BIO - TERMS - FREQUENCY > 1 PT 3

Question 1

action spectrum

Answer 1

A graph for which relative light sensitivity of a physiological response is plotted against the wavelength of light. // A plot of the efficiency of light at promoting a light-dependent process such as photosynthesis as a function of wavelength.

Question 2

ADP (adenosine 5′-diphosphate // adenosine diphosphate)

Answer 2

A ribonucleoside 5’-diphosphate serving as phosphate group acceptor in the cell energy cycle. // Nucleotide produced by hydrolysis of the terminal phosphate of ATP. Regenerates ATP when phosphorylated by an energy-generating process such as oxidative phosphorylation.

Question 3

alkane

Answer 3

A hydrocarbon containing only single bonds. // A class of compounds of carbon and hydrogen that contains only single bonds.

Question 4

amine

Answer 4

A class of compounds containing one or more organic substituents bonded to a nitrogen atom, RNH2, R2NH, or R3N. // An organic compound containing nitrogen and derived from ammonia by replacing one or more hydrogen atoms on ammonia with an alkyl group.

Question 5

anaphylaxis

Answer 5

A hypersensitivity reaction involving IgE antibodies, mast cells, and basophils. // A rapid-onset and systemic allergic reaction to antigen, for example to insect venom injected directly into the bloodstream, or to foods such as peanuts. Severe systemic reactions can be potentially fatal due to circulatory collapse and suffocation from tracheal swelling. It usually results from antigens binding to IgE bound by Fcε receptors on mast cells, leading to systemic release of inflammatory mediators.

Question 6

antigen–antibody complex

Answer 6

A noncovalent aggregate between antigen and antibody. // The combination of an antigen with the antibody that is specific for it; the basis of immune protection and many diagnostic tests.

Question 7

aqueous humor

Answer 7

The fluid between the cornea and the lens of the eye. // A clear watery fluid formed by the ciliary process within the eye and circulates within the anterior cavity of the eye and then drains through the circular canal called the scleral venous sinus.

Question 8

Attenuated

Answer 8

An infection in which normally severe symptoms or pathology are mild or inconsequential; a state of reduced virulence. (Chapter 1) // Having mild or inconsequential instead of normally severe symptoms or pathology as an outcome of infection; having a state of reduced virulence. (Chapter 5)

Question 9

autotroph

Answer 9

An organism that uses carbon dioxide (CO2) as its principal carbon source; chemoautotroph, photoautotroph. // An organism that can synthesize its own complex molecules from very simple carbon and nitrogen sources, such as carbon dioxide and ammonia.

Question 10

Base pairing

Answer 10

The specific interaction between two bases in opposite strands of a double-stranded nucleic acid. // Complexation of the complementary pair of polynucleotide chains of nucleic acids through hydrogen bonds between complementary purine and pyrimidine bases adenine (A) with thymine (T) or uracil (U), cytosine (C) with guanine (G).

Question 11

bioremediation

Answer 11

The use of microbes to remove an environmental pollutant. // The use of living organisms to remove metals and xenobiotics from the environment.

Question 12

brain stem

Answer 12

Brain region composed of the midbrain, pons, and medulla oblongata. // The diencephalon, midbrain, pons, and medulla. (Some anatomists exclude the diencephalon.)

Question 13

capsule

Answer 13

A collection of axons that connect the cerebrum with the brain stem. // An outer, viscous covering on some bacteria composed of a polysaccharide or polypeptide.

Question 14

carrier

Answer 14

Organism (usually refers to humans) that harbors pathogens and transmits them to others. // An individual who carries a recessive allele that is not expressed (that is, is obscured by a dominant allele).

Question 15

cerebrospinal fluid (CSF)

Answer 15

In the central nervous system, the fluid produced by the choroid plexus that flows through the ventricular system to the subarachnoid space. // A clear, colorless fluid that circulates in the ventricles, subarachnoid space, and central canal to protect and support the brain and spinal cord.

Question 16

chiasma (plural chiasmata)

Answer 16

X-shaped connection visible between paired homologous chromosomes during meiosis. Represents a site of chromosomal crossing-over, a form of genetic recombination. // A visible change of partners in two of a group of four chromatids during the first meiotic prophase. In the diplotene stage of meiosis, the four chromatids of a bivalent are associated in pairs, but in such a way that one part of two chromatids is exchanged. This point of “change of partner” is the chiasma.

