Biology: Age 13

6 illustrated Biology lessons for Age 13.

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…