1
Q
what do muscles do
A
bring about movement at a joint
2
Q
what do extensors do
A
contracts to cause extension of joint
3
Q
what do flexors do
A
contract to reverse the movement of extensors
4
Q
what are synovial joints
A
bones that articulate in a joint and are separated by a cavity filled by synovial fluid which allows them to move freely
5
Q
what do ligaments do
A
hold bones in place and control and restrict amount of movement in the joint
6
Q
what do tendons do
A
attaches muscles to bones and enables muscles to power joint movement
7
Q
what is the function of cartilage
A
protects the bones within a joint
8
Q
what are the types of joints
A
ball and socket, gilding joint, hinge joint and pivot joint
9
Q
what are the details of each type joint
A
ball and socket: round head fits into cup-shaped socket
gilding: flat surfaces that slide over each other
Hinge: convex surface fits into a concave surface
Pivot: part of 1 bone fits into a ring-shaped structure and allows rotations
10
Q
what are muscles made up of
A
bundles of muscle fibres bound together by connective tissue and are made continuous with tendons
11
Q
how many cells make up a muscle fibre
A
one
12
Q
what is a special feature of a muscle cell and why does it occur
A
multinucleate
during prenatal development where several cells fuse together to form an elongated fibre
13
Q
what is inside a muscle fibre
A
cytoplasm, mitochondria + organelles and myofibrils
14
Q
what are myofibrils
A
composed of repeated sarcomeres
15
Q
what are sarcomeres
A
contractile units
16
Q
what are sarcomeres made up of
A
thin filaments of mostly actin and thicker filaments of mostly myosin
17
Q
what happens to the filaments during contractions
A
they slide over each other
18
Q
what is the appearance of muscle when actin filaments act on their own (relaxes)
A
light bands on the sarcomere
19
Q
what does a muscle normally look like
A
striped
20
Q
what is the appearance of a muscle when both actin and myosin act together (contraction)
A
dark bands
21
Q
explain why the width of the stripes visible on the micrographs of skeletal muscle changes when the muscles contract
A
actin filaments are pulled to the centre of the sarcomere - shortening the sarcomere
dark stripes are produced by regions of overlapping actin and myosin
these stripes will be wider as more overlap during contraction
stripe of just myosin will appear narrower
22
Q
what is actin associated with
A
troponin and tropomyosin
23
Q
what generally happens when a muscle contracts
A
when it contracts, the muscle shortens
the myosin heads change orientation which bring abt movement of actin
myosin heads attach to actin and dip forward to allow actin to slide over the myosin
24
Q
what releases calcium ions and when
A
when a nerve impulse arrives at the neuromuscular junction, calcium ions are released from the sarcoplasmic reticulum
25
what does the release of calcium ions initiate
the movement of protein filaments
26
what do calcium ions attach to and what does it make it do
troponin molecule and moves it
27
what results from the troponin molecule moving
the tropomyosin on the actin filament shifts and exposes the myosin-binding sites on actin
28
what happens to the myosin-bonding sites after they have been exposed
myosin heads bind to the sites and cross-bridges form
29
what happens when myosin heads bind to actin
ADP and Pi on the myosin heads are released
the myosin changes shape and the heads move forward
30
What happens after the myosin heads nod forward
results in the relative movement of filaments as attached actin moves over myosin
31
how do myosin heads detach from actin
An ATP molecule binds to the myosin head
32
what happens to the ATP molecule bound to the myosin head
its hydrolysed to ADP and Pi
the hydrolysis changes shape of the myosin head which returns upright and enables the cycle to start again
33
what is a contraction in terms of myosin heads and actin filaments
collective bending of many myosin heads combine to move actin filaments relative to myosin filament
34
what happens to calcium ions when a muscle relaxes
it is actively pumped out of the sarcoplasm via ATP
35
what happens when a muscle relaxes
calcium ions actively pumped ut of the sarcoplasm via ATP
troponin and tropomyosin move back and block myosin binding-sites (in absence of ATP, cross-bridges remain attached - rigor mortis)
36
what is ATP synthesis in terms of its series of reactions
a series of enzyme-controlled reactions
37
what is the equation for ATP synthesis
ADP + Pi → ATP
38
why must ions that form ATP be separated from water
the phosphate ions become hydrated in water and separation requires energy
39
why is storing ATP in water better
it has higher energy that ADP and Pi in water therefore is a way of storing chemical potential energy
ATP keeps the phosphate separated from water but can be brought together in an energy-yielding reaction when energy is required in the cell
40
what can the energy transfer during hydration of ATP do to a cell
increase its cell temperature
41
compare the bonds between H and C in glucose and H and O in water and what does that mean for ATP Synthesis
bonds in water are stronger than those in glucose therefore input of enerfy needed to break the bonds in glucose is not as great as the energy released when bonds in carbon dioxide and water are formed:
this releases energy which can be used in ATP synthesis
42
what would happen to the cell if glucose and oxygen were brought together directly
it would release lots of energy which would, in turn, damage the cell
43
what happens instead of oxygen and glucose being brought together directly
glucose splits in a series of small steps - producing CO2 as a waste product
hydrogen from glucose is eventually combined with oxygen to form water and releases lots of energy
44
what is glycolysis
splitting of sugar
is the initial stage of carbohydrate breakdown
45
where does glycolysis occur
in the cell cytoplasm
46
what is the first stage of glycolysis
glycogen stores must be converted to glucose
glucose is stable and unreactive therefore an input of energy via ATP is required to start glycolysis
47
what is needed to convert glycogen to glucose and why
ATP as glucose is stable and unreactive and requires an input of energy to make it unstable
48
what occurs after glycogen has been converted to glucose in glycolysis - second stage of glycolysis
2 phosphate groups are added to glucose from 2 ATP molecules which increases the reactivity of glucose
Glucose can now be split into2x phosphorylated 3-carbon compounds
49
what occurs after the phosphorylated 3-carbon compound intermediates have been formed
- third stage of glycolysis
each intermediate is oxidised to produce pyruvate
2 hydrogen atoms from each intermediate is removed and taken up by co-enzyme NAD to produce reduced NAD
produces 2 ATP per pyruvate
4ATP produced total
50
what property of glucose compared to pyruvate allows for the direct creation of ATP
glucose is at a higher energy level than pyruvate, so upon conversion of glucose to pyruvate, energy becomes available for ATP synthesis
