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Key Words Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Abiotic

A

An ecological factor that makes up part of the non-biological environment of an organism (e.g. temperature, pH)

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2
Q

Acetylcholine

A

One of a group of chemicals, called neurotransmitters, released by neurones. It diffuses across the gap between adjacent neurones and so passes an impulse from one neurone to the next

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3
Q

Action Potential

A

Change that occurs in the electrical charge across the membrane of an axon when it is stimulated and a nerve impulse passes

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4
Q

Actin

A

Filamentous protein which is involved in contraction within cells, especially muscle cells

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5
Q

Activation Energy

A

Energy required to bring about a reaction. The activation energy is lowered by the presence of enzymes

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6
Q

Active Site

A

A group of amino acids that makes up the region of an enzyme into which the substrate fits in order to catalyse a reaction

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6
Q

Active Immunity

A

Resistance to disease resulting from the activities of an individual’s own immune system whereby an antigen induces plasma cells to produce antibodies

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7
Q

Active Transport

A

Movement of a substance from a region where it is in a low concentration to a region where it is in a high concentration. The process requires the expenditure of metabolic energy

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8
Q

Adenosine Triphosphate (ATP)

A

An activated nucleotide found in all living cells that acts as an energy carrier. The hydrolysis of ATP leads to the formation of ADP and inorganic phosphate, with the release of energy

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9
Q

Adrenaline

A

A hormone produced by the adrenal glands in times of stress that prepares the body for an emergency

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10
Q

Aerobic

A

Connected with the presence of free oxygen. Aerobic respiration requires free oxygen to release energy from glucose

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11
Q

Allele

A

One of a number of alternative forms of a gene. For example, the gene for the shape of pea seeds has two alleles: one for ‘round’ and one for ‘wrinkled’

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12
Q

Allele Frequency

A

The number of times an allele occurs within the gene pool

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13
Q

Allergen

A

A normally harmless substance that causes the immune system to produce an immune response

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14
Q

Allergy

A

The response of the immune system to an allergen

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15
Q

Anaerobic

A

Connected with the absence of oxygen. Anaerobic respiration releases energy from glucose or other foods without the presence of oxygen

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16
Q

Antibiotic

A

A substance produced by living organisms that can destroy or inhibit the growth of microorganisms

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17
Q

Antibiotic Resistance

A

The development in microorganisms of mechanisms that prevent antibodies from killing them

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18
Q

Antibody

A

A protein produced by lymphocytes in response to the presence of the appropriate antigen

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19
Q

Anticodon

A

A sequence of three adjacent nucleotides on a molecule of transfer RNA that is complementary to a particular codon on a messenger RNA molecule

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20
Q

Antidiuretic Hormone (ADH)

A

A hormone produced by the hypothalamus that passes to the posterior pituitary gland from where it is secreted. ADH reduces the volume of water in urine by increasing water reabsorption in the kidneys

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21
Q

Antigen

A

A molecule that triggers an immune response by lymphocytes

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22
Q

Antioxidant

A

Chemical which reduces or prevents oxidation. Often used as an additive to prolong the shelf-life of certain foods

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23
Q

Apoplastic Pathway

A

Route through the cell walls and intercellular spaces of plants by which water and dissolved substances are transported

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24
Q

Artificial Selection

A

Breeding of organisms by human selection of parents/gametes in order to perpetuate certain characteristics and/or to eliminate others

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25
Q

Asthma

A

A chronic illness in which there is resistance to air flow to the alveoli of the lungs as a result of the airways becoming inflamed due to an allergic response to an allergen

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26
Q

Atheroma

A

Fatty deposits in the walls of arteries often associated with high cholesterol levels in the blood.

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27
Q

Autonomic Nervous System

A

Part of the nervous system, controlling the muscles and glands, that is not under voluntary control

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28
Q

Autosome

A

A chromosome which is not a sex chromosome

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29
Q

Axon

A

A process extending from a neurone that conducts action potential away from the cell body

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30
Q

B Cell (B Lymphocyte)

A

Type of white blood cell that is produced and matures within the bone marrow. B lymphocytes produce antibodies as part of their role in immunity

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31
Q

Benedict’s Test

A

A simple biochemical reaction to detect the presence of reducing sugars

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32
Q

Biodiversity

A

The range and variety of genes, species and habitats within a particular region

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33
Q

Biomass

A

The total mass of living material, normally measured in a specific area over a given period of time

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34
Q

Biotic

A

An ecological factor that makes up part of the living environment of an organism (food availability, competition, predation)

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35
Q

Biosensor

A

A device that uses biological molecules to measure the level of certain chemicals

