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A Level Biology Revision > Keywords > Flashcards

Keywords Flashcards

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1
Q

Topic : Causes of disease

Pathogen

A

A micro-organism that causes disease

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2
Q

Topic : Enzymes and Digestive system

Digestion

A

Physical and chemical breakdown of food

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3
Q

Topic : Enzymes and Digestive system

Hydrolysis

A

Splitting up of molecules by adding water to them.

Enzymes do this to help break down molecules.

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4
Q

Topic : Enzymes and Digestive system

Monomer

A

One of many small molecules that combine to form a

larger one

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5
Q

Topic : Enzymes and Digestive system

Polymer

A

Larger molecule made up of repeating smaller

molecules

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6
Q

Topic : Enzymes and Digestive system

Condensation Reaction

A

When 2 monosaccharides combine, water is removed

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7
Q

Topic : Enzymes and Digestive system

Glycosidic Bond

A

The bond in a disaccharide

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8
Q

Topic : Enzymes and Digestive system

Peptide Bond

A

The bond between 2 amino acids in a protein, formed

by a condensation reaction

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9
Q

Topic : Enzymes and Digestive system

Polypeptide

A

A long chain of amino acids

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10
Q

Topic : Enzymes and Digestive system

Hydrogen Bonds

A

Weak bonds between oxygen and hydrogen holding the

secondary structure of a protein in a coil

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11
Q

Topic : Enzymes and Digestive system

Activation Energy

A

The minimum amount of energy needed to bring about

a reaction

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12
Q

Topic : Enzymes and Digestive system

Active site

A

The region on an enzyme where the substrate fits

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13
Q

Topic : Enzymes and Digestive system

Substrate

A

The molecule on which the enzyme acts

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14
Q

Topic : Enzymes and Digestive system

Enzyme-Substrate Complex

A

Formed when an enzyme and a substrate fit together

and form temporary bonds

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15
Q

Topic : Enzymes and Digestive system

Denaturation

A

Permanent changes in the structure of a protein;
enzyme’s active site changes shape so the substrate no
longer fits

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16
Q

Topic : Enzymes and Digestive system

Competitive Inhibitor

A

Molecule that binds to the active site of an enzyme

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17
Q

Topic : Enzymes and Digestive system

Non-competitive inhibitor

A

Bind to the enzyme at a position other than the active

site

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18
Q

Topic : Cells and movement in and out of them

Resolution

A

The minimum distance apart 2 objects are, so that they

look like separate objects under the microscope

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19
Q

Topic : Cells and movement in and out of them

Cell Fractionation

A

The process by which cells are broken up and the

organelles separated out

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20
Q

Topic : Cells and movement in and out of them

Prokaryotic Cells

A

Cells that lack a nucleus and any membrane-bound

organelles

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21
Q

Topic : Cells and movement in and out of them

Eukaryotic Cells

A

Cells that have a nucleus, chromosomes and other

membrane-bound organelles

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22
Q

Topic : Cells and movement in and out of them

Saturated Lipids

A

Fatty acids with only C-C single bonds

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23
Q

Topic : Cells and movement in and out of them

Unsaturated Lipids

A

Fatty acids with one or more C=C double bonds

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24
Q

Topic : Cells and movement in and out of them

Hydrophilic

A

Attracted to water

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25
Q

Topic : Cells and movement in and out of them

Hydrophobic

A

Attracted to fat

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26
Q

Topic : Cells and movement in and out of them

Extrinsic Proteins

A

Proteins on the surface of the bilayer

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27
Q

Topic : Cells and movement in and out of them

Intrinsic Proteins

A

Proteins spanning the bilayer

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28
Q

Topic : Cells and movement in and out of them

Diffusion

A

The net movement of molecules or ions from a region

of high concentration to a region of low concentration

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29
Q

Topic : Cells and movement in and out of them

Osmosis

A

The passage of water from a region of high water
potential to a region of low water potential, across a
partially permeable membrane

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30
Q

Topic : Cells and movement in and out of them

Active Transport

A

The movement of molecules or ions into or out of a cell
from a region of lower concentration to a region of
higher concentration using energy and carrier
molecules