51
what happens to the phosphate from the intermediates in step 3
can be transferred to ADP
2ADP + 2Pi → 2ATP
substrate level phosphorylation
52
what is substrate level phosphorylation
when energy for ATP formation comes from substrates
53
what are the products from glycolysis
2x ATP
2x Hydrogen pairs (diatomic)
2x pyruvate
2x reduced NAD
54
if oxygen is available, what happens to pyruvate
pyruvate passes into the mitochondria and it is completely oxidised to carbon dioxide and water
55
what occurs in the Link reaction
pyruvate is decarboxylated and dehydrogenated
decarboxylation : carbon dioxide is released as waste prodcut
dehydrogenation: 2 hydrogen atoms are removed and taken up by the conenzyme NAD to form reduced NAD
56
What are the products of the link reaction and what does it/they combine with
the decarboxylation and dehydrogenation produces a 2 carbon molecule which combines with co-enzyme A to form acetyl co-enzyme A (acetyl CoA)
57
what are the important reactions in the Krebs cycle
Phosphorylation - adding phosphate
decarboxylation - breaks off carbon dioxide
redox
58
what does acetyl coenzyme A (acetyl CoA) (2 carbon) combine with to start the Krebs cycle
a 4 carbon compound to form a 6-carbon compound
59
what happens to the 6-carbon compound to form the 5 carbon compound in the Krebs cycle
carbon dioxide breaks off and 2 hydrogen molecules are released which combine with NAD to form reduced NAD
60
what happens to the 5 carbon compound when it is converted to the 4-carbon compound in the Krebs cycle
ATP and carbon dioxide is released
3x 2H are released
2x of 2H combine with NAD to form reduced NAD
1x of 2H combine with FAD to form reduced FAD
61
how many steps of the Krebs cycle involve
decarboxylation
dehydrogenation
substrate level phosphorylation
2
4
1
62
How many
ATP
Reduced NAD
Reduced FAD
CO2
are made per pyruvate in the krebs cycle
1 ATP
3 reduced NAD
1 reduced FAD
2CO2
63
where does the Krebs cycle take place
in the mitochondrial matrix where the enzymes that catalyse the reactions are located
64
what is an overall summary of the Krebs cycle products
each 2-carbon molecule produces
2x carbon dioxided
4x pairs of H - 3x of which combine with NAD to form reduced NAD and 1x of which combine with FAD to produce reduced FAD
65
what are the hydrogen atoms involved in after combining with co-enzymes in Krebs cycle
ATP synthesis via the electron transport chain
66
what happens to the co-enzymes after they are reduced in the Krebs cycle
they carry the 2H⁺ and electrons to the electron transport chain on the inner mitochondrial membrane
67
what happens to the electrons once they are delivered to the electron transport chain in the inner mitochondrial membrane
they pass from 1 electron carrier to the next via redox reactions
each carrier is reduced when it gains the electron and oxidised when it is passed on
68
how is a high H⁺ concentration produced in the inter-membrane space in a mitochondria
protons move across the inner mitochondrial membrane
69
what occurs after a high H⁺ conc is produced in the inter-membrane space in the mitochondria
H⁺ diffuse back into mitochondrial matrix down the electrochemical gradient which allows ATP synthase to catalyse ATP synthesis
70
what occurs after the diffusion of H⁺ back into the mitochondrial matrix
electrons and H⁺ recombine with oxygen to form water
71
what happens to the electron transport chain in the mitochondria if the supply pf oxygen stops
electron transport chain stops and the synthesis of ATP stops
72
what does the electron transport chain do in terms of "osmosis"
chemiosmosis occurs
73
how is ATP synthase described
as a stalked molecule due to its shape and location in the mitochondrial membrane
74
what does H⁺ do to ATP synthase
causes a conformational change to the active site which enables ADP and Pi to bind to it
75
what is the process of oxidative phosphorylation
when the reduced NAD and the reduced FAD result in ATP
each reduced NAD results in 3ATP
each reduced FAD results in 2ATP
76
what does total number of ATP molecules produced by 1 glucose depend on
cell efficiency
77
how much energy does the oxidation of 1 mol of glucose typically release
2880
78
What does ATP do to glycolysis
inhibits the enzyme in the 1st step of glyoclysis
79
how can the enzyme responsible for glucose phosphorylation exist
in the presence of ATP, the shape is changed and is therefore inactive
when ATP is broken down, the enzyme is converted back to active form
80
what happens to the enzyme for glucose phosphorylation when ATP is present
its active site shape is changed and therefore becomes inactive
81
how can rate of aerobic respiration can be determined be measured
by measuring the uptake of oxygen using a respirometer
82
how can rate of respiration be influenced
by any factor that influences the rate of enzyme controlled reactions
83
what happens to respiration if oxygen supply is cut
no oxygen to accept the electrons and hydrogen ions, therefore the electron transport chain stops
reduced NAD isn't oxidised therefore respiration reactions cannot occur
84
can you oxidise NAD in absence of oxygen
yes
85
what can oxidise NAD when oxygen is not present
the pyruvate formed at the end of glycolysis is reduced to lactate
lactate accepts the 2x 2H ions and the oxidised form of NAD is regenerated
86
How is ATP produced during anaerobic respiration
partial breakdown of glucose but is very inefficient
87
what is the end product of anaerobic respiration
lactate/ lactic acid in solution
88
what happens to the pH of a muscle cell as lactate builds up
pH falls and inhibits enzymes that catalyse glycolysis
- any activity and glycolysis dependent on enzymes ceases
89
what does lactate do to enzymes
the amino acids in the structure of enzymes are +vely and -vely charged
as hydrogen ions accumulate in the cytoplasm, they neutralise the -vely charged groups in the active site 5herefore the attraction between groups on the substrate and active site are affected and the substrate may no longer bind
90
what kind of pH range do enzymes function over
very narrow
91
is lactate ever converted back into pyruvate
yes
92
how is lactate converted to pyruvate
its oxidised to carbon dioxide and water via the Krebs cycle and energy is released to synthesise of ATP in the liver
93
what is oxygen debt
excess oxygen requirement
94
what might lactate also be converted to
Glycogen and stored in the liver
95
how much ATP do cells store
not very much
96
how is immediate regeneration of ATP achieved
using creatine phosphates that are hydrolysed to release energy
97
what does hydrolysis of creatine phosphates release
energy for regeneration of ATP
Creatine Phosphates provide the Pi
98
what happens to aerobic respiration at the start of exercise
aerobic respiration cannot meet demands for energy because the supply of oxygen is insufficient
99
what does endurance-type exercise do to the muscles and how can the exercise be sustained for long periods
