Alevel Biology key terms

studied byStudied by 0 people
0.0(0)
learn
LearnA personalized and smart learning plan
exam
Practice TestTake a test on your terms and definitions
spaced repetition
Spaced RepetitionScientifically backed study method
heart puzzle
Matching GameHow quick can you match all your cards?
flashcards
FlashcardsStudy terms and definitions

1 / 251

encourage image

There's no tags or description

Looks like no one added any tags here yet for you.

252 Terms

1
Abiotic
An ecological factor that makes up part of the non-biological environment of an organism, e.g. temperature, pH, rainfall and humidity
New cards
2
Acetylcholine
A group of chemicals called neurotransmitters, released by neurones. It diffuses across the synapse between adjacent neurones and passes an impulse from one neurone to the next
New cards
3
Action Potential
Change that occurs in the electrical charge across the membrane of an axon when it is stimulated and a nerve impulse passes
New cards
4
Actin
Filamentous protein which is involved in contraction within cells, specifically muscle cells.
New cards
5
Activation Energy
Energy required to bring about a reaction
New cards
6
Active Immunity
Resistance to disease resulting from the activities of an individual's own immune system whereby an antigen induces plasma cells to produce antibodies
New cards
7
Active Site
A group of amino acids that makes up the region of an enzyme into which the substrate fits in order to catalyse a reaction
New cards
8
Active Transport
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
New cards
9
Adenosine Triphosphate (ATP)
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.
New cards
10
Adrenaline
A hormone produced by the adrenal glands in times of stress that prepares the body for an emergency
New cards
11
Aerobic
Connected with the presence of free oxygen. Aerobic respiration requires free oxygen to release energy from glucose
New cards
12
Alelle
One of a number of alternative forms of a gene.
New cards
13
For example, the gene for the shape of pea seeds has two alleles: one for 'round' and one for 'wrinkled'
New cards
14
Allergen
A normally harmless substance that causes the immune system to produce an immune response.
New cards
15
Allergy
The response of the immune system to an allergen
New cards
16
Examples include hay fever and asthma
New cards
17
Anaerobic
Connected with the absence of oxygen. Anaerobic respiration releases energy from glucose or other foods without the presence of oxygen
New cards
18
Antibiotic
A substance produced by living organisms that can destroy or inhibit the growth of microorganisms
New cards
19
Antibiotic Resistance
The development in microorganisms of mechanisms that prevent antibiotics from killing them
New cards
20
Antibody
A protein produced by lymphocytes in response to the presence of the appropriate antigen
New cards
21
Anticodon
A sequence of three adjacent nucleotides on a molecule of transfer RNA that is complementary to a particular codon on a messenger RNA molecule
New cards
22
Antidiuretic Hormone (ADH)
A hormone produced by the hypothalamus that passes to the posterior pituitary gland from where it is secreted. Reduces the volume of water in urine by increasing water reabsorption in the kidneys
New cards
23
Antigen
A molecule that triggers an immune response by lymphocytes
New cards
24
Antioxidant
Chemical which reduces or prevents oxidation. Often used as an additive to prolong the shelf-life of certain foods
New cards
25
Apoplastic Pathway
Route through the cell walls and intercellular spaces of plants by which water and dissolved substances are transported
New cards
26
Artificial Selection
Breeding of organisms by human selection of parents/gametes in order to perpetuate certain characteristics and/or to eliminate others
New cards
27
Asthma
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
New cards
28
Atheroma
Fatty deposits in the walls of arteries, often associated with high cholesterol levels in the blood
New cards
29
Autonomic Nervous System
Part of the nervous system that controls the muscles and glands but is not under voluntary control
New cards
30
Autosomes
A chromosome which is not a sex chromosome
New cards
31
Axon
A process extending from a neurone that conducts action potentials away from the cell body
New cards
32
B Cell (B Lymphocyte)
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
New cards
33
Benedict's Test
A simple biochemical reaction to detect the presence of reducing sugars
New cards
34
Biodiversity
The range and variety of genes, species and habitats within a particular region
New cards
35
Biomass
The total mass of living material, normally measured in a specific area over a given period of time
New cards
36
Biotic
An ecological factor that makes up part of the living environment of an organism. e.g. food availability, competition and predation
New cards
37
Biosensor
A device that uses biological molecules to measure the level of certain chemicals
New cards
38
Biuret Test
A simple biochemical reaction to detect the presence of protein
New cards
39
Body Mass Index (BMI)
A person's body mass in kilograms divided by the square of their height in metres
New cards
40
Cancer
A disease, resulting from cells that break away from an original tumour to form secondary tumours elsewhere in the body
New cards
41
Carcinogen
A chemical, a form of radiation, or other agent that causes cancer
New cards
42
Cardiac Cycle
A continuous series of events which make up a single heart beat
New cards
43
Cardiac Output
The total volume of blood that the heart can pump each minute (stroke volume x heart rate)
New cards
44
Carrier Molecule (Carrier Protein)
A protein on the surface of a cell that helps to transport molecules and ions across plasma membranes
New cards
45
Casparian Strip
A distinctive band of suberin around the endodermal cells of a plant root that
