20: Photosynthesis - Problems Flashcards
(15 cards)
An experiment is carried out to determine the requirement of photosynthesis. Two variegated leaves are cut from a destarched plant and put into test tubes containing potassium hydroxide or water. The test tubes were put under sunlight for 4 hours.
Explain why leaves from a destarched plant were used in this experiment. (1)
Destarching removes all the starch in the leaves. This makes sure that the starch detected at the end of the experiment is made during the experiment.
An experiment is carried out to determine the requirement of photosynthesis. Two variegated leaves are cut from a destarched plant and put into test tubes containing potassium hydroxide or water. The test tubes were put under sunlight for 4 hours.
Explain why potassium hydroxide is added in tube X. (1)
Potassium hydroxide removes carbon dioxide from the air inside the test tube.
An experiment is carried out to determine the requirement of photosynthesis. Two variegated leaves are cut from a destarched plant and put into test tubes containing potassium hydroxide or water. The test tubes were put under sunlight for 4 hours.
Explain the conclusion drawn from comparing the results for the green part of leaf X and the non-green part of leaf Y. (2)
No conclusion can be drawn,
because two different variables were compared at the same time.
The electron micrograph below shows two chloroplasts X and Y in a leaf.
Based on the electron micrograph, describe three structural differences between chloroplasts X and Y. (3)
The density of thylakoid in chloroplast X is higher than that in chloroplast Y.
Chloroplast X has more grana than chloroplast Y.
Chloroplast Y has more starch grains than chloroplast X.
The electron micrograph below shows two chloroplasts X and Y in a leaf.
With reference to the electron micrograph, deduce and explain which chloroplast can produce more carbohydrates. (2)
Chloroplast Y
Chloroplast Y contains more starch grains than chloroplast X. This indicates chloroplast Y produces more carbohydrates than chloroplast X.
The electron micrograph below shows two chloroplasts X and Y in a leaf.
With reference to the electron micrograph, deduce and explain which chloroplast can capture more light energy. (2)
Chloroplast X
Chloroplast X contains more grana than chloroplast Y. This provides a larger surface area to pack more chlorophyll for absorbing light.
DSE 2016 IB Q3
The diagram below shows the electron micrograph of an organelle.
Label A and B, and state the functional relationship between A and B. (2+3)
A: Thylakoid membrane
B: Stroma
Photochemical reactions take place at A,
which provides ATP and NADPH
for carbon fixation to take place at B.
or:
Carbon fixation takes place at B,
which generates NADP
for photochemical reactions to take place at A.
(AL Bio 2011 I Q5)
(AL Bio 2012 I Q6)
A scientist measured the amount of photosynthetic products produced by three samples of green algae using light flashes. The table below shows the experimental results.
Explain the hypothesis that the rate of light reaction is faster than that of dark reaction based on the experimental results. (2)
By comparing the results of X and Y, when the duration of dark period increases and the duration of light period remains unchanged,
the amount of photosynthetic products increases from 2 to 5 arbitrary units.
A scientist measured the amount of photosynthetic products produced by three samples of green algae using light flashes. The table below shows the experimental results.
Explain the results in sample Z. (1)
The products in the light reaction are used up. Therefore, the amount of products produced in sample Z is the same as that in sample Y.
A scientist measured the amount of photosynthetic products produced by three samples of green algae using light flashes. The table below shows the experimental results.
Explain the difference in the amount product produced ed in X if the light intensity is increased. (2)
The amount of photosynthetic products would remain the same.
The rate of photosynthesis in sample X is **limited by the dark reactions*. Increasing the light intensity would not affect the rate of dark reactions.
DSE 2017 IB Q7
The diagram below shows an experimental set-up for investigating the effect of light intensity on the rate of photosynthesis.
State and explain the assumption behind using the volume of oxygen released per unit time to indicate the photosynthetic rate. (2)
The rate of respiration of the plant remains constant throughout the experiment,
such that any change in the net production of oxygen can be attributed to the change in photosynthetic rate.
DSE 2017 IB Q7
The diagram below shows an experimental set-up for investigating the effect of light intensity on the rate of photosynthesis.
Suggest and explain two modifications to this experimental set-up to make sure that the result is sue to the independent variable only. (5)
- Place a thermometer in the beaker,
to ensure that the temperature is constant,
as temperature is also a factor that may affect the photosynthetic rate. - Add a heat shield or use a cold light source to conduct this experiment
to avoid heating up of water in the beaker
as temperature is also a factor that may affect the photosynthetic rate.
DSE 2017 IB Q7
The diagram below shows an experimental set-up for investigating the effect of light intensity on the rate of photosynthesis.
State the significance of two products of the photochemical reactions to the whole photosynthetic process. (4)
ATP is produced in photochemical reactions,
which provides energy for the Calvin cycle.
NADPH is also produced in photochemical reactions,
which reduces the 3-C compound to form triose phosphate.
