Energy used to power photosynthesis & ultimately cellular respiration originates from which energy source?
a) Glucose.
b) ATP.
c) Carbon dioxide.
d) The sun.

• A. Glucose.
• B. ATP.
• C. Carbon dioxide.
• D. The sun.

Answer: (D)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored in glucose.
2. Identify the role of the sun in photosynthesis: The sun provides the light energy necessary for photosynthesis. This energy is captured by chlorophyll in the chloroplasts of plant cells.
3. Recognize the conversion of energy: During photosynthesis, light energy from the sun is converted into chemical energy in the form of glucose, which can later be used in cellular respiration to produce ATP.
4. Connect photosynthesis to cellular respiration: Cellular respiration is the process by which cells convert glucose into ATP, the energy currency of the cell, using oxygen. The glucose used in cellular respiration is produced during photosynthesis.
5. Conclude the origin of energy: The ultimate source of energy for both photosynthesis and cellular respiration is the sun, as it initiates the process of energy conversion in photosynthesis.