Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology Unit 5 > 11 Muscle contraction > Flashcards

11 Muscle contraction Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

EXAM QUESTION

What is the role of phosphocreatine (PC) in providing energy during muscle
contraction? (2)

A
  1. (Phosphocreatine) provides
    phosphate/phosphorylates;
  2. To make ATP;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

EXAM QUESTION

There is a lot of variation in the time taken for PC to be re-formed in people of a very
similar age.
Suggest one reason for this variation. (1)

A 
One suitable suggestion;
eg
1. Genetic differences;
2. Level of fitness/amount of regular exercise
done/mass of muscle;
3. Sex;
4. Ethnicity
5. Metabolic rate;
6. Number of fast/slow muscle fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

EXAM QUESTION

Use your knowledge of fast muscle fibres to explain the effect of age on them. (4)

A
  1. (From graph, phosphocreatine) takes longer to
    remake as people get older;
  2. Fast muscle fibres used for
    rapid/brief/powerful/strong contractions;
  3. Phosphocreatine used up rapidly during
    contraction/to make ATP;
  4. (As people get older) slower metabolic
    rate/slower ATP production/slower respiration;
  5. Anaerobic respiration involved;
  6. ATP used to reform phosphocreatine;
  7. Lots of phosphocreatine in fast fibres;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

EXAM QUESTION

You could use an optical microscope and a slide of stained muscle tissue to find the
diameter of one of the muscle fibres. Explain how. (2)

A

Measure with graticule/eyepiece scale;

Calibrate against something of known size:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

EXAM QUESTION

A student found the mean diameter for the slow muscle fibres in a section. Give two
precautions that she should have taken when sampling the fibres. Give a reason for
each precaution. (2)

A

Equivalent measurements taken;
At random to avoid bias/avoid choice of particular fibres;
Large number to be representative/minimise effect of
extremes/of anomalies;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

EXAM QUESTION

When the sarcomeres contract, what happens to the length of

the I-band?

the A-band?

A

Decreases;

Nothing / stays the same length /
does not change;

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

EXAM QUESTION

The length of each sarcomere in the diagram is 2.2 μm. Use this information to calculate the magnification of the diagram. Show your working.

Image = 67mm

A
  1. M = I/O
  2. M=67mm/2.2um
  3. 67 x 1000 = 67,000um
  4. 67,000/2.2 = 30454
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

People who have McArdle’s disease produce less ATP than healthy people. As a
result, they are not able to maintain strong muscle contraction during exercise. Use
your knowledge of the sliding filament theory to suggest why. (3)

A 
(Idea ATP is needed for:)
1. Attachment/cross bridges
between actin and myosin;
2. ‘Power stroke’ / movement of
myosin heads / pulling of
actin;
3. Detachment of myosin
heads;
4. Myosin heads move back/to
original position / ‘recovery
stroke’;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the part played by each of the following in myofibril contraction.

Tropomyosin (2)

Myosin (2)

A
  1. Moves out of the way when calcium
    ions bind;
  2. Allowing myosin to bind (to
    actin)/crossbridge formation;
1. Head (of myosin) binds to actin and
moves/pulls/slides actin past;
2. (Myosin) detaches from actin and
re-sets/moves further along (actin)
3. This uses ATP;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Suggest and explain one advantage of:

the high glycogen content of fast muscle fibres (anaerobic)(2)

many capillaries supplying slow muscle fibres (aerobic)(2)

A 
(Glycogen broken down) gives (lots
of) glucose for glycolysis/anaerobic
respiration;
2. Glycolysis/anaerobic respiration not
very efficient/only yields 2 ATP per
glucose;
1. (Many capillaries) give high
concentration/lots of oxygen/
shorter diffusion pathway for
oxygen/large surface area for
oxygen exchange/diffusion;
2. Good glucose supply with little
glycogen present;
3. Allows high rate of/more aerobic
respiration OR prevents build-up of
lactic acid/(muscle) fatigue;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

EXAM QUESTION

Cannabinoid receptors are found in the pre-synaptic membrane of neuromuscular
junctions. When a cannabinoid binds to its receptor, it closes calcium ion channels.
Suggest how cannabinoids could prevent muscle contraction (4)

A 
1. Prevents influx of calcium ions (into
pre-synaptic membrane);
2. (Synaptic) vesicles don’t fuse with
membrane / vesicles don’t release
neurotransmitter;
3. Neurotransmitter does not diffuse
across synapse/does not bind to
receptors (on post-synaptic
membrane);
4. No action potential/depolarisation (of
post-synaptic membrane)/ sodium
(ion) channels do not open /
prevents influx of sodium ions;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

EXAM QUESTION

Multiple sclerosis (MS) is a disease that involves damage to the myelin sheaths of
neurones. Movement in MS sufferers may be jerky or slow.

Damage to the myelin sheaths of neurones can lead to problems controlling the
contraction of muscles.
Suggest one reason why. (2)

A 
One suitable suggestion; explained;
Eg
1. Action potentials travel more
slowly/don’t travel;
2. So delay in muscle
contraction/muscles don’t
contract/muscles contract slow(er);
OR
3. Action potentials/depolarisation ‘leaks’
to adjacent neurones;
4. So wrong muscle (fibres) contract;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Myofibrils:

How are they arranged?
What do they share? (4)
Made up of? (4)

A

To provide maximum force

Nuclei and cytoplasm/sarcoplasm (high conc. mitochondria and ER)

2 protein filaments

  • Actin (thin)
  • Myosin (thick)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Myofibrils made up of alternating bands:
Alternating bands:
I-band? (3)
A-band (2)

A

Light-coloured because no overlap
Z-line - centre of each I-band
Sarcomere = distance between adjacent Z-lines

Dark-coloured because overlap
H-zone - light-coloured region at centre of each A-band

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give 4 features of slow twitch fibres

Adaptations suited to role? (2)

A

Contract slowly
Less powerful
Longer period (endurance)
Aerobic

Many capillaries
Many mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give 4 features of fast twitch fibres

Adaptations suited to role? (1)

A

Contract rapidly
Powerful contractions
Short period (intensive)
Anaerobic

Lots of glycogen

17
Q

Give 4 pieces of evidence for the sliding filament theory

A 
When muscle contracts:
I-band decreases
Z-lines move closer together 
A-band stays the same 
H-zone decreases
18
Q

Define neuromuscular junction

A

The point where a motor neurone meets a muscle fibre.

19
Q

Define motor unit

A

Multiple muscle fibres supplied by a single motor neurone.

20
Q

STAGE 1

Stimulation (5)

A
  1. Influx of calcium ions into pre-synaptic membrane
  2. Synaptic vesicles fuse with membrane and release neurotransmitter
  3. Neurotransmitter diffuses across synapse and binds to receptors on post-synaptic membrane
  4. Action potential/depolarisation of post-synaptic membrane
  5. Influx of sodium ions;
21
Q

STAGE 2
contraction
Tropomyosin (2)

Myosin (3)

A
  1. Moves out of the way when calcium ions bind
  2. Allowing myosin to bind to actin/crossbridge formation
  3. Head of myosin binds to actin and moves/pulls/slides actin past
  4. Myosin detaches from actin and re-sets/moves further along actin
  5. This uses ATP (ATP to ADP and Pi using ATPase)
22
Q

STAGE 3

Relaxation (3)

A
  1. Calcium ions actively transported out
  2. Tropomyosin blocks actin filament
  3. Myosin heads are unable to bind
23
Q

How is energy supplied during muscle contraction? (3)

A

Phosphocreatine
Provides phosphate/phosphorylates
To make ATP

Biology Unit 5 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions