RP6 - Photosynthesis Flashcards

1
Q

What is photosynthesis?

A

The process by which plants synthesise glucose using light energy from the Sun

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2
Q

Describe how you would investigate the effect of light intensity on the rate of photosynthesis in an aquatic plant

A

● Place cut pondweed in a boiling tube (containing sodium hydrogen carbonate solution) at a fixed distance from a light source
● Count the number of bubbles produced in one minute using stopwatch
● Repeat several times at different distances/light intensities, and calculate a mean for each distance
● Plot a graph of light intensity (x) against rate of photosynthesis (bubbles per minute, y)

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3
Q

Why is it best to use an LED light source rather than a lamp?

A

A lamp will emit more heat energy than an LED - therefore it may change the temperature of the experiment and affect the rate of photosynthesis

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4
Q

What is the relationship between the distance from a light source and light intensity?

A

Inverse square law - light intensity∝1 / distance2

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5
Q

How can the measurement of oxygen production be made more accurate?

A

If the the pondweed is placed under a filter funnel with an inverted measuring cylinder over the spout, the volume of oxygen produced can be determined

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6
Q

Why is sodium hydrogen carbonate solution used during this experiment?

A

It releases CO2, which is used by the pondweed during photosynthesis

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7
Q

Why can the number of bubbles produced be used to calculate the rate of photosynthesis?

A

Oxygen bubbles are formed as a product during photosynthesis. The number of bubbles produced in a given time is proportional to the rate of photosynthesis

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