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OCR A level bio > Module 5 > Flashcards

Module 5 Flashcards

1
Q

Absicisic acid (ABA)

A

Plant hormone that stimulates stomatal cloning, maintains see dormancy and triggers cold protective responses

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2
Q

Abscission

A

Shedding of leaves in plants

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3
Q

Acetylcholine

A

A type of neurotransmitter used for communication between neurones

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4
Q

Actin

A

Type of protein filament found in myofibrils. Forms thin filaments consisting of two long twisted chains

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5
Q

Actin-myosin binding site

A

Site of actin which normally blocked by tropmyosin. During muscle contraction, becomes exposed, allowing a myosin head to attach

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6
Q

Actin-myosin cross-bridge

A

Cross bridge formed when a myosin head attaches to the myosin binding site on an actin filament

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7
Q

Adenylyl cyclase

A

An enzyme which catalyses the conversion of ATP to cAMP

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8
Q

Adrenal glands

A

Glands at top of kidneys and produce adrenaline and steroid hormones

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9
Q
A
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9
Q

Adrenaline

A

Hormone which is secreted under stressful conditions. Serves as primary messanger and actives adenylyl cyclase

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10
Q

Afferent arteriole

A

Larger diameter arterioles which carries blood to glomerulus for ultrafiltration

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11
Q

Alkaloids

A

Group of nitrogenous compounds found in plants. Bitter tasting and affect metabolism of animals/insects which take them in

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12
Q

All or nothing principle

A

Principle which describes how any generator potential which reaches or exceeds threshold potential will produce an action potential

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13
Q

Alpha cells

A

Found in pancreas which secrete glucagon into blood to raise glucose conc

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14
Q

Anisotropic bands

A

Darker bands in a myofibril which consist of overlapping actin and myosin filaments

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15
Q

Anabolic steroids

A

Class of performance enhancing drugs which are structurally similar testosterone and used illegally by atheletes

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16
Q

Anterior pituitary gland

A

Region of pituitary gland which produces and secretes hormones

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17
Q

Antidiuretic hormones (ADH)

A

A hormone released from the posterior pituitary gland that increases the reabsorption of water in the kidney tubules

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18
Q

Aquaporin

A

A membrane channel used for selective transport of water in and out of cell

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19
Q

Autonomic nervous system

A

A branch of nervous system that carries nerve impulses to muscles and glands. Controls involuntary activities and two divisions: sympathetic and parasympathetic

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20
Q

Auxins

A

Class of plant hormones which control elongation, produce tropsims, prevent abscission, maintain apical dominance

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21
Q

Axon

A

Extension from a nerve cell which carries impulses away from the cell body

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22
Q

Beta cells

A

Found in pancreas and secrete insulin into blood to lower glucose conc

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23
Q

Bile canaliculi

A

Vessels which collect bile produced by hepatocytes

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24
Q

Cardiac muscle

A

Myogenic muscle in walls of heart

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25
Q

CNS

A

Brain and spinal cord

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26
Q

Cerebrum

A

Largest region of brain, consisting of two hemispheres- recieving sensory info from receptors and sends info via motor neurons to effectors

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27
Q

Cerebellum

A

Region of the brain that controls muscle coordination and non-voluntary movement

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28
Q

Cholinergetic synapse

A

Synaose which uses the neurotransmitter acetylcholine

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29
Q

Creatine phosphate

A

Compound stored in muscles which serves as phosphate reserve enabling ATP regeneration

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30
Q

Cyclic AMP (cAMP)

A

Second messenger involved in action of adrenaline that activates protein kinase

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31
Q

Dendron

A

Extension from a nerve cells which carries impulses towards the cell body

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32
Q

Depolarisation

A

Rapid influx of sodium ions into cell which causes it to lose its negative charge and the membrane potential to increase

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33
Q

Ectotherm

A

Organism which is dependent on its environment to maintain its body temp

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34
Q

Effector

A

Organ, tissue or cell which produces a response to a stimulus

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35
Q

Efferent arteriole

A

Smaller diameter arteriole which carries blood away from the glomerulus after ultrafiltration

