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Biology > A Level - Keywords > Flashcards

A Level - Keywords Flashcards

1
Q

cell signalling

A

how cells communicate with each other. Done with nervous impulses or hormones

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2
Q

Stimulus

A

change in an environment that causes a response

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3
Q

Response

A

change in behaviour/physiology as a results of a stimulus

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4
Q

Ectotherm

A

an organism that relies on external sources of heat to regulate body temperature

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5
Q

Endotherm

A

an organism that can control the generation or loss of heat to maintain its body temperature using physiological or behavioural responses

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6
Q

Homeostasis

A

the maintenance of the internal environment in a constant state despite external changes

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7
Q

Negative feedback

A

a process that brings about a reversal of any change in conditions in order to return to
an optimum steady state. Essential for homeostasis.

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8
Q

Positive feedback

A

a process that increases any change detected by the receptors. Does not lead to homeostasis

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9
Q

Generator potential

A

Small depolarisation caused by sodium ions entering the cell

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10
Q

Resting potential

A

when neurone is at rest (no stimulus), -70mV.

sodium/potassium ion pumps [3 out/2 in], K+ leakage

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11
Q

Depolarisation

A

loss of polarisation due to entry of Na+ entering the cell. Potential difference across membrane becomes less negative

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12
Q

Threshold potential

A

creates and action potential there is a big enough stimulus for enough Na+ enter the cell for the potential difference to exceed -50mV

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13
Q

Action potential

A

Membrane is depolarised to +40mV. All or nothing response. Transmitted along the axon membrane

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14
Q

Repolarisation

A

membrane becomes polarised again due to loss of K+ through v-g channels. Potential difference across membrane becomes more negative

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15
Q

Hyperpolarisation

A

too many K+ diffuse out - potential difference under -70mV

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16
Q

Refractory period

A

following an action potential, there is a need to redistribute sodium and potassium ions and restore resting potential. During this time another impulse cannot be generated. Ensures impulses separated, determines maximum frequency of impulse transmission, ensure impulse passes in one direction only along axon

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17
Q

Local currents

A

movements of ions along the neurone

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18
Q

Saltatory conduction

A

how the action potential ‘jumps’ from one Node of Ranvier to the next

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19
Q

Endocrine glands

A

produce and secrete hormones directly into the blood - they have no ducts.

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20
Q

Exocrine glands

A

do not produce hormones - they secrete molecules into a duct which carries them to where they are needed .

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21
Q

Hormone

A

molecules released by endocrine glands into the blood and act as messengers carrying a signal from the endrocrine gland to the target tissue.

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22
Q

Target cells/tissue

A

possess specific receptors on their cell surface membrane which is complementary in shape to a hormone molecule.

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23
Q

Neurotransmitter

A

a chemical that diffuses across the synaptic cleft to transmit a signal to the post- synaptic membrane

