Cell Biology Fundamentals

Diffusion is one of the most important ways substances move around your body. It works faster when there's a bigger concentration gradient, higher temperature, or larger surface area. Think about how your lungs have a massive surface area and good ventilation - this makes gas exchange incredibly efficient.

Your intestines use similar tricks with villi - tiny finger-like projections that massively increase surface area for absorbing nutrients. Root hair cells in plants do the same job, extending outwards to grab more water and minerals from soil.

Osmosis specifically moves water across membranes. If a potato slice gains mass in an experiment, water moved in by osmosis. If it loses mass, water moved out - simple as that.

Quick Tip: Remember that diffusion goes from high to low concentration, but active transport can work against this gradient using energy.

Cell structure differs between organisms. Eukaryotes (animals and plants) have nuclei and are much larger than prokaryotes (bacteria) which have free-floating DNA instead. Plant cells have extra bits like chloroplasts for photosynthesis and cell walls for support that animal cells don't need.

Cell division through mitosis creates two identical daughter cells. It's your body's way of growing and repairing damage. The process involves growth, DNA replication, then splitting everything equally between two new cells.

Stem cells are brilliant because they haven't specialised yet. Embryonic ones can become any cell type, whilst adult stem cells are more limited but still crucial for repairs.