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31
Q

Topic : Lungs and Lung Disease

Pulmonary
Ventilation

A

Tidal Volume x Ventilation Rate

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32
Q

Topic : Lungs and Lung Disease

Short Diffusion Pathway

A

Thin alveoli walls allow materials to cross quickly as the

path is short

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33
Q

Topic : Lungs and Lung Disease

Diffusion Gradient

A

Movement of air and blood help to maintain diffusion

gradients – keep Oxygen moving in and CO2 out

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34
Q

Topic : Lungs and Lung Disease

Pulmonary Fibrosis

A

Thickening of lung epithelia due to scarring

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35
Q

Topic : Lungs and Lung Disease

Asthma

A

An allergic reaction where histamine is released and the

airway linings become inflamed

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36
Q

Topic : Lungs and Lung Disease

Emphysema

A

Destruction of the elastic tissue in the lungs due to

smoking

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37
Q

Topic : The Heart and Heart Disease

Atrial Systole

A

Contraction of the atria

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38
Q

Topic : The Heart and Heart Disease

Ventricular Systole

A

Contraction of the ventricles

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39
Q

Topic : The Heart and Heart Disease

Diastole

A

Relaxation of the heart

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40
Q

Topic : The Heart and Heart Disease

Cardiac Output

A

The volume of blood pumped by one ventricle of the

heart in one minute

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41
Q

Topic : The Heart and Heart Disease

Myogenic

A

Contraction of the heart is initiated from within the

muscle itself

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42
Q

Topic : The Heart and Heart Disease

Sino-atrial node

A

SAN, sends out the initial wave of electrical activity to

make the atria contract

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43
Q

Topic : The Heart and Heart Disease

Atrio-ventricular node

A

AVN, sends a wave of electrical activity down the
bundle of His, making the ventricles contract from the
base upwards

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44
Q

Topic : The Heart and Heart Disease

Atheroma

A

A fatty deposit in the wall of an artery

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45
Q

Topic : The Heart and Heart Disease

Aneurysm

A

Weakened artery walls swell and may burst

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46
Q

Topic : The Heart and Heart Disease

Thrombosis

A

When an atheroma breaks and a blood clot forms

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47
Q

Topic : The Heart and Heart Disease

Myocardial Infarction

A

A heart attack

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48
Q

Topic : The Heart and Heart Disease

Low-density lipoproteins

A

Transport cholesterol to tissues that may get deposited

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49
Q

Topic : The Heart and Heart Disease

High-density lipoproteins

A

Remove cholesterol from tissues

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50
Q

Topic : Immunity

Non-Specific Defences

A

Mechanisms that don’t distinguish between one type of

pathogen or another e.g. skin

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51
Q

Topic : Immunity

Specific Defences

A

Mechanisms that do distinguish between different

pathogens e.g. lymphocytes

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52
Q

Topic : Immunity

Phagocytosis

A

Pathogens are engulfed into vesicles (called

phagosomes) and broken down by enzymes

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53
Q

Topic : Immunity

Antigens

A

Part of an organism that is recognised as non-self and

triggers an immune response (usually they are proteins)

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54
Q

Topic : Immunity

Cell-mediated Immunity

A

T lymphocytes recognise antigen-presenting cells that

have been invaded and undergo mitosis to respond

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55
Q

Topic : Immunity

Humoral Immunity

A

Immunity involving B cells and antibodies

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56
Q

Topic : Immunity

Antigenic Variability

A

Viruses such as flu have many different strains with

different antigens on them

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57
Q

Topic : Immunity

Antibodies

A

Proteins synthesised by B cells, consisting of heavy and

light chains and variable and constant regions

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58
Q

Topic : Immunity

Antigen-Antibody Complex

A

Formed when antigens bind to a specific site on the

antibody

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59
Q

Topic : Immunity

Complementary Shape

A

Antigens have a shape that means they fit into their

specific antibody

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60
Q

Topic : Immunity

Monoclonal Antibodies

A

Isolation and cloning of a single type of antibody

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61
Q

Topic : Immunity

Passive Immunity

A

The introduction of antibodies from an outside source

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62
Q

Topic : Immunity

Active Immunity

A

Stimulation of antibody production by the individual’s

own immune system

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63
Q

Topic : Immunity

Vaccination

A

The introduction of a substance into the body with the
purpose of stimulating active immunity against a
particular disease

