hce_kmu
105年
普通生物及生化概論
第 80 題
Which of the following statements about the Calvin cycle is true?
I. Sugarcane opens stomata on days, while pineapple opens stomata at nights.
II. On hot and dry days, sugarcane is more efficient to fix $CO_2$ than rice.
III. Rubisco is an enzyme involved in the first major step of carbon fixation in rice; its substrate molecules are ribulose-1,5-bisphosphate and $CO_2$ and its product is a three-carbon compound.
IV. Sugarcane and pineapple can use phosphoenolpyruvate carboxylase to capture more $CO_2$ into a four-carbon compound in mesophyll cells.
I. Sugarcane opens stomata on days, while pineapple opens stomata at nights.
II. On hot and dry days, sugarcane is more efficient to fix $CO_2$ than rice.
III. Rubisco is an enzyme involved in the first major step of carbon fixation in rice; its substrate molecules are ribulose-1,5-bisphosphate and $CO_2$ and its product is a three-carbon compound.
IV. Sugarcane and pineapple can use phosphoenolpyruvate carboxylase to capture more $CO_2$ into a four-carbon compound in mesophyll cells.
- A I and II
- B II and III
- C III and IV
- D I, II, and III
- E I, II, III, and IV
思路引導 VIP
如果你是一株生長在極度乾旱沙漠中的植物，當白天的太陽非常強烈且空氣乾燥時，你認為開放氣孔獲取二氧化碳會面臨什麼風險？為了克服這個問題，你會選擇在什麼時間點獲取二氧化碳，並使用什麼樣特性的酵素來確保即便二氧化碳濃度很低也能成功捕捉它？
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AI 詳解
AI 專屬家教
恭喜你準確判斷出所有敘述皆正確！這道題目非常全面地考察了植物光合作用中三種主要路徑（$C_3$、$C_4$ 與 CAM）的生理差異與環境適應性。
植物路徑的生理適應
在敘述 III 中，你精確掌握了 $C_3$ 植物（如水稻）的核心機制，即利用 Rubisco 酵素將 $CO_2$ 固定於 $RuBP$ 上。而敘述 IV 則點出 $C_4$ 植物（甘蔗）與 CAM 植物（鳳梨）的共通點：它們都演化出利用 PEP carboxylase 作為二氧化碳捕手的能力，能在葉肉細胞中形成四碳化合物（如草醯乙酸或蘋果酸），這讓它們在極端環境中更具競爭力。敘述 I 與 II 則進一步延伸到生態層面，區分了 CAM 植物夜間開放氣孔的節水特性，以及 $C_4$ 植物在乾熱條件下避免「光呼吸」作用，進而比 $C_3$ 植物擁有更高固碳效率的優勢。
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