PCAT Pearson Biology Section Exam 2023

Cell Theory - ANSWER-Discovered in the 17th century 1. All living things are composed of cells 2. The cell is the basic unit of life 3. The chemical reactions of life take place inside the cell 4. Cells arise from only preexisting cells 5. Cells carry genetic information in the form of DNA. This genetic material is passed from parent cell to daughter cell 6 Kingdoms - ANSWER-Bacteria, Archaea, Protista, Fungi, Plantae, and Animalia Prokaryotic - ANSWER-"before nucleus", lacks a membrane-bound nucleus Eukaryotic - ANSWER-has a membrane-bound nucleus Cell Membrane/Plasma Membrane - ANSWER-encloses the cell and exhibits selective permeability; regulates the passage of materials in and out of the cell; permeable to both small non polar and small polar molecules Fluid Mosaic Model - ANSWER-model that the cell membrane consists of a phospholipid bilayer with proteins embedded throughout Phospholipid Bilayer - ANSWER-specific structure that forms spontaneously; long, non-polar, hydrophobic "fatty" chains of carbon and hydrogen face each other, with the phosphorous-containing, polar, hydrophilic heads facing outwards Carrier Proteins - ANSWER-how charged ions and larger charged molecules cross the membrane; assisted Nucleus - ANSWER-controls the activities of the cell, including cell division; surrounded by a nuclear membrane; contains DNA Histones - ANSWER-DNA is complexed with these proteins to form chromosomes; DNA winds around this to make it more compact, and these are involved in the regulation of gene transcription Nucleolus - ANSWER-dense structure in the nucleus where rRNA synthesis occurs rRNA - ANSWER-ribosomal RNA; necessary for protein synthesis Ribosome - ANSWER-site of protein production and are synthesized by the nucleolus; free ribosomes are found int he cytoplasm and bound ribosomes are on the ER Endoplasmic Reticulum (ER) - ANSWER-network of membrane-enclosed spaces involved in the transport of materials throughout the cell, particularly those materials destined to be recreated by the cell. rER - ANSWER-contains ribosomes to give it its rough appearance; plays role in production of proteins sER - ANSWER-does not contain ribosomes and is involved in metabolism and production of lipids Golgi Apparatus - ANSWER-receives vesicles and their contents from the sea and then modifies them (glycosylation), repackages them into vesicles, and distributes them to the cell surface by exocytosis Mitochondria - ANSWER-site of aerobic respiration within the cell and hence the suppliers of energy (ATP); has an outer and inner phospholipid bilayer Cytoplasm - ANSWER-most of the cell'e metabolic activity occurs in the cytoplasm, which include the cytosol and all of the organelles in the cell. transport within the cytoplasm occurs by cyclosis Vacuoles/Vesicles - ANSWER-membrane-bound sacs involved in the transport and storage of materials that are ingested, recreated, processed, or digested by the cell; vacuoles are larger than vesicles and are more likely to be found in plants Centrioles - ANSWER-involved in spindle organization during cell division and are not bound by a membrane. animal cells usually have a pair of centrioles oriented at right angels to each other that lies in a region called the centrosome; plant cells do not have these Lysosomes - ANSWER-membrane-bound vesicles that contain hydrolytic enzymes; break down material ingested by the cell; can commit autolysis Hydrolytic Enzyme - ANSWER-involved in intracellular digestion Autolysis - ANSWER-an injured or dying tissue may "commit suicide" by rupturing the lysosome membrane and releasing its hydrolytic enzymes Cytoskeleton - ANSWER-supports the cell, maintains its shape, and aids in cell motility. comprised of microtubules, microfilaments, and intermediate filaments Microtubules - ANSWER-hollow rods made up of polymerized tubular that radiate throughout the cell and provide it with support; provide a framework for organelle movement within the cell; what centrioles, cilia, and flagellum are comprised of Microfilaments - ANSWER-solid rods of actin, which are important in cell movement as well as support; muscle contraction; move materials across the plasma membrane Simple Diffusion - ANSWER-net movement of dissolved particles down their concentration gradients - from region of high to low concentration; passive process that doesn't require energy Osmosis - ANSWER-simple diffusion of water from a region of low to high solute concentration Hypertonic/Plasmolysis - ANSWER-when the cytoplasmic concentration is higher than the inside of the cell causing the cell