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Which of the following is True?
- a. Photosynthesis evolved in an atmosphere with little no oxygen.
- b. Photosynthesis occurs only in plants.
- c. Oxygen is necessary for photosynthesis.
- d. Carbon dioxide is necessary for photorespiration.
Introduction:
In the plants, the biochemical process occurring in the chloroplasts converting the inorganic molecules into organic molecules is photosynthesis. This process includes trapping of light energy and converting it into the chemical energy, which can be used by the plants for their functioning.
Answer to Problem 1MC
Correct answer:
The photosynthesis had start occurring when the atmosphere has no or little oxygen.
Therefore, option (a) is correct.
Option (a) is given as “Photosynthesis evolved in an atmosphere with little or no oxygen”
Explanation of Solution
Justify reason for the correct statement:
The prokaryotic cells (aerobic) were engulfed by the other cells and the cells modify and become eukaryotic cells. The aerobic bacterium established the mutual relationship between them. The prokaryote that was engulfed becomes mitochondria in the eukaryotic cell (protists). The cyanobacterium was engulfed by the eukaryotic cells having mitochondria. The cyanobacterium evolves and becomes chloroplast in the eukaryotic cells.
In the inner membrane of the chloroplasts, the foldings are stromules. There are photosynthetic pigments that help in the trapping of sunlight. The sunlight converts into potential energy stored in the molecules of glucose by the chloroplasts. The oxygen is formed in the chloroplasts.
Hence, option (a) is correct.
Justify reasons for incorrect statements:
Option (b) is given as “Photosynthesis occurs only in plants”.
The photosynthetic pigments are present in some algae, protists, apart from plants. They all can prepare their own food by the process of photosynthesis. Hence, it is a wrong answer.
Option (c) is given as “Oxygen is necessary for photosynthesis”.
Plants require sunlight to convert water and carbon dioxide into sugars and oxygen is released as a byproduct. The oxygen is a product of photosynthesis and hence not required in photosynthesis. Hence, it is a wrong answer.
Option (d) is given as “Carbon dioxide is necessary for photorespiration”.
Carbon dioxide is the product of photorespiration when plants take up the light and oxygen. Hence, it is a wrong answer.
Hence, options (b), (c), and (d) are incorrect.
The engulfing of the aerobic bacterium and cyanobacterium by the early eukaryotic cells and the formation of the mutual relationship between them had led to the origination of the eukaryotic cells having “mitochondria and chloroplasts”. This had lead to the formation of food by plants by the process of photosynthesis.
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Chapter 7 Solutions
Biology
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