which statement explains why oxygen molecules easily diffuse across a cell membrane while dna molecules do not?  a. dna molecules contain carbon atoms, while oxygen molecules have only oxygen atoms.  b. dna molecules have phosphate groups that the cell membrane repels.  c. oxygen molecules are very small, while dna molecules are very large.  d. oxygen molecules are more useful to a cell than are dna molecules.

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

carbon atoms, hydrogen, oxygen, and nitrogen.

evidence and logical support is essential for a scientist to do in order to maintain credibility. this is because no one can believe without any logic and without any evidence.hence a scientist can maintain credibility by proving himself and by answering logically so experiments prove very beneficial. logical hypothesis give conclusion which is acceptable. therefore, there are two main factors to maintain credibility by a scientist is evidence and logical support.

69 is the correct math for the amino acids