1. In Earth's early days, all over the planet countless photosynthetic bacteria performed photosynthesis. 在地球早期，整个星球上有无数的光合细菌在进行光合作用。
2. Photosynthetic life is impossible there because sunlight is completely absent, but life such as the microbes that flourish deep within earth may still be possible. 因为那里完全没有阳光，所以不可能有光合作用的生命，但像在地球深处蓬勃生长的微生物之类的生命可能仍然存在。
3. The answer to this riddle lies in the metabolic activity of early photosynthetic life-forms that slowly but surely transformed the chemical composition of Earth's atmosphere. 这个谜题的答案在于早期光合生命形式的新陈代谢活动，这种活动缓慢但一定改变了地球大气的化学成分。
4. The ancestors of plants were photosynthetic single-celled organisms that gave rise to plants presumably lacked true roots, stems, leaves, and complex reproductive structures such as flowers. 植物的祖先是进行光合作用的单细胞生物，由此产生的植物可能缺乏真正的根、茎、叶和复杂的生殖结构，如花朵。
5. The photosynthetic responses determine the habitat of p. rubens and p. mariana in the climax forest. 光合反应决定红云杉和黑云杉在顶极林中的生态环境。
