MCAT – Biology Exam Question and Answers

MCAT – Biology Exam Question and Answers 4 Basic Tenets of Cell Theory - Correct Answer️️ -1.) All living things are composed of cells 2.) The cell is the basic functional unit of life 3.) Cells arise only from preexisting cells 4.) Cells carry genetic information in the form of DNA (which is passed from parent to daughter cells) Why are viruses not considered living? - Correct Answer️️ -Viruses are not considered living because they are: -Acellular -Unable to reproduce without a host cell -Able to use RNA as their genetic material Eukaryotes - Correct Answer️️ -Cells contain a nucleus and other membrane-bound organelles The cell membrane + organelle membranes are composed of phospholipids May form multi-cellular organisms Cytosol - Correct Answer️️ -Suspends membrane-bound organelles in eukaryotes Allows for diffusion of molecules throughout the cell Why do eukaryotic cells have membrane-bound organelles? - Correct Answer️️ - Membrane-bound organelles allow for the compartmentalization of function. Why are cell membranes and organelle membranes composed of phospholipids? - Correct Answer️️ -Phospholipids create a hydrophilic surface, which electrostatically interacts with the aqueous environments inside and the outside of the cell. Hydrophobic inner portion provides a highly selective barrier between the interior of the cell + external environment Nucleus - Correct Answer️️ -Contains DNA organized into chromosomes Surrounded by nuclear membrane/envelope Nuclear membrane/envelope - Correct Answer️️ -A double membrane that surrounds the nucleus of a eukaryotic cell Separates the nuclear and cytosolic environments Contains nuclear pores -Facilitates selective material exchange between nucleus + cytosol Nucleolus - Correct Answer️️ -Darker-staining subsection of the nucleus Location of rRNA synthesis (produces ribosomes) Mitochondria - Correct Answer️️ -Semi-autonomous cellular organelles that contain some of their own genes, replicate independently of the nucleus via binary fission, and initiate apoptosis Outer membrane → separates mitochondrial + cytosolic environments Intermembrane space → located between inner + outer membranes Inner membrane → contains the molecules + enzymes of the ETC -Christae → convoluted structures that ↑ surface area available to ETC enzymes Matrix → space within the inner membrane Mitochondrial DNA - Correct Answer️️ -Circular molecules of DNA found outside of the nucleus in eukaryotic cells and replicate independently. Matrilineally inherited. Extranuclear inheritance (cytoplasmic inheritance) - Correct Answer️️ -Transmission of genetic material independent of the nucleus Ex. replication of mitochondria by binary fission Why are mitochondria considered to be semi-autonomous? - Correct Answer️️ -The mitochondria are considered semi-autonomous because they: -Contain some of their own genes -Replicate independently of the nucleus via binary fission -Initiate apoptosis by releasing ETC enzymes Lysosomes - Correct Answer️️ -Membrane-bound structures containing hydrolytic enzymes (endosomes) that break down substances ingested by endocytosis + cellular waste products Can initiate autolysis (apoptosis) by releasing its endosomes, which directly degrade cellular components. Endosomes - Correct Answer️️ -Transport materials to th