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36
Q

Endocrine signalling

A

Type of signalling that uses hormones secretes by endocrine cells into blood which produces effect on receptors

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37
Q

Endotherm

A

Organism which can regulate its own body temp without relying on external heat sources

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38
Q

Ethene

A

Plant hormones which stimulates the ripening of fruit and promotes abscission in deciduous trees

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39
Q

EPSP

A

Impulse which stimulates an action potential in the postsynaptic neuron

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40
Q

Excretion

A

Removing metabolic waste from an organism

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41
Q

Flight or fight

A

Physiological reaction of body in response to a potentially dangerous situ

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42
Q

Geotropism

A

Plants growth response to gravity

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43
Q

Gibberellins

A

Plant hormones which control stem elongation, trigger growth of pollen tube during fertilisation and stimulate mobilisation of food storage reserves during seed germination

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44
Q

Glomerular filtration rate

A

Method of measuring kidney function which asseses amount of blood plasma filtered per unit of time and produces value above 90mL/min in healthy adults

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45
Q

Glomerulus

A

Bundle of blood vessels at beginning of a kidney nephron where ultrafiltration occurs

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46
Q

Haemodialysis

A

Type of dialysis used where patients blood fed into a dialysis machine and passed across an artificial membrane to remove waste

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47
Q

Hepatic artery

A

Main artery which supplies the liver tissue with oxygenated blood from the heart

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48
Q

Hepatic portal vein

A

Main vein which carries blood rich in nutrients from the small intestine and pancreas to the liver

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49
Q

Hepatic vein

A

Main vein which takes deoxygenated blood away from the liver back to the heart

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50
Q

Homeostasis

A

Maintaining constant internal environment around an optimum despite external change

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51
Q

Hormones

A

Cell signalling molecules produced by endocrine glands and released into blood. They travel to target cells and bind to specific receptors , initiating response. Long lasting effects

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52
Q

Hyperpolarisation

A

Drop in membrane potential below the resting potential after repolarisation due to open potassium ion channels

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53
Q

Hypothalamus

A

Region of brain which serves as control centre for the autonomic nervous system. Responsible for hormone production, regulation of water poten of body fluids

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54
Q

IPSP

A

An impulse which inhibits the next neurone from generating an action potential

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55
Q

Islet of Langerhans

A

Region of pancreas which contains a and b cells

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56
Q

Isotropic bands

A

Lighter bands in a myofibril, consisting of non-overlapping actin and myosin filaments

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57
Q

Kupffer cell

A

Specialised type of macrophage which is located within the sinusoids of the liver and removes pathogens and dead cells

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58
Q

Loop of henle

A

A large hairpin shaped loop found in kidney tubule used to regulate the water and salt conc of blood

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59
Q

Neurotransmitters

A

Chemicals are used for communication between neurones and their target cells. Stored in synaptic vesicles in presynaptic neurone and released into synaptic cleft

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60
Q

Medulla oblongata

A

Region of brain regulating autonomic activities such as ventilation, heart rate and peristalsis.

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61
Q

Metabolic waste

A

Productss produced in metabolic reactions which have no benefit to organism

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62
Q

Monoclonal antibodies

A

Antibodies which have been produced by plasma cells that are identical clones of the same parent cell

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63
Q

Motor neurone

A

Neurone which carries nerve impulses from CNS to effector

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64
Q

Myelination

A

Formation of myelin sheath around nerve cells by Schwann cells

65
Q

Myofibrils

A

Tiny contractile muscle fibres which group together. Numerous myofibril bundles constitute muscles. Contain two protein filaments: Actin, myosin

66
Q

Negative feedback

A

Product of a process which counteracts change to maintain an equilibrium

67
Q

Neuromuscular junction

A

Excitatory synapse formed between a motor neurone and a muscle fibre that uses acetylcholine

68
Q

Nodes of ranvier

A

Unmyelinated sections of nerve cells which allow for the propagation of an action potential due to their many ion channels

69
Q

Osmoreceptors

A

Type of receptor found in the hypothalamus which can detect the water conc of blood plasma to maintain an appropriate water balance in the body

