Question

which is a component of the modern cell theory that was not part of the original cell theory?
○ all organisms are made of cells.
○ all cells are similar in composition and metabolic activities.
○ all cells come from preexisting cells.
○ a cell is the basic unit of structure and function for all living things.

Explanation:

1. Recall original cell theory components: All organisms are made of cells, cells are the basic unit of structure/function, and cells come from preexisting cells (added later to original, but wait—modern cell theory has additions like cells having similar composition/metabolic activities. Wait, original cell theory (Schleiden, Schwann, Virchow later added "cells come from preexisting cells"). Wait, no: Original cell theory (1830s) had: 1. All organisms are made of cells. 2. Cells are the basic unit of structure/function. Then Virchow added "all cells come from preexisting cells" (which is now part of modern, but wait the option "All cells are similar in composition and metabolic activities" is a modern addition. Let's analyze each option:

• "All organisms are made of cells": Part of original.
• "All cells are similar in composition and metabolic activities": This is a modern cell theory component, not in original.
• "All cells come from preexisting cells": Added by Virchow, now part of modern, but was it original? Original (Schleiden/Schwann) didn't have this initially, but Virchow's addition is now standard. Wait, but the key: Modern cell theory includes that cells have similar chemical composition and metabolic processes, which was not in original.
• "A cell is the basic unit...": Part of original.

So the correct option is "All cells are similar in composition and metabolic activities".

Answer:

All cells are similar in composition and metabolic activities (the second option: "All cells are similar in composition and metabolic activities").