WA2 Practice Paper: Weighted Assessment 2 — question paper

Section A: Multiple-choice questions[10 marks]

Answer all questions. For each question, write the letter (A, B, C or D) of the correct answer.

1. 1

   Iodine solution turns blue-black with

   1. Astarch
   2. Bglucose
   3. Cprotein
   4. Dfat
   ( )
2. 2

   Biuret solution turns violet in the presence of

   1. Astarch
   2. Breducing sugars
   3. Cprotein
   4. Dwater
   ( )
3. 3

   An enzyme is denatured at high temperatures because

   1. Aits substrate is used up
   2. Bit dissolves in the water
   3. Cits active site changes shape so the substrate no longer fits
   4. Dits pH rises to zero
   ( )
4. 4

   Lipase digests fats into

   1. Aamino acids
   2. Bglucose
   3. Cglycogen
   4. Dglycerol and fatty acids
   ( )
5. 5

   Bile helps fat digestion by

   1. Achemically digesting fat
   2. Bemulsifying fat into tiny droplets
   3. Cneutralising fat molecules
   4. Dconverting fat to glucose
   ( )
6. 6

   Most nutrient absorption occurs in the

   1. Asmall intestine
   2. Bstomach
   3. Clarge intestine
   4. Doesophagus
   ( )
7. 7

   Which vessel carries blood away from the heart to the body?

   1. Athe vena cava
   2. Bthe pulmonary artery
   3. Cthe hepatic vein
   4. Dthe aorta
   ( )
8. 8

   Blood group O is the universal donor because its red cells carry

   1. Aboth A and B markers
   2. Bonly the O marker
   3. Cneither A nor B markers
   4. Dextra antibodies
   ( )
9. 9

   Valves in the heart ensure that blood

   1. Acarries more oxygen
   2. Bmoves in one direction only
   3. Cclots faster
   4. Dbypasses the ventricles
   ( )
10. 10

    During the cardiac cycle, systole is when the heart muscle

    1. Acontracts and ejects blood
    2. Brelaxes and refills
    3. Cstops briefly
    4. Dreceives blood from the lungs only
    ( )

Section B: Structured questions[30 marks]

Answer all questions in the spaces provided.

1. 1

   A food sample is tested with several reagents.

   1. (a)

      Complete the table: reagent and positive result for (i) reducing sugars and (ii) protein.

      [2]
   2. (b)

      Describe the ethanol emulsion test for fats.

      [3]
   3. (c)

      Explain why the synthesis of starch from glucose and of polypeptides from amino acids is called condensation.

      [3]
   4. (d)

      State the elements present in proteins but absent from carbohydrates.

      [2]
2. 2

   An enzyme experiment measures how quickly a starch–amylase mixture loses its iodine colour at different pH values.

   1. (a)

      State the substrate and the products of amylase.

      [3]
   2. (b)

      Sketch-in-words the graph of time to lose the colour against pH, and explain its shape.

      [4]
   3. (c)

      State one variable the student must keep constant and explain why.

      [3]
3. 3

   The heart and blood vessels form the transport network of the body.

   1. (a)

      Name the vessel that carries deoxygenated blood from the heart to the lungs.

      [1]
   2. (b)

      Explain why the left ventricle has a thicker wall than the right ventricle.

      [3]
   3. (c)

      A heart beats 72 times per minute, ejecting 75 cm³ per beat. Calculate the cardiac output in litres per minute.

      [3]
   4. (d)

      Name the blood component that engulfs bacteria.

      [1]
   5. (e)

      State one reason a group A patient must not receive group B blood.

      [2]