F. F. Blackman performed experiments to investigate the effects of various factors on photosynthesis. In one of his experiments, Blackman found that if light intensity was low, photosynthesis could be accelerated by increasing the amount of light, but not by increasing the temperature or carbon dioxide concentration. What can you conclude from this specific experiment?

Question

A.  Light is important for photosynthesis
B.  Carbon dioxide is important for photosynthesis
C.  High temperatures are important for photosynthesis
D.  Photosynthesis generates oxygen

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

  Gather Content
What do you already know about photosynthesis? What other information is related to the question?

  Choose Answer
Do you have all the information needed to draw a supported conclusion?

  Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  Light is important for photosynthesis

Clarify Question
What is the key concept addressed by the question?
        · The question asks you to draw a conclusion about photosynthesis based on Blackman’s experimental results.
What type of thinking is required?
        · You are being asked to weigh and judge, or evaluate, Blackman’s experimental results and use that information to draw a conclusion.

  Gather Content
What do you already know about photosynthesis? What other information is related to the question?
        · Recall that photosynthesis is a process of creating organic molecules from inorganic carbon sources using light energy. Photosynthesis is comprised of the light reactions and the Calvin cycle. Light and carbon dioxide are inputs of photosynthesis and oxygen and carbohydrate (among other molecules) are outputs of photosynthesis.
        · The observation that photosynthesis could be accelerated by increasing the amount of light but not by increasing temperature or carbon dioxide concentration is telling. How is this observation important to drawing a conclusion about photosynthesis in this experiment?

  Choose Answer
Do you have all the information needed to draw a supported conclusion?
        · Let’s unpack each option and see how well it is supported by experimental observations. We know that plants need to carbon dioxide, but increasing carbon dioxide did not increase photosynthesis in this experiment. Likewise, increasing temperature did not increase photosynthesis either. And while we know that photosynthesis generates oxygen, there is no connection between experimental observations and that outcome, so that is not a supported conclusion.
        · The process of elimination leaves us with light being important for photosynthesis as the logical conclusion, but why else would that make sense? Experimental observations showed that as light increased, so did photosynthesis. The fact that increased carbon dioxide did not increase photosynthesis would support the conclusion that light is essential.

  Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Answering this question correctly depended on your ability to evaluate Blackman’s experimental results and draw an accurate conclusion based on those observations.
        · If you got the correct answer, good thinking! If you got an incorrect answer, were you able to weigh Blackman’s observations and correlate that with a conclusion? Were you able toeliminate carbon dioxide and high temperatures as options based on the observations?