Question 17

chromatid

Answer 17

(krō′mă-tid) One of the two strands of a chromosome joined by a centromere. // In mitosis or meiosis, one of the two identical strands resulting from self-duplication of a chromosome.

Question 18

co-receptor

Answer 18

In immunology: an accessory receptor on B cells or T cells that does not bind antigen but binds to a co-stimulatory signal and helps activate the lymphocyte, by helping to activate an intracellular signaling pathway. // Cell-surface protein that increases the sensitivity of a receptor to its ligand by binding to associated ligands and participating in signaling. The antigen receptors on T cells and B cells act in conjunction with co-receptors, which are either CD4 or CD8 on T cells, and a co-receptor complex of three proteins, one of which is the complement receptor CR2, on B cells.

Question 19

Complementation test (trans test)

Answer 19

Test to determine whether two mutations that produce similar phenotypes are in the same or different genes. // Introduction of two recessive mutations into the same cell to determine whether they are alleles of the same gene, that is, whether they affect the same genetic function. If the mutations are allelic, the genotype m1 +/+ m2 will exhibit a mutant phenotype, whereas if they are nonallelic, it will exhibit the wild phenotype.

Question 20

conjunctiva

Answer 20

The membrane that folds back from the eyelids and attaches to the sclera of the eye. // (kon-jŭnk-tı̄′vă) Epithelial layer covering the anterior surface of the sclera and the posterior surface of the eyelids.

Question 21

coordination number (secondary valence)

Answer 21

The number of molecules or ions directly bound to the metal atom in a complex ion.

Question 22

Cyclooxygenase

Answer 22

The key enzyme for the synthesis of prostaglandins, prostacyclin, and thromboxane. // An enzyme that is important in the production of a group of powerful biochemical compounds called prostanoids, which include such compounds as prostaglandins, prostacyclin, and thromboxane.

Question 23

Deletion mutation

Answer 23

Loss of one or more bases in a nucleic acid. (Chapter 3) // A mutation resulting from the deletion of one or more nucleotides from a gene or chromosome.

Question 24

Diastereomers

Answer 24

Geometric isomers. // Non–mirror-image stereoisomers; diastereomers have the same coniguration at one or more chirality centers but differ at other chirality centers.

Question 25

Dissociation (Ds)

Answer 25

The separation of a compound into positive and negative ions in solution. See also ionization. // A transposable element in maize, originally detected as an agent that mediates chromosome breakage in response to the effect of Activator (Ac), another transposable element.

Question 26

DNA topoisomerase (topoisomerase)

Answer 26

An enzyme that catalyzes the introduction or removal of supercoils from DNA. // Enzyme that binds to DNA and reversibly breaks a phosphodiester bond in one or both strands. Topoisomerase I creates transient singlestrand breaks, allowing the double helix to swivel and relieving superhelical tension. Topoisomerase II creates transient doublestrand breaks, allowing one double helix to pass through another and thus resolving tangles.

Question 27

eclipse period

Answer 27

The time during viral multiplication when complete, infective virions are not present. // The phase of viral infection during which the viral nucleic acid is uncoated from its protective shell and no infectious virus can be detected inside cells. (Chapter 2)

Question 28

electrolyte

Answer 28

A substance that dissolves in water to form solutions that conduct electricity. // (ē-lek′trō-lı̄t) Chemical that dissociates when added to water and can conduct an electrical current; includes salts, bases, and acids.

Question 29

Embryo

Answer 29

An organism in the early stages of development; in humans, the first two months in the uterus. // (em′brē-ō) Organism in the early stages of development; in humans, the embryonic stage extends from the third to the eighth week of development.

Question 30

Enzyme-substrate complex

Answer 30

Enzyme with a noncovalently bound substrate. // A temporary union of an enzyme and its substrate.

Question 31

ester linkage

Answer 31

Bonding between fatty acids and glycerol in bacterial and eukaryotic phospholipids: O C O C // The bonds that form between a carboxylic acid and an alcohol to form an ester, such as those in triglycerides.

Question 32

FAD (flavin adenine dinucleotide)

Answer 32

The coenzyme of some oxidation-reduction enzymes; contains riboflavin. // Flavin adenine dinucleotide; a coenzyme that functions in the removal and transfer of hydrogen ions (H1) and electrons from substrate molecules.

