Substitutions, additions, or deletions of one or more nucleotides in the dna molecule are called
a. genetic variations
c. recombinant dna
b. gene mutations
d. dna fragmentation select the best answer from the choices provided

Look at the following answer choices and determine which belongs in the both category. testable, can be disproven explains natural phenomena, has evidence to support it prediction, tentative, one or more scientists working together well established, many different scientists working independently, highly reliable

For a to be healthy, it has to have lots of different kinds of plants and animals. all of the different types of plants and animals in an ecosystem. name four types of ecosystems from those listed in the video. b) c) d) most living things live here. all living things depend on how an ecosystem like a game of sticks? why should we build new buildings on existing land? name four extinct species from those listed in the video. b) c) d) the best way to wipe out a species is to the largest ecosystem in the world is this percent of the world is covered by water. how many of all species in the world live in the ocean? list five things you can do to increase biodiversity. b) c) d) e) how many species are we losing per hour?

Which statement describes a way in which the digestive and excretory systems work together? a. the nephrons absorb nutrients from food going to the large intestine. b. the excretory system balances blood gases in the small intestine. c. the intestinal villi filter blood and send wastes to the bladder. d. the excretory system balances the salts and water obtained from digested food