Paper 1: Topic 4 Bioenergetics - Respiration (LV) Flashcards
Describe respiration
A series of exothermic reactions which are occurring continually inside all living cells (all plant and animal cells) to produce ATP
REMEMBER do not say it produces energy - this is impossible.
What is the difference between breathing and respiration?
- Breathing is the process of ventilation i.e. inhalation and exhalation
- Breathing occurs in the lungs and involves the ribcage and the diaphragm
- Respiration is a series of chemical reactions that are taking place inside every living cell
What is the purpose of respiration?
To break down glucose to enable energy to be released for other chemical reactions inside the cell
To produce ATP
REMEMBER: energy can’t be produced/made/created
Define the term exothermic
A chemical reaction which transfers energy into the environment in the form of heat
State 3 uses of the energy released by respiration
- To build NEW larger molecules from smaller molecules e.g. build NEW proteins from amino acids, to build NEW complex carbohydrates from simple sugars, to build NEW lipids from fatty acids and glycerol
- To enable muscles to contract and bring about movement
- To maintain body temperature in birds and mammals
Write the word equation for aerobic respiration
Glucose + oxygen → carbon dioxide + water + ATP
Hint: do not write energy as a product as energy can’t be made or created
Give 5 examples of reactions involved in metabolism
- Respiration
- Conversion of glucose to starch, glycogen or cellulose
- Production of amino acids from glucose and nitrate ions in plant cells Which are then used to synthesise NEW proteins
- Breakdown of excess proteins to form urea for excretion in a process called deamination
- Production of NEW lipids from 3 fatty acids and 1 glycerol
What happens to the energy transferred in respiration?
It is used by the organism for metabolism that synthesise NEW molecules.
Note: Metabolism involves all enzyme controlled processes in a cell (or organism) which can either build up NEW molecules (anabolic reactions) or break down large molecules (catabolic reactions).
State the two different types of respiration
Aerobic
Anaerobic
Describe aerobic respiration
The complete breakdown of glucose in the presence of oxygen to produce ATP, carbon dioxide and water
State the useful product of aerobic respiration
ATP
State the waste products of aerobic respiration
Water and carbon dioxide
Describe anaerobic respiration in human muscles
The INCOMPLETE breakdown of glucose in the ABSENCE of oxygen to produce ATP and lactic acid
State the useful product of anaerobic respiration in skeletal muscles
ATP
State the waste products of anaerobic respiration in skeletal muscles
Lactic acid
Describe anaerobic respiration in plant and yeast cells
The INCOMPLETE breakdown of glucose in the ABSCENCE of oxygen to produce ATP, ethanol and carbon dioxide
State the useful product of aerobic respiration
ATP
State the waste products of aerobic respiration
Carbon dioxide and water
Which form of respiration transfers the most energy?
Aerobic respiration
Aerobic respiration produces 36 ATP whereas anaerobic respiration only produces 2 ATP
What is the term used to describe anaerobic respiration in yeast cells?
Alcoholic fermentation
What is the economic importance of fermentation?
Hint: think of 2 useful products that can be made from fermentation
It is used in
- MAKING bread and
- MAKING alcoholic drinks (e.g. beer, wine)
Hint: do not just say ‘bread’ and ‘alcohol’
Describe 5 changes that occur in the body during exercise
- Increased heart rate
- Increased breathing rate
- Increased depth of breathing
- Vasodilation of the arterioles at the skin’s surface
- Vasconstriction of the arterioles to the digestive system
Explain the reasons for the changes observed in the body during exercise
To deliver more oxygen to respiring muscle cells
To deliver more glucose to respiring muscle cells
To remove more heat from respiring muscle cells
To remove more lactic acids from contracting muscle cells
To remove more carbon dioxide from respiring muscle cells
Hint: you must remember to put the word MORE in to each sentence you write in this answer
Describe and explain what happens to the rate of respiration in muscle cells during exercise
Description - remember to say what happens inside the cells
- Rate of respiration increases
Explanation:
- This produces more ATP - so more energy can be transferred to the environment
- If more aerobic respiration occurs then more carbon dioxide will be produced
- If more anaerobic respiration occurs then more lactic acid will be produced
- The muscle cells will also have a higher oxygen demand and a higher glucose demand so they can respire aerobically for longer
Describe what happens in muscles as a consequence of long periods of vigorous exercise
Lactic acid accumulates
An oxygen debt occurs
Muscle fatigue occurs
Explain the term oxygen debt
The quantity of EXTRA oxygen the body requires after exercise to
- react with the accumulated lactic acid
- and oxidise it (break it down) to glucose in the liver
HInt: do not say ‘amount of oxygen’
Explain what happens to the lactic acid produced as a result of anaerobic respiration
- Blood flowing through the muscles transports lactic acid to the liver
- The liver converts some of the lactic acid back into glucose (for respiration)
- Some of the lactic acid is broken down to carbon dioxide and water
Describe how you can test for the producion of carbon dioxide
- Test*: Bubble the gas through limewater
- Negative result*: the solution will remain colourless and transparent
- Positive result*: the solution will turn a milky white colour
Write the chemical equation for aerobic respiration
Hint: remember to balance your equation
C6H12O6 + 6O2 → 6CO2 + 6H2O + 36 ATP
Write the word equation for anaerobic respiration in skeletal muscles
Glucose → lactic acid + 2 ATP
Write the word equation for anaerobic respiration in yeast or algal cells
Glucose → Ethanol + Carbon dioxide + 2 ATP
Explain why blood flow to the skeletal muscles increases during exercise
To deliver more oxygen and more glucose to the skeletal muscles
- This means more aerobic respiration can take place
- This means more ATP is produced and more energy is released
- This means the muscles can contract more frequently and for longer
Remember: the delivery of MORE oxygen also prevents anaerobic respiration occurring and prevents the production of lactic acid
Explain why blood flow to the heart muscles (cardiac muscle) increases during exercise
Please note: this question is about supplying the muscle that actually makes up the actual heart walls (not the skeletal muscles than cause movement)
- During exercise the heart rate has to increase
- This requires more* energy to be released from *more ATP
- So the heart muscle cells need to carry out more aerobic respiration
- Increasing the blood flow to the heart muscle supplies the heart muscle cells with more* oxygen and *more glucose
- This means the heart can contract more frequently AND it can contract more forcefully
- This then means the blood flows faster to the skeletal muscles
What is meant by the term ‘muscle fatigue’
When muscles are unable to contract efficiently (due to the accumulation of lactic acid)
Predict the colour change for each test tube when using hydrogen carbonate indicator.
Hydrogencarbonate indicator will turn purple as there is less carbon dioxide than atmospheric levels. The indicator will turn yellow as carbon dioxide levels increase above atmospheric levels.
