GCSE Biology: Cell Biology — Topic Revision Workbook

Inside GCSE Biology: Cell Biology — Topic Revision Workbook

name the parts of animal, plant and bacterial cells and tell eukaryotic from prokaryotic, size up specialised cells and work out magnification 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 exam-style application task. About 30 minutes.

Learning objectives

• cell structure — eukaryotic versus prokaryotic cells, plasmids, and the organelles of animal, plant and bacterial cells with their functions;
• specialised cells and microscopy — sperm and red blood cell adaptations, magnification (image ÷ real size) and unit conversions between mm and µm;
• cell division and stem cells — the cell cycle, mitosis and chromosome number, and embryonic, adult and meristem stem cells with the ethics of their use;
• transport and surface area — diffusion, osmosis and active transport, and surface-area-to-volume ratio;
• exam-style application — a 6-mark extended answer linking surface-area-to-volume ratio and diffusion distance.

Activities in this book

1. Task 1 — Cell Structure & Organelles

   eukaryotic cells (animal, plant, fungi) have a true nucleus enclosing their DNA. Prokaryotic cells (bacteria) are smaller and have no nucleus — their DNA is a single loop free in the cytoplasm, plus small rings called plasmids. Learn what each organelle does, not just its name.

2. Task 2 — Specialised Cells & Microscopy

   specialised cells are shaped for a job: sperm have a tail and many mitochondria; red blood cells lose their nucleus and fill with haemoglobin. For microscopy, magnification = image size ÷ real (actual) size. Always convert to the same unit first — remember 1 mm = 1000 µm.

3. Task 3 — Cell Division & Stem Cells

   in the cell cycle the DNA is copied so each chromosome has two copies, then the cell divides by mitosis into two genetically identical daughter cells with the same chromosome number. Stem cells are undifferentiated: embryonic, adult (bone marrow) and, in plants, meristem cells at the tips of roots and shoots.

4. Task 4 — Transport & Surface Area

   three ways substances cross the cell 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.

5. Task 5 — Exam-Style Application

   exam questions reward joined-up biology: link a structure to its function, and back up a claim with a reason. For a 6-mark question, plan three or four 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 triangle. Cover magnification = image ÷ real size, and always convert to the same unit (1 mm = 1000 µm) before dividing.
• Model mitosis. Emphasise that the DNA is copied first, so daughter cells keep the same chromosome number (46 in humans) 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.