| A | B |
|---|
| cold-blooded | cannot regulate body temperature |
| warm-blooded | able to regulate body temperature |
| mammary gland | produces milk |
| milk | a food made by the bodies of mammals to feed their young |
| monotreme | mammal that lays eggs |
| marsupial | mammal that raises young in a pouch |
| placental | mammals that nourish their babies with an umbilical cord |
| umbilical cord | connects baby mammal to its mother |
| placenta | nourishes the unborn mammal young |
| air sacs | aid in bird respiration |
| albumen | "white" of egg that provides nourishment |
| yolk | "yellow" of egg that develops into a chick |
