Concept explainers
What do some photosynthetic bacteria use as a source of electrons instead of water?
a. oxygen (O2)
b. hydrogen sulfide (H2S)
c. organic compounds (e.g., CH3COO–)
d. nitrate (NO3–)
Introduction:
In the photophosphorylation reaction, electrons are required. These electrons are acquired from water molecules. The molecule is split and oxygen is generated as a by-product.
Answer to Problem 1TYK
Correct answer:
Some of the photosynthetic bacteria use hydrogen sulfide (H2S) instead of water as a source of electrons.
Explanation of Solution
Explanation/Justification for the correct answer:
Option (b) is given that hydrogen sulfide is used an alternative source of energy by some photosynthetic bacteria instead of water. Some of the bacteria may not use water molecule as a source of electrons and use hydrogen sulfide instead. For example, a sulfur bacteria Thiobacillus oxidizes sulfur by sulfate production required for growth of plants. Some of them also use other different molecules such as iron ions. Hence, Option (b) is correct.
Explanation for incorrect answers:
Option (a) is given that oxygen (O2) is used an alternative source of energy by some photosynthetic bacteria instead of water. In this process, oxygen is released as a by-product and does not act as an electron source. So, it is a wrong answer.
Option (c) is given that organic compounds like acetate are used as an alternative source of energy by some photosynthetic bacteria instead of water. The organic compounds such as acetate ions also do not provide electrons. So, it is a wrong answer.
Option (d) is given that nitrate
Hence, options (a), (c), and (d) are incorrect.
Thus, some photosynthetic bacteria use hydrogen sulfide as an alternative source of energy.
Want to see more full solutions like this?
Chapter 26 Solutions
Biological Science (7th Edition)
- The green sulfur bacteria, using sunlight as an energy source for photosystem I, are unable to split water molecules to release O2, but they are able to release which inorganic product molecule? A. hydrogen sulfide B. glucose C. elemental sulfur D. oxygen E. carbon dioxidearrow_forwardSince the air bubbles in bread are generated by yeast, how will the spaces in this bread compare to those in a loaf made using normal yeast? A. more bubbles B. differently-shaped bubbles C. smaller bubbles D. bubbles more on the interior of the loafarrow_forwardWhich statement about thylakoids in eukaryotes is not correct? a. Thylakoids are assembled into stacks. b. Thylakoids exist as a maze of folded membranes. c. The space surrounding thylakoids is called stroma. d. Thylakoids contain chlorophyll.arrow_forward
- Which of the following has the strongest tendency to gain electrons? Select one: O a. FAD O b. Oxygen O c. Coenzyme Q O d. Cytochrome Carrow_forwardWhich of the following is not an electron acceptor? A. Oxygen B. Sulfates C. Hydrogen sulfide D. Nitratesarrow_forwardDefine the following terms: a. autotroph b. chemoautotroph c. photoautotroph d. photoheterotroph e. chemoheterotropharrow_forward
- Which of the following coenzymes accepts electrons that was removed in the succinate of the Krebs Cycle? A. ADP B. FAD C. GDP D. NAD+arrow_forwardWhat class does the enzyme that catalyzes the pictured reaction belong to? A. transferase B. lyase C. hydrolase D. oxidoreductasearrow_forwardYeast is a facultative anaerobe. This means that alcohol fermentation takes place only if: a. the temperature is close to 37°C b. the atmosphere does not contain oxygen c. sugar is provided to the cells d. light is provided to the cellsarrow_forward
- In an anaerobic environment, facultative anaerobes use what kind of pathway to produce ATP? A.Krebs cycle and fermentation b.Glycolysis and fermentation c.Photosynthesis and the Calvin Benson cycle d. Krebs cycle and oxidative phosphorylation Why is free oxygen toxic to obligate anaerobes? A.They produce catalase and superoxide dismutase. B.They use fermentation pathways rather than oxidative phosphorylation to produce ATP. C.They do not produce the right enzymes to degrade oxygen radicals. D.They cannot use oxygen as the final electron acceptor in respiration. You are subculturing an obligate anaerobe from a tube of thioglycolate media. How far down do you dip the inoculating loop to retrieve the bacteria? A.All the way to the bottom of the media. B.Just into the top of the media C.Anywhere in the media is fine. D.Into the middle of the mediaarrow_forward1. What is the chemical composition of ATP? Identify the components according to the organic compound. 2. How important is water in harvesting energy from ATP molecules? 3. What is the importance of pigment in photosyntheis?arrow_forwardWhich bacteria is a photosynthetic autotroph? why? ( in brief)arrow_forward
- BiochemistryBiochemistryISBN:9781305577206Author:Reginald H. Garrett, Charles M. GrishamPublisher:Cengage LearningConcepts of BiologyBiologyISBN:9781938168116Author:Samantha Fowler, Rebecca Roush, James WisePublisher:OpenStax College