Resources from Plants (Edexcel A (SNAB) A Level Biology)

Exam Questions

52 mins5 questions
1a
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2 marks

The diagram below shows a cross-sectional view of the boundary between two adjacent plant cells.


4-2-q1a-plant-cell-wall---sq

Identify the structures labelled B - E. Structure A has been identified for you.

Label Structure
A plasma membrane
B  
C  
D  
E  

1b
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2 marks

State the functions of the structures labelled B and C in the diagram at part (a).

1c
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3 marks

The image below shows a transmission electron micrograph of most of a single plant cell.

The cell was taken from a leaf. Fv5IeeQ4_4-2-q1b-plant-cell-electron-micrograph---sq

(i)

Identify structure X.

(1)

(ii)

Object Y is known as an artefact, which is an error in the preparation of the specimen of an electron micrograph, showing something that is not really there. 

Use your knowledge of plant cell structure to identify the plant cell organelle that object Y could most easily be mistaken for.

Explain your answer.

(2)

1d
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1 mark

Cellulose plays a vital role in supporting a plant and keeping it upright.

Identify from the list I - IV, two other compounds that play an important role in strengthening plant tissues. 

  1. collagen
  2. amylopectin
  3. lignin
  4. water
  A II and III
  B III only
  C I and IV
  D III and IV

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2a
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6 marks

Mustard cress (Sinapis alba) seeds can be used to demonstrate the effect of mineral deficiencies on plant growth. 

These seeds can be grown on damp cotton wool in petri dishes, as shown below.


cress-sachs---sq

The cotton wool can be soaked with various mineral-deficient solutions and the effect on the growing plants observed. Sterile solutions containing all the necessary mineral ions for growth can be purchased. Also available are versions of the solutions that are each lacking in one particular mineral ion.

Five petri dishes were prepared with cotton wool and around 30 mustard cress seeds each. Each dish was illuminated with the same light intensity and wavelength, and kept in the same temperature-controlled room for 5 days. After that time, the growth of the germinating cress plants was observed.

Dish number Deficient mineral ion Observations
1  Phosphate / PO3- Dull green leaves, stunted shoot growth
2  Potassium / K+ Yellow or purple leaf tints, small leaves, browning at leaf edges
3  Magnesium / Mg2+  
4  Nitrate / NO3-  
5  Calcium / Ca2+  

Predict the observations for dishes 3, 4 and 5.

The observations of dishes 1 and 2 have been completed for you. 

Explain your prediction in each case. 

2b
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2 marks

The potassium-deficient seedlings in Dish 2 of the experiment in part (a) showed yellow leaves after 5 days of germination and growth.

However, the earliest leaves that appeared in germination were not yellow, they were a normal green colour.

Explain why.

2c
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2 marks

For the experiment described in part (a), describe and explain a possible control set-up that would be required to help validate the experimental conclusions.

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3a
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2 marks

The diagram below shows a section of a cellulose molecule.

4-2-q3a-cellulose---sq

Name parts J and K.

3b
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3 marks

State the role of cellulose in plant cell walls and explain how its structure is related to this role.

3c
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3 marks

Explain how the structure of amylopectin allows it to be hydrolysed quickly to supply cells with glucose for respiration.

3d
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4 marks

Describe two similarities and two differences between the structures of cellulose and starch.

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4a
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4 marks

A student wanted to compare the tensile strengths of the following plants' fibres, with the aim of advising which would make a good sustainable substitute for plastic-based rope. 

  • Jute (Corchorus olitorius)
  • Flax (Linum usitatissimum)
  • Hemp (Cannabis sativa L. variety

Devise and set out the steps the student should take in an experiment to test the tensile strength of the various plant fibres.

You may assume that the samples of fibre have already been extracted from the respective plants and supplied to the student fully prepared for the experiment. 

Your experimental design should make use of all of the following pieces of equipment. 

retort stand metal weights each 10g clamp micrometer gauge weighting pan scales clamp

The units of measure at this stage should be kg. 

4b
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3 marks

Before starting the investigation, the student drew out a blank results table, shown below. 

Fibre sample
Fibre diameter /mm Mass before breaking / kg
Attempt 1 Attempt 2 Attempt 3 Mean
 Jute          
 Flax          
 Hemp          

The student wished to be able to use the data in the table to calculate each fibre's tensile strength in the unit kg mm-2.

(i)

Deduce the calculation that the student would have to do to find the cross-sectional area of a piece of the various fibres. You may assume that all the fibres are circular in cross-section.

(1)

(ii)

Explain the reason for performing three repeats for each type of fibre. 

(2)

4c
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3 marks

After the experiment, the student's partially completed results table looked like this:

Fibre sample Fibre cross-sectional area / mm2 Mean mass before breaking / kg Tensile strength / kg mm-2
 Jute 5.72 0.60 0.105
 Flax 2.54 0.08 0.031
 Hemp 9.62 1.20  

(i)
Complete the table by calculating the missing value in the greyed-out box of the table above. 

(1)

(ii)

The student concluded that of the three fibres, hemp would be recommended for further analysis into making a rope from sustainable materials.

Evaluate this conclusion.

(2)

4d
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1 mark

Identify the plant tissues from the list I. - IV. that contribute significantly to the tensile strength of fibres such as those in the experiment in part (a).

  1. sclerenchyma
  2. phloem
  3. xylem
  4. cambium
  A I. and III.
  B I. and IV.
  C II. and III.
  D III. and IV.

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5a
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4 marks

Severe headaches are a symptom of migraine.

Sumatriptan is a drug that can reduce the symptoms of migraine.

Adults with migraine took part in a double blind trial to investigate the effects of sumatriptan.

Describe how the double blind trial for this drug could have been carried out.

5b
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1 mark

Patients with a migraine attack were given either 10mg sumatriptan, 20mg sumatriptan or a placebo to treat the pain.

Patients recorded how long it took for them to be free of pain.

The results of this drug trial are shown in the graph below. 


4-2-q5b-sumatriptan-graph---sq

(1)

After 90 minutes, the difference in the percentage of patients free of pain between those taking a placebo and those taking 20 mg sumatriptan is...

  A 37%
  B 40%
  C 77%
  D 79%

5c
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3 marks

Using the information in the graph in part (b), describe the effects of sumatriptan on the treatment of the symptoms of migraine.

5d
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3 marks

Using the information in the graph, deduce what conclusions can be drawn from this drug trial.

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