AP BIOLOGY UNIT 2 TEST Exam Questions with 100% Correct Answers

What is the Endosymbiosis Theory? Correct Answer - Mitochondria and Chloroplasts share similar origin, they were prokaryotes that began living in smaller cells. - Prokaryotic cells (w/ mitochondria and chloroplasts) were engulfed by the ancestors of the eukaryotic cell. - This is evidenced by the double membrane structure, because prokaryotes and eukaryotes have ribosomes and DNA, and reproduce independently in the cell. What is the Cell Theory? Correct Answer -All living organisms are composed of cells. They may be unicellular or multicellular. -The cell is the basic unit of life. -Cells arise from pre-existing cells. Why are cells so small? Correct Answer - To maintain a large surface area to volume ratio. - Large surface area includes faster rates of chemical exchange between cell and environment What are three basic features of all cells? Correct Answer - They are all bounded by a selective barrier (plasma membrane) - All cells contain chromosomes, which carry genes in the form of DNA - All cells have ribosomes, tiny complexes that make proteins according to instructions from the genes. What is the difference between a prokaryote and a eukaryotic cell? Correct Answer - In a EC, most of the DNA is in the nucleus, which is bounded by a double membrane. In the PC, the DNA is in the nucleoid (not bounded by a double membrane) - The interior of a PC is called the cytoplasm, which is also the region between the nucleus and the plasma membrane of a EC. The cytoplasm of an EC has a variety of different organelles with specialized structure/function. These membrane-bound structures are absent in PC's, they only have ribosomes. - EC's are a lot larger than PC's, they are more complex. What structures are found in a PC? Correct Answer - Nucleoids, Cytoplasm & Cytosal, Plasma Membrane, Cell Wall What is the function of the nucleus? What structures are found within the nucleus? Correct Answer - It contains most of the genes in the eukaryotic cell. It is the most conspicuous organelle in a eukaryotic cells. - The nuclear envelope encloses the nucleus, separating its contents from the cytoplasm. This is a double membrane, each membrane has a lipid bilayer with associated proteins.