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64
Q

Topic : Immunity

Herd Immunity

A

Vaccinating most of a population so that no-one has the

disease and transmission is stopped

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65
Q

Topic : Variation

Interspecific Variation

A

Differences between different species

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66
Q

Topic : Variation

Intraspecfic Variation

A

Differences between members of the same species

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67
Q

Topic : DNA and Meiosis

Nucleotide

A

Section of DNA made up of sugar, phosphate and a base

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68
Q

Topic : DNA and Meiosis

Complementary

A

A always bonds to T and C always bonds to G (they are

complementary to each other)

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69
Q

Topic : DNA and Meiosis

Gene

A

A section of DNA that codes for making a polypeptide

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70
Q

Topic : DNA and Meiosis

Triplet Code

A

3 bases code for an amino acid

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71
Q

Topic : DNA and Meiosis

Chromosome

A

Thread-like structure made of protein and DNA, passes

hereditary information on

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72
Q

Topic : DNA and Meiosis

Homologous Chromosomes

A

2 chromosomes determining the same characteristics

one from mother, one from father

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73
Q

Topic : DNA and Meiosis

Allele

A

One of the different forms of a gene

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74
Q

Topic : DNA and Meiosis

Meiosis

A

Cell division that produces 4 haploid (half the

chromosomes), genetically different, daughter cells

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75
Q

Topic : DNA and Meiosis

Locus

A

Position of a gene on a chromosome

76
Q

Topic : DNA and Meiosis

Independent Segregation

A

Homologous pairs randomly separate during meiosis 1,

into separate cells

77
Q

Topic : DNA and Meiosis

Crossing Over

A

The process where chromatids break and rejoin with

their homologous chromosome to exchange alleles

78
Q

Topic : Genetic Diversity

Selective Breeding

A

Breeding individuals with desired characteristics
together and selecting the offspring that show the
desired characteristics

79
Q

Topic : Genetic Diversity

Founder Effect

A

A few individuals colonise a new region, carrying a small

amount of the alleles of the larger population

80
Q

Topic : Genetic Diversity

Genetic Bottleneck

A

A drop in allele variety due to a large decrease in

population size

81
Q

Topic : The Variety of Life

Affinity for Oxygen

A

Haemoglobin (Hb) with a high affinity takes up oxygen
easily and releases in less readily. Hb with a low affinity
takes up oxygen less easily, but releases it more readily.

82
Q

Topic : The Variety of Life

Associating

A

The process by which Hb combines with oxygen (in the

lungs)

83
Q

Topic : The Variety of Life

Dissociating

A

The process by which Hb releases oxygen (in the

tissues)

84
Q

Topic : The Variety of Life

Oxygen Dissociation Curve

A

The s-shaped curve shown by how Hb binds oxygen

first molecule is hard to load, next 3 load easily

85
Q

Topic : The Variety of Life

Starch

A

Storage molecule in plants, it is coiled, insoluble and can

by hydrolysed to form α-glucose

86
Q

Topic : The Variety of Life

Glycogen

A

Storage molecule in animals, which has short chains so

it can be readily hydrolysed to α-glucose

87
Q

Topic : The Variety of Life

Cellulose

A

Parallel chains of β-glucose joined by hydrogen bonds,

forms microfibrils for strength

88
Q

Topic : The Variety of Life

Chloroplasts

A

Organelle in plant cells containing grana, thylakoids and

stroma. Photosynthesis occurs here.

89
Q

Topic : The Cell Cycle

Semi-conservative Replication

A

The way DNA makes exact copies of itself by unwinding
the double helix. Each chain acts as a template for the
new strands.

