Question

photosynthesis application questions

1. a classmate states:

\plants only perform photosynthesis during the day, so they dont need to respire at
night.\
a. evaluate the accuracy of this statement.
b. provide scientific evidence to support your argument.

1. compare photosynthesis to cellular respiration using the following criteria:

. energy use or production
. inputs and outputs
. where in the cell the process occurs
. time of day each process can occur
write a short paragraph summarizing the relationship between the two
processes.

Explanation:

Question 1a

The statement is inaccurate. Plants perform photosynthesis (needing light, in chloroplasts) during the day, but cellular respiration (in mitochondria, for energy) occurs 24/7. At night, photosynthesis stops, but respiration continues to produce ATP for plant functions like growth, nutrient transport, and maintenance. So plants do respire at night.

• Photosynthesis: Occurs in chloroplasts, uses light energy, inputs \( \ce{CO_2} \), \( \ce{H_2O} \), produces \( \ce{O_2} \) and glucose (\( \ce{C_6H_{12}O_6} \)): \( 6\ce{CO_2} + 6\ce{H_2O} \xrightarrow[\text{Chloroplast}]{\text{Light Energy}} \ce{C_6H_{12}O_6} + 6\ce{O_2} \).
• Cellular Respiration: Occurs in mitochondria, releases energy from glucose, inputs \( \ce{O_2} \) and glucose, produces \( \ce{CO_2} \), \( \ce{H_2O} \), and ATP: \( \ce{C_6H_{12}O_6} + 6\ce{O_2} \xrightarrow[\text{Mitochondria}]{\text{Enzymes}} 6\ce{CO_2} + 6\ce{H_2O} + \text{ATP (Energy)} \).
• Time of Day: Photosynthesis needs light (daytime), but respiration happens continuously (day/night) as it is essential for energy production.
• Energy: Photosynthesis stores energy (light → chemical in glucose); respiration releases energy (glucose → ATP for cell work).
• Inputs/Outputs: Photosynthesis takes in \( \ce{CO_2} \)/\( \ce{H_2O} \), outputs \( \ce{O_2} \)/glucose. Respiration takes in \( \ce{O_2} \)/glucose, outputs \( \ce{CO_2} \)/\( \ce{H_2O} \)/ATP. Their inputs/outputs are complementary (e.g., \( \ce{O_2} \) from photosynthesis is used in respiration, \( \ce{CO_2} \) from respiration is used in photosynthesis).
• Cellular Location: Photosynthesis in chloroplasts (plant cells with chlorophyll); respiration in mitochondria (all eukaryotic cells, including plant cells).

Photosynthesis and cellular respiration are complementary processes. Photosynthesis (in chloroplasts, daytime) uses light energy to convert \( \ce{CO_2} \) and \( \ce{H_2O} \) into glucose (storing energy) and \( \ce{O_2} \). Cellular respiration (in mitochondria, 24/7) breaks down glucose using \( \ce{O_2} \) to release energy (as ATP) for cell functions, producing \( \ce{CO_2} \) and \( \ce{H_2O} \) as byproducts. The \( \ce{O_2} \) from photosynthesis fuels respiration, while \( \ce{CO_2} \) from respiration fuels photosynthesis. Together, they form a cycle that sustains energy flow and matter recycling in ecosystems (e.g., plants use photosynthesis to make food, then respiration to use that food’s energy; animals rely on plants’ glucose and \( \ce{O_2} \) for their respiration, and release \( \ce{CO_2} \) back to the environment for plants’ photosynthesis).

Answer:

The statement is inaccurate. Plants perform photosynthesis during the day (requiring light) but carry out cellular respiration continuously, including at night, to generate energy (ATP) for essential metabolic processes like growth, nutrient uptake, and maintenance.

Question 1b