Multiple Choice
In the context of evolutionary biology, are fungi more closely related to plants or animals?
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Intro to Organic Chemistry
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Which statement is true regarding the earliest photosynthetic organisms on Earth?
A
They relied on aerobic respiration for energy production.
B
They were eukaryotic organisms that evolved in the ocean.
C
They used hydrogen sulfide as an electron donor, releasing sulfur as a byproduct.
D
They used water as an electron donor, releasing oxygen as a byproduct.
Verified step by step guidance1
Understand the context of early photosynthetic organisms: These organisms are believed to have existed billions of years ago and played a crucial role in shaping Earth's atmosphere.
Recognize the difference between aerobic and anaerobic processes: Aerobic respiration requires oxygen, while anaerobic processes do not. Early Earth had a very low oxygen concentration, making aerobic respiration unlikely for the earliest organisms.
Differentiate between prokaryotic and eukaryotic organisms: The earliest photosynthetic organisms were prokaryotic, not eukaryotic. Eukaryotic cells are more complex and evolved later.
Identify the electron donors used by early photosynthetic organisms: Early photosynthetic organisms, such as certain types of bacteria, used hydrogen sulfide (H₂S) as an electron donor, not water (H₂O).
Understand the byproducts of these processes: When using hydrogen sulfide as an electron donor, sulfur is released as a byproduct, not oxygen. Oxygenic photosynthesis, which releases oxygen, evolved later with cyanobacteria.
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