90
Q

Topic : The Cell Cycle

Mitosis

A

Cell division where 2 daughter cells are produced that

have the same number of chromosomes as the parent

91
Q

Topic : The Cell Cycle

Haploid

A

Cells have half the number of chromosomes

92
Q

Topic : The Cell Cycle

Diploid

A

Cells have a full set of chromosomes

93
Q

Topic : The Cell Cycle

Prophase

A

Chromosomes become visible, nuclear envelope

disappears

94
Q

Topic : The Cell Cycle

Metaphase

A

Chromosomes align along equator of cell

95
Q

Topic : The Cell Cycle

Anaphase

A

Chromatids move to opposite poles

96
Q

Topic : The Cell Cycle

Telophase

A

Nuclear envelope reforms

97
Q

Topic : The Cell Cycle

Cell Cycle

A

A cell’s regular cycle of division, followed by periods of

growth

98
Q

Topic : Cellular Organisation

Cell Differentiation

A

Cells become specialised in their structure to suit their

roles

99
Q

Topic : Cellular Organisation

Tissue

A

A collection of similar cells that perform a specific

function

100
Q

Topic : Cellular Organisation

Organ

A

A combination of tissues, co-ordinated to perform a

variety of functions

101
Q

Topic : Cellular Organisation

Organ Systems

A

Organs working together as a single unit

102
Q

Topic : Exchange and transport

Surface area to volume ratio

A

For exchange to be efficient, an organism needs a large
surface area to volume ratio (bigger animals have a
smaller ratio)

103
Q

Topic : Exchange and transport

Spiracles

A

Pores on the body surface of insects that open and

close to allow gases to diffuse in and out

104
Q

Topic : Exchange and transport

Gill Lamellae

A

Parts of fish gills that increase the surface area and

where the blood flows through for gas exchange

105
Q

Topic : Exchange and transport

Countercurrent Exchange

A

Blood and water flow in opposite directions to maintain

a diffusion gradient

106
Q

Topic : Exchange and transport

Stomata

A

Pores in the underside of a leaf that can be opened and

closed by guard cells

107
Q

Topic : Exchange and transport

Double Circulatory System

A

Blood passes through the heart twice on a full circuit of

the body

108
Q

Topic : Exchange and transport

Arteries

A

Blood vessels that carry blood away from the heart

small lumens, thick muscle and elastic layers

109
Q

Topic : Exchange and transport

Veins

A

Blood vessels that carry blood back to the heart (large

lumens, thin muscle and elastic layers, have valves)

110
Q

Topic : Exchange and transport

Tissue Fluid

A

Fluid that surrounds the cells of the body, it supplies

nutrients to the cells and removes waste products

111
Q

Topic : Exchange and transport

Ultrafiltration

A

Filtration assisted by blood pressure

112
Q

Topic : Exchange and transport

Apoplastic Pathway

A

Route through the cell walls by which water and

minerals are transported into the plant

113
Q

Topic : Exchange and transport

Symplastic Pathway

A

Route through the cytoplasm and plasmodesmata of

plant cells by which water and minerals are transported

114
Q

Topic : Exchange and transport

Cohesion

A

Water molecules stick together by hydrogen bonds

115
Q

Topic : Exchange and transport

Cohesion-Tension

A

Transpiration pull on the water puts the xylem under

pressure

116
Q

Topic : Exchange and transport

Transpiration

A

Evaporation of water from a plant

117
Q

Topic : Exchange and transport

Xerophytes

A

Plants adapted to living in dry conditions

118
Q

Topic : Classification

Species

A

A group of similar organisms that can breed together to

produce fertile offspring

119
Q

Topic : Classification

Classification

A

Grouping of organisms

120
Q

Topic : Classification

Taxonomy

A

Theory and practice of biological classification

121
Q

Topic : Classification

Phylogeny

A

The evolutionary relationships between organisms

122
Q

Topic : Evidence for Relationships Between Organisms

DNA Hybridisation

A

A technique used to determine the similarities between

the DNA of different organisms

123
Q

Topic : Evidence for Relationships Between Organisms

Hybridisation

A

Double strands form with one strand from each species,
closely related organisms will share complementary
bases