Question 33

filtration

Answer 33

The passage of a liquid or gas through a screenlike material; a 0.45-μm filter removes most bacteria. // A procedure used to separate a mixture composed of an insoluble solid and a liquid by pouring the mixture through filter paper or some other porous membrane or layer.

Question 34

FMN (flavin mononucleotide)

Answer 34

Riboflavin phosphate, a coenzyme of certain oxidationreduction enzymes. // Flavin mononucleotide; a coenzyme that functions in the transfer of electrons in the electron transport chain.

Question 35

G1-Cdk

Answer 35

Cyclin–Cdk complex formed in vertebrate cells by a G1-cyclin and the corresponding cyclin-dependent kinase (Cdk).

Question 36

Gap gene

Answer 36

A gene that controls the formation of adjacent segments in the body of Drosophila. // In Drosophila development, a gene that is expressed in specific broad regions along the anteroposterior axis of the early embryo, and which helps designate the main divisions of the insect body.

Question 37

Germ cell

Answer 37

A reproductive cell capable when mature of being fertilized and reproducing an entire organism (cf. Somatic cell). // A cell in the germ line of an organism, which includes the haploid gametes and their specified diploid precursor cells. Germ cells contribute to the formation of a new generation of organisms and are distinct from somatic cells, which form the body and leave no descendants.

Question 38

glycogenesis

Answer 38

(glı̄′kō-jen′ĕ-sis) Formation of glycogen from glucose. // The process of converting glucose to glycogen.

Question 39

Gram positive // gram-positive bacteria

Answer 39

Bacteria that retain the crystal violet color after decolorizing by alcohol; they stain dark purple. // Description for bacteria that stain positive with Gram stain due to a thick layer of peptidoglycan cell wall outside their inner (plasma) membrane.

Question 40

hair cell

Answer 40

Specialized sensory cell in the inner ear. // An auditory cell that transduces sound into a change in membrane potential or a vestibular cell that transduces head movements into a change in membrane potential.

Question 41

Henderson-Hasselbalch equation

Answer 41

The equation that relates protonation states to pK and pH. // An equation for determining the extent of dissociation of a weak acid at various pH values.

Question 42

homolog

Answer 42

Genes or proteins that possess a clear sequence and functional relationship to each other. // One of two or more genes that are similar in sequence as a result of derivation from the same ancestral gene. The term covers both orthologs and paralogs. See homologous chromosomes.

Question 43

hydrocarbon

Answer 43

An organic compound that contains only carbon and hydrogen.

Question 44

hyperkalemia

Answer 44

An electrolyte imbalance characterized by high levels of blood potassium. // An abnormal condition in which blood potassium levels are higher than normal.

Question 45

immune complex

Answer 45

A circulating antigen-antibody aggregate capable of fixing complement. // Complexes formed by the binding of antibody to its cognate antigen. Activated complement proteins, especially C3b, are often bound in immune complexes. Large immune complexes form when sufficient antibody is available to cross-link multivalent antigen; these are cleared by cells of the reticuloendothelial system that bear Fc receptors and complement receptors. Small, soluble immune complexes form when antigen is in excess; these can be deposited in small blood vessels and damage them.

Question 46

in situ

Answer 46

“In position”; that is, in its natural position or location. // From the Latin, meaning in the natural place; refers to experimental treatments performed on cells or tissue rather than on extracts from them.

Question 47

Infectious mononucleosis

Answer 47

An infectious disease caused by Epstein-Barr virus; characterized by an increase in the number of lymphocytes with a single nucleus. (Chapter 5) // The common form of infection with the Epstein–Barr virus. It consists of fever, malaise, and swollen lymph nodes. Also called glandular fever.

Question 48

innervation

Answer 48

The provision of synaptic input to a cell or collection of cells. // (in-er-vā′shŭn) Functional connection of a neuron with a body structure.

Question 49

ionic compound

Answer 49

A chemical structure composed of ions. // A compound composed of cations and anions bound together by electrostatic attraction.

Question 50

karyotype

Answer 50

Display of the full set of chromosomes of a cell, arranged with respect to size, shape, and number. // The chromosome constitution of a cell or an individual; chromosomes arranged in order of length and according to position of centromere; also, the abbreviated formula for the chromosome constitution, such as 47, XX + 21 for human trisomy-21.

