2.9 Photosynthesis Paper 2 Possible Questions …holdenscienceeducation.wikispaces.com/file/view/2.9_Photosynth... · IB Questionbank Biology 1 2.9 Photosynthesis Paper 2 Possible

IB Questionbank Biology 1

2.9 Photosynthesis Paper 2 Possible Questions Extended Response

1. (a) State the location in the chloroplast of the following reactions of photosynthesis.

Light-independent reactions: .......................................................................................

Light-dependent reactions: .......................................................................................... (2)

(b) Explain what happens to the electrons in the light-dependent reactions of photosynthesis.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (3)

(Total 5 marks)

2. (a) Explain why carbon dioxide concentration is a limiting factor of photosynthesis.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(b) Explain the relationship between the structure of the chloroplast and its function.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................


(3)

(c) State two products of the light-dependent reactions.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 8 marks)

3. Up to two additional marks are available for the construction of your answers. (2)

(a) Living organisms at every trophic level are part of the carbon cycle. Draw a labelled

diagram of the carbon cycle to show the processes involved. (9)

(b) Explain, using an example of a food chain, how trophic levels can be deduced. (4)

(c) Explain methods that can be used to measure the rate of photosynthesis. (5)

(Total 20 marks)


(a) All organisms in an ecosystem are involved in the carbon cycle. Outline the roles of

living organisms in the carbon cycle. (8)

(b) Explain how triose phosphate is produced and used in the chloroplasts of a plant. (5)

(c) Explain the conditions that are needed to allow a seed to germinate. (5)

(Total 20 marks)


5. (a) Draw a labelled diagram of the structure of a chloroplast as seen with an electron

microscope. (4)

(b) Describe how water is carried by the transpiration stream. (7)

(c) Explain how flowering is controlled in long-day and short-day plants. (7)

(Total 18 marks)

6. The graph below shows the results of an experiment to determine the effect of salt (NaCl)

concentration on photosynthesis of the freshwater green alga Chlorella vulgaris. The

experiment attempted to determine the effect of salt concentration on the light-dependent

reactions overall and separately on photosystem I and photosystem II.

[Source: M M El-Sheekh, “Inhibition of the water splitting system by sodium chloride stress in the green alga

Chlorella vulgaris”, Brazilian Journal of Plant Physiology, Volume 16, Issue 1, Figure 1, (2004)]

(a) Describe the effect of salt concentration on the activity of the light-dependent reactions

overall.

......................................................................................................................................

...................................................................................................................................... (1)

(b) Compare the effect of increasing salt concentration on photosystem I with the effect on

photosystem II.

......................................................................................................................................

...................................................................................................................................... (1)


(c) When salt concentration is increased, some algal cells increase their rates of cyclic

photophosphorylation. Deduce the reasons for this.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(d) Using the graph, predict the effect of high salt concentration on the growth of Chlorella

vulgaris. Give a reason for your answer.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(Total 6 marks)


7. Primary production is directly related to the amount of photosynthesis that occurs in a cubic

metre of water. In the waters around Bermuda (32° N) in the Atlantic Ocean, microscopic

phytoplankton are the producers. They use trace nutrients from seawater in their metabolism.

These nutrients are a limiting factor in total population size. A dense phytoplankton population

makes the water cloudy. The data shows primary production per day for each month for the year

2000 at different water depths.

[Source: DataStreme Ocean, American Meteorological Society (2004). Reprinted with permission.]

(a) State the month when total photosynthesis was greatest.

...................................................................................................................................... (1)

(b) Identify, with a reason, the water depth that receives no light.

......................................................................................................................................

...................................................................................................................................... (1)


(c) In the upper 40 m there is a drop in photosynthesis from March to June. This is probably

due to lack of nutrients, reducing the population density.

Suggest, with a reason other than nutrient levels, what might have increased

photosynthesis at 100 m from April to August.

......................................................................................................................................

...................................................................................................................................... (1)

(d) Compare production in March with production in September.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (3)

(Total 6 marks)


8. Global atmospheric carbon dioxide levels are rising. A study was carried out to test if the

temperature dependence of photosynthesis was altered by elevated atmospheric CO2.

Maize plants were grown in natural sunlight in controlled environmental chambers at different

temperatures using current atmospheric and doubled CO2 levels.

The graph below shows daily patterns of CO2 exchange at three different temperatures.

