Photosynthesis Floating Leaf Disk Lab

Title: Net rate of photosynthesis in English Ivy is higher in warmer temperatures than in colder temperatures.

Hypothesis: Photosynthesis is a series of chemical processes by which green plants, algae and cyanobacteria utilize the energy in sunlight to convert carbon dioxide in the presence of water into simple sugars with oxygen as a byproduct. A simplified formula for photosynthesis can be written as CO2 + H2O (CH2O)n + O2. Photosynthesis occurs in plant organelles called chloroplasts, which capture energy from sunlight and store it as energy molecules NADPH and ATP, which are then used to drive this photosynthetic conversion of CO2 and H2O to simple sugar and O2.

All photosynthetic plants undergo both photosynthesis and respiration (a series of chemical reactions by which cells convert the energy found in the bonds of organic molecules such as glucose into ATP to power cellular activities). Unlike photosynthesis, which uses carbon dioxide and produces oxygen, respiration uses oxygen and produces carbon dioxide. If both processes occur simultaneously, the amount of oxygen produced by photosynthesis is usually countered by the amount of oxygen used in respiration. As a result, “gross photosynthesis” (the total amount of oxygen produced by photosynthesis) is difficult to measure. Instead, “net photosynthesis” (the amount of oxygen produced during photosynthesis but not used in respiration) can be used as a proxy to measure the overall rate of photosynthesis.

Prior studies were conducted to determine whether the net rates of photosynthesis were higher in English Ivy (Hedera helix) exposed to higher levels of light than English Ivy exposed to lower levels of light. Results supported the hypothesis that photosynthesis occurred at a higher rate with higher levels of light exposure. It is commonly understood that enzymatic reactions generally are slowed by decreasing temperatures. Given that photosynthesis is an enzyme-dependent series of...