| A | B |
|---|
| Amniotic egg | A shelled, water-retaining egg that allows reptile, bird, and certain mammal embryos to develop on land |
| Neurotoxin | A poison that attacks the nervous system, causing blindness, paralysis, or suffocation |
| Hemotoxin | A poison that attacks the red blood cells and blood vessels, destroying circulation |
| Endotherm | An organism that is internally warmed by a heat-generating metabolic process |
| Down feathers | Feathers with smooth barbules, allowing the barbules to interlock |
| Contour feathers | Feathers with hooked and smooth barbules, allowing the barbules to interlock |
| Placenta | A structure that allows an embryo to be nourished with the mother's blood supply |
| Gestation | The period of time during which an embryo develops before being born |
| Mammary glands | Specialized organs in mammals that produce milk to nourish the young |
