Why would an experimenter want a control group?

Aperson with age is more likely to catch diseases that healthy people usually don’t catch. what are these infections called?

The phylogenetic tree illustrates the relationship between humans and our closest living relatives. the tree was based on biochemical comparisons, including dna and amino acid sequences. according to the biomolecular data, we could infer that

Contrast how pollination is different among gymnosperms and angiosperms.