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24
Q

Cholinergic synapse

A

use acetylcholine as the neurotransmitter

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25
Acetylcholinesterase
enzyme that breaks down acetylcholine in the synaptic cleft
26
Summation
how several small potential changes across the axon/dendron membrane can combine to produce one larger change in potential difference across the membrane
27
First messenger
hormones that transmits a signal around the body in the blood
28
Second messenger
cAMP which transmits a signal inside the cell
29
Hepatocytes
liver cells
30
Diabetes mellitus
a disease in which you can’t control your blood glucose concentrations effectively
31
Hyperglycemia
Blood glucose levels are too high
32
Hypoglycemia
blood glucose levels are too low
33
Glycogenolysis
glycogen being converted into glucose. Occurs in the liver.
34
Gluconeogenesis
fatty acids/amino acids --> glucose. Occurs in the liver.
35
Glycogenesis
glucose being converted into glycogen. Occurs in the liver.
36
Myogenic
muscle can initiate its own contractions
37
Excretion
removal of the unwanted / toxic / waste, products of metabolism
38
Deamination
``` Removes the amine group from amino acid - produces a keto acid (can be respired) and also produces ammonia (soluble and highly toxic). Occurs in the liver ```
39
Ornithine cycle
ammonia is converted into urea
40
Ultrafiltration
filtration at molecular level in glomerulus by the basement membrane - smaller molecules (urea, water, glucose, amino acids, ions) are filtered out of the blood into the lumen of the Bowman's capsule.
41
Selective reabsorption
useful substances are reabsorbed from the nephron (most happens in the PCT) into the blood e.g. glucose. Excretory substances remain in the nephron. E.g. urea
42
Hairpin countercurrent multiplier
arrangement of a tubule in a sharp U shape so one part passes close to another with the fluid in opposite directions. This allows exchange between the contents and can be used to create a high concentration of solutes.
43
Osmoregulation
control and regulation of water potential of the blood and bodily fluids. Controlled by the kidney (particularly the collecting duct)
44
Osmoreceptors
monitor changes in water potential of the blood. Found in the hypothalamus.
45
Neurosecretory cells
make ADH in the hypothalamus in response to low water potential in the blood. This collects in the terminal bulb found in the posterior pituitary gland where ADHis released.
46
ADH
anti diuretic hormone. Increases reabsorption of water.
47
Dialysis
use of a partially permeable membrane to filter the blood
48
Clones
genetically identical to their one parent. They are formed by as exual reproduction (mitosis in eukaryotes; binary fission in prokaryotes)
49
Vegetative propagation
the production of structures in an organism that can grow into new organisms, genetically identical to the parent (clones).
50
Biotechnology
the industrial use of living organisms to produce food, drugs or other products
51
Asepsis
absence of unwanted microbes
52
Aseptic technique
any measure to avoid unwanted microbes contaminating culture/products
53
Primary metabolites
Produced during normal (log) growth phase. Essential for normal cell growth/reproduction. Match growth in population (i.e. same pattern as growth curve)
54
Secondary metabolite
Produced after/not produced during the (log / rapid / main) growth phase. Not essential for normal, cell growth
55
Immobilised enzymes
enzymes attached to an insoluble material in order to keep them separate from the reaction mixture.
56
Recombinant DNA
DNA from two different sources which is combined / joined
57
Restriction enzyme
cuts DNA with sticky ends. Specific restriction site.
58
Gene therapy
treating genetic disorders using genetic technology
59
Xenotransplant
Transplant of tissues/organs between animals of different species.
60
Genome
all the genetic information in an organism
61
Ecosystem
any group of living organisms and non-living things occurring together and the interrelationships between them
62
Habitat
the place where an organism lives
63
Population
all of the organisms of one species who live in the same place, at the same time and breed together
64
Community
all the populations of different species who live in the same place at the same time and can interact with each other
65
Niche
the role of an organism in the ecosystem
66
Biotic factors
living organisms in an ecosystem that can affect each other
67
Abiotic factors
non-living things in an ecosystem that can affect the living organisms
68
Trophic level
stage in a food chain
69
Producers
start of food chains (usually plants), converts energy from sunlight into chemical energy (glucose) in photosynthesis. Supply the chemical energy to the rest of the food chain.
70
Primary consumers
get their energy by feeding on producers
71
Secondary consumers
get their energy by feeding on primary consumers
72
Decomposers
feed on waste and dead organisms
73
Biomass
the dry mass of living material in an organism
74
Gross primary productivity
rate at which plants convert light energy into chemical energy in photosynthesis. e.g. Units: MJ m-2 yr-1
75
Net primary productivity (NPP)
rate of production of new biomass available for heterotrophic consumption and therefore the amount of energy available to them. e.g. Units: kg ha-1 yr-1 NPP = gross primary productivity - respiration (R)
76
Succession
is a natural directional change in species composition in an area over a period of time. Happens in a series of recognisable stages. Where one community (sere) changes the conditions for the next e.g. depth of soil. Results in a climax community e.g. woodland
77
Primary succession
is a natural directional change in species composition in an area over a period of time. Happens in a series of recognisable stages. Where one community (sere) changes the conditions for the next e.g. depth of soil. Begins with bare ground/rock, which a pioneer species e.g. algae/moss colonises first. Results in a climax community e.g. woodland
78
Climax community
final stage in succession in which the community is in equilibrium with environment.
79
Deflected succession
When something e.g. grazing/burning/trampling of plants prevents succession and therefore the establishment of the next community
80
Secondary succession
When succession takes place on a previously colonised, but damaged habitat. It does not start from bare ground.
81
Decomposers
microorganisms which break down dead and waste organic material e.g. bacteria, fungi
82
Nitrogen fixation
converting nitrogen into compounds useable for plants (nitrates/ammonium ions)
83
Rhizobium
Nitrogen fixing bacteria. Convert Found in root nodules of legumes plants or free in the soil. Convert nitrogen gas into ammonium ions.
84
Nitrification
absorbing ammonium ions. Done by nitrifying bacteria
85
Nitrosomanas
nitrifying bacteria. Convert ammonium ions into nitrites
86
Nitrobacter
nitrifying bacteria. Convert nitrites into nitrates
87
Denitrification
Done by denitrifying bacteria. Remove nitrates from the soil by converting nitrates to nitrogen gas. Done in anaerobic conditions.
88
Carrying capacity
the maximum number of population supported by a particular habitat, determined by limiting factor
89
Intraspecific competition
competition for resources between members of the same species
90
Interspecific competition
competition for resources between members of two or more different species
91
Biological resource
they are living and timber is of use to humans
92
Sustainable production
harvesting in amounts which leave sufficient organisms to grow and replenish what has been harvested. It can be carried on indefinitely via replanting, coppicing etc.
93
Coppicing
trees cut close to ground/down stumps and several new growths form. Wood used for fire wood, furniture.
94
Standards
Trees left uncoppiced in a coppiced woodland. Can be used for large timber e.g. planks when needed. These have higher value. Increases number of habitats within the coppiced woodland
95
Pollarding
trees cut close to start of branches and several new growths form.
96
Conservation
maintaining biodiversity between species, genetic diversity within species and a variety of habitats and ecosystems.
97
Preservation
protecting land which is unused by humans to maintain natural biodiversity.
98
Dynamic conservation
preservation of organisms or environments that are at risk from human activity. This requires management and the creation of new habitats, which may need may need reclamation of land.

Biology (24 decks)

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