Past Paper 2018 paper 1 mistakes

Question 1

What causes Salmonella (bacteria) ‘s symptoms?

Answer 1

Toxins

Question 2

A person with AIDS may take longer than a healthy person to recover from a Salmonella infection. Explain why

Answer 2

with AIDS the immune system is weakened
so the white blood cells cannot kill Salmonella

Question 3

How do you change an investigation to allow the student to check if the results are repeatable?

Answer 3

Repeat and look to see if results are similar

Question 4

What other cleaning factor should someone choose when considering a cleaning liquid apart from effectiveness and cost?

Answer 4

Side Effects

Question 5

Name three substances transported in blood plasma.

Answer 5

Glucose
Protein
Urea

Question 6

Why is more red blood cells per cm^3 of blood an advantage?

Answer 6

More hemoglobin
more oxygen reaches muscles
More aerobic respiration

Question 7

Which type of blood vessel carries blood into the right atrium

Answer 7

vena cava

Question 8

What condition can be treated with an artificial pacemaker?

Answer 8

Irregular Heartbeat

Question 9

Why does the mouthpiece of an aphid contain a high concentration of dissolved sugars after feeding?

Answer 9

The mouth piece entered the phloem

Question 10

Why would magnesium deficiency cause symptoms like yellow leaves and stunted growth?

Answer 10

The leaves are yellow due to a lack of chlorophyll
Therefore less light is absorbed
Therefore less photosynthesis
Therefore less sugar and glucose created
So more stunted growth

Question 11

How would a scientist use PVY protein to produce PVY monoclonal antibody?

Answer 11

inject the protein / it into a mouse
combine lymphocytes with
tumour / cancer cells to make
hybridoma (cells)
find a hybridoma which makes a
monoclonal antibody specific to
PVY
(the scientist) clones (the
hybridoma) to produce many
cells (to make the antibody)

Question 12

Test for protein?

Answer 12

• Biuret reagent (allow CuSO4 and NaOH) tests for protein
• add Biuret reagent to sample
• solution will turn (from blue) to lilac if positive

Question 13

Test for sugars?

Answer 13

• Benedict’s reagent tests for sugars
• add Benedict’s reagent to milk and boil / heat (allow any
  temperature above 60 °C)
• solution will turn (from blue) to (brick) red / brown / orange /
  yellow / green if positive

Question 14

Give a reason why the measurement for the time taken for the indicator to become colourless might be inaccurate.

Answer 14

It is based on opinion, so results will vary

Question 15

How does bile increase the rate at which milk is broken down?

Answer 15

bile emulsifies fats
creates a larger surface area (of
fat)
(so) lipase can break down fat
(to produce fatty acids) more
quickly / effectively