70
Q

Pacinian corpuscle

A

Type of sensor receptor which detects changes in pressure on the skin

71
Q

Pancreas

A

Organ which has exocrine and endocrine functions and is involved in digestion and homeostatic control of blood glucose conc levels

72
Q

Paracrine signalling

A

Type of signalling between adjacent cells

73
Q

Parasympathetic NS

A

Branch of autonomic NS which is active under normal, resting conditions- inhibiting effectors, slowing down activity

74
Q

Peritoneal dialysis

A

Type of dialysis which dialysis fluid is placed inside the abdomen and waste subsances are passed across the peritoneal membrane from the blood

75
Q

Pheromones

A

Cell signalling molecule produced by an organism which affects the social behaviour of other members of the same species

76
Q

Photoperodism

A

Plants growth response to seasonal changes in the length of daylight

77
Q

Pituitary gland

A

Small, hormones producing gland located at base of brain. In two regions: anterior and posterior

78
Q

Positive feedback

A

Process which causes an increase in change away from the normal

79
Q

Posterior pituitary gland

A

Region of p gland that stores and secretes hormones produced by hypothalamus

80
Q

Posttsynaptic neurone

A

Neurone after synapse which contains specific receptor proteins on its membrane, complementary to the neurotransmitter

81
Q

Presynaptic neurone

A

Neurone before the synapse which releases neurotransmitters from synaptic vesicles into cleft

82
Q

Receptors

A

Specialised structure which detects specific type of stimulus

83
Q

Reflex

A

Rapid, automatic response to a sensory stimulus by the body. Serves as protective mechanism

84
Q

Reflex arc

A

Pathway of neurones involved in reflex actions

85
Q

Resting potential

A

Potential difference across cell membrane of a neurone at rest typically between -60- and -70mV

86
Q

Saltatory conduction

A

Setting up of localised circuits between nodes of Ranvier which allows for rapid propagation of action potential

87
Q

Schwann cells

A

Cells which form myelin sheath around nerve cells in the peripheral ns

88
Q

Second messanger model

A

Mechanism which a hormone has an effect in cell by triggering production of second messanger such as cAMP

89
Q

Selective reabsorption

A

Selective uptake of useful substances along the kiney nephron using membrane transport proteins

90
Q

Sensory neurone

A

Neurone which carries nerve impulses from receptors to CNS

91
Q

Sinusoid

A

Type of vessel found in the liver which is formed from convergence of the hepatic artery and hepatic portal vein

92
Q

Skeletal muscle

A

Voluntary muscle responsible for movement. Makes up most of the body muscle and attached to the skeleton by tendons

93
Q

Smooth muscle

A

Involuntary muscle under control of autonomic NS. Found in walls of blood vessels, digestive tract and organs

94
Q

Somatic NS

A

Branch of NS which carries impulses to skeletal muscles- controls voluntary

95
Q

Summation

A

Combination of impulses which stimulate the generation of an action potwnrial in the postsynaptic neuron

96
Q

Sympathetic NS

A

Branch of autonomic NS which is active under stressful conditions. Stimulates effectors, speeding up activity

97
Q

Synapse

A

Junction between two nerve cells or nerve cell and effector

98
Q

Synaptic vesicles

A

Located in presynaptic neurone and store neurotransmitters. Upon fusion with presynaptic membrane, contents released into synaptic cleft

99
Q

Ornithine cycle

A

Cycle of reactions responsible for producing urea from ammonia for detoxification and excretion

100
Q

Type 1

A

Autoimmune disorder in which beta cells destroyed and pancreas fails to produce sufficient insulin characterised by uncontrolled high blood g levels

101
Q

Type 2

A

Where body fails to produce enough insulin or pancreas no longer reacts to insulin

102
Q

Ultrafiltration

A

Removal of small substances from blood through pressure created by structure of kidney nephron

103
Q

Acetyl Coenzyme a

A

Two carbon molecule formed in oxidative decarboxylation where an acetyl group is bound by coenzyme A. Oxidised in Krebs cycle

