Final answer:
Anoxygenic photosynthesis does not release oxygen as it uses other electron donors like hydrogen sulfide or thiosulfate, unlike oxygenic photosynthesis which uses water and releases oxygen.
Step-by-step explanation:
When discussing the types of photosynthesis, it is important to understand the difference between oxygenic and anoxygenic photosynthesis. In oxygenic photosynthesis, which is carried out by plants, algae, and cyanobacteria, water (H₂O) is the source of electrons and oxygen is released as a byproduct.
Anoxygenic photosynthesis does not produce oxygen because it uses other substances such as hydrogen sulfide (H₂S) or thiosulfate (S₂O₃) as electron donors, resulting in the production of elemental sulfur or sulfate ions instead of oxygen. Therefore, the statement 'All Pk photosynizers are anoxygenic' suggests that these particular photosynthetic organisms do not produce oxygen during their process of photosynthesis.