1. Mammals have _______ glands which secrete milk.   mammary   pituitary   adrenal   Hint Half-n-half Clue   2. _______ animals spend much of their time in air.   Arboreal   Aerial   Aquatic   Half-n-half Clue   3. Frogs have _______ as their hearing organs.   external eardrums   sensitive feelers   lateral lines   Half-n-half Clue   4. The nerve carrying messages from the eye to the brain is the _______ nerve.   olfactory   auditory   optical   Half-n-half Clue   5. Which of the following two develop first in a tadpole?   Front Legs   Hind Legs   6. _______ animals live on land.   Aerial   Terrestrial   Arboreal   Half-n-half Clue   7. Pick the "odd one out" (with reference to crustaceans and molluscs).   Crab   Mussel   Shrimp   Half-n-half Clue