20 points! Match these items.
1.ozonosphere
absorbs most ultraviolet rays.
2.stratosphere
lowest layer of the atmosphere
3.troposphere
starts seven miles above the earth
4.greenhouse effect
layer composed of layers
5.ionosphere
important for its radiowave reflection 6.thermosphere

6. in the dna double helix, how are the two strands of dna held together? a. chemical bonds between base pairs hold the two strands of dna together. b. hydrogen bonds between the base pairs hold the two strands of dna together. c. hydrogen bonds between sugar groups and phosphate groups hold the two strands of dna together. d. chemical bonds between sugar groups and phosphate groups hold the two strands of dna together.

For each of the following, decide whether the statement describes photosynthesis, cellular respiration, or both. releases energy in the form of atp. stores energy in glucose molecules. performed by producers. performed by consumers.

How do tides affect the organisms living in intertidal zones? a. no organisms live in intertidal zones due to the tumultuous environment. b. the mechanical forces of the waves keeps the organisms clean. c. only plants live in intertidal zones because the animals float away with the waves and never return. d. the mechanical forces of the waves can dislodge the organisms from their habitat.