ensures higher oxygen to supply the muscle cells and aerobic respiration can regenerate ATP as quickly as its broken down as quickly as its broken down
100
what are prolonged periods of strenuous but submaximal activity dependent on
dependent on maintaining continuous supply of ATP for muscle contraction
101
What is aerobic respiration
the splitting of a respiratory substrate reuniting hydrogen with atmospheric oxygen to release a large amount of energy and carbon dioxide as a waste product
102
what are the 4 stages of respiration
Glycolysis
Link reaction
Kreb's Cycle
Oxidative phosphorylation
103
where does oxidative phosphorylation occur
inner mitochondrial membrane
104
What is oxidative phosphorylation
the process in which ATP is synthesised via chemiosmosis in the electron transport chain in the mitochondria
105
what does oxidative phosphorylation generate
the majority of ATP in aerobic respiration
106
what does it mean that the cardiac muscle is myogenic
heart's ability to initiate its own contraction
107
what is cardiac output
stroke volume x heart rate
108
what is aerobic capacity
the ability to take up, transport and use oxygen
109
how is adequate supply of oxygen maintained by
increased cardiac output
faster breathing rate
deeper breathing rate
110
what is cardiac output
volume of blood pumped by the heart in a minute
111
what is stroke volume
the volume of blood pumped out of the left ventricle each time the ventricle contracts - cm³
112
during exercise, what happens to muscle action and blood flow
greater muscle action so more blood returns to the heart - venous return
113
what is venous return
the process of blood flow back to the heart via the veins
114
how does exercise increase stroke volume and cardiac output
during exercise, the heart fills with a larger volume of blood therefore the heart fills with a larger volume of blood. The heart muscle is stretched to a greater extent causing it to contract with greater force and so more blood is expelled
115
is all blood expelled from the heart when at rest
no, about 40% stays in the heart
116
what factors cause differences in resting heart rate
heart size
genetics
body size
117
what is the usual resting heart rate of a person with a larger heart
usually lower as it expels more blood therefore doesn't have to beat as frequently
118
where does depolarisation of the cardiac muscle begin
in the Sinoatrial node (SAN)
119
what is the SAN also known as
the pace maker node
120
what is the SAN
ana rea of specialised muscle fibres located in the right atrium beneath the opening of the superior vena cava
121
what happens when the SAN depolarises
Generates an electrical impulse which spread from the right atrium to the left atrium causing them to contract at the same time
122
why can't the impulse generated by the SAN be sent to the ventricles directly
region of non-conductive tissue - annulus fibrosus
123
what does the electrical impulse generated by the SAN do instead
stimulates the atrioventricular node
124
why is there a slight delay occurring between atrial systole and ventricular systole
to allow time for the ventricles to effectively fill with blood
125
what does the AVN pass the impulse to and what does it do
the AVN passes depolarisation into the conducting bundle of His - Purkyne fibres - which spread through ventricle to initiate ventricular systole
126
What is the spread of depolarisation in cardiac muscle called and what can it be measured with
wave of depolarisation
detected with an electrocardiogram - ECG
127
what can an ECG detect
wave of depolarisation
any diseases that affect the wave of depolarisation within the heart can also affect the ECG pattern
128
what are factors that would increase the heart rate
low pH
stretch receptors respond to muscle movement
decrease in blood pressure
adrenaline
129
what is the sympathetic nervous system
stimulation prepares the body for action
eg, increases breathing rate increases heart rate and stroke volume etc
130
what is the parasympathetic nervous system
controls systems when resting and digesting
eg, decreases breathing rate, decreases heart rate and stroke volume
131
where is adrenaline released from
adrenal glands on the kidneys
132
what does adrenaline have a direct effect on
the SAN
133
what does adrenaline cause in the body
increases heart rate to prep body for physical activity
causes dilation of arterioles supplying skeletal muscles and constriction of arterioles supplying non-essential organs
134
what does the P wave signify in an ECG
depolarisation of atria resulting in atrial contraction
135
What does the QRS complex (dip then big below resting then big spike then dip below resting again ) on and ECG signify
the wave of depolarisation resulting in the contraction of ventricles
136
what does the PR interval (from the start of the P wave to the start of the R spike) on an ECG signify
the time taken for impulses to be conducted from the SAN across the atria to the ventricles through the AVN
137
What does the T wave on the ECG signify - the small hump increase after the straight ST segment
repolarisation of the ventricles during the heart's relaxation phase (diastole)
138
What is bradycardia classed as and what can it mean
heart rate less than 60bpm
can signify: hypothermia, heart disease, medicine
also common in athletes
139
what is tachycardia classed as and what can it signify
a heart rate that is greater than 100bpm
can signify: coronary heart disease, anaemia or heart failure
140
what is a period of Ischaemia
a period where the heart muscle doesn't receive blood due to atherosclerosis in the coronary arteries
141
what can ECGS also provide information on
abnormal heartbeats, areas of damage and inadequate blood flow
142
Where is the ventilation centre
the medulla oblongata
143
how does the ventilation centre cause inhalation
sends nerve impulses to external intercostal muscles and the diaphragm and both sets of muscles contract
deep inhalation also uses upper chest muscles and neck muscles
144
what happens to the bronchioles when the lungs inflate
stretch receptors a stimulated and send inhibitory impulses back to make muscles relax
145
what does a small increase in carbon dioxide do to ventilation
causes a large increase in ventilation
146
what does carbon dioxide form in the plasma
dissolves to form carbonic acid
147
how do u calculate ventilation rate
tidal volume x number of breaths per minute
148
give the equation for carbon dioxide dissolving to form carbonic acid
CO₂ + H₂O → H⁺ + HCO₃⁻
149
what detects a rise in H⁺ after increase in carbon dioxide and what happens
chemoreceptors that are sensitive to H⁺ in ventilation centre
sends impulses to the other parts of the ventilation centre which then sends impulses to stimulate the muscles involved in breathing
150
what does an increase in carbon dioxide do to blood pH
increases blood pH
151
what is negative feedback
counteracts any change in internal condition
all changes are reversed back to optimum conditions
152
what is control of carbon dioxide levels in blood an example of
