Biology: Age 13

15 illustrated Biology lessons for Age 13.

How snails make baby snails Every garden snail has both sperm and eggs, but it still needs a partner to reproduce. The two snails swap spe…
Heart, vessels and lungs at work When you run, your muscles need much more oxygen and fuel, so your lungs and heart work harder. The heart pump…
Identical copies or varied young A strawberry plant sends out runners that grow into new plants identical to the parent, with no partner needed…
How We Breathe In When you breathe in, the diaphragm under your lungs tightens and flattens while your ribs lift up and out. Thi…
Breathing In When you breathe in, the diaphragm pulls flat and the ribs swing up and out. That makes more room in the chest…
A Gene and a Mutation A gene is a set of instructions for building a protein. A mutation changes those instructions, so the protein …
Bacteria That Survive Antibiotics kill many bacteria, but a few may survive because of random changes. Those survivors multiply, so …
Game Points and Dopamine Winning points in a game can make your brain's reward circuit release dopamine. That dopamine signal makes the…
DNA Code and Proteins DNA looks like a twisted ladder, and its rungs are made of four chemical bases. A gene is a sequence of these …
Nerve cells passing a message Nerve cells are long, branching cells that carry messages around the body. A message travels as a tiny electri…
One X or two X Red-green color blindness is inherited through chromosomes. Boys have one X and one Y, so a single changed X c…
Whale Breath Hold A sperm whale can stay underwater for over an hour while a human diver cannot. Its body stores and saves oxyge…
Five Fingers in a Flipper A sea turtle's front flipper looks like a smooth paddle, but inside it has the same arm bones as a land reptil…
Ice Edge Flower Pockets A huge ice sheet once covered most of a mountain slope. In a few small bare-rock pockets near the sea, some pl…
Inside the Heart and Its Vessels Your heart is a muscular pump that pushes blood around your whole body without ever stopping. Arteries carry t…