IB Biology HL Exam Review 2022/2023 with 100% correct answers

Outline the cell theory. Living organisms are composed of cells. Cells are the smallest unit of life. Cells come from pre-existing cells. Discuss the evidence for the cell theory. The nature of scientific theories could be introduced here: the accumulation of evidence that allows a hypothesis to become a theory; whether a theory should be abandoned when there is evidence that it does not offer a full explanation; and what evidence is needed for a theory to be adopted or rejected. State that unicellular organisms carry out all the functions of life (Name the six functions). Metabolism, response, homeostasis, growth, reproduction, and nutrition. Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles, and cells using the appropriate SI unit. Molecules: 1 nm Thickness of membranes: 10 nm Viruses: 100 nm Bacteria: 1 um Organelles: (up to) 10 um Most cells: (up to) 100 um Explain the importance of the surface area to volume ratio as a factor limiting cell size. The rate of heat production/waste production/resource consumption of a cell is a function of its volume, whereas the rate of exchange of materials and energy (heat) is a function of its surface area. State that multicellular organisms show emergent properties. [pen analogy] Emergent properties arise from the interaction of component parts: the whole is greater than the sum of its parts. How do multicellular organisms differentiate to carry out specialized functions? By expressing some of their genes but not others. What two abilities do stem cells have? Stem cells retain the capacity to divide and have the ability to differentiate along different pathways.