Combined Science Daily Practice (Higher)
Mark Scheme — 13 marks total
Higher TierMarking Instructions
- • Accept equivalent answers unless the mark scheme states otherwise.
- • M marks are for method — award even if the final answer is wrong.
- • A marks are for accuracy — only award if the method mark has been earned.
- • B marks are independent and can be awarded without other marks.
- • Where a range of answers is acceptable, this is indicated in the mark scheme.
Explain why plants need nitrate ions from the soil.
Acceptable Answer
Nitrate ions contain nitrogen, which is needed to make amino acids. Amino acids are joined together to make proteins. Proteins are needed for growth and repair of cells, and for making enzymes.
A student tests four solutions with universal indicator. Results: A = red, B = green, C = purple, D = orange. (a) Which is neutral? (b) Which is a strong alkali? (c) Put them in order of pH, lowest first.
Acceptable Answer
(a) B (green = pH 7 = neutral) (b) C (purple = pH 13-14 = strong alkali) (c) A (red, pH ~1), D (orange, pH ~4), B (green, pH 7), C (purple, pH ~14)
A 100W light bulb is left on for 5 hours. Electricity costs 30p per kWh. (a) Calculate the energy used in kWh. (b) Calculate the cost.
Acceptable Answer
(a) Energy = 0.1 kW × 5 h = 0.5 kWh (b) Cost = 0.5 × 30p = 15p
Describe the process of mitosis and explain why it is important.
Acceptable Answer
DNA replicates. Chromosomes line up at the centre. They are pulled apart to opposite ends. The cell divides into two daughter cells, each with identical DNA. Important for: growth (making new cells), repair (replacing damaged cells), and asexual reproduction.