homoeostasis operating via negative feedback
153
what controls movement
motor cortex in the brain
154
what colour are short twitch muscle fibres
darker
155
what are short twitch muscle fibres specialised for
slow contractions and are adapted for long periods of exercise and therefore do not fatigue quickly
156
what colour are fast twitch muscle fibres
pale
157
what are fast twitch muscle fibres adapted for
rapid release for energy during intense exercise
the contractions are intense and in short bursts
158
what do slow twitch fibres have high levels of and fast twitch muscles have lower levels of
mitochondria and myoglobin
159
what gives slow twitch muscle fibres its darker colour
lots of myoglobin present
160
what do fast twitch muscle fibres have high levels of and slow twitch muscle fibres have low levels of
creatine phosphate and glycogen
161
how is thermal energy dispersed during exercise
via sweating to maintain thermal balance
162
what is homeostasis
the control of internal conditions / maintenance of a stable internal environment
163
what does the homeostatic system consist of
receptors, a control mechanism and effectors which interact toge`ther
164
what happens once receptors detect a deviation from norms of controlled conditions
receptors are connected to a control centre which turns on/off effectors to bring the conditions back to the norm
165
what are the effectors
muscles of glands
166
what is positive feedback
increases the original change in conditions
167
what does negative feedback control
metabolic pathway
168
what are allosteric enzymes
when an enzyme is inactivated bc the active site is changed by the binding of an inhibitor
169
how is change in temperature detected
by thermoreceptors in the skin
170
what happens once a change in temperature is detected
impulses sent to thermoregulation centre in the hypothalamus which initiate heatgain/loss response
171
what does a heat loss response look like
stimulates glands to produce sweat
inhibits arteriole contraction, hair erector muscles, liver and skeletal musclesw
172
what does a heat gain response look like
stimulates arterioles in the skin, hair erector muscles, the liver and skeletal muscles
inhibits the sweat glands
173
what is shivering
uncontrolled contraction of usually voluntary muscles and can increase body temperature
174
what is vasoconstriction
constriction of blood vessels
175
what happens during vasoconstriction in cold conditions
muscles in arterioles contract, arterioles contract, blood glow to the surface capillaries are reduced, blood is then diverted through dilated shunt vessels and blood flows further from the skin surface
therefore less energy is lost
176
what is vasodilation
dilation of blood vessels
177
what happens during vasodilation in warm conditions
shunt vessels constrict, muscles in walls of the capillares relax, blood flows through arterioles, arterioles dilate, more blood flows closer to the surface
therefore more energy is lost
178
what controls constriction of arterioles and shunt vessels
hypothalamus
179
what happens to the excess energy when our bodies are warmer than surroundings
radiates energy
180
what is conduction
invades direct contact between objects and energy transfer from one to another
181
what is convection
energy loss by bulk movement of air
182
what is evaporation
energy needed to convert water from liquid to vapour
- sweating only has a cooling effect when it evaporates
183
what does high humidity do to rate of evaporation
makes them much
184
what are 2 factors contributing to high infection rates
increased exposure to pathogens
suppressed immunity with hard exercise
185
what is the effect of moderate exercise on the immune system
increases the number and actitvity of natural killer cells
186
where are natural killer cells found and what do they do
found in the blood and the lymph
do not use specific antigen recognition but provides non-specific immunity against cells invaded by viruses and cancerous cells
187
what dop NKCs release and what does it do
perforin
makes pores in targeted cell membranes which allow other molecules to enter and cause apoptosis
188
what does prolonged, high-intensity exercise cause
fall in activity and no. cells at NKCs, phagocytes, B-cells, T helper cells
specific immune system is temporarily depressed
189
what does a decrease in T-helper cells do
reduces the amount of cytokines to activate lymphocytes, therefore decreasing the quantity of antibody produced
190
what, other than respiration, can occur in muscles during exercise
inflammatory response as the muscle fibres may be damaged
191
what hormones can physical and psychological stress release
cortisol and adrenaline
192
what effect does adrenaline and cortisol have on immune system
suppress the immune system
193
what is a joint disorder
pain, inflammation and restricted movement around joint
194
how can the articular cartilage on knee cause pain
the cartilage covers the surface of the bone and can wear down so that bones may grind against each other causing damage leading to inflammation and arthritis
195
what is patella tendonitis
occurs when kneecap doesn't guide smoothly across femur due to damage of articular cartilage on the femur
196
what can occur to the Bursae on the knee that can cause pain
it cushions the points of contact between bones, tendons and ligaments can swell up with extra fluid which may push against other tissues in the joint causing inflammation and tenderness
197
what is keyhole surgery
a non-invasive method which uses fibre optics to repair damaged joints quickly
also cheaper than conventional methods and recovery time is shorter
198
what is a prosthesis
an artificial body part which enables those with injuries and disabilities to regain the appearance or function of a particular body part as well as participate in sports and can be connected either internally or externally
199
where are cruciate ligaments attached
attached to the end of femur and end of tibia
200
what does the posterior cruciate ligament do
prevents knee from bending too far back
201
what does the anterior cruciate ligament do
prevents knee from bending too far forwards
202
what are the advantages of physical activity on blood pressure
increasing arteriole vasodilation lowers blood pressure
203
what are the advantages of physical activity on blood cholesterol
decreases LDL levels and increase HDL levels which transports cholesterol to liver where it is broken down
204
what does physical activity do to insulin sensitivity
increases inuslin sensitivity of msucle fbres which improves blood glucose regulation and decreases likelihood of developing type 2 diabetes
205
what is the effect of physical activity on bone density
increases bone density
reduces its loss during old age which delays the onset and the progression of osteoperosis
206
how can a sedentary lifestyle lead to type 2 diabetes
high blood glucose levels can reduce the sensitivity of cells to insulin therefore the body doesn't produce enough insulin and the body cells don't respond to the insulin produced
