To determine which two substances the Calvin cycle produces, let's analyze the substances listed.
The Calvin cycle is a part of the photosynthetic process in plants that takes place within the chloroplasts. Its main goal is to produce molecules that can be used to form glucose, which is essential for providing energy and metabolic intermediates within the plant.
The key substances indicated as results of the Calvin cycle are:
1. ADP - Adenosine Diphosphate is formed when ATP (Adenosine Triphosphate) releases energy and a phosphate group. The Calvin cycle uses ATP, and as a result, ATP is converted to ADP within the process.
2. A 3-carbon sugar - One of the main products of the Calvin cycle is a 3-carbon sugar called G3P (Glyceraldehyde-3-phosphate). From G3P, glucose and other carbohydrates can be synthesized.
Given these points, the two substances produced by the Calvin cycle are:
1. ADP (representing substance C)
2. A 3-carbon sugar (representing substance D)
Therefore, the correct answer is:
C. ADP
D. A 3-carbon sugar