to shrivel Hypotonic - ANSWER-when the cytoplasmic concentration is lower than the inside of the cell causing the cell to lyse Isotonic - ANSWER-when the cytoplasmic concentration is the same as the inside of the cell causing water to move back and forth between the cell membrane Facilitated Diffusion - ANSWER-passive transport; net movement of dissolved particles down their concentration through special channels or carrier proteins in the cell membrane; no energy required Active Transport - ANSWER-net movement of dissolved particles against their concentration gradients with the help of transport proteins; requires energy; Energy-independant carriers - ANSWER-facilitate the movement of compounds along a concentration gradient Symporters - ANSWER-move two or more ions or molecules in the same direction across the membrane Antiporters - ANSWER-exchange one or more ions for another ion or molecule across the membrane Pump - ANSWER-energy-dependent carriers; Na/K pump Endocytosis - ANSWER-process in which the cell membrane invaginate, forming a vesicle that contains extracellular medium; allows cel to bring in large volumes of extracellular material inside the cell Pinocytosis - ANSWER-ingestion of fluids or small particles Phagocytosis - ANSWER-engulfing of large particles; particles may bind to receptors on the cell membrane before being engulfed Exocytosis - ANSWER-a vesicle within the cell fuses with the cell membrane and releases a large volume of contents to the outside; fusion of the vesicle with the cell membrane can play an important role in cell growth and intercellular signaling Brownian movement - ANSWER-kinetic energy spreads small suspended particles throughout the cytoplasm of the cell; intracellular circulation Cyclists or streaming - ANSWER-the circular motion of cytoplasm around the cell transports molecules; intracellular circulation Endoplasmic reticulum - ANSWER-the ER forms a network of channels throughout the cytoplasm and provides a direct continuous passageway from the plasma membrane to the nuclear membrane; intracellular circulation Diffusion - ANSWER-if cells are in direct or close contact with the external environment, this can serve as a sufficient means of transport for food and oxygen form the environment to the cells; extracellular circulation Circulatory system - ANSWER-complex animals whose cells are too far away from the external environment require this; include vessels to transport fluid and a pump to drive it; extracellular circulation Cell Division - ANSWER-process by which the cell doubles its organelles and cytoplasm, replicates its DNA and then divides into two; unicellular organisms=reproduction/multicellular organisms=growth, development, and replacement of worn-out cells Interphase - ANSWER-period of growth and chromosome replication; spends 90% of cell life here; after replication-- two identical sister chromatids by a centromere; DNA is uncoiled (called chromatin) Centromere - ANSWER-holds sister chromatids together Interphase G1 - ANSWER-phase initiates interphase; described as the active growth phase and can vary in length; the cell increase in size and synthesizes proteins; this length determines the cell cycle length Interphase S - ANSWER-period of DNA synthesis Interphase G2 - ANSWER-period where the cell prepares to divide in G2; grows and synthesizes proteins M - ANSWER-when mitosis or meiosis occurs, resulting in tow identical or four non-identical daughter cells Mitosis - ANSWER-divison and distribution of the cell's DNA to its two daughter cells such that each cell receives a complete copy of the original genome; takes place in somatic cells Prophase-Mitosis - ANSWER-chromosomes condense, centriole pairs separate and move towards opposite poles of the cell; the spindle apparatus from between them, and the nuclear membrane dissolves, allowing the spindle fibers to interact with the chromosomes Metaphase-Mitosis - ANSWER-the centriole pairs are now at opposite poles of the cell; the fibers of the spindle apparatus attach to each chromatid at its corresponding kinetochore (protein location on the centromere); spindle fibers align the chromosomes at the center of the cell forming the metaphase plate Anaphase-Mitosis - ANSWER-the centromeres split so that each chromatid has its own distinct centromere, allowing sister chromatids to separate; the sister chromatids are pulled towards opposite poles of the cell by the shortening of the spindle fibers composed of microtubules Telophase-Mitosis - ANSWER-the spindle apparatus disappears; a nuclear membrane forms around each set of newly formed chromosomes; thus