Biology a level work, Schemes and Mind Maps of Biology

Download Biology a level work and more Schemes and Mind Maps Biology in PDF only on Docsity!

WJEC (Eduqas) Biology A-level

Topic 1.2: Photosynthesis

Questions by Topic

The diagram below shows the events involved in photosynthesis.

(a) (i) Name stages Y and Z in the light dependent stage.

[1]

Y....................................................................................

.........

Z....................................................................................

.........

(ii) What is represented by circles A?

[1]

(iii) Complete the boxes above to show the reactions occurring at point B.

[1]

(c) Plants take up minerals from the soil. These are combined with the products of the light independent

stage to produce other molecules needed by the plant.

Give three examples of minerals taken up from the soil and state what molecules are produced when

each example combines with the products of the light independent stage.

[3]

(a) Choose a letter or letters from the electron micrograph above that indicate. (^) [3]

2. The electron micrograph below shows part of a palisade cell, including one chloroplast.

(ii) Suggest how many times the Calvin cycle must occur to produce one molecule of glucose.

[1]

Diuron is a weed-killer which is a very specific and sensitive inhibitor of photosynthesis. It blocks the

electron carrier binding site on photosystem II. This stops the electron flow from where it is generated, in

photosystem II, to the electron carrier. This reduces the ability of the plant to convert light energy into

chemical energy.

Diuron only blocks electron flow from photosystem II. It has no effect on photosystem I or other reactions

in photosynthesis, such as light absorption or carbon fixation in the Calvin cycle.

(a) Explain the effects of Diuron on non-cyclic photophosphorylation and why cyclic photophosphorylation

is not affected.

[4]

(b) Suggest why a plant would die when the weedkiller Diuron is sprayed onto it.

[3]

(c) The Calvin cycle is shown below with some of the intermediate compounds drawn.

(i) Name compounds 1, 2 and 3 shown on the diagram above.

[3]

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

..........

2....................................................................................

(b) The Rf value of the pigments can be calculated using the following formula.

Rf= distance moved by pigment from origin dist ance moved by solvent front from origin

Calculate the Rf value of the yellow band and use the following table of Rf values to identify it. Show your working. (^) [3]

Rf value =^ ..

Pigment Rf value

xanthophyll 0.

chlorophyll b 0.

chlorophyll a 0.

carotene 0.

Identity of yellow band

(d) Use your knowledge of photosynthesis to explain the role of these pigments in the production of ATP. (^) [3]

(e) Calvin worked out that the ribulose bis^ phosphate is regenerated so that the reactions are in the form of a cycle, which is summarised below: Carbon dioxide (CO 2 )

Ribulose bisphosphate (RuBP) Glyceraldehyde-3-phosphate (GP)

Triose phosphate (TP)

Glucose

Compound X is a hydrogen carrier and compound Y is the universal energy currency in cells.

(i) Complete the diagram to show how compounds X and Y change during the cycle.

[2]

(ii) Which series of reactions provides the compounds X and Y in chloroplasts? [1]

(iii) State precisely where the production of X occurs in chloroplasts. [1]

(f) How many molecules of triose phosphate would be needed to synthesise three molecules of glucose?

(Total 10 marks)

[1]

[1]