104
Q

ATP

A

Universal energy carrier found in all living cells

105
Q

Aerobic respiration

A

Form of cellular respiration that takes place in prescence of o2 and produces co2, water and atp

106
Q

Alcoholic fermentation

A

Takes place in plant root cells and yeast cells producing ethanol and co2

107
Q

ATP synthase

A

Enzyme found in cellular membranes that phosphorylates ADP to form ATP as protons flow through it

108
Q

Chemiosmotic theory

A

Synthesis of ATP through movement of protons down their conc gradient across a semi permeable membrane, catalysed by ATP synthase

109
Q

Chlorophyll

A

Photosynthetic pigment found in thylakoids of chloroplasts that absorb light energy. A and B

110
Q

Chloroplast

A

Organelle found in plants and algae which is the site of photosynthesis

111
Q

Citrate

A

6 carbon molecule formed in first stage of Krebs cycle from reaction of acetyl coenzyme A and oxaloacetate

112
Q

Coenzyme A

A

Coenzyme which binds an acetyl group to form acetyl coenzyme A during oxidative decarboxylation of aerobic respiration

113
Q

Coenzymes

A

Molecules which help enzymes carry out their function e.g. NAD, FAD

114
Q

Cristae

A

Folds of inner mitochondrial membrane which provides large SA for oxidative phosphorylation

115
Q

Cyclic photophosphorylation

A

Formation of ATP including only Photosystem 1

116
Q

Decarboxylation

A

Removal of CO2 molecule

117
Q

Dehydrogenation

A

Removal of hydrogen atom

118
Q

Electron acceptor

A

O2 acts as final electron acceptor in ETC

119
Q

Electron carrier

A

Proteins which accept and release electrons e.g. NADP, NADP

120
Q

Electron transport chain

A

Series of electron carrier proteins which transfer electrons in chain of oxidation-reduction reactions

121
Q

FAD

A

Coenzyme that becomes reduced when takes up hydrogen atoms during krebs cycle, forming reduced FAD

122
Q

Fermentation

A

Anaerobic resp which does not involve an ETC

123
Q

GP

A

3 carbon molecule reduced by reduced NADP in light-independant stage of photosynthesis o form two molecules of TP.

124
Q

Glycolysis

A

An anaerobic process that takes place in the cytosol of the cell and breaks
down glucose into two molecules of pyruvate. Two molecules of ATP and two molecules of
reduced NAD are also formed.

125
Q

Grana

A

Stacks of thylakoids connected by intergranal lamellae

126
Q

Hexose bisphosphate

A

The compound formed from the phosphorylation of glucose in
glycolysis. It splits into two molecules of triose phosphate.

127
Q

Inner mitochondrial membrane

A

The mitochondrial membrane that segregates the matrix
from the intermembrane space. It is the site of the electron transport chain.

128
Q

Intermembrane space

A

The small space between the inner and outer mitochondrial
membranes. The electron transport chain results in a high proton concentration here.

129
Q

Krebs cycle

A

A series of oxidation-reduction reactions in the matrix of the mitochondria in
which acetyl coenzyme A is oxidised, generating reduced NAD, reduced FAD, ATP and
carbon dioxide.

130
Q

Lactate dehydrogenase

A

Enzyme which catalyses the conversion of pyruvate to lactate

131
Q

Lamellae

A

Membranous channels that connect adjacent grana in a chloroplast.

132
Q

Light-dependant reaction

A

The first stage of photosynthesis that uses light energy to
produce ATP, reduced NADP and oxygen. It takes place in the thylakoids of the chloroplast.

133
Q

Light-harvesting system

A

A collection of protein and chlorophyll molecules found in the
thylakoid membranes of chloroplasts that absorbs light energy of varying wavelengths and
transfers it to the reaction centre. It is also known as an antennae complex.

134
Q

Light independant reaction

A

The second stage of photosynthesis, also known as the
Calvin cycle, in which the products of the light-dependent stage and carbon dioxide are used
to build organic molecules. It does not require light energy and takes place in the stroma.

