Question

use your knowledge of the mechanism of photosynthesis and the data presented in the chart to determine which of the statements below is a correct explanation for the students data. cup 4 had the slowest rate of photosynthesis because it had the least baking soda. cup 1 had a low rate of photosynthesis because 0.5 grams of baking soda did not provide a sufficient amount of co₂. cup 2 had the highest rate of photosynthesis because 5 disks were floating at the end of 10 minutes using a 50 watt light bulb. cup 3 had the same rate of photosynthesis as cup 1 because they had the same ratio of disks floating to wattage of light.

Explanation:

• Cup 4: Baking soda is a source of \(CO_2\). In photosynthesis, \(CO_2\) is used as a reactant (\(6CO_2 + 6H_2O

ightarrow C_6H_{12}O_6+6O_2\)). Cup 4 has \(0\) grams of baking soda (\(CO_2\) source), so no photosynthesis occurs (as shown by \(0\) disks floating), which means it has the slowest rate (rate \( = 0\)).

• Cup 1: It has \(0.5\) grams of baking soda (same as Cups 2 and 3). The low rate is due to the low - wattage light bulb (\(25\) watts). Light is needed to excite electrons in photosystem I and II. A lower - wattage bulb provides less light energy for the light - dependent reactions of photosynthesis.
• Cup 2: Cup 3 (\(75\) watts, \(9\) disks) has a higher rate than Cup 2 (\(50\) watts, \(5\) disks). The number of disks floating is related to the amount of \(O_2\) produced (a by - product of photosynthesis). More \(O_2\) (more disks floating) generally indicates a higher rate of photosynthesis when other factors (like \(CO_2\) source amount) are constant.
• Cup 3 vs Cup 1: Cup 3 (\(75\) watts, \(9\) disks) has a much higher rate than Cup 1 (\(25\) watts, \(3\) disks). The ratio \(\frac{\text{disks}}{\text{wattage}}\) is \(\frac{3}{25}= 0.12\) for Cup 1 and \(\frac{9}{75}=0.12\), but the actual number of disks (a measure of \(O_2\) production) and wattage (light energy input) show that Cup 3 has a higher absolute rate of photosynthesis (more \(O_2\) produced in the same time).

Answer:

Cup 4 had the slowest rate of photosynthesis because it had the least baking soda.