When more than one variable changes during a scientific experiment,
A.
the outcome of the experiment may not be linked to any one specific variable.

B.
the outcome of the experiment is linked to the variable that changes last.

C.
the outcome of the experiment is linked to the variable that changes the most.

D.
the outcome of the experiment is linked to the variable that changes first.

answer: b: experiments that showed that all cells are similar in how they metabolize and in their composition

explanation:

the answer will be a) proteins i believe

1. amino acid refers to the fundamental building block of proteins, comprising of an amino group and a carboxyl group.

2. catalyst refers to any substance, which increases the rate of chemical reaction without being used up in the reaction.

3. a complex molecule containing he genetic code is dna or deoxyribonucleic acid.

4. an enzyme refers to a molecule of protein, which is unique in accelerating up a particular chemical reaction in the biological systems.

5. nucleic acid refers to an sequence of sugars, phosphates, and nitrogenous bases, for example, dna and rna.

6. a protein refers to a large, composite organic molecule comprising of a huge number of amino acids associated together with the of peptide bonds.

7. rna refers to a nucleic acid that takes part in the production of proteins.

8. substrate refers to a compound, which takes part in a chemical reaction, and is chemically modified by the reaction.