blood glucose levels cannot be controlled leading to decreased absorption of glucose of blood
207
what can happen to cells if there is a decreased absorption of glucose in blood
cells break down fatty acids and proteins leading to weight loss
208
what is blood doping
artificially enhancing the uptake, transport and delivery of oxygen in the blood
209
what are hormones
chemical messengers released directly into the blood
210
why are hormones usually released in inactive form or in secretory vesicles
to prevent the endocrine glands themselves from being affected
211
what does the pituitary gland secrete
growth hormone, follicle stimulating hormone and antidiuretic hormone
stimulates growth, controls testes and ovaries and causes absorption of water in the kidneys
212
what does the thyroid gland secrete
thyroxine
raises the basal metabolic rate
213
what does the adrenal gland secrete
adrenaline
raises the basal membrane rate, dilates blood vessels, preps body for action
214
what does the pancreas secrete
insulin
lowers the blood glucose concentration
215
what hormone do the ovaries secrete
oestrogen
promotes the development of the ovaries and the development of female secondary sexual characteristics
216
what hormone do the testes secrete
testosterone
promotes development of male secondary sexual characteristics
217
how do hormones affect their targets once reached
either enter target cells or bind to complementary receptor molecules on outside of cell membranes or act by direct/indirect control of transcription
218
what are peptide hormones
protein chains about 10-300 amino acids
219
can peptide hormones pass through cell surface membranes and why/why not
no they can't as they are charged
220
how do peptide hormones pass through the cell surface membranes
bind to receptors on the cell membrane
221
what do peptide hormones activate after binding to receptors in cell surface membrane and what does it do
activates a second messenger in the cytoplasm which bring about a chemical change in the cell (directly or indirectly by affecting the gene transcription)
222
what are 2 examples of peptide hormones
insulin and EPO
223
what are steroid hormones
hormones formed from lipids and have complex ring structures
224
how do steroid hormones pass through the cell surface membrane
passes through and binds directly to a receptor molecule in the cytoplasm
225
what happens once the steroid hormone binds to receptor molecule in cytoplasm
hormone-receptor complex brings about characteristic response with results from effect on transcription
226
what is the hormone-receptor complex
a transcription factor
227
what is the transcription initiation complex
the complex of RNA polymerase, associated transcription factors that are bound to DNA
228
in what form are most transcription factors synthesised
inactive form and then converted to active form by action of hormone growth factors and regulatory molecules
229
how can transcription of a gene be prevented
protein repressor molecules attaching to promotor region of DNA
230
what is EPO (erythroprotein)
peptide hormone produced naturally by the kidneys and stimulates formation of new RBCs in the bone marrow
can be used to treat anaemia
231
what is testosterone and how does it work
a steroid hormone in the androgen family
causes development of male sexual organs and secondary sexual characteristics
it modifies gene expression to alter development of cell
232
why is testosterone most effective as a steroid
is quickly broken down
- synthetic anabolic steroids which are manufactured to overcome this
233
what can anabolic steroids do
can cause high bps, liver damage, impotence, decrease sperm production, changes in menstrual cycles, kidney failure and heat disease, increased aggression
234
how can you detect anabolic steroids
detected in urine
235
what medical reasons might someone be prescribed anabolic steroids
muscle wasting diseases an osteoperosis
236
what is creatine
an amino acid derived compound
237
where can u naturally find creatine
meat and fish
238
what happens when creatine is ingested
is absorbed unchanged and carried in the blood stream to tissues
239
what does creatine do and what is the theoretical benefit to it
increase the amount of creatine phosphate in muscles
the theoretical improvement: improvement in performance during repeated short-duration, high-intensity exercise
240
what are the adverse effects of taking creatine
diarrhoea, nausea, vomiting, high bp, kidney damage and muscle cramps
241
Which term describes the ability of heart muscle to contract without external stimulation?
myogenic
242
Some drugs used to treat cancer have also been shown to reduce the
ventricular ejection fraction.
Describe how the safe dose of a cancer drug could be determined.
test the drug on healthy individuals then test on a group of individuals with cancer
to determine dose that does not reduce ventricular ejection fraction
243
Explain why it is necessary for the cardiac output of marathon runners to increase during a race.
increase supply of oxygenated blood to muscles to allow aerobic respiration to provide more energy to meet the increased demands
244
Doctors sometimes prescribe beta-blockers for their patients.
Beta-blockers are a type of drug with antihypertensive properties.
Beta-blockers work by blocking the effects of a hormone called adrenaline.
Adrenaline is produced by the adrenal glands located on top of each kidney.
Adrenaline acts on the heart to cause changes in heart rate.
Deduce how adrenaline can cause a change in heart rate.
adrenaline carried int he blood
acts on the sinoatrial node
increasing the frequency of impulses produced by the SAN therefore increasing the rate at which the heart contracts
245
1. calculate the % change in male heart rate caused by increasing dose from very low to very high
2.Deduce the effect of beta-blockers on the supply of blood to muscle during exercise.
((200-90) / 200) = 55%
the larger the dose the greater the decrease in heart rate
reducing the heart rate reduces the cardiac output
therefore, reducing the supply of blood to the muscle
increasing the dose has a greater effect on males than females
246
The trace produced by a spirometer can be used to determine the respiratory minute
ventilation and the oxygen consumption of an individual.
A student compared the spirometer trace for a pair of healthy, genetically identical twins.
State two variables that would have to be controlled to make this a valid comparison.
level of fitness, body mass and exposure to the same environmental conditions
247
The demand for oxygen changes during exercise. The change in demand affects the breathing rate. At the start of exercise, breathing rate increases. Explain how starting to exercise causes an increase in breathing rate.
exercise initiates impulses from the motor cortex
impulses sent to the medulla oblongata
leading to increased impulses to intercostal muscles
248
The demand for oxygen changes during exercise. The change in demand affects the breathing rate.
