BIO 251 Exam 2 Review Questions and Accurate Answers Exam 2026

BIO 251 Exam 2 Review Questions and Accurate Answers Exam 2026 Cell division in which the nucleus divides into nuclei containing the same number of chromosomes - Correct Ans-Mitosis The resting phase of mitosis. Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases - Correct Ans-Interphase Cells that have left the cycle and cease dividing for a long time (or permanently) - Correct Ans-G Zero (G0) Phase The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins. - Correct Ans-G1 Phase The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated. - Correct Ans-S Phase The second gap, or growth phase, of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs. Growth and preparation for mitosis - Correct Ans-G2 Phase First and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus - Correct Ans-Prophase Second phase of mitosis, during which the chromosomes line up across the center of the cell - Correct Ans-Metaphase The third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles - Correct Ans-Anaphase The final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed. - Correct Ans-Telophase Division of the cytoplasm during cell division - Correct Ans-Cytokinesis Cell division that produces reproductive cells (gametes) in sexually reproducing organisms - Correct Ans-Meiosis BIO 251 BIO 251 Compare and Contrast Mitosis and Meiosis - Correct Ans-Mitosis produces two diploid (2n) somatic cells that are genetically identical to each other and the original parent cell, whereas meiosis produces four haploid (n) gametes that are genetically unique from each other and the original parent (germ) cell. Number of Chromosomes in Humans... - Correct Ans-46 Haploid Number of Chromosomes In Humans - Correct Ans-23 Control center of the cell; a part of the cell containing DNA and RNA and responsible for growth and reproduction - Correct Ans-Nucleus Processes and transports proteins made at attached ribosomes; synthesizes phospholipids - Correct Ans-Rough Endoplasmic Reticulum (RER) Fatty acid and steroid synthesis; detoxifies toxic substances - Correct Ans-Smooth Endoplasmic Reticulum (SER) A cell organelle that helps make and package materials to be transported out of the cell - Correct Ans-Golgi Complex Cell organelle filled with enzymes needed to break down certain materials in the cell - Correct Ans-Lysosomes Produce hydrogen peroxide, detoxifies harmful substances, oxidizes fatty acids, and protects cell from free radicals - Correct Ans-Peroxisomes - Hollow, cylindrical organelle that disposes of unnecessary and damaged proteins - Contain enzymes that break down tagged, targeted proteins into short peptides and amino acids - Correct Ans-Proteasomes - Located near the nucleus and help to organize cell division - Form mitotic spindle during mitosis - Correct Ans-Centrioles A structure in cells containing two centrioles from which the spindle fibers develop and organized - Correct Ans-Centrosome Point of growth for cilium or flagellum - Correct Ans-Basal Body Cell component responsible for energy production; powerhouse of the cell - Correct Ans-Mitochondria Organelle responsible for protein synthesis - Correct Ans-Ribosomes Network of protein filaments that aid in intracellular support, cell movement, and moves organelles. - Correct Ans-Cytoskeleton BIO 251 BIO 251 The basic unit of structure and function in all living things. Composed of plasma (cell membrane), cytoplasm, cytosol, nucleus, and cytoskeleton - Correct Ans-Cells Clear gel within the cell sometimes referred to as intracellular fluid (ICF) - Correct Ans Cytosol All the fluid and components between the nucleus and the cell membrane; includes the cytosol as well as the cytoskeleton - Correct Ans-Cytoplasm Phospholipid bilayer that surrounds all cells and regulates what enters and leaves the cell; also provides protection for cells. - Correct Ans-Cell membrane (plasma membrane) Plasma membrane layers composed of phospholipid molecules arranged with polar heads facing the outside and nonpolar tails facing the inside. Contains Transmembrane proteins, Peripheral proteins, Cholesterol, and sugar (glycolipids and glycoproteins) - Correct Ans-Phospholipid Bilayer Integral proteins in the cell membrane, that extends all the way through the membrane touching both the ICF and ECF - Correct Ans-Transmembrane Proteins The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane. - Correct Ans-Peripheral Protein Holds phospholipids still and can stiffen membrane - Correct Ans-Cholesterol Does not use ATP as an energy source, occurs from high to low concentration. Includes: Simple diffusion, facilitated diffusion, and osmosis. - Correct Ans-Passive Transport Moves along concentration gradient, from higher to lower concentration - Correct Ans Simple Diffusion The transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins - Correct Ans-Facilitated Diffusion Movement of water across semipermeable membrane from low solute concentration to high solute concentration - Correct Ans-Osmosis BIO 251 BIO 251 Solutions have high ECF osmolarity, water moves out of cell, cell shrinks - Correct Ans Hypertonicity Solutions have same osmolarity, no net movement of water in or out of cell - Correct Ans-Isotonicity Solutions have low ECF osmolarity, water moves into the cell causing swelling and potential bursting - Correct Ans-Hypotonicity What tonicity are most intravenous (IV) solutions? - Correct Ans-Isotonic Solution Utilizes energy to move substances against the concentration gradient; from lower to higher concentration Depends on factors: ATP, Membrane proteins, Concentration of molecules, Membrane potentials - Correct Ans-Active Transport Movement of material that is due to the electrochemical gradient established by primary active transport - Correct Ans-Secondary Active Transport Process by which a cell takes material into the cell by infolding of the cell membrane (uses