Practice Questions for Exam 2

Practice Questions for Exam 2 1) Plasma membranes are selec.vely permeable. This means that A) anything can pass into or out of a cell as long as the membrane is intact and the cell is healthy. B) the plasma membrane allows some substances to enter or leave a cell more easily than others. C) glucose cannot enter the cell. D) plasma membranes must be very thick. 2) Which of the following substances would have the most trouble crossing a biological membrane by diffusing through the lipid bilayer? A) O2 B) CO2 C) Na+ D) a small, nonpolar molecule such as butane (C4H10) 3) Which of the following statements regarding diffusion is false? A) Diffusion is a result of the thermal energy of atoms and molecules. B) Diffusion requires no input of energy into the system. C) Diffusion occurs when par%cles spread from areas where they are less concentrated to areas where they are more concentrated. D) Diffusion occurs even aNer equilibrium is reached and no net change is apparent. 4) Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of A) exocytosis. B) passive transport. C) ac.ve transport. 5) Osmosis can be defined as A) the diffusion of water. B) the diffusion of nonpolar molecules. C) ac.ve transport. D) the diffusion of a solute. 6) In the lab, you use a special balloon that is permeable to water but not sucrose to make an "ar.ficial cell." The balloon is filled with a solu.on of 20% sucrose and 80% water and is immersed in a beaker containing a solu.on of 40% sucrose and 60% water. Which of the following will occur? A) Water will leave the balloon. B) Water will enter the balloon. C) Sucrose will leave the balloon. D) Sucrose will enter the balloon. 7) A cell that has neither a net gain of water nor a net loss of water when it is immersed in a solu.on must be A) isotonic to its environment. B) hypertonic to its environment. C) hypotonic to its environment. 8) In a hypotonic solu.on, an animal cell will A) lyse. B) experience turgor. C) neither gain nor lose water. D) shrivel. 9) Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentra.on gradient. A) energy and transport proteins; down B) transport proteins; down C) energy and transport proteins; against D) transport proteins; against 10) Which of the following processes can move a solute against its concentra.on gradient? A) osmosis B) passive transport C) facilitated diffusion D) ac%ve transport 11) The process of a white blood cell engulfing a bacterium is A) osmosis. B) receptor-mediated endocytosis. C) exocytosis. D) phagocytosis. 12) Kine.c energy differs from chemical energy in that A) kine.c energy is stored energy that has the poten.al to do work, and chemical energy is the energy of movement. B) kine.c energy can be converted into various forms of energy, whereas chemical energy can only be converted into heat. C) kine%c energy is the energy of a moving object, whereas chemical energy is the poten%al energy of molecules. D) chemical energy is a par.cular form of kine.c energy. 13) Glucose molecules provide energy to power the swimming mo.on of sperm. In this example, the sperm are changing A) chemical energy into kine%c energy. B) chemical energy into poten.al energy. C) kine.c energy into poten.al energy. D) kine.c energy into thermal energy. 14) Most of a cell's enzymes are A) lipids. B) proteins. 15) When an enzyme catalyzes a reac%on A) it lowers the ac%va%on energy of the reac%on. B) it raises the ac.va.on energy of the reac.on. C) it acts as a reactant. D) it is used once and discarded. 16) The ac.ve site of an enzyme is A) the region of a substrate that is changed by an enzyme. B) the highly changeable por.on of an enzyme that adapts to fit the substrates of various reac.ons. C) the region of an enzyme that aOaches to a substrate. D) the region of a product that detaches from the enzyme. 17) Which of the following statements regarding enzymes is true? A) Enzymes are inorganic. B) An enzyme's func.on is unaffected by changes in pH. C) Enzymes catalyze specific reac%ons. D) All enzymes depend on protein cofactors to func.on. 18) Hea.ng inac.vates enzymes by A) breaking the covalent bonds that hold the molecule together. B) removing phosphate groups from the enzyme. C) causing enzyme molecules to s.ck together. D) changing the enzyme's three-dimensional shape. 19) The diameter of most animal and plant cells ranges from A) 0.1 to 1.0 micrometers. B) 1.0 to 10 micrometers. C) 10 to 100 micrometers. D) 100 to 1,000 micrometers. 20) As cell size increases, the A) volume and surface area decrease. B) volume increases propor%onally more than the surface area. C) surface area increases propor.onally more than the volume. D) ra.o of surface area to volume stays the same. 21) In the plasma membrane, the phospholipid heads A) are hydrophilic and face outward toward the aqueous solu%on on both sides of the membrane. B) are hydrophilic and face inward, shielded from water. C) are hydrophobic and face outward toward the aqueous solu.on on both sides of the membrane. D) are hydrophobic and face inward, shielded from water. 22) ________ cells lack a membrane-enclosed nucleus. A) Plant B) Prokaryo%c C) Eukaryo.c D) Fungal 23) The nucleus of a cell A) is surrounded by a single layer of membrane. B) is contained within the nucleolus. C) contains DNA. D) is the primary loca.on of protein synthesis. 24) An immune system cell called the plasma cell produces thousands of an.bodies (a type of protein) per second for release into the body. What type of intracellular structure would you expect to be very prominent within the cell? A) the smooth endoplasmic re.culum B) the rough endoplasmic re%culum C) peroxisome D) microtubules 25) The Golgi apparatus A) is composed of stacks of membranous vesicles that are con.nuous with one another. B) stores, modifies, and packages proteins. C) strings together amino acids to produce proteins. D) is the site of carbohydrate breakdown. 26) Which of the following statements about lysosomes is false? A) Lysosomes help to digest worn-out or damaged organelles. B) Lysosomes synthesize proteins from the recycled amino acids. C) Lysosomes fuse with food vacuoles to expose nutrients to lysosomal enzymes. D) Lysosomes destroy harmful bacteria engulfed by white blood cells. 27) The func.on of mitochondria is A) cellular respira%on. B) lipid synthesis. C) photosynthesis. D) intracellular diges.on. 28) The func.on of chloroplasts is A) cellular respira.on. B) lipid synthesis. C) photosynthesis. D) intracellular diges.on. 29) Mitochondria differ from chloroplasts in that mitochondria A) convert light energy from the sun to chemical energy, whereas chloroplasts convert one form of chemical energy to another. B) contain three different membrane-bound compartments, whereas chloroplasts contain two. C) contain membrane folds called cristae, whereas chloroplasts contain disklike vesicles in stacks called grana. D) are not found in plants, whereas chloroplasts are not found in animals. 30) The fluid mosaic model describes the plasma membrane as consis.ng of A) a phospholipid bilayer with embedded carbohydrates. B) two layers of phospholipids with cholesterol sandwiched between them. C) carbohydrates and phospholipids that can driN in the membrane. D) diverse proteins embedded in a phospholipid bilayer. 31) Which of the following statements regarding membrane protein func.on is false? A) Membrane proteins serve as enzymes. B) Membrane proteins act as receptors to molecules like hormones. C) Membrane proteins form junc.ons between cells. D) Membrane proteins produce phospholipids.