Mark Scheme – Gcse Biology – 8461-1H – June 2021.

Question Answers Extra information Mark AO / Spec. Ref. 01.1 any two from: • (microscope) slide • cover slip • dye / stain allow named dye / stain ignore water 2 AO1 4.1.1.5 RPA1 • (mounted) needle • pipette / dropper • scalpel • forceps / tweezers ignore knife allow swab (to collect cells) 01.2 eyepiece / lens do not accept objective lens 1 AO1 4.1.1.5 RPA1 01.3 to focus (the image / cells) allow to make the cells / image clear(er) allow to improve resolution (of the image) ignore to move the stage up / down do not accept reference to magnification 1 AO1 4.1.1.5 RPA1 01.4 any one from: • no cells in the field of view • slide not in the correct 1 AO3 4.1.1.5 RPA1 position • mirror not in correct position allow light / microscope not switched on / plugged in • (objective) lens not clicked into place or (objective) lens dirty • (student is) looking at a (large) air bubble • (the microscope is) not focussed allow student did not stain the cells allow idea of magnification not being high enough 01.5 Level 2: Scientifically relevant features are identified; the way(s) in which they are similar/different is made clear and (where appropriate) the magnitude of the similarity/difference is noted. 4‒6 AO2 Level 1: Relevant features are identified and differences noted. 1‒3 AO1 No relevant content 0 Indicative Content Differences: • red blood cell has no nucleus or plant cell has a nucleus • red blood cell has no cell wall or plant cell has a cell wall • red blood cell is a biconcave disc or there are many different shapes of plant cell • red blood cell contains haemoglobin or plant cells do not contain haemoglobin • red blood cells do not contain chlorophyll or plant cells (may) contain chlorophyll • red blood cell has no chloroplasts or plant cell has chloroplasts • red blood cell has no (permanent) vacuole or plant cell has (permanent) vacuole • red blood cells are (much) smaller than plant cells 4.1.1.2 4.2.2.3 Similarities: both have: • cytoplasm • cell membrane • pigments (although they are different) ignore references to mitochondria and ribosomes for Level 2, consideration of both red blood cells and plant cells is required. 01.6 water enters (the cells) by allow water enters and the cell 1 AO2 osmosis / diffusion starts to swell ignore explanations of osmosis plant cell has a cell wall (which allow red blood cell has no cell 1 AO1 prevents it from bursting) wall (so it swells and bursts) 4.1.3.2 4.1.1.2 Total 13 Question Answers Extra information Mark AO / Spec. Ref. 02.1 any two from: • sterilise equipment / surfaces (before use) • (use) sterilised agar ignore ‘clean’ unqualified ignore wash hands allow description of how to sterilise equipment allow description of how to sterilise agar 2 AO1 4.1.1.6 RPA2 • secure lid of the Petri dish with (adhesive) tape • only lift lid of Petri dish a little (when setting up plate) or lift lid of Petri dish at an angle (when setting up plate) 02.2 B and it kills the fewest bacteria or it has the smallest area where no bacteria were growing allow it has the smallest clear / white area 1 AO3 4.1.1.6 RPA2