Lab 1: Leaf Lab
Assignment 1 Questions
1. Based on what you already know about photosynthesis, develop a testable hypothesis to explain the influence of an increase in light intensity on the photosynthetic rate in tomato leaves.
2. What is the relationship between an increase in light intensity and photosynthetic rate in tomato leaves? Does this relationship support the hypothesis that you formulated?
As light intensity increases then the rate of photosynthesis increases linearly until a point is reached when the rate levels off. The light intensity beyond which the light response curve plateaus is called the light saturation point of photosynthesis. At this point increases in light intensity do not cause increases in photosynthetic rate, so other factors (eg. CO2 levels) apart from the supply of light must be limiting the photosynthetic process. 3. Photosynthetic saturation is the maximum rate of photosynthesis. What was the value for photosynthetic saturation in tomato leaves? What value of light intensity produced photosynthetic saturation in tomato leaves? Based on what you know about photosynthesis, provide possible reasons for what causes photosynthetic saturation
4. What is the relationship between an increase in light intensity and photosynthetic rate in leaves from a corn plant? How does this relationship compare with what you observed for tomato plants?
5. Photosynthetic saturation is the maximum rate of photosynthesis. What value of light intensity produced photosynthetic saturation in corn leaves? Photosynthesis first must be determined by plotting O2 evolution vs time at different light levels. The rates calculated from each O2 evolution curve are then plotted against light level. [ For example, the figure below shows O2 evolution curves when photosynthesis was allowed to occur in the presence of two different light levels.