Step 1: Analyzing the statements
Statement A: The first action spectrum of photosynthesis was observed by Cladophora experiments.
This is correct. The action spectrum of photosynthesis was first observed using Cladophora (a type of algae).
Statement B: Chlorophyll 'b' will be blue-green in the chromatogram.
This is incorrect. Chlorophyll 'b' appears yellow-green in the chromatogram, not blue-green.
Statement C: In the biosynthetic phase of photosynthesis, ATP and NADPH are used.
This is correct. In the Calvin cycle, ATP and NADPH are used to convert carbon dioxide into glucose.
Statement D: In photosynthesis, light saturation occurs at 10% of full sunlight.
This is correct. Light saturation occurs when the rate of photosynthesis no longer increases with an increase in light intensity.
Statement E: In CAM plants, RuBisCo will be absent.
This is incorrect. RuBisCo is present in CAM plants, where it plays a role in the fixation of carbon during the night.
Final Answer: \[
A - \text{Correct}, \quad C - \text{Correct}, \quad D - \text{Correct}
\]