GCSE Biology: Cell Biology — Deep Revision Workbook

Inside GCSE Biology: Cell Biology — Deep Revision Workbook

sort cell types and name the organelles with their jobs, size up specialised cells and work microscopy maths with mm and µm, revise the cell cycle, mitosis and stem cells, master diffusion, osmosis, active transport and surface-area-to-volume ratio, then finish with an extended exam-style application. About 45 minutes.

Learning objectives

• cell types and organelles — eukaryotic versus prokaryotic cells, plasmids, and the organelles of animal, plant and bacterial cells with their functions;
• specialised cells and microscopy — sperm, muscle and red blood cell adaptations, magnification (image ÷ real size), rearranging the formula, and mm–µm conversions;
• the cell cycle, mitosis and stem cells — DNA copying, chromosome number, rounds of division, and embryonic, adult and meristem stem cells with their ethics;
• transport and surface area — diffusion, osmosis and active transport, and surface-area-to-volume ratio;
• extended exam application — a 6-mark answer comparing the three transport processes and applying them to a root hair cell.

Activities in this book

1. Section 1 — Cell Types & Organelles

   eukaryotic cells (animal, plant, fungi) keep their DNA inside a true nucleus; prokaryotic cells (bacteria) are much smaller and have no nucleus — their DNA is a single loop free in the cytoplasm, plus small rings called plasmids. Learn the job of each organelle, not just its name, and remember plant cells have extras: cell wall, chloroplasts and a permanent vacuole.

2. Section 2 — Specialised Cells & Microscopy

   specialised cells are shaped for a job: sperm carry many mitochondria for energy, red blood cells lose their nucleus to fit more haemoglobin. For microscopy, magnification = image size ÷ real size, so real size = image size ÷ magnification. Always convert to the same unit first — 1 mm = 1000 µm.

3. Section 3 — Cell Cycle, Mitosis & Stem Cells

   in the cell cycle the DNA is copied first, so each daughter cell keeps the full chromosome number and is genetically identical. Mitosis makes body cells for growth and repair. Stem cells are undifferentiated: embryonic, adult (e.g. bone marrow) and, in plants, meristem cells at the tips of roots and shoots.

4. Section 4 — Transport & Surface Area

   three ways substances cross the membrane: diffusion (high to low concentration), osmosis (water across a partially permeable membrane) and active transport (against the gradient, using energy from respiration). Small cells have a large surface-area-to-volume ratio; the ratio falls as an object gets bigger, which is why large organisms need exchange surfaces.

5. Section 5 — Extended Exam-Style Application

   exam questions reward joined-up biology: link a structure to its function, and back up each claim with a reason. For a 6-mark question, plan four or five clear points, use the correct key terms, and answer every part of the question.

Suggestions for teaching

• Start with the cell. Make sure learners can label and give the function of every organelle in an animal, plant and bacterial cell before moving on.
• Drill the magnification formula both ways. Cover magnification = image ÷ real size and real size = image ÷ magnification, always converting to the same unit (1 mm = 1000 µm) first.
• Model mitosis. Emphasise that the DNA is copied first, so daughter cells keep the same chromosome number and are genetically identical.
• Compare the three transport processes. Contrast diffusion, osmosis and active transport by concentration gradient and energy use.
• Work the SA:V idea. Calculate ratios for cubes of different sizes to show why large organisms need exchange surfaces and transport systems.