Biology: Age 12

15 illustrated Biology lessons for Age 12.

Rods and Cones in the Eye The retina lines the back of the eye. Rod cells help you see shapes in dim light, while cone cells help you se…
Genes and Traits Genes are sections of DNA. They carry instructions that help build and run a body, and they can affect visible…
Eyes, Ears, and the Fear Switch Light and sound enter through your eyes and ears. Signals travel through a brain relay to two almond-shaped cl…
Cat Purr Vibrations A cat's purr starts when air moves from the lungs through the trachea. The moving air makes thin folds in the …
Virus Entering a Cell A virus attaches to the outside of a cell and sends its genetic material inside. The cell then makes new virus…
Underground Root Threads Below the soil, pale threads join the roots of different plants. Water, nutrients and warning signals can trav…
Sunlit Slope and Rising Air Sunlight warms the rocky slope, and the air just above it becomes lighter. That rising air forms a column that…
Warm Sand Nest A buried clutch of eggs rests in a flask-shaped chamber under the sand. The sand near the middle is warmer tha…
Warm Sand and Sea Turtle Eggs Sea turtle eggs do not get their sex only from genes. The temperature of the sand around each egg decides whet…
Air's Path Through the Body When you breathe in, air enters through your nose or mouth and travels down a tube in your neck. It then split…
Giraffe Bending to Drink A giraffe lowers its long neck to a pool. Special neck arteries and one-way valves keep blood moving to its he…
Warm Sand, Cool Sand A crocodile egg's sex is decided while it incubates, not by chromosomes like in mammals. Eggs in a warm nest o…
Muscle pairs at the elbow When you bend your arm, the muscle at the front of your upper arm gets shorter and fatter. The muscle behind i…
Animals Carry Seeds Rainforest trees often make fruit that animals eat. The animals carry the seeds away in their dung or on their…
Same Bones, Different Jobs Humans, whales, bats, and horses have forelimbs built from the same set of bones. Those bones are shaped and s…