Which of the following is not a characteristic of animals?
(1) all animals have a definite shape.
(2) all animals are many-celled.
(3) all animals use energy.
(4) the cells of all animals have nuclei and organelles.

Which of the following statements regarding anfinsen's denaturing experiments with ribonuclease a (rnase a) are valid? exposing the denatured protein to air oxidation and then dialysis to remove urea restored the protein to its original functionality. removing urea by dialysis and then allowing air oxidation of the denatured protein restored the protein to its original functionality. denaturing the protein with both urea and β-mercaptoethanol yielded an inactive protein. anfinsen concluded that protein folding is determined by its primary sequence.

I’m doing some practice exam questions for biology, and i’m not sure how to do these 3 parts to the question.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?