Open shapes (○, Δ, □) represent current atmospheric CO2 levels and closed shapes (●, ▲, ■)

represent elevated CO2 levels.

[Reprinted from: Kim, S H et al. 2007. “Temperature dependence of growth, development, and photosynthesis in maize under elevated CO2”. Environmental and Experimental Botany. Vol 61. Pp 224–236.]

(a) (i) State the time at which carbon dioxide exchange rate is maximal.

........................................................................................................................... (1)

(ii) Explain the reasons for maximum carbon dioxide exchange rate at this time.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)


(b) State the temperature that resulted in the highest rate of photosynthesis under current

atmospheric conditions.

...................................................................................................................................... (1)

(c) Using the data in the graph, discuss whether rising carbon dioxide levels in the

atmosphere will increase growth rates in maize.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(Total 6 marks)


(a) Draw a labelled diagram showing the tissues present in a dicotyledonous leaf. (4)

(b) Outline the light-dependent reactions of photosynthesis. (6)

(c) Explain the effect of light intensity and temperature on the rate of photosynthesis. (8)

(Total 20 marks)


10. The rate of photosynthesis in the marine seagrass, Zostera marina, was investigated under a

range of pH conditions. After a period of darkness, the plants were illuminated at a constant

light intensity at 15°C and the rate of photosynthesis was measured. Zostera marina can use

both dissolved carbon dioxide (CO2) and hydrogen carbonate ions for photosynthesis. The rate

of photosynthesis is plotted on the y-axis on the left. In addition, the concentration of carbon

dioxide was measured for each pH investigated and is plotted on the y-axis on the right.

[Source: Plant physiology by AMERICAN SOCIETY OF PLANT PHYSIOLOGISTS. Copyright 2008 Reproduced

with permission of AMERICAN SOCIETY OF PLANT BIOLOGISTS in the format CD ROM via Copyright

Clearance Center.]

(a) State the carbon dioxide concentration at pH 7.2.

......................................................................................................................................

...................................................................................................................................... (1)


(b) Calculate the percentage decrease in the rate of photosynthesis from pH 7 to pH 7.5.

......................................................................................................................................

...................................................................................................................................... (1)

(c) Outline the relationship between pH and the rate of photosynthesis.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(d) Suggest how Zostera marina can perform photosynthesis even at very low carbon dioxide

concentrations.

......................................................................................................................................

...................................................................................................................................... (1)

(e) Based on the information and data provided, discuss the role of one limiting factor, other

than carbon dioxide, and suggest how this would affect the rate of photosynthesis.

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(Total 7 marks)


11. The effect of temperature on photosynthesis was studied in sweet orange (Citrus sinensis) using

leaf discs. The production of oxygen was used to measure the rate of photosynthesis.

Gross photosynthesis refers to the sum of net photosynthesis and respiration. Net photosynthesis

was calculated by subtracting the rate of respiration in the dark from gross photosynthesis.

[Source: Adapted from R Ribeiro et al. 2006. Ciência e Agrotecnologia. Vol 30. Pp 670–678.]

(a) Identify the optimum temperature for photosynthesis in this plant.

...................................................................................................................................... (1)

(b) Determine the difference between gross photosynthesis and net photosynthesis at 40°C

and 50°C.

40°C: ..........................................................................................................................

50°C: .......................................................................................................................... (2)

(c) Deduce what happens to the rate of respiration as the temperature increases between 40°C

and 50°C.

...................................................................................................................................... (1)


(d) (i) Describe the general pattern of change in photosynthesis in sweet orange as the

temperature increases.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (1)

(ii) Compare the effect of temperature on photosynthesis with the effect of temperature

on respiration in sweet orange.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(Total 7 marks)

12. Explain the reasons for

(a) a large area of thylakoid membrane in the chloroplast.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(b) low rates of photosynthesis in plants growing beneath trees, where the light has already

passed through the trees’ leaves.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................


(2)

(c) large amounts of RuBP carboxylase in the chloroplast;

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 6 marks)


13. The graph below shows the variation in the concentration of atmospheric carbon dioxide since

1970.

375

370

365

360

355

350

345

340

335

330

325

320

19

70

19

75

19

80

19

85

19

90

19

95

20

00

COconcentration

/ ppm

2

[Source: C D Keeling and T P Whorf, Atmosphere CO2 concentrations (ppm) derived from in situ air samples,

collected at Mauna Loa Observatory, Hawaii]

The annual fluctuation is mainly the result of changes in the levels of photosynthesis associated

with the seasons in Northern Hemisphere forests.