Explain the effect of exercise on the changes in oxygen consumption.
exercise will increase oxygen consumption bc of increased aerobic respiration bc more energy/ ATP is needed by muscles
oxygen was required to convert lactate into pyruvate/ glucose
oxygen consumption begins to decrease after exercise
249
Describe how a spirometer trace can be used to calculate the respiratory minute ventilation
find the difference in peak to trough volume
find ventilation rate
tidal volume x ventilation rate
250
Describe how a spirometer trace can be used to calculate the consumption per minute.
difference in volume of one peak/ trough compared to a subsequent one
(time / 2 peaks/ troughs) x 60
251
As levels of activity increase, the heart can respond to the changing demand for oxygen.
Describe how the sinoatrial node (SAN) is involved in bringing about a change in heart rate as the level of activity increases.
more stimulation/ depolarisation of the SAN from the sympathetic nervous system
causing more frequent waves of depolarisation from the SAN to the atria leading to more frequent contraction of atria
252
Explain how a single gene can give rise to acetylcholinesterase molecules with different
primary structures.
pre-mRNA splicing
different exons are removed therefore producing different sequences of amino acids
253
Explain how the acetylcholinesterase gene can be expressed in some tissues but not
others.
chemical signals/ hormones bind to receptors found only found in some tissues
regulating a transcription factor
transcription factor binds to the promotor region of the gene therefore switching on and off transcription
254
Beta cells in the pancreas produce insulin when there is an increase in glucose levels in the blood. Transcription factors are involved in the activation of the insulin gene.
Explain how transcription factors could activate insulin gene expression in beta cells.
interaction between transcription factors and promotor region on gene
RNA polymerase binds to the promotor region
transcription/ mRNA produced for insulin gene
255
Extracellular enzymes are produced by specialised cells.
Explain how groups of cells can produce the same enzyme.
genes can be activated or deactivated
these cells receive the same stimulus
all of these cells have the gene for the enzyme activated
resulting in production of mRNA for the enzyme
256
Some fish produce another anti-freeze protein, called AFP II.
The tissues of these fish were tested for the presence of AFP II and the mRNA coding for
AFP II.
The results are shown in the table.
AFP II: present in all tissues
AFP II mRNA: present only in liver tissues
Explain the distribution of the AFP II protein and AFP II mRNA.
AFP II gene is activated only in liver cells and transcription of AFP II occurs only in liver cells
translation of AFP II takes place only in liver cells
the protein is secreted from the liver via exocytosis
presences of protein in all tissues prevents freezing in all parts of the body
257
Describe how a tissue differs in structure from a system.
a tissue contains one type of cell and a system contains different tissues
258
Describe how mesenchymal stem cells can give rise to different types of cell.
different stimuli activate different genes
genes activated are transcribed mRNA translated on ribosomes to produce proteins
proteins determine the structure and function of cells
different genes activated result in different types of cell being produced
259
Doses of testosterone are used to enhance performance in sports by increasing muscle
mass and therefore strength.
* Testosterone increases the activity of an enzyme in the liver that breaks down HDL.
* The production of cholesterol is catalysed by the enzyme HMG CoA reductase
(HMGCR).
* Testosterone increases levels of mRNA for HMGCR.
Explain why using testosterone as a performance-enhancing drug is unacceptable in
terms of risks to health.
testosterone increases production of LDL/cholesterol
testosterone reduces HDLs
high cholesterols associated with increased risk of CVD
role of HDL transporting cholesterol from bloodstream to th liver
LDLs accumulate cholesterol and development of atherosclerosis
testosterone associated with increased synthesis of enzyme HMGCR which in involved in cholesterol production
performance enhancing drugs can harm the health of an athlete by increasing risk of CVD
260
Female marathon runners have smaller bodies, with a larger ratio of skin surface to body mass than males.
Male marathon runners have less body fat than females: 5–11% compared with 10–15%.
Comment on how gender could affect thermoregulation in marathon runners.
an increase on body temp causes a greater increase in rate of sweating in males than in females
males lose heat faster as they produce sweat at a faster rate
females have a larger SA:Volume that allows for faster heat loss
males have less body fat which may allow faster heat loss
261
The purpose of the placebo for testosterone is to
show that testosterone has an effect
262
Athletic competitions often take place during the summer months when ambient
temperatures are high. High ambient temperatures affect marathon runners.
Heat stress occurs when the core body temperature rises above 40 °C.
Describe how thermoregulatory mechanisms are controlled to help marathon runners avoid heat stress.
thermoreceptors in the skin detect an increase in temperature
thermoregulatory centre in hypothalamus is stimulated
hypothalamus sends impulses to seat glands
increased blood flow to the surface of skin due to vasodilation
decreased metabolic rate
263
Explain the role of the brain in reducing the student's heart rate after the exercise.
chemoreceptors detect a change in carbon dioxide
the cardiovascular control centre receives impulses from chemoreceptors and sends impulses to the heart
therefore impulses are transmitted along the parasympathetic nervous system to the SAN therefore reducing heart rate
264
Describe how the brain reduces the activity of the sweat glands after the exercise.
thermoreceptors detect a decrease in temperature
thermoregulatory centre sends fewer impulses to sweat glands
265
Explain how the extensor and flexor muscles bring about movement of the lower leg.
tendons attach muscles to bones
muscles act as an antagonistic pair
when the extensor muscle contracts, it pulls on the tibia to extend the leg
266
Deduce how athletes with transtibial amputations are able to move their prosthetic limbs
during a race.
the muscles are still attacked to the bones in the lower leg and the prosthetic limb is attached to the lower leg, allowing movement
267
Explain why too much exercise could be harmful to the human body.
