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9. (a) State a precise role for each of the following in photosynthesis: (i) Carbon dioxide .......................................................................................................... - Leaving Cert Biology - Question 9 - 2007
Question 9
9. (a) State a precise role for each of the following in photosynthesis: (i) Carbon dioxide .......................................................................... show full transcript
Worked Solution & Example Answer:9. (a) State a precise role for each of the following in photosynthesis: (i) Carbon dioxide .......................................................................................................... - Leaving Cert Biology - Question 9 - 2007
Step 1
State a precise role for each of the following in photosynthesis: (i) Carbon dioxide
Answer
Carbon dioxide (CO₂) is essential in photosynthesis as it supplies carbon, which is a key building block in the formation of carbohydrates. During the process, CO₂ combines with water in the presence of sunlight to produce glucose and oxygen, allowing plants to create their own food.
Step 2
State a precise role for each of the following in photosynthesis: (ii) Water
Answer
Water (H₂O) plays a crucial role in photosynthesis by providing hydrogen ions and electrons necessary for the formation of glucose. Water is split during the light-dependent reactions, releasing oxygen as a byproduct and providing the energy required for the synthesis of carbohydrates.
Step 3
Answer the following questions in relation to an activity that you carried out to investigate the influence of light intensity OR carbon dioxide concentration on the rate of photosynthesis. (i) Name the plant that you used.
Answer
The plant that I used for the investigation was Elodea, a common aquatic plant known for its rapid photosynthetic activity.
Step 4
Answer the following questions in relation to an activity that you carried out to investigate the influence of light intensity OR carbon dioxide concentration on the rate of photosynthesis. (ii) How did you vary light intensity OR carbon dioxide concentration?
Answer
To vary light intensity, I changed the distance of a lamp from the plant or adjusted the wattage of the light source. Alternatively, if investigating carbon dioxide concentration, I altered the quantity of sodium bicarbonate (NaHCO₃) added to the water.
Step 5
Answer the following questions in relation to an activity that you carried out to investigate the influence of light intensity OR carbon dioxide concentration on the rate of photosynthesis. (iii) State a factor that you kept constant during the investigation.
Answer
During the investigation, I kept the temperature constant to ensure that it did not affect the rate of photosynthesis.
Step 6
Answer the following questions in relation to an activity that you carried out to investigate the influence of light intensity OR carbon dioxide concentration on the rate of photosynthesis. (iv) How did you ensure that the factor that you mentioned in (iii) remained constant?
Answer
I ensured that the temperature remained constant by conducting the experiment in a temperature-controlled environment and using a water bath to maintain a stable temperature throughout the investigation.
Step 7
Answer the following questions in relation to an activity that you carried out to investigate the influence of light intensity OR carbon dioxide concentration on the rate of photosynthesis. (v) How did you measure the rate of photosynthesis?
Answer
The rate of photosynthesis was measured by counting the number of oxygen bubbles produced per minute or by calculating the volume of oxygen released over time.
Step 8
Answer the following questions in relation to an activity that you carried out to investigate the influence of light intensity OR carbon dioxide concentration on the rate of photosynthesis. (vi) Using labelled axes, sketch a graph to show how the rate of photosynthesis varied with the factor mentioned in (ii) above.
Answer
In the graph, the vertical axis should be labeled 'Rate of Photosynthesis (e.g., bubbles/min or volume/time)' and the horizontal axis should be labeled either 'Light Intensity (distance)' or 'CO₂ Concentration (g/L)'. The curve should illustrate how the rate of photosynthesis increases with increasing light intensity or CO₂ concentration up to an optimal point before leveling off.