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36
Q

Biuret Test

A

A simple biochemical reaction to detect the presence of proteins

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37
Q

Body Mass Index (BMI)

A

A person’s body mass in kilograms divided by the square of their height in metres

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38
Q

Calvin Cycle

A

A biochemical pathway that forms part of the light-independent reaction of photosynthesis, during which carbon dioxide is reduced to form carbohydrates

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39
Q

Cancer

A

A disease, resulting from cells that break away from an original tumour to form secondary tumours elsewhere in the body

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40
Q

Carcinogen

A

A chemical, a form of radiation, or other agent that causes cancer

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41
Q

Cardiac Cycle

A

A continuous series of events which make up a single heart beat

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42
Q

Cardiac Muscle

A

Type of muscle found only in the heart. It has fewer striations than skeletal muscle and can contract continuously throughout life without stimulation by nerve impulses

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43
Q

Cardiac Output

A

The total volume of blood that the heart can pump each minute. It is calculated as the volume of blood pumped at each beat (stroke volume) multiplied by the number of heart beats per minute (heart rate)

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44
Q

Carrier Molecule (carrier protein)

A

A protein on the surface of a cell that helps to transport molecules and ions across plasma membranes

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45
Q

Casparian Strip

A

A distinctive band of suberin around the endodermal cells of a plant root that prevents water passing into xylem via the cell walls. The water is forced through the living part of the endodermal cells

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46
Q

Centrifugation

A

Process of separating out particles of different sizes and densities by spinning them at high speeds in a centrifuge

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47
Q

Cholinesterase

A

Enzyme that breaks down and therefore inactivates the neurotransmitter, acetylcholine, in the synapse

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48
Q

Cholesterol

A

Lipid that is an important component of cell-surface membranes. Excess in the blood can lead to atheroma

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49
Q

Chromatid

A

One of the two strands of a chromosome that are joined together by a single centromere prior to cell division

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50
Q

Chromosome

A

A thread-like structure made of protein and DNA by which hereditary information is physically passed from one generation to the next

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51
Q

Climax Community

A

The organisms that make up the final stage of ecological succession

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52
Q

Clone

A

A group of genetically identical cells or organisms formed from a single parent as the result of asexual reproduction or by artificial means

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53
Q

Co-dominance

A

Condition in which both alleles for one gene in a heterozygous organism contribute to the phenotype

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54
Q

Codon

A

A sequence of three adjacent nucleotides in mRNA that codes for one amino acid

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55
Q

Cohesion

A

Attraction between molecules of the same type. It is important in the movement of water up a plant

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56
Q

Collagen

A

Fibrous protein that is the main constituent of connective tissues such as tendons, cartilage and bone

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57
Q

Community

A

All the living organisms present in an ecosystem at a given time

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58
Q

Complementary DNA

A

DNA that is made from mRNA in a process that is the reverse of normal transcription

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59
Q

Condensation

A

Chemical process in which two molecules combine to form a more complex one with the elimination of a simple substance, usually water. Many biological polymers, such as polysaccharides and polypeptides, are formed by condensation

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60
Q

Conservation

A

Method of maintaining ecosystems and the living organisms that occupy them. It requires planning and organisation to make best use of resources while preserving the natural landscape and wildlife

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61
Q

Consumer

A

Any organism that obtains energy by ‘eating’ another. Organisms feeding on plants are known as primary consumers and organisms feeding on primary consumers are known as secondary consumers

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62
Q

Continuous Variation

A

Variation in which organisms do not fall into distinct categories but show gradations from one extreme to the other

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63
Q

Coronary Arteries

A

Arteries that supply blood to the cardiac muscle of the heart

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64
Q

Coronary Heart Disease (CHD)

A

Any condition, for example atheroma and thrombosis, affecting the coronary arteries that supply heart muscle

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65
Q

Correlation

A

When a change in one variable is reflected by a change in the second variable

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66
Q

Co-transport

A

The transport of one substance coupled with the transport of another substance across a plasma membrane in the same direction through the same protein carrier

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67
Q

Countercurrent System

A

A mechanism by which the efficiency of exchange between two substances is increased by having them flowing in opposite directions

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68
Q

Covalent Bond

A

Type of chemical bond in which two atoms share a pair of electrons, one from each atom

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69
Q

Crossing Over

A

The process whereby a chromatid breaks during meiosis and rejoins to the chromatid of its homologous chromosome so that their alleles are exchanged

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70
Q

Cuticle

A

Exposed non-cellular outer layer of certain animals and the leaves of plants. It is waxy and impermeable to water. It therefore helps to reduce water loss

