Key Concepts in Biology | Edexcel GCSE Combined Science Biology, Higher tier (1SC0)
Key Concepts in Biology
- 147 questions
- 9 subtopics
- Paper 1
- Paper 1 and Paper 2
Key Concepts in Biology is examined in both biology papers, Paper 1 and Paper 2, as the key concepts that run through the whole course.
It covers eukaryotic and prokaryotic cells, specialised cells, microscopy and magnification, size, scale and units, enzyme action, denaturation and the factors affecting enzyme activity, enzymes in synthesis and digestion with rate calculations, diffusion, osmosis and active transport, and the potato osmosis practical with percentage change in mass.
Sample questions from Key Concepts in Biology
Answer each one closed book first, then open the answer.
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Eukaryotic and prokaryotic cells
Explain why muscle cells contain very large numbers of mitochondria.
Show the answer
Mitochondria are the site of aerobic respiration, and contracting muscle needs a large and continuous supply of energy. -
Specialised cells and their adaptations
Explain why the nucleus of a sperm cell is haploid.
Show the answer
It carries only one set of chromosomes, so that fertilisation restores the full number rather than doubling it. -
Microscopes and magnification calculations
Explain how improvements in microscope technology have changed our understanding of cells.
Show the answer
Greater magnification and resolution revealed organelles that were previously invisible, which allowed scientists to work out what each one does. -
Size, scale and units in cell biology
What does the prefix micro mean, and which unit is used for measuring most cells?
Show the answer
Micro means 10⁻⁶, and cells are usually measured in micrometres. -
Enzyme action and denaturation
Why is the mechanism of enzyme action described as a lock and key model?
Show the answer
Only one substrate fits the active site, in the same way that only one key fits a particular lock. -
Factors affecting enzyme activity
Two enzymes act on the same substrate but have optimum pH values of 3 and 8. Explain why they can still both be described as specific.
Show the answer
Specificity refers to the match between active site and substrate shape, while the optimum pH only describes the conditions in which that shape is held. -
Enzymes in synthesis and digestion, and rate calculations
Name the enzyme group that breaks down carbohydrates, and state the products.
Show the answer
Carbohydrases break down carbohydrates such as starch into simple sugars such as glucose. -
Diffusion, osmosis and active transport
State three factors that increase the rate of diffusion into a cell.
Show the answer
A steeper concentration gradient, a larger surface area and a shorter diffusion distance all increase the rate.
The 9 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Eukaryotic and prokaryotic cells | What makes a cell eukaryotic, the functions of the nucleus, partially permeable membrane, mitochondria and ribosomes, how the cellulose cell wall, chloroplasts and permanent vacuole suit plant cells, and the circular chromosomal DNA, plasmids, flagellum and smaller ribosomes of a bacterium. | 14 |
| Specialised cells and their adaptations | What a specialised cell is, how the acrosome, haploid nucleus, mitochondria and tail adapt a sperm cell, the nutrient store and membrane change of an egg cell, and how the cilia of ciliated epithelial cells sweep mucus away from the lungs. | 8 |
| Microscopes and magnification calculations | Magnification and resolution, why electron microscopes resolve finer detail and what they revealed, preparing, staining and focusing an onion slide, total magnification, the magnification equation and calculating actual size in micrometres, rules for scientific drawings, and reducing error when measuring cells. | 16 |
| Size, scale and units in cell biology | Typical sizes of bacterial and animal cells, orders of magnitude and when to estimate, the prefixes milli, micro, nano and pico, converting sizes to metres in standard form and calculating size ratios and magnification from them, and the symbols for much less than, much greater than, approximately and proportional to. | 21 |
| Enzyme action and denaturation | Enzymes as biological catalysts, the active site and substrate, specificity and the lock and key model, lowering the energy needed to start a reaction, and how high temperature and extreme pH permanently denature an enzyme so its substrate no longer fits. | 12 |
| Factors affecting enzyme activity | How temperature, substrate concentration and pH affect enzyme activity, optimum temperature and pH, the amylase and starch investigation with buffers, iodine and a water bath, its variables, errors and results, and accuracy, precision, repeatability, reproducibility, and random and systematic errors. | 26 |
| Enzymes in synthesis and digestion, and rate calculations | Calculating rate as 1 divided by time and as volume per unit time, comparing rates, carbohydrases, proteases and lipases and their products, enzymes building carbohydrates, proteins and lipids, and giving calculated answers to an appropriate number of significant figures. | 19 |
| Diffusion, osmosis and active transport | Diffusion as net movement down a concentration gradient without energy, the factors that increase its rate, osmosis through a partially permeable membrane and water entering root hair cells, and active transport against a gradient using carrier proteins and energy from respiration to take up mineral ions. | 10 |
| Osmosis in potatoes and percentage change in mass | Preparing and blotting potato cylinders and the variables in the osmosis investigation, why tissue gains or loses mass, calculating percentage change in mass and final mass, using repeats and means, and writing up an investigation from aim and hypothesis to conclusion and evaluation, and other ways to communicate findings. | 21 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
Edexcel GCSE Combined Science Biology, Higher tier Active Recall Guide
Every topic, not just this one. 968 questions with their answers.