Theory:

Different types of cell size
Size of a cell varies across wide limits. Cell sizes can range from nanometers to micrometres. A smaller cell has more volume and surface area than a larger cell.
  • As cell grows, increases of volume more quickly than its surface area. If a cell is enormous, its smaller surface area will not allow enough nutrients to enter or exit the cell soon.
  • If we take the case of a white blood cell, a larger cell handles its nutrients efficiently with the help of more than one nuclei inside it.
  • In the case of microvilli, a cell type in the small intestine, a larger cell has many folds and protrusions. These folding's increase the surface area available for transportation of the material.
Do you know?
  
The smallest cell found is a mycoplasma cell or PPLO (Pleuro Pneumonia Like Organisms, which is about \(0.1 micron\) in diameter.

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Mycoplasma
  • The most elongate cells are the nerve cells measuring about a meter in length.
  • The longest part of a neuron is the axon.
Neuron.svg
Neuron
 
The largest cell is eggs of the ostrich, which is about \(15 cm\) in diameter.
 
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Eggs of the ostrich
 
Interesting facts about the cell in the human body - Ovum is the largest cell in the human body.
 
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Human female ovum
  • Sperm is the male gamete which is the smallest cell in the human body.
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Structure of sperm
Reference:
https://upload.wikimedia.org/wikipedia/commons/b/b5/Neuron.svg
https://pixabay.com/photos/ostrich-egg-egg-large-egg-bouquet-2750297/