What is the outermost covering of trees and some plants called?

What substance, found in food, helps move wastes through the body?

What body system is the human heart part of?

What is a cell that provides energy for another organism called?

What is an urolith?

What connects flower buds to the stem?

What is the cell where a virus reproduces called?

What part of the flower surrounds the inside parts of the flower?

What is on your tongue that allows you to taste the differences in different foods?

What is the basic unit of function and structure in living organisms?

What organ filters blood and helps regulate salt and water levels?

What are the tiny blood vessels that connect arteries and veins?

What is made by white blood cells to help fight off infection?

What do conifers use to hold seeds?

What is an algal bloom that occurs in salt water called?

What are the small bones that make up a backbone called?

What does the substance melanin control?

What natural biological defense system protects the body from disease and fights off germs?

What is the human body's largest organ?

What do many types of birds, such as geese, do just before it begins to get colder?

What nerve tissue transmits light signals from your eye lens to the brain?

What is the outside covering of a plant's root called?

Fish take in oxygen through their gills; what do insects take in oxygen through?

What part of the brain controls hunger?

What do you count on a tree to tell how old it is?