Which of these is a common characteristic of cnidarians?

a. they have four legs.

b. they have tentacles with stinging cells.

c. they live only in the oceans.

d. they live only at the surface of the water.

Identify the missing parts of the carbon cycle

According to the rna world hypothesis, rna acted as the genetic material and catalyzed reactions in ancient cells. what conclusion can you draw from this?               a.  this implies that dna and proteins aren't essential in cells today.    b.  this implies that rna can catalyze any chemical reaction that enzymes catalyze.    c.  this implies that if a cell has a problem with its dna, its rna can compensate for the damaged dna.    d.  this implies that dna and proteins evolved after rna.

Conservationists to restore ecosystems. which activity will positively affect the abiotic conditions of an ecosystem?