Fundamentals
The core facts every aspirant should own — each a titled nugget with a real-world story, the concept in plain words, and a memory trick. Works even when the internet doesn't.
300 fundamentals
“The insulin that keeps millions alive is now brewed by bacteria we reprogrammed.”
PCR amplifies a DNA segment into many copies; gel electrophoresis separates DNA fragments by size using an electric field.
“The insulin that keeps millions alive is now brewed by bacteria we reprogrammed.”
A restriction enzyme cuts DNA at specific sites; DNA ligase joins DNA fragments together — the scissors and the glue.
“The insulin that keeps millions alive is now brewed by bacteria we reprogrammed.”
A vector (like a plasmid) carries the gene of interest; the host cell (like a bacterium) receives it and expresses the product.
“The insulin that keeps millions alive is now brewed by bacteria we reprogrammed.”
They recognise specific palindromic sequences and cut only at those exact sites.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
Energy moves one-way through an ecosystem — from the sun to producers to consumers — and is lost as heat at each step.
Memory trick: nutrients cycle, but energy flows one way and dissipates as heat.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
A frequent error is thinking energy is recycled like nutrients. In reality, energy moves one-way through an ecosystem — from the sun to producers to consumers — and is lost as heat at each step.
Memory trick: nutrients cycle, but energy flows one way and dissipates as heat.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
Only about 10% of the energy at one trophic level passes to the next.
Memory trick: because only ~10% moves up, food chains are short and energy pyramids are upright.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
A frequent error is thinking most energy is transferred up the food chain. In reality, only about 10% of the energy at one trophic level passes to the next.
Memory trick: because only ~10% moves up, food chains are short and energy pyramids are upright.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
The feeding positions in a food chain: producers, primary consumers, secondary consumers, and decomposers.
Memory trick: decomposers close the loop by returning nutrients to the soil.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
A frequent error is forgetting decomposers, which recycle nutrients back to producers. In reality, the feeding positions in a food chain: producers, primary consumers, secondary consumers, and decomposers.
Memory trick: decomposers close the loop by returning nutrients to the soil.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
Real ecosystems are interlinked food webs rather than single isolated food chains.
Memory trick: a food web is many interconnected food chains — more realistic and stable.
“Only about 10% of energy passes up each step of a food chain — which is why lions are rare and grass is everywhere.”
A frequent error is assuming each organism eats only one type of food. In reality, real ecosystems are interlinked food webs rather than single isolated food chains.
Memory trick: a food web is many interconnected food chains — more realistic and stable.