Measuring Photosynthesis and Respiration

The video tutorial explains how to test productivity in an ecosystem by measuring dissolved oxygen levels in a fish tank. The process involves preparing bottles with Elodea plants, setting them under light and dark conditions, and analyzing the changes in dissolved oxygen levels after 48 hours. The experiment demonstrates the roles of photosynthesis and cellular respiration in ecosystem productivity.

What is one method to test productivity in an ecosystem?

• Measuring the amount of sunlight

• Counting the number of species

• Observing animal behavior

• Measuring cellular respiration

Why is it important to measure dissolved oxygen levels in the fish tank?

• To determine the water temperature

• To assess the initial oxygen available for respiration

• To check for the presence of fish

• To measure the pH level of the water

What was the initial dissolved oxygen level in the fish tank?

• 10.0 mg/L

• 6.5 mg/L

• 5.3 mg/L

• 7.4 mg/L

What is the purpose of ensuring no air bubbles are present in the bottles?

• To prevent contamination

• To ensure accurate dissolved oxygen readings

• To keep the Elodea healthy

• To maintain water temperature

What is the significance of using identical pieces of Elodea in both bottles?

• To enhance photosynthesis

• To prevent contamination

• To maintain a constant variable for accurate comparison

• To ensure consistent light exposure

Why is one bottle covered with black paper?

• To measure only cellular respiration

• To prevent algae growth

• To keep the water cool

• To block harmful UV rays

What process is being measured in the bottle exposed to light?

• Only cellular respiration

• Neither photosynthesis nor cellular respiration

• Both photosynthesis and cellular respiration

• Only photosynthesis

What does the presence of air bubbles in the light-exposed bottle indicate?

• Increased water temperature

• Contamination in the water

• Photosynthesis occurring

• Decreased oxygen levels

After 48 hours, what was the dissolved oxygen level in the bottle kept in the dark?

• 6.5 mg/L

• 5.3 mg/L

• 10.0 mg/L

• 7.4 mg/L

What conclusion can be drawn from the increase in dissolved oxygen in the light-exposed bottle?

• Photosynthesis increased oxygen levels

• The Elodea plant died

• Photosynthesis did not occur

• Cellular respiration decreased