GCSE BIOLOGY 8461/2H Paper 2H Mark scheme Specimen (set 2) Version: 1.0

Question Answers Extra information Mark AO / Spec. Ref. / Demand 01.1 times are very short / in milliseconds or milliseconds cannot be measured with a stopwatch 1 AO3 4.5.2.1 Standard 01.2 to increase validity / repeatability or to get representative results because of variation in results allow to give a more reliable mean value allow to identify any anomalies 1 1 AO2 4.5.2.1 Standard 01.3 (they have included) 468 / the 7th result (which) is anomalous / is a much higher value (than the others) allow identification of anomaly in the table 1 1 AO3 4.5.2.1 Standard 01.4 275 259 1.06 (: 1) an answer of 1.06 (: 1) scores 2 marks allow max 1 mark if wrong number of sig. figs. 1 1 AO2 4.5.2.1 Standard 01.5 2.59 × 10 –1 seconds 1 AO2 4.5.2.1 Standard 7MARK SCHEME – GCSE BIOLOGY – 8461/2H – SPECIMEN (SET 2) 01.6 any two from: • cannot compare mean to B as it has been incorrectly calculated • C’s mean reaction time is the longest, not the shortest • only measured one type of reaction or cannot generalise to all reaction types • other factors can influence reaction time allow examples 2 AO3/ 4.5.2.1 Standard 01.7 involves (the conscious part of) the brain allow voluntary (re)action 1 AO2 4.5.2.1 Standard Total 11 8MARK SCHEME – GCSE BIOLOGY – 8461/2H – SPECIMEN (SET 2) Question Answers Extra information Mark AO / Spec. Ref. / Demand 02.1 (molecules are) (too) large cannot pass through (filtration) membrane / (holes in) filter allow ‘is not filtered out of the blood’ 1 1 AO1 4.5.3.3 Standard 02.2 glucose is reabsorbed all of it ignore ‘is absorbed’ unless qualified by ‘into blood’ 1 1 AO1 4.5.3.3 Standard 02.3 (molecules / ions) small so pass through filter or not all is reabsorbed more water reabsorbed on a hot day due to more water lost in sweat allow the body needs to maintain the right balance of ions and urea in the blood ignore ‘are filtered’ unqualified ‘more’ needed at least once to gain both marks 1 1 1 AO1 AO2 4.5.3.3 Standard 9MARK SCHEME – GCSE BIOLOGY – 8461/2H – SPECIMEN (SET 2) 02.4 Level 3: A judgement, strongly linked and logically supported by a sufficient range of correct reasons, is given. 5–6 AO3 AO2 4.5.3.3 Level 2: A judgement, supported by some relevant reasons is Standard given. 3–4 Level 1: Relevant points are made. If there is a judgement, this is asserted, but not logically linked to the points made. 1–2 No relevant content 0 Indicative content pro transplant: • (dialysis requires repeated treatments to prevent) build-up of toxins or to prevent raised blood pressure between sessions • inconvenience of dialysis, eg long sessions of immobility or repeated hospital visits • (dialysis requires restricted diet) to prevent build-up of urea / ions • there is a greater risk of infection with dialysis eg repeated puncturing of skin or use of non-sterile equipment allows entry of microorganisms • there is a risk of blood clots with dialysis • dialysis more expensive in the long term / 2+ years or examples given eg 2 yrs dialysis = £60 000 compared with 2 yrs after transplant = (£51 000 + £5 000) = £56 000 • transplant is a long term treatment or may remain healthy for many years con transplant: • shortage of kidney donors leading to long waiting time • requires death of another person or live donation leaving a person with just one kidney • exploitation of poor people for donor kidneys (paying for organs) • need to match tissue type • rejection – role of wbcs / lymphocytes • need immunosuppressant drugs – susceptibility to infection • dangers of surgery – physical damage / infection / brain damage from anaesthetic • high initial cost – limited funding (either personal or NHS / CCG) Total 13 10MARK SCHEME – GCSE BIOLOGY – 8461/2H – SPECIMEN (SET 2) Question Answers Extra information Mark AO / Spec. Ref. / Demand 03.1 any two from: • sprinkled through air • air spaces between stones • thin layer over stones (for efficient diffusion) • slow flow (for efficient diffusion) 2 AO2 4.7.3.1 4.7.3.2 4.4.2.1 Standard 03.2 green algae 1 AO1 4.7.2.1 4.7.4.1 Standard 03.3 (large / small) protist 1 AO1 4.7.4.1 Standard