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71
Q

Deciduous

A

Term applied to plants that shed all their leaves together at one season

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72
Q

Denaturation

A

Permanent changes due to the unravelling of the three-dimensional structure of a protein as a result of factors such as changes in temperature or pH

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73
Q

Dendrite

A

A process, usually branched, extending from the cell body of a neurone, which conducts impulses towards the cell body

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74
Q

Denitrifying Bacteria

A

Bacteria that converts nitrates to nitrogen gas as part of the nitrogen cycle

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75
Q

Depolarisation

A

Temporary reversal of charges on the cell-surface membrane of a neurone that takes place when a nerve impulse is transmitted

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76
Q

Diabetes

A

A metabolic disorder in which the body is unable to regulate the level of blood glucose. There are two forms of the disorder - Type I and Type II diabetes

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77
Q

Diastole

A

The stage in the cardiac cycle when the heart muscle relaxes

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78
Q

Differentiation

A

The process by which cells become specialised for different functions

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79
Q

Diffusion

A

The movement of molecules or ions from a region where they are in high concentration to one where their concentration is lower

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80
Q

Diploid

A

A term applied to cells in which the nucleus contains two sets of chromosomes

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81
Q

Dipolar

A

Having a pair of equal and opposite electrical charges

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82
Q

Directional Selection

A

Selection that operates towards one extreme in a range of variation

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83
Q

Discontinuous Variation

A

Variation shown when the characteristics of organisms fall into distinct categories (e.g. blood groups in humans)

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84
Q

DNA Helicase

A

Enzyme that acts on a specific region of the DNA molecule to break the hydrogen bonds between the bases causing the two strands to separate and expose the nucleotide bases in that region

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85
Q

DNA Replication

A

The process in which the double helix of a DNA molecule unwinds and each strand acts as a template on which a new strand is constructed

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86
Q

Dominant Allele

A

A term applied to an allele that is always expressed in the phenotype of an organism

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87
Q

Ecological Niche

A

Describes how an organism fits into its environment. It describes what a species is like, where it occurs, how it behaves, its interactions with other species and how it responds to its environment

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88
Q

Ecosystem

A

All the living and non-living components of a particular area

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89
Q

Ectothermic

A

An animal that uses the environment to regulate its body temperature

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90
Q

Effector

A

An organ that responds to stimulation by a nerve impulse resulting in a change or response

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91
Q

Electron

A

Negatively charge subatomic particle that orbits the positively charge nucleus of all atoms

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92
Q

Electron Carrier Molecules

A

A chain of carrier molecules along which electrons pass, releasing energy in the form of ATP as they do so

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93
Q

Emphysema

A

A disease in which the walls of the alveoli break down, reducing the surface area for gaseous exchange, thereby causing breathlessness in the patient

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94
Q

Endocytosis

A

The inward transport of large molecules through the cell-surface membrane

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95
Q

Endotherm

A

An animal maintaining its body temperature by physiological mechanisms

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96
Q

Enzyme

A

A protein or RNA that acts as a catalyst and so alters the speed of a biochemical reaction

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97
Q

Epidemiology

A

The study of the spread of disease and the factors that affect this spread

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98
Q

Eukaryotic Cell

A

A cell that has a membrane-bound nucleus and chromosomes. The cell also possesses a variety of other membranous organelles, such as mitochondria and endoplasmic reticulum

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99
Q

Exocytosis

A

The outward bulk transport of materials through the cell-surface membrane

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100
Q

Facilitated Diffusion

A

Diffusion involving the presence of protein carrier molecules to allow the passive movement of substances across plasma membranes

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101
Q

Gamete

A

Reproductive (sex) cell that fuses with another gamete during fertilisation

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102
Q

Gel Electrophoresis

A

A technique used to separate DNA fragments of different lengths by placing them on agar gel and passing a voltage across them

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103
Q

Gene

A

Section of DNA on a chromosome coding for one or more polypeptides

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104
Q

Gene Pool

A

The total number of alleles in a particular population at a specific time

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105
Q

Gene Marker

A

A section of DNA that is used to indicate the location of a gene or other section of DNA

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106
Q

Gene Mutation

A

A change to one or more nucleotide bases in DNA resulting in a change in genotype which may be inherited

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107
Q

Gene Therapy

A

A mechanism by which genetic diseases (e.g. cystic fibrosis) may be cured by masking the effect of the defective gene by inserting a functional gene

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108
Q

Generator Potential

A

Depolarisation of the membrane of a receptor cells as a result of the stimulus

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109
Q

Genetic Engineering

A

The process by which genes are manipulated, altered or transferred from organism to organism. Also know as recombinant DNA technology

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110
Q

Genetically Modified Organism (GMO)