New cards
46
prevents water passing into xylem via the cell walls. The water is forced through the living part (protoplast) of the endodermal cells
New cards
47
Centrifugation
Process of separating out particles of different sizes and densities by spinning them at high speed in a centrifuge
New cards
48
Cholesterol
Lipid that is an important component of cell-surface membranes. Excess in blood can lead to atheroma
New cards
49
Chromatid
One of the two strands of a chromosome that are joined together by a single centromere prior to cell division
New cards
50
Chromatin
The material that makes up chromosomes. It consists of DNA and the protein histone
New cards
51
Chromosome
A thread-like structure made of protein and DNA by which hereditary information is physically passed from one generation to the next
New cards
52
Climax Community
The organisms that make up the final stage of ecological succession
New cards
53
Clone
A group of genetically identical cells or organisms formed from a single parent as the result of asexual reproduction or by artificial means
New cards
54
Codon
A sequence of three adjacent nucleotides in mRNA that codes for one amino acid
New cards
55
Cohesion
Attraction between molecules of the same type. It is important in the movement of water up a plant
New cards
56
Collagen
Fibrous protein that is the main constituent of connective tissues such as tendons, cartilage and bone
New cards
57
Community
All the living organisms present in an ecosystem at a given time
New cards
58
Complementary DNA
DNA that is made from messenger RNA in a process that is the reverse of
New cards
59
normal transcription
New cards
60
Condensation
Chemical process in which two molecules combine to form a more complex one with the elimination of a simple substance, usually water
New cards
61
Consumer
Any organism that obtains energy by 'eating' another.
New cards
62
Plant eaters = primary consumers, primary consumer eaters = secondary consumers
New cards
63
Continuous Variation
Variation in which organisms do not fall into distinct categories but show
New cards
64
gradations from one extreme to the other
New cards
65
Coronary Arteries
Arteries that supply blood to the cardiac muscle of the heart
New cards
66
Coronary Heart Disease (CHD)
Any condition, for example, atheroma and thrombosis, affecting the coronary arteries that supply heart muscle
New cards
67
Correlation
When a change in one variable is reflected by a change in the second variable
New cards
68
Countercurrent System
A mechanism by which the efficiency of exchange between two substances is increased by having them flowing in opposite directions
New cards
69
Co-transport
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
New cards
70
Crossing over
The process whereby a chromatid breaks during meiosis and rejoins to the
New cards
71
chromatid of its homologous chromosome so that their alleles are exchanged
New cards
72
Covalent bond
Type of chemical bond in which two atoms share a pair of electrons, one from each atom
New cards
73
Cuticle
Exposed non-cellular outer layer of certain animals and the leaves of plants.
New cards
74
Waxy, impermeable to water = reduces water loss
New cards
75
Deciduous
Term applied to plants that shed all their leaves together at one season
New cards
76
Denaturation
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
New cards
77
Depolarisation
Temporary reversal of charges on the cell-surface membrane of a neurone that takes place when a nerve impulse is transmitted
New cards
78
Diastole
The stage in the cardiac cycle when the heart muscle relaxes
New cards
79
Differentiation
The process by which cells become specialised for different functions
New cards
80
Diffusion
The movement of molecules or ions from a region where they are in high concentration to one where their concentration is lower
New cards
81
Dipolar
Having a pair of equal and opposite electrical charges
New cards
82
Diploid
A term applied to cells in which the nucleus contains two sets of chromosomes
New cards
83
Dominant Allele
An allele that is always epressed in the phenotype of an organism, even in the heterozygous
New cards
84
Ecological Niche
Describes how an organism fits into its environment. It describes what a
New cards
85
species is like, where it occurs, how it behaves, its interactions with other species and how it responds to its environment
New cards
86
Ecosystem
All the living and non-living components of a particular area
New cards
87
Effector
An organ that responds to stimulation by a nerve impulse resulting in a
New cards
88
change or response
New cards
89
Electron
Negatively charged subatomic particle that orbits the positively charged nucleus of all atoms
New cards
90
Emphysema
A disease in which the walls of the alveoli break down, reducing the surface area for gaseous exchange, thereby causing breathlessness in the patient
New cards
91
Enzyme
A protein or RNA that acts as a catalyst and so alters the speed of a biochemical reaction
New cards
92
Epidemiology
The study of the spread of disease and the factors that affect this spread
New cards
93
Eukaryotic Cell
Cell that has a membrane-bound nucleus and chromosomes. The cell also possesses a variety of other membranous organelles, such as mitochondria and endoplasmic
New cards
94
reticulum
New cards
95
Exocytosis
The outward bulk transport of materials through the cell-surface membrane
New cards
96
Facilitated diffusion
Diffusion involving the presence of protein carrier molecules to allow the
New cards
97
passive movement of substances across plasma membranes
New cards
98
Gamete
Reproductive cell that fuses with another gamete during fertilisation
New cards
99
Gene
Section of DNA on a chromosome coding for one or more polypeptides
New cards
100
Gene Marker
A section of DNA that is used to indicate the location of a gene or other section of DNA
New cards

