GCSE Combined Science Higher Short Paper A
Covers Cell Biology, Organisation, Infection and Response and 3 more.
Questions
Question 1 [4 marks]
Bonding, Structure and the Properties of Matter
A polymer chain is made from 250 repeating ethene monomer units.
Each monomer unit has a length of 0.25 nm when incorporated into the polymer chain.
Calculate the total length of the polymer chain, in nm.
Question 2 [4 marks]
Bioenergetics
A plant takes up 45 cm^3 of carbon dioxide during 15 minutes of photosynthesis.
Calculate the mean rate of carbon dioxide uptake, in cm^3 per minute.
Question 3 [5 marks]
Cell Biology
A student investigates the effect of hydrogen peroxide concentration on the rate of the reaction catalysed by catalase in celery extract, measuring the volume of oxygen gas produced in 60 seconds.
Using 1% hydrogen peroxide, 18 cm^3 of oxygen gas is collected in 60 seconds. Using 3% hydrogen peroxide, 54 cm^3 of oxygen gas is collected in 60 seconds.
Calculate the percentage increase in the rate of reaction caused by using the higher concentration of hydrogen peroxide.
Question 4 [5 marks]
Infection and Response
A new antiviral drug is trialled at a dose of 8 mg per kg of body mass.
Calculate the dose, in mg, needed for a patient with a body mass of 72 kg, and calculate this dose in grams.
Question 5 [5 marks]
Organisation
Cardiac output is the volume of blood pumped by the heart in one minute.
A patient has a heart rate of 72 beats per minute and a stroke volume of 70 cm^3.
Calculate the cardiac output, in dm^3 per minute. Use cardiac output = heart rate x stroke volume.
Question 6 [5 marks]
Infection and Response
Vaccination can protect an individual against future infection by a specific pathogen.
Explain how vaccination can protect an individual against future infection by a specific pathogen.
Question 7 [6 marks]
Atomic Structure and the Periodic Table
Group 7 of the periodic table contains the halogens, which react by gaining one electron to form a negative ion.
Explain, in terms of electronic structure, why reactivity decreases going down Group 7 of the periodic table.
Question 8 [6 marks]
Infection and Response
A pharmaceutical company trials a new antibiotic. In preclinical testing on animals, the maximum safe dose is found to be 15 mg per kg of body mass.
In the phase 1 human trial, doctors use only 20% of this maximum safe dose, calculated using the average body mass of the trial's 60 kg volunteers.
Calculate the maximum safe dose for a 60 kg volunteer, and calculate the dose that will actually be used in the phase 1 trial.
Model solutions
| Question 1[4 marks] | |
|---|---|
| Answer or working | Marks |
| using total length = number of units x length per unit | M1 |
| substituting 250 x 0.25 | M1 |
| 62.5 | A1 |
| the unit nm | B1 |
| Final answer: 62.5 nm | |
| Question 2[4 marks] | |
|---|---|
| Answer or working | Marks |
| using rate = volume / time | M1 |
| substituting 45 / 15 | M1 |
| 3 | A1 |
| the unit cm^3 per minute | B1 |
| Final answer: 3 cm^3 per minute | |
| Question 3[5 marks] | |
|---|---|
| Answer or working | Marks |
| finding the rate with 1% hydrogen peroxide, 18 / 60 = 0.3 cm^3 per second | M1 |
| finding the rate with 3% hydrogen peroxide, 54 / 60 = 0.9 cm^3 per second | M1 |
| finding the increase in rate, 0.9 - 0.3 = 0.6 cm^3 per second | M1 |
| (0.6 / 0.3) x 100 | M1 |
| 200% | A1 |
| Final answer: 200% increase in the rate of reaction | |
| Question 4[5 marks] | |
|---|---|
| Answer or working | Marks |
| using dose = rate per kg x body mass | M1 |
| substituting 8 x 72 | M1 |
| 576 mg | A1 |
| converting mg to g by dividing by 1000 | M1 |
| 0.576 g | A1 |
| Final answer: 576 mg, which is 0.576 g | |
| Question 5[5 marks] | |
|---|---|
| Answer or working | Marks |
| using cardiac output = heart rate x stroke volume | M1 |
| substituting 72 x 70 | M1 |
| 5040 cm^3 per minute | A1 |
| dividing by 1000 to convert cm^3 to dm^3 | M1 |
| 5.04 dm^3 per minute | A1 |
| Question 6[5 marks] | |
|---|---|
| Answer or working | Marks |
| the vaccine containing a dead or inactive/weakened form of the pathogen (or its antigens) | B1 |
| this stimulating the immune system to produce antibodies specific to the antigen | B1 |
| the person not suffering symptoms of the disease | B1 |
| memory (lymphocyte) cells remaining in the blood | B1 |
| a faster and greater secondary immune response if infected again, destroying the pathogen before symptoms occur | B1 |
| Final answer: Vaccination stimulates antibody and memory cell production for a faster secondary response | |
| Question 7[6 marks] | |
|---|---|
| Answer or working | Marks |
| halogen atoms having more electron shells further down the group | B1 |
| the outer shell being further from the nucleus (a larger atomic radius) | B1 |
| there being increased shielding by inner electron shells | B1 |
| there being a weaker force of attraction between the nucleus and an incoming electron | B1 |
| it being harder for the atom to attract (gain) an extra electron into its outer shell | B1 |
| stating the atom is less reactive further down the group | B1 |
| Final answer: Larger atoms with more shielding attract an extra electron less strongly, so reactivity decreases down Group 7 | |
| Question 8[6 marks] | |
|---|---|
| Answer or working | Marks |
| maximum safe dose = 15 x 60 | M1 |
| 900 mg | A1 |
| using phase 1 dose = 20% of the maximum safe dose | M1 |
| substituting 0.20 x 900 | M1 |
| 180 mg | A1 |
| stating a much lower dose is used in phase 1 to minimise risk to the small number of healthy volunteers, since a human's response may differ from an animal's | B1 |
| Final answer: Maximum safe dose 900 mg; the phase 1 trial uses 180 mg (20% of this), to minimise risk to human volunteers | |