(a) (i) Describe the overall trend shown in the graph.

...........................................................................................................................

........................................................................................................................... (1)

(ii) Suggest a cause for the overall trend throughout the period 1970–1999.

...........................................................................................................................

........................................................................................................................... (1)


(b) (i) Using a clear label, identify any one point on the graph which shows the CO2 level

in mid-summer. (1)

(ii) Explain why the concentration of CO2 varies with the seasons.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(c) Identify one gas, other than CO2 , which is contributing to the enhanced greenhouse

effect.

..................................................................................................................................... (1)

(Total 6 marks)

14. The unicellular green alga Phaeodactylum tricornutum is photosynthetic. Cell biologists

genetically modified this organism by adding a glucose transporter gene. The modified and

unmodified algae were grown in a nutrient medium under a series of different conditions and

the growth rate of the cells was measured.

12

10

8

6

4

2

0

0 2 4 6 8 0 2 4 6 8

Time / days

Cell density /10 cells cm

Key:

= light and no glucose in the medium

= light and glucose in the medium

= dark and glucose in the medium

Unmodified algae Modified algae

–37

[Source: L A Zaslavskaia, et al., Adapted (2001) Science, 292, pages 2073–2075]

(a) State the role of glucose in the metabolism of cells.

..................................................................................................................................... (1)


(b) Deduce where you would expect to find the glucose transporter protein in the modified

algae cells.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c) Compare the effect of light on the modified and the unmodified cells.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

Commercially, unmodified algae are grown in shallow sunlit ponds or illuminated containers.

The cells only grow in the top few centimetres. However, the modified algae can grow at any

depth.

(d) Explain why the modified algae can grow at any depth whereas the unmodified algae can

only grow at the surface.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 8 marks)


15. Copepods are very small crustaceans and an important component of plankton in the Arctic sea

ice. The distribution of copepods, which feed on microalgae, can be related to the food and

predators. The biomass of microalgae was measured and the concentration of chlorophyll a was

calculated. The graphs below show how the concentration of chlorophyll a and copepods

change with depth.

Dep

th /

m

Microalgae

Chlorophyll a / mg m–3

Dep

th /

m

Copepods

Relative numbers

[Source: Martin Fortier, et. al., Visual predators and the diel vertical migration of copepods under Arctic sea ice during the midnight

sun” (2001), vol. 23, issue 11, pp. 1263–1278, by permission of Oxford University Press]

(a) State the amount at a depth of 30 m below sea level of

(i) chlorophyll a;

..........................................................................................................................

(ii) copepods.

.......................................................................................................................... (2)


(b) Describe the distribution of microalgae.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(c) Discuss factors that could affect the distribution of copepods.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3)

(Total 7 marks)


16. The cyanobacterium (Calothrix elenkenii) is cultivated as a source of photosynthetic pigments

for use in research and industry. The chart below shows the quantity of two of the pigments

produced when exposed to a day of continuous dark, a day of 16 hours light and 8 hours dark

and a day of continuous light. This was repeated in both aerobic and anaerobic conditions.

Key:

Dark

Dark

Light – Dark

Light – Dark

Light

Light

Aerobic

Anaerobic

6.05.55.04.54.03.53.02.52.01.51.00.50.0

Amount of Pigment / g cm–3μ

Chlorophyll

β-Carotene

[Source: Reprinted from Journal of Plant Physiology, Vol 161, Parsanna et al., “Modulation of pigment…” pages 1125–1132,

copyright (2002), with permission from Elsevier.]

(a) Identify the light conditions that cause most chlorophyll to be made when the

cyanobacterium is cultivated anaerobically.

.................................................................................................................................... (1)

(b) Calculate the percentage increase in chlorophyll grown anaerobically in the light,

compared with anaerobically in the dark.

.................................................................................................................................... (1)

(c) Compare pigment production in different aerobic conditions.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)


(d) Discuss why having more than one photosynthetic pigment is an advantage to

cyanobacterium.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (3)

(Total 7 marks)

17. Studies were carried out on the leaves of the wild type of the flowering mustard plant

(Arabidopsis thaliana) to determine the pigment composition of the thylakoid membrane. The

results were compared with the leaves of a mutant strain of the plant. These studies were

repeated using thylakoid membranes from leaves grown in cultures deficient in either iron or

magnesium.