each nucleus contains the same number of chromosomes (diploid 2N) as the original; chromosomes uncoil resuming their interphase form Cytokinesis-Mitosis - ANSWER-cytoplasm divides into two daughter cells, each with a complete nucleus and its own set of organelles Meiosis - ANSWER-sexual reproduction; sex cells are produced; similar to mitosis in that a cell duplicates its chromosomes before undergoing the process; produces a haploid number (1N); involves 2 divisions of primary sex cells resulting in 4 haploid cells called gametes Interphase-Meiosis - ANSWER-parent cell's chromosomes are replicated during interphase resulting in the 2N of the sister chromatids Prophase I-Meiosis - ANSWER-chromatin condenses into chromosomes, the spindle apparatus forms, and the nucleoli and nuclear membrane disappear; synapsis occurs creating a tetrad and crossing over creating a chiasma Synapsis - ANSWER-in this process homologous chromosomes come together and intertwine Tetrad - ANSWER-4 chromatids of 2 pairs of sister chromatids Crossing Over - ANSWER-chromatids of homologous chromosomes break at a corresponding point and exchange equivalent pieces of DNA Chiasma - ANSWER-point of contact between these homologous chromosomes where crossing over can occur Metaphase I-Meiosis - ANSWER-homologous pairs (tetrads) align ate the equatorial plate, and each pair attaches to a separate spindle fiber at the kinetochore Anaphase I-Meiosis - ANSWER-homologous pairs separate and are pulled to opposite poles of the cell (disjunction); each chromosome separates from its homologue of maternal origin and either chromosome can end up in either daughter cell; thus the distribution of homologous chromosomes to the two intermediate daughter cells is random with respect to parental origin Nondisjunction - ANSWER-occurs when cells do not separate appropriately during meiosis; results in the daughter cells having an incorrect number of chromosomes Telophase I-Meiosis - ANSWER-a nuclear membrane forms around each new nucleus at this point each chromosome still consists of sister chromatids joined at the centromere Second Meiotic Division - ANSWER-same as First Meiotic Division but is not proceeded by chromosomal replication; chromosomes sign at equator, separate and move to opposite poles, and are surrounded by a re-formed nuclear membrane; the new cells have the haploid number of chromosomes Na/K Pump - ANSWER-3 Na out/ 2 K in Metabolism - ANSWER-sum of all chemical reactions that can occur in the body Catabolic reaction - ANSWER-break down large chemicals and release energy Anabolic reaction - ANSWER-build up large chemicals and require energy Ingestion - ANSWER-the acquisition and consumption of food and other raw materials Digestion - ANSWER-the process of converting food into a usable soluble form so it can pass through membranes in the digestive tract and enter the body; large to small molecules to be absorbed into the bloodstream Absorption - ANSWER-the passage of nutrient molecules through the lining of the digestive tract into the body proper; absorbed molecules pass through cells lining the digestive tract by diffusion or active transport Transport - ANSWER-the circulation of essential compounds required to nourish the tissues and the removal of waste products from the tissues Assimilation - ANSWER-the building up of new tissues from digested food materials Respiration - ANSWER-the consumption of oxygen by the body; cells use oxygen to convert glucose into ATP, a ready source of energy for cellular activities Excretion - ANSWER-the removal of waste products (urea, water, CO2) produced during metabolic processes like respiration and assimilation Synthesis - ANSWER-the creation of complex molecules from simple ones/anabolism Regulation - ANSWER-the control of physiological activities; the body's metabolism functions to maintain its internal environment in a changing external environment; the steady state of the internal environment is known as homeostasis and includes regulation by hormones and the nervous system Irritability - ANSWER-ability to respond to stimulus and is part of regulation Growth - ANSWER-an increase in size caused by cell division and synthesis of new materials Reproduction - ANSWER-the generation of additional individuals in a species Carbohydrates - ANSWER-disaccharides are hydrolyzed into monosaccharides, most of which can be converted into glucose or glycolytic intermediates; glycogen stored in the liver can be converted, when needed into a glycolytic intermediate Fats - ANSWER-stored in adipose tissue in the form of triglycerides; hydrolyzed by lipase to fatty