A

An organism that has had its DNA altered as a result of recombinant DNA technology/ genetic engineering

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111
Q

Genotype

A

The genetic composition of an organism

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112
Q

Glomerulus

A

A cluster of blood capillaries enclosed by the renal (Bowman’s capsule) in the kidney

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113
Q

Glucagon

A

A hormone produced by alpha-cells of the islets of Langerhans in the pancreas that increases blood glucose levels by initiating the breakdown of glycogen to glucose

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114
Q

Gluconeogenesis

A

The conversion of non-carbohydrate molecules to glucose

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115
Q

Glycogenesis

A

The conversion of glucose to glycogen

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116
Q

Glycogenolysis

A

The conversion of glycogen to glucose

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117
Q

Glycolysis

A

First part of cellular respiration in which glucose is broken down anaerobically in the cytoplasm to two molecules of pyruvate

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118
Q

Glycoprotein

A

Substance made up of a carbohydrate molecule and a protein molecule. Parts of the cell-surface membrane and certain hormones are glycoproteins

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119
Q

Granum (plural grana)

A

A stack of thylakoids in a chloroplast that resembles a pile of coins. This is the site of the light-dependent reaction of photosynthesis

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120
Q

Guard Cell

A

One of a pair of cells that surround a stoma in plant leaves and control its opening and closing

121
Q

Habitat

A

The place where an organism normally lives and which is characterised by physical conditions and the types of other organisms present

122
Q

Haemoglobin

A

Globular protein in blood that readily combines with oxygen to transport it around the body. It comprises four polypeptide chains around an iron-containing haem group

123
Q

Haploid

A

Term referring to cells that contain only a single copy of each chromosome

124
Q

Heterozygous

A

Condition in which the alleles of a particular gene are different

125
Q

Histones

A

Proteins which together with DNA, make up the chromosomes of eukaryotic cells

126
Q

Homeostasis

A

The maintenance of more or less constant internal environment

127
Q

Homologous Chromosomes

A

A pair of chromosomes, one maternal and one paternal, that have the same gene loci and therefore determine the same features. They are not necessarily identical, however, as individual alleles of the same gene many vary. They are capable of pairing during meiosis

128
Q

Homozygous

A

Condition in which the alleles of a particular gene are identical

129
Q

Human Genome

A

The totality of the DNA sequences on the chromosomes of a single human cell

130
Q

Human Genome Project

A

International scientific project to map the entire sequence of all the base pairs of the genes in a single human cell

131
Q

Hydrogen Bond

A

Chemical bond formed between the positive charge on a hydrogen atom and the negative charge on another atom of an adjacent molecule

132
Q

Hydrolysis

A

The breaking down of large molecules into smaller ones by the addition of water molecules

133
Q

Hyperthermia

A

A condition that results from the core body temperature rising above normal

134
Q

Hypothalamus

A

Region of the brain adjoining the pituitary gland that acts as the control centre for the autonomic nervous system and regulates the body temperature and fluid balance

135
Q

Hypothermia

A

A condition that results from the core body temperature falling below normal

136
Q

Immunity

A

The means by which the body protects itself from infection

137
Q

Insulin

A

A hormone, produced by the beta-cells of the islets of Langerhans in the pancreas, which decreases blood glucose levels by, amongst other things, increasing the rate of conversion of glucose to glycogen

138
Q

Intercropping

A

The practice of growing two or more crops in close proximity usually to produce a greater yield on a piece of land

139
Q

Interspecific Competition

A

Competition between organisms of different species

140
Q

Interspecific Variation

A

Differences between organisms of different species

141
Q

Intraspecific Competition

A

Competition between organisms of the same species

142
Q

Intraspecific Variation

A

Differences between organisms of the same species

143
Q

Intrinsic Proteins

A

Proteins of the cell-surface membrane that completely span the phospholipid bilayer from one side to the other

144
Q

Introns

A

Portions of DNA within a gene that do not code for a polypeptide. The introns are removed from pre-messenger RNA after transcription

145
Q

Ion

A

An atom or group of atoms that has lost or gained one or more electrons. Ions therefore have either a positive or negative charge

146
Q

Ion Channel

A

A passage across the cell-surface membrane made up of a protein that spans the membrane and opens and closes to allow ions to pass in and out of the cell

147
Q

Islets of Langerhans

A

Groups of cells in the pancreas comprising large alpha-cells, which produce the hormone glucagon, and small beta-cells, which produce the hormone insulin

148
Q

Isotope

A

Variation of a chemical element that have the same number of protons and electrons but a different number of neutrons. While their chemical properties are similar they differ in mass

149
Q

In Vitro

A

Refers to experiments carried out outside the living body (e.g. in test tubes)