Strain of Plant Mineral Deficiency Chlorophyll /

g g–1

leaf

Carotenoids /

g g–1

leaf

None 454 16

Wild Type Iron 441 71

Magnesium 317 64

None 387 67

Mutant Iron 317 81

Magnesium 172 95

[Source: Lu et al, (1995), Botanical Bulletin of Academia Sinica, 36, pages 175–179]

(a) State the concentration of chlorophyll found in the leaves of the mutant strain of plant

when deficient in iron.

.................................................................................................................................... (1)

(b) (i) Calculate the percentage increase in carotenoids found in the wild type when

magnesium is deficient.

.......................................................................................................................... (1)


(ii) Suggest why magnesium deficiency causes the changes shown in the pigment

content of the leaves.

..........................................................................................................................

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(c) Using the data in the table, outline the effects of iron deficiency on the pigment content of

the leaves.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 6 marks)


18. Plants that grow in the desert have many adaptations that enable them to cope with full sunlight

and low water availability, such as thicker leaves with reduced surface area. Researchers have

also observed that leaf pubescence (presence of white leaf surface hairs) may be another

adaptation to dry environments. A study was done to evaluate the effects of leaf pubescence on

two species of Californian plants, Encelia farinosa, a desert species with pubescent leaves and

Encelia californica, a native of the moist coast with non-pubescent leaves.

The graph below shows the absorption spectrum of intact leaves of both species in the

photosynthetically active spectrum between the wavelengths 400 nm (blue light) and 800 nm

(red light) of light.

Absorption

/ %

100

90

80

70

60

50

40

20

10

0

400 450 500 550 600 650 700 750 800

Blue Green Yellow Orange Red

Wavelength / nm

Key:

E. californica

E. farinosa

30

[Source: From J. Ehleringer et al., “Leaf Pubescence: Effects on Absorptance and Photosynthesis in a Desert Shrub”, Science (23

April 1976), vol. 192, issue 4237, pp. 376-377. Reprinted with permission from AAAS]

(a) Calculate the difference in absorption between E. farinosa and E. californica at 600 nm.

....................................................................................................................................

.................................................................................................................................... (1)

(b) Suggest a possible explanation for the decrease in absorption at 550 nm for E. californica.

....................................................................................................................................

.................................................................................................................................... (1)

(Total 2 marks)


19. The following graph shows the rate of CO2 uptake of three leaves of Encelia farinosa with

different absorbance coefficients (x) (proportion of light absorbed) which is related to the degree

of pubescence of the leaf. The higher the coefficient the more light is absorbed.

Rate of CO2 uptake /

n mol CO2 cm–2 sec–1

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

x = 0.82

x = 0.65

x = 0.53

0 50 100 150 200 250

Light intensity / mmol cm–2 sec–1

[Source: From J. Ehleringer et al., “Leaf Pubescence: Effects on Absorptance and Photosynthesis in a Desert Shrub”, Science (23

April 1976), vol. 192, issue 4237, pp. 376-377. Reprinted with permission from AAAS]

(a) Using the graph above, compare the maximum CO2 uptake of E. farinosa at absorbance

coefficients 0.82 and 0.53.

....................................................................................................................................

.................................................................................................................................... (1)

(b) (i) Using the data, deduce the relationship between pubescence and light absorption.

..........................................................................................................................

.......................................................................................................................... (1)


(ii) Evaluate the relationship of leaf pubescence and CO2 uptake.

..........................................................................................................................

.......................................................................................................................... (1)

(c) Suggest how natural selection may have caused the difference in leaf pubescence between

E. farinosa and E. californica.

....................................................................................................................................

.................................................................................................................................... (1)

20. Further research was carried out to evaluate the relationship between leaf pubescence during the

growing season of E. farinosa and its water use efficiency. Water use efficiency is defined as

the amount of CO2 uptake divided by the amount of water lost by transpiration from the leaf.

The graph below shows the seasonal change in leaf pubescence and water use efficiency of E.

farinosa. The period of maximum growth is indicated on the graph. During the course of the

year the optimum temperature for photosynthesis remains at 30C while the air temperature

fluctuates from a high of 38C in the summer months (May–September) to a low of 8C during

the winter months (December–February).