acids and glycerol and carried by the blood to the tissues for oxidation; yield the highest number of ATP Proteins - ANSWER-degrades these only when there is not enough carbs or fats available; undergo a transamination reaction in which they lose an amino group Oxidative Deamination - ANSWER-removes an ammonia molecule directly from the AA Enzymes - ANSWER-protein; organic catalysts; any substrate that affects the rate of a chemical reaction without itself being changed; crucial to living things and regulate metabolic activity by speeding up certain reactions/decrease AE; most are reversible Coenzyme - ANSWER-many enzymes are conjugated (consist of AA attached to another group by covalent bonds); both must be present to function Substrate - ANSWER-molecule upon which an enzyme acts on Active Site - ANSWER-area on each enzyme to which the substrate binds Lock and Key Model - ANSWER-theory that the spacial structure of an enzyme's active site is exactly complementary to the spacial substrate of its substrate Induced Fit Theory - ANSWER-active site having flexibility of shape; when the appropriate substrate comes in contact with the active site, the conformation of the active site changes to fit the substrate Enzyme Temperature - ANSWER-the rate of the enzyme increases as the temperature increases until optimal temperature is reached; beyond the optimal temp, the heat alters the enzymes shape of the active site and deactivates it, leading to a rapid drop in rate Enzyme pH - ANSWER-around 7.2 except pepsin- pH=2 and pancreatic enzymes- pH=8.5 Enzyme Concentration - ANSWER-when low, the active sites are unoccupied, and reaction rate is low; when high, the active sites are occupied and the reaction rate is high until vmax is reached Competitive Inhibition - ANSWER-the active site of an enzyme is specific for a particular substrate or class of substrates; but possible for similar substrate to bind; needs a higher concentration of the substrate to win over the competitor Noncompetitive Inhibition - ANSWER-a noncompetitive inhibit is a substrate that forms strong covalent bonds with an enzyme, making it unable to bind with its substrate, ad consequently a noncompetitive inhibitor cannot be displaced by the addition of excess substrate Allosteric Inhibition - ANSWER-when inhibition takes place at a site other than the active site Hydrolysis - ANSWER-function to digest large molecules into smaller components Lactase - ANSWER-hydrolyses lactose to the monosaccharides glucose and galactose Proteases - ANSWER-degrade proteins to amino acids Lipases - ANSWER-break down lipids to fatty acids and glycerol Cofactors - ANSWER-many enzymes require the incorporation of a nonprotein molecule to become active such as a metal cation Prosthetic Groups - ANSWER-cofactors that bind to the enzyme by strong covalent bonds Genetics - ANSWER-study of how traits are inherited from one generation to the next Gene - ANSWER-the basic unit of heredity composed of DNA and are located on chromosomes Allele - ANSWER-when a gene exists in more than one form, the alternative forms are called this Genotype - ANSWER-the genetic makeup of an individual Phenotype - ANSWER-the physical makeup of an individual Genetic Crosses - ANSWER-Mental crossed two homozygous pea plants to produce the progeny characteristics Law of Segregation - ANSWER-1. Genes exist in alternative forms 2. An organism has 2 alleles for each inherited trait; one from each parent 3. The 2 alleles segregate during meiosis, resulting in gametes that carry only one allele for any given inherited trait 4. If 2 alleles are different, one will take dominance over the other recessive trait Monohybrid Cross - ANSWER-cross between two purebred pea plants; 100% Pp Progeny - ANSWER-parents Filial - ANSWER-progeny offspring Punnentt Square - ANSWER-parental alleles on outside of boxes; cross the potential gamete alleles for all of the possible outcomes Testcross - ANSWER-a diagnostic tool used to determine the genotype of an organism; only with a recessive phenotype can the genotype be predicted Law of Independent Assortment - ANSWER-explanation for the inheritance of a single allele and also can be extended to a dihybrid cross Dihybrid Cross - ANSWER-when there is more than one trait being crossed; TtPp x TtPp = 9:3:3:1 between two heterozygotes Drosophila melanogaster - ANSWER-fruit fly; helped to provide explanations for mendelian genetic patterns because it 1. reproduces often and in large numbers 2. its chromosomes are large and easily recognizable in size and shape 3. its chromosomes are few 4. mutations occur relatively frequently