Dead Echinoderms are naturally recycled to make which product? a) They are the main ingredient in livestock feed.
b) They are the main ingredient in limestone.
c) They are the main ingredient in toothpaste.
d) They are the main ingredient in collagen.

I'm so confused! If someone could help, it would mean a lot. Thank you and PLEASE no links!

18. over time, how do sand dunes tend to migrate? a. perpendicular to the movement of the wind b. in the same direction as the wind blows c. toward the wind d. in random directions

Do plant cells perform cellular respiration?

True or false: (a) the strings of little red dots represent carbohydrates. (b) the model is called a bilayer because there are two main types of molecules present, lipids and proteins. (c) the many black lines represent amino acid tails. (d) this model shows membrane transport. (e) the blue ovals are hydrophobic. (f) the blue ovals represent phospholipid heads.