Wat

er u

se e

ffci

ency

/ a

rbit

rary

unit

s

6

5

4

2

1

0 M J J A S O N D J F M A M

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.00

Pu

bescen

ce Thick

ness /m

m

Key:

Water use effciency

Pubescence thickness

Time of the year / month maximum growth period

new leaves emerge

3

[Source: Ecology by William K. Smith and Park S. Nobel. Copyright 1977 by Ecological Society of America. Reproduced with

permission of Ecological Society of America in the format of CD-Rom via Copyright Clearance Center.]


(a) State the month with the highest water use efficiency.

.................................................................................................................................... (1)

(b) Outline the changes in leaf pubescence of E. farinosa during the year.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(c) Analyse the change in the level of water use efficiency between July and December for E.

farinosa.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 11 marks)


21. There are many abiotic factors that affect the rate of photosynthesis in terrestrial plants. Wheat

is an important cereal crop in many parts of the world. Wheat seedlings were grown at three

different concentrations of carbon dioxide (in parts per million) and the rate of photosynthesis

was measured at various light intensities.

50

40

30

20

10

00 5 10 15 20

Light intensity / × 10 lumen m

2

3

2

2

2

–2

–1

Rat

e o

f p

hoto

syn

thes

is /

l

CO

m

in

key:

1300 ppm CO

500 ppm CO

280 ppm CO

[Source: Adapted from J P Kimmins, 1997 Forest Ecology, (2nd edition) page 161]

(a) Describe the relationship between the rate of photosynthesis and light intensity for wheat

seedlings grown at a CO2 concentration of 500 ppm.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)


(b) Outline the effect of CO2 concentration on the rate of photosynthesis of the wheat

seedlings.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(c) The normal atmospheric concentration of CO2 is 370 ppm. Deduce the effect of doubling

the CO2 concentration to 740 ppm on the growth of wheat plants.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

22. Leaf area and chlorophyll levels were measured in sun leaves and shade leaves of Hedera helix

(English Ivy) and Prunus laurocerasus (Cherry Laurel). Sun leaves developed under maximal

sunlight conditions while shade leaves developed at reduced sunlight levels in the shadow of

other leaves.

Species Leaf Type Chlorophyll/

g ml-1

Leaf Area/

cm2

Ivy Shade 4.3 72.6

Sun 3.8 62.9

Laurel Shade 4.7 38.7

Sun 4.2 25.7

[Source: D Curtis, Plant Ecology independent project, 1990]


(a) Calculate the percentage increase in the amount of chlorophyll in shade leaves of ivy

compared to sun leaves of ivy

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (1)

(b) Suggest a reason for the differences in chlorophyll concentration and leaf area in sun and

shade leaves in these two species.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 10 marks)


(a) Draw a labelled diagram showing the structure of a plasma membrane. (4)

(b) Outline the role of chlorophyll and the effects of temperature, light intensity and carbon

dioxide concentration on the rate of photosynthesis. (6)

(c) Explain the production of energy during aerobic respiration from pyruvate that has been

produced by glycolysis. (8)

(Total 20 marks)

24. Explain how the light-independent reactions of photosynthesis rely on light-dependent

reactions. (Total 8 marks)



(a) Draw and label the action spectrum of photosynthesis. (4)

(b) Explain the relationship between the structure of the chloroplast and the light-dependent

reactions of photosynthesis. (8)

(c) Outline the potential harmful effects of increased carbon dioxide concentration on the

ecosystem and state one measure that could be taken to reduce the amount of carbon

dioxide in the atmosphere. (6)

(Total 20 marks)

26. Explain the reactions involving the use of light energy that occur in the thylakoids of the

chloroplast. (Total 8 marks)

27. Outline the effect of temperature, light intensity and carbon dioxide concentration on the rate of

photosynthesis. (Total 6 marks)

28. State two products of the light dependent reaction of photosynthesis.

............................................................................................................................................... (Total 2 marks)


29. (a) Photosynthesis consists of two groups of reactions. State the names of the two groups of

reactions.

.....................................................................................................................................

..................................................................................................................................... (1)

(b) Draw and label the action spectrum of photosynthesis.

(3)

(c) Explain the concept of limiting factors with reference to light intensity.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 6 marks)


30. (a) Photosynthesis consists of two sets of reactions. State the names of these two sets.

......................................................................................................................................