150
Q

In Vivo

A

Refers to experiments that are carried out within living bodies

151
Q

Krebs Cycle

A

Series of aerobic biochemical reactions in the matrix of the mitochondria of most eukaryotic cells by which energy is obtained through the oxidation of acetylcoenzyme A produced from the breakdown of glucose

152
Q

Latent Heat of Vaporisation

A

Heat taken in by a liquid in order to transform it into a vapour

153
Q

Ligament

A

A tough, fibrous connective tissue, rich in collagen, that joins bone to bone

154
Q

Light-dependent Reaction

A

Stage of photosynthesis in which light energy is required to produce ATP and reduced NADP

155
Q

Light-independent Reaction

A

Stage of photosynthesis which does not require light energy directly but does need the products of the light-dependent reaction to reduce carbon dioxide and so form carbohydrate

156
Q

Limiting Factor

A

A variable that limits the rate of a chemical reaction

157
Q

Link Reaction

A

The process linking glycolysis with the Krebs cycle in which hydrogen and carbon dioxide are removed from pyruvate to form acetylcoenzyme A in the matrix of the mitochondria

158
Q

Locus

A

The position of a gene on a chromosome/DNA molecule

159
Q

Loop of Henle

A

The portion of the nephron that forms a hairpin loop that extends into the medulla of the kidney. It has a role in the reabsorption of water

160
Q

Lumen

A

The hollow cavity inside a tubular structure such as the gut of a xylem vessel

161
Q

Lymph

A

A slightly milky fluid found in lymph vessels and made up of tissue fluid, fats and lymphocytes

162
Q

Lymphocytes

A

Types of white blood cells responsible for the immune response. They become activated in the presence of antigens. There are two types: B and T

163
Q

Meiosis

A

The type of nuclear division in which the number of chromosomes is halved

164
Q

Mesophyll

A

Tissue found between the two layers of epidermis in a plant leaf comprising an upper layer of palisade cells and a lower layer of spongy cells

165
Q

Metabolism

A

All the chemical processes that take place in living organisms

166
Q

Microvilli

A

Tiny finger-like projections from the cell-surface membrane of some animal cells

167
Q

Middle Lamella

A

Layer made up of pectins and other substances found between the walls of adjacent plant cells

168
Q

Mitosis

A

The type of nuclear division in which the daughter cells have the same number of chromosomes as the parent cell

169
Q

Monoclonal Antibody

A

An antibody produced by a single clone of cells

170
Q

Monomer

A

One of many small molecules that combing to form a larger one know as a polymer

171
Q

Mono-unsaturated fatty acid

A

Fatty acid that possesses a carbon chain with a single double bond

172
Q

Motor Neurone

A

Neurone that transmits action potential from the central nervous system to an effector (e.g. muscle or gland)

173
Q

Multiple Alleles

A

Term used to describe a gene that has more than two possible alleles

174
Q

Mutagen

A

Any agent that induces a mutation

175
Q

Mutation

A

A sudden change in the amount or the arrangement of the genetic material in the cell

176
Q

Myelin

A

A fatty substance that surrounds axons and dendrites in certain neurones

177
Q

Myocardial Infarction

A

Otherwise known as a heart attack, results from the interruption of the blood supply to the heart muscle, causing damage to an area of the heart with consequent disruption to its function

178
Q

Myosin

A

The thick filamentous protein found in skeletal muscle

179
Q

NAD (Nicotinamide Adenine Dinucleotide)

A

A molecule that carries electrons and hydrogen ions during aerobic respiration

180
Q

NADP (Nicotinamide Adenine Dinucleotide Phosphate)

A

A molecule that carries electrons produced in the light-dependent reaction of photosynthesis

181
Q

Negative Feedback

A

A series of changes, important in homeostasis, that result in a substance being restored to its normal level

182
Q

Nephron

A

Basic functional unit of the mammalian kidney responsible for the formation of urine

183
Q

Neurone

A

A nerve cell, comprising a cell body, axon and dendrites, which is adapted to conduct action potential

184
Q

Neuromuscular Junction

A

A synapse that occurs between a neurone and a muscle

185
Q

Neurotransmitter

A

One of a number of chemicals that are involved in communication between adjacent neurones or between nerve cells and muscles. Two important examples are acetylcholine and noradrenaline

186
Q

Nitrifying Bacteria

A

Microorganisms that convert ammonium compounds to nitrites and nitrates

187
Q

Nitrogen Fixation

A

The incorporation of atmospheric nitrogen gas into organic nitrogen-containing compounds

