How many years did the precambrian era span? 2.5 billion 5 million 5,000 none of the above

The following image is of a diatom. it lives in water and gets food from photosynthesis. it is encased in a hard shell made of something similar to glass or sand . a diatom is a(n) because it has a) multi-celled organism; specialized parts. b) vertebrate; a skeleton. c) insect; an exoskeleton. d) single-called organism; only one cell.

Which of the following molecules can be broken down into simple sugars? a. nucleic acid b. protein c. lipid d. carbohydrate

If a keystone species is removed from an ecosystem