Biology · Cell biology. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
All living things are made of cells. Animal and plant cells are eukaryotic: their DNA is held inside a nucleus. Bacterial cells are prokaryotic: they are much smaller and have no nucleus. Their DNA is a single loop in the cytoplasm, often with small extra rings called plasmids.
Each sub-cellular structure has one job. If you know the job, you can work out which cells need more of that structure.
As an organism develops, cells differentiate. They gain different sub-cellular structures so that they can do one job well. Most animal cells differentiate early. Many plant cells can differentiate all through life.
Students give the ratio of the sizes as the number of orders of magnitude. Write the ratio as a power of ten first: the power is the answer.
Answer: 3 orders of magnitude.
Type what you are stuck on. The helper finds the explanation, worked examples and the notes to read, free and instant.
Microscopy and culturing microorganisms →Take a Biology test