2022 과학주제탐구 pH농도에 따른 효소의 작용 탐구(1320박서우,1522민윤아,1719김시운)

Summary

The presentation explores how pH affects enzyme activity. The student presenter had learned that enzymes are proteins and wondered whether conditions that denature proteins could affect them. The experiment tested potato catalase by measuring how long a piece of potato-juice-treated filter paper took to rise in hydrogen peroxide.

Hypothesis and method

The hypothesis was that the filter paper would rise fastest in a neutral solution. To investigate, the students varied the solution’s pH while attempting to keep other conditions constant.

Materials: Four beakers, hydrogen peroxide, sodium hydroxide, hydrochloric acid, pH test paper, a stopwatch, latex gloves, a dropper, filter paper, and a potato.

Procedure:

1. Make potato juice and cut the filter paper into equal-sized pieces.
2. Prepare solutions at different pH levels, adjusting them with hydrochloric acid or sodium hydroxide.
3. Apply potato juice to the filter paper.
4. Place the paper in each beaker and time how long it takes to rise.

Results and evaluation

The first attempt failed because the filter paper pieces were too large, so the students repeated the experiment with smaller pieces.

The second attempt recorded these times:

• pH 3: 18.98 seconds
• pH 5.5: 24.7 seconds
• pH 7.5: 14.18 seconds

The students judged the experiment inconclusive. Although the paper rose fastest at pH 7.5, the results did not form a clear curve consistent with their expectations or establish the optimum pH. They identified several possible sources of error:

• The hydrogen peroxide concentration was calculated incorrectly.
• The pH values were not measured or set precisely.
• The amount of potato juice on each piece of filter paper was inconsistent.

Lessons and next steps

The presentation emphasizes planning experiments carefully, controlling conditions consistently, and carrying out the procedure calmly. The students also suggested investigating how temperature affects enzyme activity in a future experiment.

Speakers and sources

• Student presenter(s): The subtitles do not distinguish individual speakers. The video title credits 1320 박서우, 1522 민윤아, and 1719 김시운.
• External sources: No specific external source is named in the subtitles. They refer generally to additional information indicating that catalase’s optimum pH is neutral.