Exercise (Edexcel A Level Biology (A) SNAB): Flashcards
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Why do breathing rate and heart rate increase during exercise?
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Why do breathing rate and heart rate increase during exercise?
Muscles respire faster, needing more oxygen and producing more carbon dioxide.
Faster breathing and heart rate deliver oxygen and remove CO₂ more quickly.
Which part of the brain controls breathing rate?
The ventilation (respiratory) centres in the medulla oblongata.
How does exercise change the pH of the blood?
Extra CO₂ forms carbonic acid, which releases H⁺ ions.
This lowers the blood pH (makes it more acidic).
Define chemoreceptor.
A chemoreceptor is a receptor that detects changes in the chemical composition of the blood, such as CO₂, O₂ or pH.
How do chemoreceptors trigger faster breathing during exercise?
They detect the fall in blood pH and send impulses to the medulla oblongata.
It then sends more frequent impulses to the intercostal and diaphragm muscles.
Which centre controls heart rate, and what does it act on?
The cardiovascular control centre in the medulla oblongata.
It controls how fast the SAN fires.
What do baroreceptors detect, and where are they found?
They detect blood pressure.
They are found in the aortic and carotid bodies.
What is the effect of sympathetic neurones on the SAN?
They release noradrenaline, making the SAN fire more frequently.
This speeds up the heart rate.
What is the effect of parasympathetic neurones on the SAN?
They release acetylcholine, making the SAN fire less frequently.
This slows down the heart rate.
During exercise, how is the heart rate increased?
Low O₂/high CO₂/low pH is detected by chemoreceptors.
Sympathetic neurones then release noradrenaline, speeding up the SAN.
The centres that control both breathing and heart rate are located in the oblongata.
The centres that control both breathing and heart rate are located in the medulla oblongata.
True or False?
The parasympathetic nervous system prepares the body for 'fight or flight'.
False.
The sympathetic system does 'fight or flight'; the parasympathetic system is 'rest and digest'.
Define tidal volume.
Tidal volume is the volume of air breathed in or out during normal breathing at rest.
Define breathing rate.
Breathing rate is the number of breaths taken in one minute.
Define spirometer.
A spirometer is apparatus that measures breathing — tidal volume, breathing rate and oxygen consumption — by producing a trace.
State the equation for respiratory minute ventilation.
respiratory minute ventilation = tidal volume × breathing rate.
A person has a tidal volume of 0.4 dm³ and a breathing rate of 12 breaths min⁻¹. Calculate the respiratory minute ventilation.
= tidal volume × breathing rate
= 0.4 × 12 = 4.8 dm³ min⁻¹
Why does a spirometer contain soda lime?
To absorb carbon dioxide from the exhaled air.
This stops CO₂ building up to levels that cause breathing distress.
How is oxygen consumption measured on a spirometer trace?
As CO₂ is absorbed, the total volume of air gradually decreases as oxygen is used.
This decrease over time gives the oxygen consumption.
How do you find breathing rate from a spirometer trace?
Count the number of peaks in one minute.
Each peak (up then down) is one breath.
Why is a t-test used in the exercise practical?
To test whether exercise has a statistically significant effect on a mean value (e.g. tidal volume).
It compares the means of two data sets.
What is the null hypothesis in a t-test comparing two means?
That there is no significant difference between the two means.
Any difference is due to chance.
When is the null hypothesis rejected in a t-test?
When the calculated t value is greater than the critical value at p = 0.05.
The difference is then unlikely to be due to chance.
Respiratory minute ventilation equals tidal volume multiplied by rate.
Respiratory minute ventilation equals tidal volume multiplied by breathing rate.
Give two health risks linked to too little exercise.
A higher risk of obesity.
A higher risk of conditions such as type 2 diabetes and coronary heart disease.
Give two health risks linked to too much exercise.
Joint damage (e.g. osteoarthritis) from wear and tear.
Suppression of the immune system, increasing infection risk.
What should you include when describing data from an exercise study?
State the trend and how the variable affects the outcome.
Quote numbers from the data to support your description.
Why can a study showing a link between low exercise and obesity not prove causation?
It shows only a correlation.
Other factors, such as diet, could also contribute to obesity.
How does excessive exercise affect the immune system?
It can suppress the immune system.
This makes the individual more susceptible to infections such as respiratory illness.
Why might a study of male joggers not apply to the whole population?
It only studied a certain group (men of one age doing one exercise).
Results could differ for women, other ages or other exercise types.
Why might professional athletes have more respiratory infections than moderately active people?
There is a correlation with excessive exercise.
But other factors, such as more exposure to people at competitions, may also be involved.
A correlation between two variables does not prove that one the other.
A correlation between two variables does not prove that one causes the other.
True or False?
Moderate exercise tends to give the best health outcomes.
True.
Both too little and too much exercise carry risks; moderate activity often shows the lowest disease incidence.
What kind of conclusion can be drawn from a single data set on exercise and health?
A correlation or association between variables.
Causation cannot be concluded without more evidence.
How does exercise level relate to the prevalence of type 2 diabetes in data studies?
Diabetes is more prevalent in inactive people in every BMI category.
Prevalence also increases as BMI increases.
Why is including numbers important when describing data?
They support and quantify your observations.
This makes the description precise rather than vague.
Define keyhole surgery.
Keyhole surgery is a less invasive procedure using small incisions, a video camera and specialised instruments.
Give two advantages of keyhole surgery over conventional surgery.
Less blood loss and scarring.
Less pain and a quicker recovery, so a shorter hospital stay.
Define prosthesis.
A prosthesis is an artificial replacement for a missing or damaged body part, such as a limb or joint.
How can a prosthesis help someone return to sport?
It replaces a lost or damaged body part.
For example, a knee prosthesis restores mobility and allows low-impact sport.
How can some prostheses be controlled by the user?
They can be connected to electronic devices.
These read signals from the nervous system to move the body part.
Define performance-enhancing drug.
A performance-enhancing drug improves athletic performance, giving an unfair advantage; most are banned in competitive sport.
What is the effect of anabolic steroids, and a risk of taking them?
They increase muscle size, giving more strength, speed and stamina.
Risks include organ damage and increased aggression.
Why are performance-enhancing drugs banned from most sports?
They give an unfair advantage.
They also carry serious health risks for the user.
What is the difference between a rationalist and an absolutist view on these drugs?
Rationalists think their use may sometimes be justified.
Absolutists think they are morally wrong and should always be banned.
Give one argument for and one against allowing performance-enhancing drugs.
For: athletes should have the freedom to choose and it may reduce inequalities.
Against: it is unfair and carries serious health risks.
Drugs that increase muscle size to boost strength and speed are called anabolic .
Drugs that increase muscle size to boost strength and speed are called anabolic steroids.
True or False?
Random drug testing is used to detect performance-enhancing drug use in athletes.
True.
Athletes who test positive may be banned and stripped of medals.
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