12) In an animal cell, DNA may be found A) only in the nucleus. C) only in the nucleus and rough ER. B) only in the nucleus and mitochondria. D) in the nucleus, mitochondria, and rough ER 13) Which type of organelle or structure is primarily involved in the synthesis of oils, phospholipids, and steroids? A) ribosome C) mitochondrion B) smooth endoplasmic reticulum D) lysosome 14) Which of the following produces and modifies polysaccharides that will be secreted? A) Golgi apparatus C) lysosome B) mitochondrion D) peroxisome 15) Hydrolytic enzymes must be segregated and packaged to prevent general destruction of cellular components. In animal cells, which of the following organelles contains these hydrolytic enzymes? A) mitochondria B) central vacuoles C) centrioles D) lysosomes 16) One of the key innovations in the evolution of eukaryotes from a prokaryotic ancestor is the endomembrane system. Which eukaryotic organelles or features might have evolved as a part of, or as an elaboration of, the endomembrane system? A) chloroplasts B) plasma membrane C) mitochondria D) nuclear envelope 17) Which of the following correctly describes the pathway taken by a protein destined for secretion from an animal cell? A) Golgi rough ER- transport vesicle- plasma membrane B) rough ER transport vesicle lysosome transport vesicle- Golgi transport vesicle plasma membrane transport vesicle plasma membrane C) rough ER D) plasma membrane transport vesicle Golgi transport vesicle rough ER 18) Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through A) gap junctions. C) tight junctions. B) desmosomes. D) intermediate filaments, 19) The fluid mosaic model of the membrane proposed that membranes A) consist of a single layer of phospholipids and proteins. B) consist of a phospholipid bilayer composed of a variety of fatty acids. C) consist of protein molecules embedded in a fluid bilayer of phospholipids. D) consist of a phospholipid bilayer between two layers of hydrophilic proteins. 21) The primary structural components of the cell membrane are A) phospholipids and proteins. C) cholesterol and proteins. 20) A primary function of cholesterol in the plasma membranes of some animals is to A) facilitate the removal of hydrogen atoms from saturated phospholipids. B) enable the membrane to stay fluid more easily when the temperature drops. C) make the membrane more rigid, allowing it to resist pressure from outside the cell. D) facilitate cell-cell interactions by binding to receptors on neighboring cells. B) glycoproteins and cholesterol. D) phospholipids and cellulose. 22) What kinds of molecules pass through a cell membrane most easily? A) large polar C) large hydrophobic B) large and hydrophilic D) small hydrophobic