respiration Flashcards
Uses of Energy in the Body
Humans need this energy to do the following things: Contract muscles Make proteins Make new cells Enable active transport to take place Grow Allow nerve impulses to be generated Maintain a constant internal body temperature
two types of respiration
It can take place with oxygen (aerobically) or without oxygen (anaerobically)
respiration definition
Respiration is the breakdown of food molecules (specifically glucose) in order to get the energy stored in the bonds out of the molecules
where respiration occurs
It occurs in all living cells, usually in the mitochondria (if the cells have them)
How is Respiration Controlled?
Respiration is a series of reactions which are catalysed by enzymes
Aerobic Respiration definition
defined as the chemical reactions in cells that use oxygen to break down nutrient molecules to release energy It is the complete breakdown of glucose to release a relatively large amount of energy for use in cell processes
Aerobic Respiration equation
It produces carbon dioxide and water as well as the useful energy Glucose + Oxygen → Carbon dioxide + Water
Aerobic respiration equation is the opposite of the
, only the other way around
Chemical Equation aerobic respiration
There are usually 3 marks given for the aerobic respiration chemical equation in an exam:
one for getting the correct formula for glucose and oxygen
one for getting the correct formula for carbon dioxide and water
one for balancing the equation correctly
Investigating Uptake of Oxygen by Respiring Organisms
We can investigate aerobic respiration in living organisms by measuring the amount of oxygen that they take from the air
This is done by measuring the change in volume in an enclosed tube containing the organisms
However, as they respire the organisms release carbon dioxide, which increases the gas volume
The carbon dioxide must therefore be removed from the tube using a chemical like soda lime or sodium hydroxide, otherwise it will make the experiment results inaccurate
Any small organisms can be used in the apparatus, including seeds or arthropods
The apparatus (shown below) is known as a respirometer
The apparatus consists of two tubes, one containing the living organisms, and the other containing glass beads to act as a control
Once the apparatus has been set up, the movement of the coloured liquid towards the insect will give a measure of the volume of oxygen taken up by the insect for respiration
The reduction of volume in the tube increases pressure, causing the coloured liquid to move
The distance moved by the liquid in a given time is measured, which will provide the volume of oxygen taken in by the insect per minute
What is a control?
A control is a duplicate experiment set up with the condition being investigated having been removed or neutralised in some way.
In the experiment above, the control is the glass beads. As they are not alive, they will definitely not be respiring.
Therefore, if the volume of oxygen in the tube with the glass beads decreases during the course of the experiment, we know that the condition being investigated (respiration in living organisms) is not the cause of it.
So, a control helps to make your experiment valid.
Investigating the Effect of Temperature on the Rate of Respiration
To investigate the effect of temperature on the rate of respiration of germinating seeds, the respirometer can be set up and the tubes submerged in a series of water baths set at different temperatures, eg 10℃, 15℃, 20℃, 25℃, 30°C
The seeds should be kept in the water bath for 15 minutes before the start of the experiment to ensure they have acclimated to the temperature
As respiration is an enzyme-controlled reaction, it is unlikely to work faster beyond around 40℃ as the enzymes will denature
Anaerobic Respiration does not require
oxygen
Anaerobic Respiration is defined as
the chemical reactions in cells that break down nutrient molecules to release energy without using oxygen
It is the incomplete breakdown of glucose to release a relatively small amount of energy for use in cell processes
products of anerobic respiration
It produces different breakdown products depending on the type of organism it is taking place in
Anaerobic Respiration in Animals
Mainly takes place in muscle cells during vigorous exercise
Glucose → Lactic acid
The lactic acid builds up in muscle cells and lowers the pH of the cells
This could denature the enzymes in cells so it needs to be removed
This happens by removing the lactic acid and carrying it to the liver (in the blood) where it is oxidised (combined it with oxygen – this is actually aerobic respiration with lactic acid as the nutrient molecules instead of glucose)
When this happens it can be broken down to carbon dioxide and water
This is the reason we continue to breath heavily and our heart rate remains high even after finishing exercise – we need to transport the lactic acid to the liver and continue getting larger amounts of oxygen into the blood to combine with the lactic acid produced
This is known as ‘repaying the oxygen debt’
The ONLY product madein Anaerobic Respiration in Animals is …
lactic acid
Anaerobic Respiration in Yeast
We take advantage of the products of anaerobic respiration in yeast by:
using it in bread making (where the carbon dioxide produced helps dough to rise)
and in brewing (where the ethanol produced makes beer)
Glucose → Ethanol + Carbon dioxide
The balanced chemical equation for anaerobic respiration in yeast is
Comparison of Aerobic & Anaerobic Respiration