Question 51

lamella

Answer 51

(lă-mel′ă; pl., lamellae, -mel′ē) Layer of bone connective tissue; forms concentric rings. // A double-membrane structure, plate, or vesicle that is formed by two membranes lying parallel to each other.

Question 52

lethal factor

Answer 52

An endopeptidase produced by Bacillus anthracis that cleaves NLRP1, inducing cell death within the infected cell, typically a macrophage. // One of the two A subunits of anthrax toxin; a protease that cleaves several activated members of the MAP kinase kinase family and causes a large fall in blood pressure and death on entry into the bloodstream of an animal.

Question 53

lipid raft

Answer 53

Small region of a membrane enriched in sphingolipids and cholesterol. // A microdomain of the plasma membrane that is enriched in cholesterol and saturated fatty acids and is more densely packed and less fluid than other regions of the membrane. (Chapters 2 and 12)

Question 54

lumen

Answer 54

(lū′men) The space inside a structure, such as where blood is transported within a blood vessel. // The space inside a hollow structure. In cells: the cavity enclosed by an organelle membrane. In tissues: the cavity enclosed by a sheet of cells.

Question 55

Maternal-effect gene

Answer 55

A gene whose product acts in the offspring of the female who carries the gene. // Gene that acts in the mother to specify maternal mRNAs and proteins in the egg. Maternaleffect mutations affect the development of the embryo even if the embryo itself has not inherited the mutated gene.

Question 56

Metaphase plate

Answer 56

The equatorial plane where duplicated chromosomes gather in a cell during the metaphase of mitosis. // Imaginary plane at right angles to the mitotic spindle and midway between the spindle poles; the plane in which chromosomes are positioned at metaphase.

Question 57

microvilli

Answer 57

(mı̄-krō-vil′ı̄; sing., microvillus -vil′ŭs) Microscopic extensions of the plasma membrane supported by microfilaments that increase the surface area for secretion or absorption. // Projections of enterocyte plasma membrane on the villi of the small intestine. Microvilli enhance the enterocyte surface to bring nutrients into the cell for metabolism and absorption.

Question 58

monocistronic // monocistronic mRNA

Answer 58

Encoding one polypeptide; refers to mRNA. (Chapter 11) // An mRNA that can be translated into only one protein.

Question 59

mutation rate

Answer 59

The probability that a gene will mutate each time a cell divides. // The rate at which changes (mutations) occur in DNA sequences.

Question 60

negative staining

Answer 60

A procedure that results in colorless bacteria against a stained background. // A technique in electron microscopy enabling fine detail of isolated macromolecules to be seen. Samples are prepared such that a very thin film of heavy-metal salt covers everywhere except where excluded by the presence of macromolecules, which allow electrons to pass through, creating a reverse or negative image of the molecule.

Question 61

neurotoxin

Answer 61

(nūr-ō-tok′sin) Chemical that alters normal activity of a neuron. // Substance with adverse effects on the central and peripheral nervous system, such as transient modulation of mood or performance of CNS.

Question 62

nociceptor

Answer 62

(nō-si-sep′ter, -tōr) Peripheral sensory receptor for the detection of painful stimuli. // Any receptor selective for potentially harmful stimuli; may induce sensations of pain.

Question 63

nuclear envelope

Answer 63

The double membrane that separates the nucleus from the cytoplasm in a eukaryotic cell. // Double membrane (two bilayers) surrounding the nucleus. Consists of an outer and inner membrane and is perforated by nuclear pores. The outer membrane is continuous with the endoplasmic reticulum.

Question 64

oocyte

Answer 64

(ō′-ō-sı̄t) Female gamete released from the ovary during ovulation. // The egg-mother cell; the cell that undergoes two meiotic divisions (oogenesis) to form the egg cell. Primary oocyte—before completion of the first meiotic division; secondary oocyte—after completion of the first meiotic division.

Question 65

organic molecule

Answer 65

Molecule containing carbon atoms; e.g., carbohydrates, proteins, lipids. // A molecule composed of carbon and hydrogen and a few other elements, including nitrogen, oxygen, or sulfur.

Question 66

oxygenic photosynthesis

Answer 66

Light-driven ATP and NADPH synthesis in organisms that use water as the electron source, producing O2. // CO2 assimilation by cyanobacteria, eukaryotic algae and green plants that evolve O2 by splitting water in the oxygen evolving complex of photosystem II and thus release oxygen to the environment.

