Topic 4 - Bioenergetics (respiration) Flashcards
Pages 61 62 63
What is the definition of respiration?
the process of transferring energy fro glucose (this happens in every living cell continuously)
What happens in respiration?
Energy is transferred from the breakdown of glucose
Is respiration exothermic or endothermic?
Exothermic (energy is transferred to the surroundings)
Why do plants and animals need to respire?
to transfer energy from their food to their cells
Give 3 ways of how organisms use the energy transferred by respiration?
1) to build up larger molecules from smaller ones (proteins fro amino acids)
2) In animals, it is used to allow the muscles to contract
3) In mammals and birds, energy is used to keep body temperature steady in cooler surroundings
What is the metabolism of a cell or body?
The sum of all the reactions that happen in a cell or body
What controls chemical reactions in cells?
enzymes
- these reactions are linked to form bigger reactions
What two things can happen in reactions in cells?
- larger molecules are made from smaller ones
- larger molecules are broken into smaller ones
Give two examples of larger molecules breaking into smaller ones
- glucose is broken down in respiration (energy transferred powers the reactions in the body that make molecules)
- excess protein is broken down to produce urea - this is excreted in urine
Give 3 examples of larger molecules being made from smaller ones?
- small glucose molecules are joined to form starch, glycogen and cellulose
- lipid molecules are each made from one molecule of glycerol + 3 fatty acids
- glucose is combined with nitrate ions to make amino acids (these then make proteins)
What is starch?
a storage molecule in plant cells
What is glycogen?
a storage molecule in animal cells
What is cellulose?
a component of plant cell walls
What is aerobic respiration?
respiration using oxygen (this is the most efficient way to transfer energy from glucose) - this happens all the time in animals and plants
Where does aerobic respiration take place?
in the mitochondria
What is the word equation for aerobic respiration?
glucose + oxygen –> carbon dioxide + water
What is the symbol equation for aerobic respiration?
C6 H12 O6 + 6O2–> 6CO2 + 6H20
When does anaerobic respiration happen?
When you do vigorous exercise and your body can’t supply enough oxygen to your muscles (you start doing anaerobic respiration as well as aerobic respiration)
What is anaerobic respiration?
the incomplete breakdown of glucose which makes lactic acid
What is the word equation for anaerobic respiration in muscle cells?
glucose –> lactic acid
What is the symbol equation for anaerobic respiration?
C6H12O6 –> 2C3H6O3
What are two disadvantages of anaerobic respiration?
-Does not transfer nearly as much energy as aerobic respiration because the glucose isn’t fully oxidised
- it is only useful in emergencies (allows you to keep using your muscles for a while longer)
What do plant and yeast cells produce when they respire anaerobically
ethanol (alcohol) and carbon dioxide
What is anaerobic respiration in yeast cells called?
fermentation
What is the word equation for anaerobic respiration in plant and yeast cells?
glucose –> ethanol + carbon dioxide
State 2 uses of yeast fermentation
Bread making- the carbon dioxide from fermentation makes the bread rise
Beer and wine making- it’s the fermentation that produces alcohol
Why do your cells respire more when you exercise?
- increased muscle contraction requires more energy
-the energy comes from increased respiration
What are the effects of increased respiration?
- you need to get more oxygen to your cells
- breathing rate and volume increase to get more oxygen into the blood
- heart rate increases to get blood around the body quicker (also removes CO2 more quickly)
Why can’t you sustain long periods of exercise?
-lactic acid builds up in the muscles, which gets painful
- long periods of exercise can cause muscle fatigue (the muscles get tired and stop contracting efficiently)
When does an oxygen debt happen?
After respiring anaerobically
What is an oxygen debt
the amount of extra oxygen your body needs to react with the build up of lactic acid and remove it fro, the cells
How does your body get rid of lactic acid?
oxygen reacts with the lactic acid to form carbon dioxide and water
What do you continue to do after you stop exercising and why?
- you continue to breathe heavily to get more oxygen into the blood and muscle cells
- pulse and breathing rate stay high whilst there are high levels of lactic acid and carbon dioxide
Name another way your body copes with high levels of lactic acid
-Blood that enter your muscles can transfer lactic acid to the liver
- In the liver, lactic acid is converted back to glucose
