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Magnification is image size divided by actual size, with both sizes in the same units. Resolution is the ability to distinguish two close points. An electron microscope can reveal finer structures than a light microscope, but different preparation methods have limitations. In a biological drawing use clear lines, useful labels and an appropriate scale; artistic shading does not substitute for accurate observation.
Video by Cognito. The video’s own board label is retained; follow the specification reference and scope notes on this lesson for assessed content.
Viewing focus: Calculate magnification and actual size
After watching, attempt these questions before opening the answers. You can also use the written lesson below.
After watching 1: What does resolution describe?
Distinguishing nearby points. A bigger blurred image need not reveal more detail.
After watching 2: Which process makes genetically matching body cells?
Mitosis. Copied chromosome sets are distributed equally.
What you'll be able to do
Magnification is image size divided by actual size, with both sizes in the same units. Resolution is the ability to distinguish two close points. An electron microscope can reveal finer structures than a light microscope, but different preparation methods have limitations. In a biological drawing use clear lines, useful labels and an appropriate scale; artistic shading does not substitute for accurate observation.
Chromosomes contain DNA carrying genes. Before mitosis, DNA is copied during the cell cycle. Mitosis separates the copied chromosomes so that daughter nuclei receive the same chromosome information, and division of the cell produces two cells. It supports growth, repair and some asexual reproduction. Mitosis is not the division that halves chromosome number for gametes; that is meiosis. Uncontrolled division can lead to tumours.
Stem cells can divide and differentiate into specialised types. Embryonic stem cells have broad potential, while adult stem cells have more limited roles in repair. Meristem cells support plant growth and cloning. Potential treatments must be evaluated using benefits, immune rejection, uncontrolled growth, evidence and ethical viewpoints. A balanced discussion distinguishes what a cell could theoretically become from a treatment proven effective and safe.
Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.
Common mistakes to avoid
Key takeaways
Question 1: A human body cell with 46 chromosomes undergoes ordinary mitosis. How many chromosomes are in each daughter cell?
46.
Check the assessed scope and practical or mathematical requirements.
An external explanation or interactive activity to use alongside the lesson. It may include extension material.
Close the notes and answer from memory. Revisit any explanation you cannot yet reconstruct.
Test yourself
Answer a few questions, then review anything you missed.
Start with the quiz above to check the key ideas. You can also choose another topic from the practice library.