188
Q

Node of Ranvier

A

A gap in the myelin sheath that surrounds the axon of a neurone

189
Q

Normal Distribution

A

A bell-shaped curve produced when a certain distribution is plotted on a graph

190
Q

Nucleotides

A

Complex chemicals made up of an organic base, a sugar and a phosphate. They are the basic units of which the nucleic acids DNA and RNA are made

191
Q

Oestrus

A

The period in the oestrous cycle immediately after ovulation when the female is the most fertile

192
Q

Oncogenes

A

Mutated versions of proto-oncogenes that result in increased cell division leading to the growth of a tumour

193
Q

Oral Rehydration Solution (ORS)

A

Means of treating dehydration involving giving, by mouth, a balanced solution of salts and glucose that stimulates the gut to reabsorb water

194
Q

Osmosis

A

The passage of water from a region of high water potential to a region where its water potential is lower, through a selectively permeable membrane

195
Q

Oxidation

A

Chemical reaction involving the loss of electrons

196
Q

Oxidation-Reduction (Redox)

A

A chemical reaction in which electrons are transferred from one substance to another substance. The substance losing electrons is oxidised and the substance gaining the electrons is reduced

197
Q

Oxidative Phosphorylation

A

The formation of ATP in the electron transport system of aerobic respiration

198
Q

Palisade Cells

A

Long, narrow cells, packed with chloroplasts, that are found in the upper region of a leaf and which carry out photosynthesis

199
Q

Parasite

A

An organism that lives on or in a host organism. It gains a nutritional advantage and the host is harmed in some way

200
Q

Passive Immunity

A

Resistance to disease that is acquired from the introduction of antibodies from another individual, rather than an individual’s own immune system. It is usually short-lived

201
Q

Pathogen

A

Any microorganism that causes disease

202
Q

Pentose Sugar

A

A sugar that possesses five carbon atoms. Two examples are ribose and deoxyribose

203
Q

Peptide Bond

A

The chemical bond formed between two amino acids during condensation

204
Q

Phagocytosis

A

Mechanism by which cells engulf particles to form a vesicle or a vacuole

205
Q

Phenotype

A

The characteristics of an organism, often visible, resulting from both its genotype and the effects of the environment

206
Q

Phloem

A

Plant tissue that transports the products of photosynthesis from leaves to the rest of the plant

207
Q

Phospholipid

A

Triglyceride in which one of the three fatty acid molecules is replaced by a phosphate molecule. They are important in the structure and functioning of plasma membranes

208
Q

Photolysis

A

Splitting of a water molecule by light such as occurs during the light-dependent reaction of photosynthesis

209
Q

Photomicrograph

A

Photograph of an image produced by a microscope

210
Q

Pioneer Species

A

A species that can colonise bare rock or ground

211
Q

Plasmid

A

A small circular piece of DNA found in bacterial cells

212
Q

Plasmodesmata

A

Fine strands of cytoplasm that extend through pores in adjacent plant cell walls and connect the cytoplasm on one cell with another

213
Q

Plasmolysis

A

The shrinkage of cytoplasm away from the cell wall that occurs as a plant cell loses water by osmosis

214
Q

Polygenes

A

Group of genes that are responsible for controlling a characteristic

215
Q

Polymer

A

Large molecule made up of repeating smaller molecules (monomers)

216
Q

Polymerase Chain Reaction (PCR)

A

Process of making many copies of a specific sequence of DNA or part of a gene. It is used extensively in gene technology and genetic fingerprinting

217
Q

Polymerases

A

Group of enzymes that catalyse the formation of long-chain molecules (polymers) from similar basic units (monomers)

218
Q

Polyunsaturated Fatty Acid (PUFA)

A

Fatty acid that possesses carbon chains with many double bonds

219
Q

Population

A

A group of individuals of the same species that occupy the same habitat at the same time

220
Q

Positive Feedback

A

Process which results in a substance that departs from its normal level becoming further from its norm

221
Q

Primary Structure of a Protein

A

The sequence of amino acids that makes up the polypeptides of a protein

222
Q

Primary Succession

A

The progressive colonisation of bare rock or other barren terrain by living organisms

223
Q

Producer

A

An organism that synthesises organic molecules from simple inorganic ones such as carbon dioxide and water. Most are photosynthetic and form the first trophic level in a food chain

224
Q

Prokaryotic Cell

A

A cell of an organism belonging to the kingdom Prokaryotae that is characterised by lacking a nucleus and membrane-bound organelles

225
Q

Proton

A

Positively charge sub-atomic particle found in the nucleus of an atom

226
Q

Protoplast

A

The living portion of a plant cell, that is, the nucleus and cytoplasm along with the organelles it contains

