
Types and Functions of PhytohormonesJenis dan Fungsi Fitohormon
| HormoneHormon | FunctionsFungsi | Production SiteLokasi Penghasilan |
|---|---|---|
| AuxinAuksin | Cell elongation, phototropism, geotropism, apical dominance, fruit developmentPemanjangan sel, fototropisme, geotropisme, dominasi apikal, perkembangan buah | Shoot tips (apical meristem)Hujung pucuk (meristem apikal) |
| EthyleneEtilena | Fruit ripening, leaf abscission, stress responsePemasakan buah, pengguguran daun, gerak balas tekanan | Ripening fruits, ageing leavesBuah masak, daun menua |
| GibberellinGiberelin | Stem elongation, seed germination, flower formationPemanjangan batang, percambahan biji benih, pembentukan bunga | Young leaves, roots, seedsDaun muda, akar, biji benih |
| CytokininSitokinin | Cell division, delays ageing, promotes bud growthPembahagian sel, melambatkan penuaan, merangsang pertumbuhan tunas | Root tips, developing fruitsHujung akar, buah berkembang |
| Abscisic Acid (ABA)Asid Absisik (ABA) | Seed dormancy, stomatal closure during stress, leaf abscissionPendormanan biji benih, penutupan stomata semasa tekanan, pengguguran daun | Mature leaves, stressed tissuesDaun matang, tisu tertekan |
🌿 TropismTropisme
Tropism is the directional growth response of plants to external stimuli.Tropisme ialah gerak balas pertumbuhan arah tumbuhan terhadap rangsangan luar.
| TypeJenis | StimulusRangsangan | Shoot ResponseGerak Balas Pucuk | Root ResponseGerak Balas Akar |
|---|---|---|---|
| PhototropismFototropisme | LightCahaya | Positive (toward light)Positif (ke arah cahaya) | Negative (away from light)Negatif (menjauhi cahaya) |
| Geotropism/GravitropismGeotropisme | GravityGraviti | Negative (away from gravity)Negatif (menjauhi graviti) | Positive (toward gravity)Positif (ke arah graviti) |
| HydrotropismHidrotropisme | WaterAir | WeakLemah | Positive (toward water)Positif (ke arah air) |
| ThigmotropismTigmotropisme | TouchSentuhan | Positive (climbing plants)Positif (tumbuhan memanjat) | VariesBerbeza |
Phototropism MechanismMekanisme Fototropisme
1. Light shines on one side of the stemCahaya menyinari satu sisi batang
2. Auxin is produced at the shoot tip and redistributes to the shaded sideAuksin dihasilkan di hujung pucuk dan bertaburan semula ke sisi gelap
3. Higher auxin concentration on the shaded side causes faster cell elongationKepekatan auksin yang lebih tinggi di sisi gelap menyebabkan pemanjangan sel lebih cepat
4. The shaded side grows faster, causing the shoot to bend toward lightSisi gelap tumbuh lebih cepat, menyebabkan pucuk membengkok ke arah cahaya
🌴 Other Hormone FunctionsFungsi Hormon Lain
| ProcessProses | Hormone(s) InvolvedHormon Terlibat | ExplanationPenerangan |
|---|---|---|
| Fruit ripeningPemasakan buah | EthyleneEtilena | Triggers softening, sweetening, and colour change in fruitsMencetuskan pelembutan, pemanisan, dan perubahan warna buah |
| Seed dormancyPendormanan biji benih | Abscisic Acid (ABA)Asid Absisik (ABA) | Prevents germination in unfavourable conditionsMenghalang percambahan dalam keadaan tidak sesuai |
| GerminationPercambahan | GibberellinGiberelin | Breaks dormancy, triggers enzyme production in seedsMemecahkan pendormanan, mencetuskan penghasilan enzim dalam biji benih |
| Leaf fallPengguguran daun | Ethylene + ABAEtilena + ABA | Causes abscission layer to form at leaf baseMenyebabkan lapisan pengguguran terbentuk di pangkal daun |
| Cell divisionPembahagian sel | CytokininSitokinin | Promotes mitosis in actively growing regionsMerangsang mitosis di kawasan pertumbuhan aktif |
| Apical dominanceDominasi apikal | AuxinAuksin | High auxin at tip suppresses lateral bud growthAuksin tinggi di hujung merencat pertumbuhan tunas sisi |
| Stomatal closurePenutupan stomata | Abscisic Acid (ABA)Asid Absisik (ABA) | During drought, closes stomata to reduce water lossSemasa kemarau, menutup stomata untuk mengurangkan kehilangan air |
💯 Quick CheckSemakan Cepat
Why does a shoot bend toward light?Mengapa pucuk membengkok ke arah cahaya?
🇲🇾 Malaysian InnovationInovasi Malaysia
🍌 Banana ripeningPemasakan pisang — Malaysian farmers use ethylene gas (or burning paper/cow dung in enclosed spaces) to ripen bananas uniformly for market.Petani Malaysia menggunakan gas etilena (atau pembakaran kertas/kot najis lembu dalam ruang tertutup) untuk memesakkan pisang secara seragam untuk pasaran.
🌴 Oil palmSawit — Gibberellin treatments are studied to increase oil palm yield. Auxin-based herbicides are used to control weeds in plantations.Rawatan giberelin dikaji untuk meningkatkan hasil sawit. Racun rumpai berasaskan auksin digunakan untuk mengawal rumpai di ladang.
🍈 Durian seasonMusim durian — Ethylene regulation affects durian fruit drop and ripening timing, crucial for Malaysia's RM2 billion durian industry.Pengawalan etilena mempengaruhi pengguguran dan masa pemasakan buah durian, penting untuk industri durian bernilai RM2 bilion Malaysia.
SPM 2019 Paper 2SPM 2019 Kertas 2
A student places two potted seedlings in different positions. One is placed horizontally (lying on its side) and left in sunlight. After two days, the shoot bends upward.Seorang pelajar meletakkan dua anak benih pasu dalam kedudukan berbeza. Satu diletakkan secara mendatar (berbaring di sisinya) dan dibiarkan di bawah cahaya matahari. Selepas dua hari, pucuk membengkok ke atas.
(a) Name the response shown by the shoot. [1 mark]Namakan gerak balas yang ditunjukkan oleh pucuk. [1 markah]
(b) Explain the mechanism of this response. [4 marks]Terangkan mekanisme gerak balas ini. [4 markah]
(c) State the adaptive value (significance) of this response to the plant. [1 mark]Nyatakan nilai adaptasi (kepentingan) gerak balas ini kepada tumbuhan. [1 markah]