Why is 4 the correct answer to number 18 ? explain why and answer this

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

Which group of algae is characterized by unicellular organisms and includes some members that would be better classified as zooflagellates? euglenophytes red algae sporozoans green algae

Which survival need shortage would most affect articular cartilage's ability to rebound after joint compression, and why does it have this effect? which survival need shortage would most affect articular cartilage's ability to rebound after joint compression, and why does it have this effect? nutrients, since the majority of cartilage is made out of polysaccharide glycosaminoglycans (gags). water, since it makes up to 80% of cartilage's content and cushion articular bone surfaces. normal body temperature, since higher temperatures would slow down necessary biochemical reactions. oxygen, since cartilage cells receive this gas directly from nearby blood vessels?