ATP) - Correct Ans-Endocytosis Process by which a cell releases large amounts of material (Uses ATP) - Correct Ans Exocytosis A type of endocytosis that means "cell drinking", brings fluids into cell - Correct Ans Pynocytosis Gel-like fluid within cells; also known as cytosol - Correct Ans-Intracellular Fluid (ICF) Fluid outside cells; sometimes called tissue fluid, and includes plasma - Correct Ans Extracellular Fluid (ECF) Glands that secrete substances outward through a duct - Correct Ans-Exocrine Glands Glands that produce sweat; found over most of the body. Found in the dermis; sometimes hypodermis. - Correct Ans-Eccrine Glands or Merocrine Glands Sweat glands in the pubic and underarm areas that secrete thicker sweat, that produce odor when come in contact with bacteria on the skin - Correct Ans-Apocrine Glands Ductless glands that empty their hormonal products directly into the blood. For example: thyroid, adrenal, and pituitary glands - Correct Ans-Endocrine Glands BIO 251 BIO 251 Exocrine glands whose secretions are made up of disintegrated cells. For example: oil glands of scalp and skin, and glands of eyelids - Correct Ans-Holocrine Glands Sheets of tightly packed cells that covers body surfaces, lines body cavities, and forms glands - Correct Ans-Epithelial Tissue - Single layer of flattened cells - Permits rapid diffusion or transport of substances - Secretes serous fluid - Locations: alveoli, glomeruli, endothelium, and serosa - Correct Ans-Simple Squamous Epithelium - Single layer of square or round cells - Responsible for Absorption and secretion, mucus production and movement - Locations: liver, thyroid, mammary and salivary glands, bronchioles, and kidney tubules - Correct Ans-Simple Cuboidal Epithelium - Single row of tall, narrow cells - Oval nuclei in basal half of cell - Brush border of microvilli, ciliated in some organs, may possess goblet cells - Absorption and secretion; secretion of mucus - Locations: lining of GI tract, uterus, kidney, and uterine tubes - Correct Ans-Simple Columnar Epithelium - Looks multilayered, but all cells touch basement membrane - Nuclei at several layers - Has cilia and goblet cells - Secretes and propels mucus - Locations: respiratory tract and portions of male urethra - Correct Ans-Pseudostratified Epithelium - Multiple cell layers; cells become flat and scaly toward surface - Resists abrasion; retards water loss through skin; resists penetration by pathogenic organisms - Locations: epidermis; palms and soles heavily keratinized - Correct Ans-Keratinized Stratified Squamous Epithelium - Same as keratinized epithelium without surface layer of dead cells - Resists abrasion and penetration of pathogens - Locations: tongue, oral mucosa, esophagus, and vagina - Correct Ans-Non-keratinized Stratified Squamous Epithelium - Two or more cell layers; surface cells square or round - Secretes sweat; produces sperm, produces ovarian hormones BIO 251 BIO 251 - Locations: sweat gland ducts; ovarian follicles and seminiferous tubules - Column-shaped cells arranged in multiple layers. - Found in the conjunctiva, pharynx, anus, and male urethra. -Stratified Columnar Epithelium - Multilayered epithelium with surface cells that change from round to flat when stretched - Allows for filling of urinary tract - Locations: ureter and bladder - Correct Ans-Urothelium (Transitional) A body tissue that provides support for the body and connects all of its parts - Correct Ans-Connective Tissue - Loosely organized fibers, abundant blood vessels - Underlies epithelia, in serous membranes, between muscles, passageways for nerves and blood vessels - Correct Ans-Areolar Connective Tissue - Empty-looking cells with thin margins; nucleus pressed against cell membrane•Energy storage, insulation, cushioning - Subcutaneous fat and organ packing - Brown fat of juveniles produces heat -Adipose Connective Tissue - Densely packed, parallel collagen fibers•Compressed fibroblast nuclei - Elastic tissue forms wavy sheets in some locations - Tendons attach muscles to bones and ligaments hold bones together Dense Regular Connective Tissue - Densely packed, randomly arranged, collagen fibers and few visible cells - Withstands unpredictable stresses - Locations: deeper layer of skin; capsules around organs - Correct Ans-Dense Irregular Connective Tissue Flexible fibrous proteins that give connective tissue tensile strength - Correct Ans Collagen Fiber Fibrous protein within connective tissue that contains a high percentage of the protein elastin that allows the fibers to stretch and return to original size - Correct Ans-Elastic Fiber Fibers made of collagen fibers that are very thin and branched. Forma tightly woven fabric that joins connective tissue to adjacent tissues. - Correct Ans-Reticular Fibers A body tissue that carries electrical messages back and forth between the brain and every other part of the body. - Correct Ans-Nervous Tissue BIO 251 BIO 251 Tissue made of cells capable of contracting/shortening; making body parts move. - Correct Ans-Muscle Tissue Voluntary, striated, multi-nucleated - Correct Ans-Skeletal Muscle Tissue - Has striations - Usually has a single nucleus - Joined to another muscle cell at an intercalated disc - Involuntary - Found only in the heart - Correct Ans-Cardiac Muscle - Lacks striations - Spindle-shaped cells - Single nucleus - Involuntary—no conscious control - Found mainly in the walls of hollow organs - Correct Ans-Smooth Muscle - The chemical substances located between connective tissue cells - Composed of fibrous proteins and a clear gel called ground substance - Correct Ans Extracellular Matrix What membrane reduces friction between organs? E.g. parietal and visceral - Correct Ans-Serous Membranes Membrane that lines the wall of a body cavity - Correct Ans-Parietal Membrane The membrane covering each organ in a body cavity - Correct Ans-Visceral Membrane The skin; composed of epidermal and dermal layers - Correct Ans-Cutaneous