Question 67

parasite

Answer 67

An organism that derives nutrients from a living host. // Organisms that obtain sustenance from a live host. In immunology, it refers to worms and protozoa, the subject matter of parasitology.

Question 68

pentose

Answer 68

A simple sugar with a backbone containing five carbon atoms.

Question 69

Peyer’s patches

Answer 69

Lymphoid organs on the intestinal wall. // Organized peripheral lymphoid organs under the epithelium in the small intestine, especially the ileum, and in which an adaptive immune response can be initiated. They contain lymphoid follicles and T-cell areas. They are part of the gut-associated lymphoid tissues (GALT).

Question 70

photophosphorylation

Answer 70

The enzymatic formation of ATP from ADP coupled to the light-dependent transfer of electrons in photosynthetic cells. // The production of ATP in a series of redox reactions; electrons from chlorophyll initiate the reactions.

Question 71

pKa

Answer 71

The negative logarithm of an equilibrium constant. // The negative common logarithm of the Ka; used to express acid strength.

Question 72

polarity

Answer 72

(1) In chemistry, the nonuniform distribution of electrons in a molecule; polar molecules are usually soluble in water. (2) In molecular biology, the distinction between the 5’ and 3’ ends of nucleic acids. // The unsymmetrical distribution of electrons in a molecule that results when one atom attracts electrons more strongly than another.

Question 73

Polyurethane

Answer 73

A step-growth polymer prepared by reaction between a diol and a diisocyanate. // Resins composed of chains of organic oil joined by urethane links to form long, flexible segments with high amounts of cross linking to make them tougher and more rigid. Derived from natural oils or petroleums, most do not melt when heated and are easily made into foam.

Question 74

Preinitiation complex

Answer 74

(transcription) A promoter-bound assembly of an RNA polymerase and initiator proteins competent to initiate transcription. (Chapter 8) // (translation) The 40S ribosomal subunit bound to translation initiation proteins and initiator tRNA. (Chapter 11)

Question 75

prosthetic group

Answer 75

A metal ion or an organic compound (other than an amino acid) that is covalently bound to a protein and is essential to its activity. // A nonpolypeptide component in a protein.

Question 76

quinone (Q)

Answer 76

A 2,5-cyclohexadiene-1,4-dione. // Small, lipid-soluble, mobile electron carrier molecule found in the respiratory and photosynthetic electrontransport chains.

Question 77

recipient cell

Answer 77

A cell that receives DNA from a donor cell during genetic recombination. // A bacterium that receives DNA from another (donor) cell during recombination in bacteria (cf. Donor cell).

Question 78

refraction

Answer 78

(rē-frak′shŭn) Bending of light waves as they pass through a material. // The bending of light rays that can occur when they travel from one transparent medium to another.

Question 79

repression

Answer 79

A decrease in the expression of a gene in response to a change in the activity of a regulatory protein. // The process of turning off the expression of a gene or set of genes in response to some signal.

Question 80

reticulocyte

Answer 80

(re-tik′ū-lō-sı̄t) Immature erythrocyte. // A young red blood cell.

Question 81

RNA-induced silencing complex (RISC)

Answer 81

A complex consisting of a protein and siRNA or miRNA that binds complementary mRNA, preventing transcription of the mRNA. // A protein complex that uses double-stranded RNA to produce and target small interfering RNAs to complementary messenger RNAs within eukaryotic cells.

Question 82

scanning electron microscope (SEM)

Answer 82

Type of electron microscope that produces an image of the surface of an object. // An electron microscope that provides three-dimensional views of the specimen magnified 1000–10,000*.

Question 83

secondary metabolite

Answer 83

A product of an industrial cell population produced after the microorganism has largely completed its period of rapid growth and is in a stationary phase of the growth cycle. See also primary metabolite. // A small naturally occurring molecule that is not essential to the growth and development of the producing organism and is not classiied by structure.

Question 84

serotonin (5-HT)

Answer 84

5-Hydroxytryptamine (5-HT), the major indolamine. // An amine neurotransmitter, 5-hydroxytryptamine.

Question 85

signal transduction

Answer 85

The process by which an extracellular signal (chemical, mechanical, or electrical) is amplified and converted to a cellular response. // The process whereby a molecular signal such as a hormone is passed internally within a cell by a system of molecules to effect a change in the cell’s state.