Explore top notes

note Note
studied byStudied by 8 people
692 days ago
5.0(1)
note Note
studied byStudied by 47 people
843 days ago
5.0(1)
note Note
studied byStudied by 84 people
555 days ago
5.0(1)
note Note
studied byStudied by 10 people
862 days ago
5.0(1)
note Note
studied byStudied by 73 people
688 days ago
5.0(1)
note Note
studied byStudied by 2132 people
707 days ago
4.9(7)
note Note
studied byStudied by 18 people
874 days ago
5.0(1)
note Note
studied byStudied by 6589 people
704 days ago
5.0(13)

Explore top flashcards

flashcards Flashcard (126)
studied byStudied by 56 people
287 days ago
5.0(2)
flashcards Flashcard (187)
studied byStudied by 24 people
829 days ago
5.0(1)
flashcards Flashcard (72)
studied byStudied by 14 people
142 days ago
5.0(1)
flashcards Flashcard (28)
studied byStudied by 2 people
33 days ago
5.0(1)
flashcards Flashcard (20)
studied byStudied by 11 people
395 days ago
5.0(1)
flashcards Flashcard (45)
studied byStudied by 3 people
739 days ago
5.0(1)
flashcards Flashcard (20)
studied byStudied by 77 people
547 days ago
5.0(1)
flashcards Flashcard (31)
studied byStudied by 39 people
45 days ago
5.0(2)
robot