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AQA A-Level Biology paper 1 2023 exam questions
A-Level Biology paper 1 2023 exam practice paper for Mock. AQA A-Level Biology paper 1 2023 exam question (***IMPORTANT***)
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A-level Biology Paper 1 2023194 marks
Q1.
The diagram shows the structure of two α-glucose molecules.
(a) On the diagram, draw a box around one chemical group in each glucose molecule
used to form a glycosidic bond.
(1)
(b) A precipitate is produced in a positive result for reducing sugar in a Benedict’s test.
A precipitate is solid matter suspended in solution.
A student carried out the Benedict’s test. Suggest a method, other than using a
colorimeter that this student could use to measure the quantity of reducing sugar in
a solution.
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(2)
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,In an investigation, a student wanted to identify the solutions in two beakers, A and B.
She knew one beaker contained maltose solution and the other beaker contained glucose
solution. Both solutions had the same concentration.
She did two separate biochemical tests on a sample from each beaker.
Test 1 – used Benedict’s solution to test for reducing sugar.
Test 2 – added the enzyme maltase, heated the mixture at 30 °C for 5 minutes, and then
Used Benedict’s solution to test for reducing sugar.
Maltose is hydrolysed by maltase.
The student’s results are shown in the table below.
Colour of solution after testing
with Benedict’s solution
Beaker Test 1 Test 2
A red red
B red dark red
(c) Explain the results for beakers A and B in the table.
Beaker A __________________________________________________________
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Beaker B __________________________________________________________
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(2)
(d) Use of a colorimeter in this investigation would improve the repeatability of the
student’s results.
Give one reason why.
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(1)
In Test 1, the student used a measuring cylinder to measure 15 cm3 of solution from a
Page 2 of 68
, beaker. The measuring cylinder gives a volume with an uncertainty of ±1 cm3. She used a
graduated syringe to measure 5.0 cm3 of Benedict’s solution. The graduated syringe gives
a volume with an uncertainty of ± 0.5 cm3. She mixed these volumes of liquid to do the
biochemical test.
(e) Calculate the percentage error for the measurements used to obtain a 20 cm3
mixture of the solution from the beaker and Benedict’s solution. Show your working.
(2)
Answer = _____________________________%
(Total 8 marks)
Q2.
(a) What is a monomer?
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(1)
(b) Lactulose is a disaccharide formed from one molecule of galactose and one
molecule of fructose.
Other than both being disaccharides, give one similarity and one difference between
the structures of lactulose and lactose.
Similarity ___________________________________________________________
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Difference __________________________________________________________
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(2)
(c) Following digestion and absorption of food, the undigested remains are processed
to form faeces in the parts of the intestine below the ileum.
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, The faeces of people with constipation are dry and hard. Constipation can be
treated by drinking lactulose. Lactulose is soluble, but is not digested or absorbed in
the human intestine.
Use your knowledge of water potential to suggest why lactulose can be used to help
people suffering from constipation.
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(2)
(d) Lactulose can also be used to treat people who have too high a concentration of
hydrogen ions (H+) in their blood.
The normal range for blood H+ concentration is 3.55 × 10–8 to 4.47 × 10–8 mol dm–3
A patient was found to have a blood H+ concentration of 2.82 × 10–7 mol dm–3
Calculate the minimum percentage decrease required to bring the patient’s blood H+
concentration into the normal range.
Answer = ____________________
(2)
(Total 7 marks)
Q3.
(a) Describe a biochemical test to confirm the presence of protein in a solution.
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