124
Q

Topic : Evidence for Relationships Between Organisms

Courtship Behaviour

A

Signals and displays between males and females of the

same species to enable successful mating to occur

125
Q

Topic : Adaptation and Selection

Adaptation

A

Organisms adjust to suit the changing environment

where they live

126
Q

Topic : Adaptation and Selection

Mutations

A

A change in the base sequence of DNA

127
Q

Topic : Adaptation and Selection

Conjugation

A

One bacterial cell transfers DNA to another bacterial

cell

128
Q

Topic : Adaptation and Selection

Antibiotics

A

Substances that can destroy or inhibit the growth of

micro-organisms

129
Q

Topic : Adaptation and Selection

Antibiotic Resistance

A

Antibiotics have a reduced effectiveness at killing

bacteria due to chance mutations

130
Q

Topic : Adaptation and Selection

Plasmids

A

Circular loops of DNA in bacteria

131
Q

Topic : Biodiversity

Biodiversity

A

The variety in the living world (including number of
different species, variety of genes and the range of
habitats)

132
Q

Topic : Populations

Ecosystem

A

Self-contained unit made up of the biotic and abiotic

factors in an area

133
Q

Topic : Populations

Population

A

A group of individuals of the same species in a habitat

134
Q

Topic : Populations

Community

A

The organisms of all species that live in the same area

135
Q

Topic : Populations

Abiotic Factors

A

Concerned with the non-living part of the environment

136
Q

Topic : Populations

Biotic Factors

A

Concerned with the living organisms in the environment

137
Q

Topic : Populations

Interspecific Competition

A

Competition between organisms of different species

138
Q

Topic : Populations

Intraspecific Competition

A

Competition between organisms of the same species

139
Q

Topic : ATP

Phosphorylation

A

The process of adding a phosphate group (e.g. ADP –>

ATP)

140
Q

Topic : Photosynthesis

Light Dependent Reaction

A

Stage of photosynthesis in which light energy is

required to produce ATP and reduced NADP

141
Q

Topic : Photosynthesis

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 CO2 and form
carbohydrate

142
Q

Topic : Photosynthesis

Oxidation

A

Loss of electrons, combining oxygen with a substance

143
Q

Topic : Photosynthesis

Reduction

A

Gain of electrons, loss of oxygen from a substance

144
Q

Topic : Photosynthesis

Electron Carrier Molecules

A

A chain of carrier molecules along which electrons pass,

releasing energy in the form of ATP as they do so

145
Q

Topic : Photosynthesis

Photolysis of Water

A

Light energy splits water molecules, yielding electrons,

hydrogen ions and oxygen (light-dependent reaction)

146
Q

Topic : Photosynthesis

Calvin Cycle

A

A biochemical pathway (part of the light-independent
reaction) where CO2 is reduced to form carbohydrate
CO2 + RuBP –> GP –> TP –> Glucose or RuBP

147
Q

Topic : Respiration

Glycolysis

A

First part of cellular respiration in which glucose is
broken down (in the cytoplasm) to 2 molecules of
pyruvate

148
Q

Topic : Respiration

Link Reaction

A

Process linking Glycolysis to the Krebs Cycle (in the
matrix of the mitochondria), where the 2 molecules of
pyruvate are converted to CO2 and acetylcoenzyme A

149
Q

Topic : Respiration

Krebs Cycle

A

Introducing acetylcoenzyme A into a cycle of oxidationreduction
reactions (in the matrix of the mitochondria)
that yield some ATP and a large number of electrons

150
Q

Topic : Respiration

Electron Transport Chain

A

Use of electrons from the Krebs Cycle to synthesise ATP

via a series of oxidation-reduction reactions

151
Q

Topic : Respiration

Anaerobic Respiration

A

Releasing energy from glucose without oxygen
(produces lactate in animals and ethanol in plants and
some micro-organisms)