268
Explain why there was no change in fingertip temperature between 0 and 3 minutes.
time is required for heat to warm the blood because of the layer of insulation in skins because it takes time for the warm blood to circulate
269
Explain the role of the nervous system in bringing about the increase in
temperature of the fingertip as shown in this investigation.
thermoreceptors detect the increase in temperature
thermoreceptors in the hypothalamus detect temperature increasing
therefore more impulses are sent along the sympathetic nervous system
which leads to constriction of shunt vessels therefore causing vasodilation of arterioles so more warm blood flows near the skin surface
270
Which of the following identifies the structures that join bones to bones in an elbow joint?
A ligaments only
B ligaments and tendons
C tendons only
D neither ligaments nor tendons
A
271
Describe the changes caused when calcium ions bind to the muscle fibres
tropomyosin is moved by troponin
myosin binding sites on actin are exposed
272
Explain how these changes cause muscles to contract.
myosin heads can bind to binding sites
bound myosin changes shape
actin filaments slide over the myosin
therefore muscle fibres shorten
ATP is hydrolysed
273
The diagram shows actin and other components (P and Q) of a thin filament in a myofibril.
Describe the interaction between P and Q that allows muscle contraction.
P is troponin which changes shape causing Q - which is tropomyosin - to move away from the myosin-binding sites on actin
274
The thick filament in a myofibril contains myosin. The myosin head contains the enzyme ATPase.
Explain the importance of the primary structure for the functioning of this enzyme.
primary structure determines interaction between amino acids
primary structure determines folding tertiary structure therefore affecting the shape of the active site
the active site is complementary to ATP
275
Describe how the concentration of calcium ions around the myofibrils is controlled.
calcium ions are released from sarcoplasmic reticulum in response to nerve impulse/ action potential
calcium channels open to allow calcium ions to cross the membrane
calcium ions taken back up into the sarcoplasmic reticulum by active transport
276
Calcium ions are required for muscle contraction.
Describe the role of calcium ions in the contraction of muscle fibres.
calcium ions bind to the troponin causing tropomyosin to be displaced, exposing myosin binding sites
277
Explain how the extensor and flexor muscles bring about movement of the lower leg.
tendons attach muscles to bones
flexor and extensor muscles act as an antagonistic pair when the extensor muscles contracts, it pulls on the tibia to extend the leg
278
Transtibial amputation involves the removal of part of the lower leg below the knee.
Extensor and flexor muscles are still attached to the parts of the lower leg bones (the tibia
and fibula) that remain.
Deduce how athletes with transtibial amputations are able to move their prosthetic limbs during a race.
the muscles are still attached to bones in the lower leg and the prosthetic limb is attached to the lower leg allowing movement
279
Muscle fibres contain a number of proteins, including actin, myosin and collagen.
The myosin binding site is found on
A actin
B sarcoplasmic reticulum
C tropomyosin
D troponin
A
280
Describe two structural differences between fast twitch muscle fibres and slow twitch
muscle fibres.
fast twitch fibres have few mitochondria present whereas slow twitch fibres have many mitochondria
fast twitch have no capillaries present whereas slow twitch fibres have many capillaries present
281
Two known causes are hip replacement surgery and some genetically inherited conditions.
A muscle fibre is a specialised body cell.
Explain how the structure of a muscle fibre is related to its specialised function.
cell surface membrane contains voltage-gated channels to allow depolarisation of muscle fibres
many mitochondria for aerobic respiration to supply ATP
presence of myofibrils/ actin and myosin
myofibrils allow contraction of muscles
282
Scientists need to investigate how varying gravity affects astronauts.
Explain what is meant by no significant difference at the 0.05 probability level for the rate of breakdown of protein.
there is more than a 5% likelihood therefore rate of protein breakdown is in the same in space as it is on earth
283
Some of the myosin in the muscle cells was broken down.
Describe how the tertiary structure of myosin is related to its function.
part folded into a specific shape with a globular head that can bind to actin
myosin has a site that can bind with ATP
part is straight to form a bundle with other myosin molecules
284
An investigation was carried out to study the effect of calcium ion concentration on muscle fibres.
Give one advantage and one disadvantage of using muscle fibres from the same sample
of muscle.
advantage: controlled variable
disadvantage: may not be representative/ only one type of muscle is tested
285
Name two molecules needed for aerobic respiration that can move into the mitochondria.
pyruvate
oxygen
reduced NAD
286
The outer mitochondrial membrane is not permeable to hydrogen ions (H+).
Explain the importance of this feature of the membrane.
to stop H⁺ diffusing out of mitochondrion
therefore maintaining a high concentration of H⁺ in the intermembrane space
so H⁺ can move down the concentration gradient by chemiosmosis to synthesise ATP
287
where does the Krebs cycle occur
in the mitochondrial matrix
288
Explain the increase in blood lactate concentration observed between 0 and 5 minutes.
muscle cells release lactate into the blood due to anaerobic respiration
insufficient oxygen for aerobic respiration
289
Give reasons why blood lactate concentration remains constant between 5 and 15 minutes.
increased oxygen supply for aerobic respiration because heart rate increases
lactate is broken down by the liver
290
During which of the following processes is ATP formed?
A glycolysis and the electron transport chain only
B glycolysis and the Krebs cycle only
C glycolysis, the Krebs cycle and the electron transport chain only
D glycolysis, the link reaction, the Krebs cycle and the electron transport chain
C
291
Explain why some ATP is broken down during glycolysis.
because the breakdown of ATP donates phosphate to the glucose
ATP supplies energy to break down the glucose to produce phosphorylated 3-carbon compounds
292
The electron transport chain occurs in the cristae of mitochondria. The electron
transport chain involves a number of carrier molecules.
Explain the role of these carrier molecules in the electron transport chain.
receive hydrogen from reduced NAD/FAD
break down hydrogen into H⁺ and electrons
electrons are transferred by a series of redox reactions
energy released is used to pump H⁺ into intermembranal space
293
The use of nandrolone has been linked to a variety of cardiovascular conditions.
Explain how the use of nandrolone could lead to atherosclerosis.
grp P - mean max % recoil = 57
Q - 38
R - 80
S - 53
use of nandralone reduces the mean maximum percentage of the aorta
there is increased risk of damage to the endothelium of arteries
inflammatory response
build-up of cholesterol leads to atheroma formation
294
The conversion of F-6-P by this enzyme is a rate-determining step in glycolysis.