227
Q

Quaternary Structure of a Protein

A

A number of polypeptide chains linked together, and sometimes associated with non-protein groups, to form a peptide

228
Q

Receptor

A

A cell adapted to detect changes in the environment

229
Q

Recessive Allele

A

The condition in which the effect of an allele is apparent in the phenotype of a diploid organism only in the presence of another identical allele

230
Q

Recognition SIte

A

A nucleotide sequence, usually of 4,6 and 8 nucleotides, that is recognised by a restriction endonuclease and to which it attaches

231
Q

Recombinant DNA Technology

A

General term that covers the processes by which genes are manipulated, altered or transferred from organism to organism. Also known as genetic engineering

232
Q

Reduction

A

Chemical process involving the gain of electrons

233
Q

Reflex Arc

A

The nerve pathway in the body taken by an action potential that leads to a rapid, involuntary response to a stimulus

234
Q

Refractory Period

A

Period during which the membrane of the axon of a neurone cannot be depolarised and no new action potential can be initiated

235
Q

Renal Capsule

A

The cup shaped portion of the start of the nephron that encloses the glomerulus

236
Q

Repolarisation

A

Return to the resting potential in the axon of a neurone after an action potential

237
Q

Resting Potential

A

The difference in electrical charge maintained across the membrane of the axon of a neurone when not stimulated

238
Q

Restriction Endonucleases

A

A group of enzymes that cut DNA molecules at a specific sequence of bases called a recognition sequence

239
Q

RNA Polyermase

A

Enzyme that joins together nucleotides to form mRNA during transcription

240
Q

Saltatory Conduction

A

Propagation of a nerve impulse along a myelinated dendron or axon in which the action potential jumps from one node of Ranvier to another

241
Q

Saprobiotic Microorganism

A

Also known as a saprophyte, this is an organism that obtains its food from the dead or decaying remains of other organisms

242
Q

Sacromere

A

A section of myofibril between two Z-lines that form the basic structural unit of skeletal muscle

243
Q

Saturated Fatty Acid

A

A fatty acid in which there are no double bonds between the carbon atoms

244
Q

Schwann Cell

A

Cell around a neurone whose cell-surface membrane wraps around the dendron or axon to form the myelin shaft

245
Q

Secondary Structure of a Protein

A

The way in which the chain of amino acids of the polypeptides of a protein is folded

246
Q

Secondary Succession

A

The recolonisation of an area after an earlier community has been removed or destroyed

247
Q

Selection

A

Process that results in the best-adapted individual in a population surviving to breed and so pass their favourable alleles to the next generation

248
Q

Selection Pressure

A

The environmental force altering the frequency of alleles in a population

249
Q

Selective Breeding

A

Breeding of organisms by human selection of parents/gametes in order to perpetuate certain characteristics and/or eliminate others

250
Q

Semi-conservative Replication

A

The means by which DNA makes exact copies of itself by unwinding the double helix so that each chain acts as a template for the next. The new copies therefore possess one original and one new strand of DNA

251
Q

Sensory Neurone

A

A neurone that transmits an action potential from sensory receptor to the central nervous system

252
Q

Serum

A

Clear liquid that is left after blood has clotted and the clots has been removed. It is therefore blood plasma without the clotting factors

253
Q

Sickle-cell Anaemia

A

Inherited blood disorder in which abnormal haemoglobin leads to read cells becoming sickle-shaped and less able to carry oxygen

254
Q

Sinoatrial Node (SAN)

A

An area of heart muscle in the right atrium that controls and coordinates the contraction of the heart. Also known as the pacemaker

255
Q

Skeletal Muscle

A

The muscle that makes up the bulk of the body and which works under conscious control. Also known as voluntary muscle

256
Q

Smooth Muscle

A

Also known as involuntary or unstriated muscle, is found in the alimentary canal and the walls of blood vessels. Its contraction is not under conscious control

257
Q

Sodium-potassium Pump

A

Protein channels across cell-surface membranes that use ATP to move sodium ions out of the cell in exchange for potassium ions that move in

258
Q

Speciation

A

The evolution of two or more species from existing species

259
Q

Species

A

A group of similar organisms that can breed together to produce fertile offspring

260
Q

Species Diversity

A

The number of different species and the number of individuals of each species within any one community

261
Q

Stabilising Selection

A

Selection that tends to eliminate the extremes of the phenotype range within a population. It arises when environmental conditions are constant

262
Q

Stem Cells

A

Undifferentiated dividing cells that occur in embryos and in adult animal tissues that require constant replacement (e.g. bone marrow)

263
Q

Stimulus

A

A detectable alteration in the internal or external environment of an organism that produces some change in that organism

264
Q

Stoma (plural stomata)