152
Q

Topic : Energy and Ecosystems

Trophic Level

A

Each stage in a food chain

153
Q

Topic : Energy and Ecosystems

Consumers

A

An organism that obtains its energy by feeding on other

organisms

154
Q

Topic : Energy and Ecosystems

Gross Production

A

Total quantity of energy that the plants in a community

convert to organic matter

155
Q

Topic : Energy and Ecosystems

Net Production

A

Gross production – respiratory losses

156
Q

Topic : Energy and Ecosystems

Energy Transfer

A

(Energy available after the transfer / energy available

before the transfer) x 100

157
Q

Topic : Energy and Ecosystems

Pyramid of Number

A

A pyramid drawn with bar lengths proportional to the

numbers of organisms present

158
Q

Topic : Energy and Ecosystems

Pyramid of Biomass

A

A pyramid drawn with bar lengths proportional to the

mass of plants/animals

159
Q

Topic : Energy and Ecosystems

Pyramid of Energy

A

A pyramid drawn with bar lengths proportional to the

energy stored in organisms

160
Q

Topic : Energy and Ecosystems

Selective Breeding

A

Breeding of organisms by human selection of parents

for certain characteristics

161
Q

Topic : Nutrient Cycles

Saprobiotic Micro-organism

A

(Saprophyte) An organisms that gets it food from the

dead or decaying remains of other organisms

162
Q

Topic : Nutrient Cycles

Greenhouse Gases

A

Gases such as methane and CO2 which trap more heat

energy, raising the Earths temperature

163
Q

Topic : Nutrient Cycles

Ammonification

A

Production of ammonia from e.g. urea and proteins

164
Q

Topic : Nutrient Cycles

Nitrification

A

Converting ammonia into nitrites and then nitrates

165
Q

Topic : Nutrient Cycles

Nitrogen Fixation

A

Conversion of nitrogen gas into nitrogen-containing

compounds

166
Q

Topic : Nutrient Cycles

Denitrification

A

Conversion of soil nitrates into mitrogen gas

167
Q

Topic : Nutrient Cycles

Leaching

A

Process by which nutrients are washed from the soil

into watercourses

168
Q

Topic : Nutrient Cycles

Eutrophication

A

Consequence of an increase in nutrients in

watercourses that leads to a decrease in biodiversity

169
Q

Topic : Inheritance and Selection

Genotype

A

The genetic composition of an organism

170
Q

Topic : Inheritance and Selection

Phenotype

A

The characteristics of an organism (often visible),

resulting from its genotype and the environment

171
Q

Topic : Inheritance and Selection

Gene

A

A length of DNA that codes for a polypeptide

172
Q

Topic : Inheritance and Selection

Allele

A

One form of a gene

173
Q

Topic : Inheritance and Selection

Homologous Chromosomes

A

A pair of chromosomes that have the same gene loci

and determine the same features

174
Q

Topic : Inheritance and Selection

Dominant

A

An allele that is always expressed in the phenotype

175
Q

Topic : Inheritance and Selection

Recessive

A

An allele that is only expressed in the phenotype when

there is another identical allele

176
Q

Topic : Inheritance and Selection

Heterozygous

A

When the alleles are different for a particular gene

177
Q

Topic : Inheritance and Selection

Homozygous

A

When the alleles are the same for a particular gene

178
Q

Topic : Inheritance and Selection

Sex Linkage

A

Any gene that is carried on the X or Y chromosome

179
Q

Topic : Inheritance and Selection

Co-dominance

A

Both alleles are equally dominant and are both

expressed in a phenotype

180
Q

Topic : Inheritance and Selection

Multiple Alleles

A

More than 2 possible alleles for a particular gene

181
Q

Topic : Inheritance and Selection

Gene Pool

A

All the alleles of all the genes of all the individuals in a

population at any one time

182
Q

Topic : Inheritance and Selection

Allelic Frequency

A

The number of times the allele occurs within a gene

pool

183
Q

Topic : Inheritance and Selection

Stabilising Selection

A

Selection that favours average individuals

184
Q

Topic : Inheritance and Selection

Directional Selection

A

Selection that favours individuals at one extreme

185
Q

Topic : Inheritance and Selection

Speciation

A

The evolution of new species from existing species

186
Q

Topic : Inheritance and Selection

Geographical Isolation

A

When a physical barrier prevents two populations from

breeding with one another

A Level Biology Revision (10 decks)

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