Explain why ATP is required for this reaction.
hydrolysis of ATP provides energy for the reaction which provides a phosphate group for phosphorylation of F-6-P
295
Liver cells can absorb lactate from the blood.
Deduce what happens to the lactate in these cells.
lactate is converted to pyruvate which is then converted to glucose which is used on respiration
296
Which of the following is another product of glycolysis?
A carbon dioxide
B glucose
C oxygen
D pyruvate
D
297
Devise an investigation using this apparatus to determine whether an increase of 10 °C
doubles the rate of respiration in yeast.
select 2 temperatures below a temperature that causes enzyme denaturing
keep pH of solution controlled with a buffer
record distance travelled by the coloured liquid in a set time
distance travelled/ time = rate
data collected during initial rate of reaction
298
Which of the following is transferred to a molecule of FAD to form reduced FAD?
A two oxygen atoms
B two hydrogen atoms
C one oxygen atom and one hydrogen atom
D one water molecule
B
299
Explain the need for reduced NAD to be oxidised in a mitochondrion.
so that hydrogen can be delivered to the electron transport chain to allow ATP synthesis to regenerate NAD
300
Devise a procedure using a continuous flow respirometer to collect the data required to
calculate the metabolic rate of an arctic ground squirrel.
use KOH to remove carbon dioxide
measure volumes of air entering and leaving chamber
decrease in volume of air represents oxygen taken up by ground squirrels for respiration
control the temperature
volume of oxygen / (mass x time) = metabolic rate
301
One adaptation these people have is a larger thorax than people living at
lower altitudes
People with this adaptation will have a lower breathing rate as their tidal volume
will be greater than those without the adaptation.
Devise a valid investigation, using a spirometer, to test this hypothesis.
select people with different thorax sizes
select people of the same sex
control temperature
measure tidal volume from spirometer trace
measure breathing rate as number of peaks in a set time
302
Explain why there was a change in core temperature during the first
20 minutes of exercise
heat is released due to increased respiration
303
State how these results support the statement that exercise increases the
risk of infection.
there are fewer neutrophils and the activity is reduced
304
All mammals have an internal skeleton that includes bone and cartilage. Bones
contain calcium ions.
(a) Explain one way in which cartilage at the ends of the bones in the knee joint
reduces wear and tear
compressible to absorb shocks
or smooth and slippery to reduce friction between bones
305
The calcium ion concentration in one species of plant has been measured. It was found to be 170 µg g–1 of plant tissue. A student made the conclusion that: Calcium ions are more important in tissue of plants than in animals.
Evaluate this conclusion
in humans, there is 130.21µg g–1 and in plants it is 170 µg g–1
concentration is not the same as important and there is no evidence of other plants being used
in plants, calcium is used in cell walls such as in calcium pectate
in humans, calcium is crucial for triggering the release of neurotransmitters across synapses, for muscle contraction and blood clotting
only one plant species is used therefore may not be representative of all plant species and humans are not representative of all animals
306
Describe what is meant by the term operon
a group of genes controlled by a single operator that are transcribed together
307
Describe the effect of lactose on the lac operon
lactose allows the lac operon to function
RNA polymerase can now bind to promoter region allowing transcription to occur so enzymes involved in metabolising lactose are made
308
Explain why there is a greater ratio of wound infections in open surgery
compared with keyhole surgery
larger opening
access for more pathogens
309
Name two products, other than the three-carbon molecule (3C), that are
formed by process J.
reduced NAD and ATP
310
Describe what would happen to the three-carbon molecule (3C) if
process K stopped.
it would be used in anaerobic respiration
reduced NAD provides hydrogen and is reduced to lactate/ lactic acid
311
The maggots respired aerobically for 20 minutes in this respirometer.
Explain why the coloured liquid moved to the left during the 20 minutes of this investigation
decrease in volume in the tube as oxygen is taken up by maggots as carbon dioxide is released is absorbed by KOH
312
Devise an investigation, using a respirometer, to find the optimum temperature for respiration in maggots.
use a range of temperatures 5-50 degrees
control age, species and size of maggots
record distance bubble travels in a set time
note first temp where the distance the bubble travels is less - previous temp is optimum
use water baths, allow time for maggots to acclimatise
repeat at each temp to calculate a mean value
313
Explain the advantages for long distance runners of having both type I and type II
muscle fibres, but not in equal quantities.
type I = slow twitch, they're predominant in long-distance
long duration activity so require muscles fibres that are slow to fatigue
low level of anaerobic respiration reduces lactic acid build-up
ATP needed over a linger time frame so provided by aerobic respiration
high mitochondria concentration for aerobic respiration
fast twitch muscle fibre allows runner to run faster towards the end
314
Explain how the myosin head could move mitochondria along the axon.
attaches to myosin-binding site
splits ATP
myosin head changes position to move mitochondria on
315
what is given off when glycerol is converted to the phosphorylated 3 carbon compound
adenosine triphosphate/ ATP
316
Explain why human muscle cells sometimes convert pyruvate to lactate.
when there is insufficient oxygen so that reduced NAD can be oxidised
NAD for use in glycolysis and some ATP can continue to be synthesised
317
Explain why rapid breathing is a symptom of carbon dioxide poisoning
raise carbon dioxide conc in the blood which reduces blood pH
that is detected by chemoreceptors resulting in impulses sent to the ventilation centre so more impulses sent along the motor neurones to muscles being involved in breathing so there is an increase in rate of intercostal muscle contraction
318
Explain why fast twitch muscle fibres contain more glycogen than slow twitch
muscle fibres.
glycogen provides a store of energy
glycogen provides glucose
glucose for respiration/ energy for contraction
fewer capillaries in fast twitch muscles means less glucose is supplied
319
At the start of the investigation, each athlete swallowed a small digital thermometer so their core body temperature could be measured. A mean core temperature was calculated. Explain why the athletes were not allowed to eat or drink during this investigation
could increase their mass
reducing the estimated level of sweat produced temperature of food/drink could alter recorded temperature
would introduce an uncontrolled variable
SNAB Biology Edexcel
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