A

A pore, mostly found in the lower epidermis of a leaf, through which gases diffuse in and out of the leaf

265
Q

Stroke Volume

A

The volume of blood pumped at each ventricular contraction of the heart

266
Q

Stroma

A

Matrix of a chloroplast where the light-independent reaction of photosynthesis takes place

267
Q

Substrate

A

A substance that is acted on or used by another substance or process. In microbiology, the nutrient medium used to grow microorganisms

268
Q

Substrate-level Phosphorylation

A

The formation of ATP by the direct transfer of a phosphate group from a reactive intermediate to ADP

269
Q

Supernatant Liquid

A

The liquid portion of a mixture left at the top of the tube when suspended particles have been separated out at the bottom during centrifugation

270
Q

Symplastic Pathway

A

Route through the cytoplasm and plasmodesmata of plant cells by which water and dissolved substances are transported

271
Q

Synapse

A

A junction between neurones in which they do not touch but have a narrow gap, the synaptic cleft, across which a neurotransmitter can pass

272
Q

Systole

A

The stage in the cardiac cycle in which the heart muscle contracts. It occurs in two stages; atrial systole when the atria contract and ventricular systole when ventricles contract

273
Q

Tendon

A

Tough, flexible but inelastic connective tissue that joins muscle to bone

274
Q

Tertiary Structure of a Protein

A

The folding of a whole polypeptide chain in a precise way, as determined by the amino acid of which it is composed

275
Q

Threshold Level/Value

A

The minimum intensity that a stimulus must reach in order to trigger an action potential in a neurone

276
Q

Thrombosis

A

Formation of a blood clot within a blood vessel that may lead to a blockage

277
Q

Thylakoid

A

Series of flattened membranous sacs in a chloroplast that contain chlorophyll and the associated molecules for the light-dependent reaction of photosynthesis

278
Q

Tidal Volume

A

The volume of air breathed in and out during a single breath when at rest

279
Q

Tissue

A

A group of similar cells organised into a structural unit that serves a particular function

280
Q

Tissue Fluid

A

Fluid that surrounds the cells of the body. Its composition is similar to that of blood plasma except that it lacks proteins. It supplies nutrients to the cells and removes waste products

281
Q

T Cell (T Lymphocyte)

A

Type of white blood cell that is produced in the bone marrow but matures in the thymus gland. They coordinate the immune response and kill infected cells

282
Q

Transcription

A

Formation of mRNA molecules from the DNA that makes up a particular gene. It is the first stage of protein synthesis

283
Q

Transducer Cells

A

Cells that convert a non-electrical signal, such as light or sound, into an electrical (nervous) signal and vice versa

284
Q

Transduction

A

The process by which one form of energy is converted into another. In microbiology, the natural process by which genetic material is transferred between one host cell and another by a virus

285
Q

Transpiration

A

Evaporation of water from a plant

286
Q

Triglyceride

A

An individual lipid molecule made up of a glycerol molecule and three fattya acids

287
Q

Trophic Level

A

The position of an organisms in a food chain

288
Q

Tumour

A

A swelling in an organism that is made up of cells that continue to divide in an abnormal way

289
Q

Tumour Suppressor Gene

A

A gene that maintains normal rates of cell division and so prevents the development of tumours

290
Q

Turgid

A

A plant cell that contains the maximum volume of water it can. Additional entry of water is prevented by the cell wall stopping further expansion of the cell

291
Q

Ultrafiltration

A

Filtration assisted by blood pressure

292
Q

Unsaturated Fatty Acid

A

A fatty acid in which there are one or more double bonds between the carbon atoms

293
Q

Vaccination

A

The introduction of a vaccine containing appropriate disease antigens into the body, by injection or mouth, in order to influence artificial immunity

294
Q

Vasoconstriction

A

Narrowing of the internal diameter of blood vessels

295
Q

Vasodilation

A

Widening of the internal diameter of blood vessels

296
Q

Vector

A

A carrier. The term may refer to something such as a plasmid, which carriers DNA into a cell, or to an organisms that carries a parasite to its host

297
Q

Voltage-gated Channel

A

Protein channel across a cell-surface membrane that opens and closes according to changes in the electrical potential across the membrane

298
Q

Water Potential

A

The pressure created by water molecules. It is the measure of the extent to which a solution gives out water. The greater the number of water molecules present, the higher (less negative) the water potential. Pure water has a water potential of zero

299
Q

Xerophyte

A

A plant adapted to living in dry conditions

300
Q

Xylem Vessels

A

Dead, hollow, elongated tubes, with lignified side walls and no end walls, that transport water in most plants

Biology (3 decks)

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