...................................................................................................................................... (1)

(b) Outline how one specific limiting factor affects the rate of photosynthesis.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (2)

(c) Explain the production of ATP by chemiosmosis during photosynthesis.

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

......................................................................................................................................

...................................................................................................................................... (3)

(Total 6 marks)


31. (a) State where in the chloroplast the enzymes of the Calvin cycle are located.

..................................................................................................................................... (1)

(b) Outline the fate of ribulose biphosphate (RuBP) during photosynthesis

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(c) A green plant is not photosynthesizing at its maximum rate when the light intensity is

increased.

Suggest why there is no increase in the rate of photosynthesis

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)


32. The graph below shows the effect of light intensity on photosynthesis at 0.1% carbon dioxide

concentration.

Rate of photosynthesis /arbitrary units

Light intensity / arbitrary units

(a) On the graph above, draw the results obtained at 0.01% carbon dioxide. (1)

(b) Outline the fate of the oxygen and hydrogen which are produced in the photolysis of

water during photosynthesis.

Oxygen: ...............................................................................................................

...............................................................................................................

Hydrogen ...............................................................................................................

............................................................................................................... (2)

(c) The energy produced in photosynthesis can enter a food chain. Explain how this energy

can be lost before it reaches the last link in the chain.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 5 marks)


33. (a) State the main photosynthetic pigment in plants.

..................................................................................................................................... (1)

(b) State the two materials used to convert carbon dioxide to organic molecules in plants.

.....................................................................................................................................

..................................................................................................................................... (2)

(c) Explain two ways in which the rate of photosynthesis can be measured.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (4)

(Total 7 marks)

34. During photosynthesis in plants, light energy is absorbed by chlorophyll. This energy is then

used to carry out photolysis, which supply substances that are needed to convert carbon dioxide

into organic molecules such as glucose.

(a) State the names of two products of photolysis in photosynthesis.

1. .................................................................................................................................

2. ................................................................................................................................. (2)

(b) Explain briefly one method for measuring the rate of photosynthesis in a plant.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

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..................................................................................................................................... (2)


(c) The rate of photosynthesis is affected by light intensity. Draw a line on the graph below

to show the relationship between light intensity and the rate of photosynthesis.

rate of photosynthesis

light intensity (2)

(d) State two factors in the environment of a plant, apart from light intensity, that can affect

the rate of photosynthesis in the plant.

1. .................................................................................................................................

2. ................................................................................................................................. (2)

(Total 8 marks)


35. (a) State the site of the light-independent reactions in photosynthesis.

..................................................................................................................................... (1)

The absorption spectrum of chlorophyll a and chlorophyll b are shown in the graph below.

Absorbance

400 500 600 700

Wavelength / nm

chlorophyll b

chlorophyll a

(b) On the graph above, draw the action spectrum of photosynthesis for a green plant. (1)

(c) Explain photophosphorylation in terms of chemiosmosis.

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..................................................................................................................................... (3)

(Total 5 marks)


36. (a) State where, in the chloroplast, the enzymes of the Calvin cycle are located.

..................................................................................................................................... (1)

(b) Explain how the proton gradient in the chloroplast is generated by chemiosmosis.

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..................................................................................................................................... (3)

(c) Explain the relationship between the position of a leaf on a tree and the photosynthetic

rate of the leaf.

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..................................................................................................................................... (2)

(Total 6 marks)


37. (a) Explain how photosynthesis can be measured both directly and indirectly.

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.................................................................................................................................... (3)

(b) Outline two uses of absorbed carbohydrates in humans.

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.................................................................................................................................... (2)

(c) The diagram below represents an energy pyramid and four trophic levels.

IV

III

II

I100 000 kJ m yr–2 –1

[Source: adapted from www.bio.miami.edu/dana/160/pyramid.gif]

(i) Identify the trophic level of the organisms indicated below.

I. ...............................................................................................................

IV. ............................................................................................................... (2)

(ii) Calculate the approximate amount of energy in kilojoules transferred in m–2

yr–1

from trophic level I to trophic level II.

..................................................................................................................... kJ (1)

(Total 8 marks)

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2.9 Photosynthesis Paper 2 Possible Questions …holdenscienceeducation.wikispaces.com/file/view/2.9_Photosynth... · IB Questionbank Biology 1 2.9 Photosynthesis Paper 2 Possible