Question 86

small nucleolar RNA (snoRNA)

Answer 86

A class of short RNAs, generally 60 to 300 nucleotides long, that guide the modification of rRNAs in the nucleolus. // Small RNAs found in the nucleolus, with various functions, including guiding the modifications of precursor rRNA.

Question 87

spectrin

Answer 87

Abundant protein associated with the cytosolic side of the plasma membrane in red blood cells, forming a network that supports the membrane. Also present in other cells. // A membrane-associated cytoskeletal protein in erythrocytes.

Question 88

Src (Src protein family)

Answer 88

Family of cytoplasmic tyrosine kinases (pronounced “sark”) that associate with the cytoplasmic domains of some enzyme-linked cell-surface receptors (for example, the T cell antigen receptor) that lack intrinsic tyrosine kinase activity. They transmit a signal onward by phosphorylating the receptor itself and specific intracellular signaling proteins on tyrosines.

Question 89

Stop transfer signal

Answer 89

A hydrophobic sequence that halts translocation of a nascent protein across the endoplasmic reticulum membrane; serves as a transmembrane domain. (Chapter 12) // Hydrophobic amino acid sequence that halts translocation of a polypeptide chain through the endoplasmic reticulum membrane, thus anchoring the protein chain in the membrane.

Question 90

Symbiont

Answer 90

An organism living in intimate association with another, dissimilar organism. // Two or more organisms that are mutually interdependent; usually living in physical association.

Question 91

telophase

Answer 91

Final stage of mitosis in which the two sets of separated chromosomes decondense and become enclosed by nuclear envelopes. // The last stage in each mitotic or meiotic division in which the chromosomes are assembled at the poles of the division spindle.

Question 92

tetrad

Answer 92

A group of four cocci. // The four cells arising from the second meiotic division in plants (pollen tetrads) or fungi (ascospores). The term is also used to identify the quadruple group of chromatids that is formed by the association of duplicated homologous chromosomes during meiosis.

Question 93

thermodynamics

Answer 93

The general study of energy and its interconversions. // The description of reaction equilibria and free energy changes.

Question 94

Topoisomerase

Answer 94

An enzyme that introduces or removes supercoils from DNA. // Enzymes that regulate the supertwisting of double-helical DNA.

Question 95

transformed

Answer 95

A cell with an altered phenotype that behaves in many ways like a cancer cell (i.e., unregulated proliferation, anchorage-independent growth in culture). // Having changed growth properties and morphology as a consequence of infection with certain oncogenic viruses, introduction of oncogenes, or exposure to chemical carcinogens. (Chapter 6)

Question 96

triacylglycerol

Answer 96

An ester of glycerol with three molecules of fatty acid; also called a triglyceride or neutral fat. // Lipids, such as those found in animal fat and vegetable oil, that are a triester of glycerol with long-chain fatty acids.

Question 97

tyrosine hydroxylase

Answer 97

A copper-containing enzyme that converts the amino acid tyrosine into dihydroxyphenylalanine (DOPA), which is subsequently converted to dopamine. // The enzyme catalyzing the committed step of catecholamine synthesis.

Question 98

V gene segment

Answer 98

A DNA sequence encoding most of the variable region of an immunoglobulin or T cell receptor polypeptide chain. There are many different V gene segments, one of which becomes joined to a D or J gene segment by somatic recombination when an individual lymphoid progenitor cell begins to differentiate into a B or T lymphocyte. // Gene segments in immunoglobulin and T-cell receptor loci that encode the first 95 amino acids or so of the protein chain. There are multiple different V gene segments in the germline genome. To produce a complete exon encoding a V domain, one V gene segment must be rearranged to join up with a J or a rearranged DJ gene segment.

Question 99

ventral

Answer 99

(ven′trăl) Toward the belly. ventricle (ven′tri-kl) Cavity within an organ such as the heart or the brain. // An anatomical reference meaning toward the belly.

Question 100

voltage

Answer 100

Measure of potential energy in separated charges; expressed in volts. // The force exerted on an electrically charged particle, represented by the symbol V and measured in volts; also called electrical potential or potential difference.

Question 101

Xenobiotics

Answer 101

Foreign substances without nutritive value. // Synthetic chemicals that are not readily degraded by microorganisms.

Question 102

γ-Aminobutyric acid (GABA)

Answer 102

An inhibitory neurotransmitter in the brain, synthesized from glutamate. // An amino acid synthesized from glutamate; the major inhibitory neurotransmitter in the central nervous system.