135
Q

Limiting factor

A

Variable which limits rate of a particular reaction

136
Q

Matrix

A

Fluid filled space within inner membrane of the mitochondria which contains mitochondrial DNA and enzymes required for aerobic respiration

137
Q

Mitochondrian

A

Organelle in eukaryotic cells which is site of aerobic resp

138
Q

NAD

A

A coenzyme that becomes reduced when it takes up hydrogen atoms during aerobic
respiration, forming reduced NAD

139
Q

NADP

A

A coenzyme that becomes reduced when it takes up hydrogen atoms during the
light-dependent stage of photosynthesis, forming reduced NADP.

140
Q

Non-cyclic photophosphorylation

A

The formation of ATP and reduced NADP involving
both photosystems I and II.

141
Q

Outer mitochondrial membrane

A

The membrane segregating the contents of the
mitochondrion from the rest of the cell. It creates optimal conditions for aerobic respiration.

142
Q

Oxaloacetate

A

A four-carbon molecule that combines with acetyl coenzyme A to produce
six-carbon citrate in the first stage of the Krebs cycle. It is eventually regenerated, allowing
the cycle to continue.

143
Q

Oxidative decarboxylation

A

The first stage of aerobic respiration (also known as the ‘link
reaction’) that takes place in the mitochondrial matrix and converts pyruvate into acetyl
coenzyme A and carbon dioxide. Reduced NAD is also formed. Overall:
Pyruvate + NAD + CoA ⟶ acetyl CoA + reduced NAD + CO2

144
Q

Oxidative phosphorylation

A

The synthesis of ATP from reduced coenzymes and oxygen in
the electron transport chain of aerobic respiration.

145
Q

Photolysis

A

Splitting of molecule of water in prescense of light that occurs during the light-dependent stage of photosynthesis
H2O ⟶ 2H+
+ 2e-
+ ½O2

146
Q

Photophosphorylation

A

The harnessing of light energy in photosynthesis to phosphorylate
ADP, forming ATP.

147
Q

Photosynthesis

A

A complex metabolic pathway that synthesises organic molecules in the
presence of light. It consists of three main stages: capturing of light energy, light-dependent
reaction, light-independent reaction. Overall:
6CO2
+ 6H2O ⟶ C6H12O6
+ 6O2

148
Q

Photosynthetic pigments

A

Molecules present in chloroplasts that absorb certain
wavelengths of light e.g. chlorophyll a, chlorophyll b, xanthophylls and carotenoids.

149
Q

Photosystem

A

Protein complex consisting of a light harvesting system and reaction centre, involved in absorption of light and transfer of elecrons in photosyntheiss

150
Q

Pyruvate

A

A three-carbon molecule produced in glycolysis. In the link reaction of aerobic
respiration, it is oxidised to acetate. During fermentation, it is converted to lactate (animals)
or ethanol and carbon dioxide (plants and microorganisms).

151
Q

Respiration

A

A set of metabolic reactions that take place in organisms and break down
respiratory substances, such as glucose, into smaller inorganic molecules, like water and
carbon dioxide. This is linked to the synthesis of ATP.

152
Q

Respiratory quotient

A

The ratio of carbon dioxide produced to oxygen consumed
during respiration. Calculated using:

Co2 produced/ o2 consumed

153
Q

Respiratory substrate

A

An organic molecule that can be broken down via the respiratory
pathways to produce ATP.

154
Q

Respirometer

A

A device used to determine respiration rate in living organisms by measuring
the change in volume of oxygen or carbon dioxide.

155
Q

RuBP

A

A five-carbon compound that reacts with carbon dioxide in
the light-independent stage of photosynthesis, forming two molecules of GP.

156
Q

RuBisCo

A

An enzyme that catalyses the reaction of
RuBP and carbon dioxide in the light-independent stage of photosynthesis.

157
Q

Thylakoids

A

A series of flattened membrane-bound compartments in chloroplasts. They are
stacked to form grana and contain the chlorophyll and other molecules needed for the
light-dependent reaction

158
Q
A
159
Q
A

OCR A level bio (10 decks)

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