B8.2 : Respiration Flashcards
Energy in respiration
- Respiration happens in every living cell. It releases energy from food and is controlled by enzymes.
- Energy is needed in construction, contraction, Homeostasis, Growth, Active transport, and Nerve impulses
Construction
- To make larger molecules from smaller molecules.
2. e.g. Proteins can be made from amino acids in plants and animals.
Contraction
To contract the muscles of animals, allowing them to move.
Homeostasis
- To keep the body temperature of warm-blooded animals (mammals and birds) relatively constant.
- Homeostasis is the process by which we maintain a constant internal environment.
Growth (respiration)
- Organisms grow through cell division.
2. This process requires energy.
Active transport
Movement of substances into or out of cells up a concentration gradient (from low to high concentration) requires energy.
nerve impulses
Sending nerve impulses through the nervous system uses energy from respiration.
Respiration
- Respiration is an exothermic reaction (releases energy) that supplies all the energy needed by living organisms.
- This reaction happens continuously in all living cells.
- The reaction can be aerobic (with oxygen) or anaerobic (without oxygen).
Anaerobic respiration in yeast
- In yeast cells, glucose is converted into ethanol (alcohol) and carbon dioxide.
- Glucose → ethanol + carbon dioxide
- C6H12O6 → 2C2H5OH + 2CO2
- This process is called fermentation and is used to make bread and alcohol.
- Releases energy
Aerobic respiration (with oxygen)
- In aerobic respiration, glucose reacts with oxygen in the mitochondria of cells to give carbon dioxide, water and energy.
- Glucose + oxygen → carbon dioxide + water
- C6H12O6 + 6O2 → 6CO2 + 6H20
Anaerobic respiration in animals
- In animals, glucose is converted to lactic acid:
- Glucose → lactic acid
- Anaerobic respiration happens when not enough oxygen reaches the muscles during periods of intense activity.
Difference between aerobic and anaerobic respiration
- Glucose
- Products
- ATP
- Oxygen
Glucose (difference between respiration)
- Aerobic respiration fully breaks down glucose. (releases more energy)
- Anaerobic respiration only partially breaks down glucose.
Products (difference between respiration)
- Aerobic respiration produces carbon dioxide and water.
2. Anaerobic respiration produces carbon dioxide and ethanol (plants and yeast) or lactic acid (animals).
ATP (difference between respiration)
Aerobic respiration produces much more adenosine triphosphate (ATP, which is a unit of energy) than anaerobic respiration.
Oxygen (difference between respiration)
Oxygen is need for aerobic but not anaerobic respiration.
Where do we get energy from?
- Energy comes from food
- Food is broken down in cells in a process called respiration
- This breakdown of food releases energy
- The energy is converted to chemical energy which we use and to heat
- Enzymes control the breakdown
Lactic Acid
- Lactic acid (lactate) is poisonous and builds up in the muscles during anaerobic exercise
- Lactic acid is sent to the liver where it must be broken down
- This breakdown requires oxygen and is called the oxygen debt
- This happens when oxygen becomes available again
Controlling body temperature - skin
- The skin provides animals ways to adjust the body temperature in different conditions.
- E.g. too hot / cold
- Most of our heat is lost by radiation, our skin is used for heat loss when we are hot and to conserve heat when we are too cold.
Skin
- It is the largest organ in the body and has several important functions.
- Protection from damage
- Prevents pathogens entering the body
- Prevents too much water lost
- Detects changes in temp
- Detects pressure and pain
- Loses heat by conduction, convection, radiation and evaporation.
Hypothalamus - homeostasis
- The hypothalamus in the brain monitors the temperature of the blood.
- Nerves bring information to the brain about the temperature of the skin.
Vasodilation
- Vasodilation occurs allowing more blood to flow close to the skin so more heat is lost due to radiation.
- (This is why you look red and flustered after exercise, your body is trying to lose heat)
- When it is too hot
Sweating
- Sweat glands, produce lots of sweat to allow increased heat loss by evaporation.
Controlling body temperature (when its hot)
- Hair muscles relax allowing more heat to be lost by convection.
- Combined vasodilation and sweating increases the heat lost from the body, reducing temp back to the optimal 37 degrees C.
Vasoconstriction
- Vasoconstriction reduces the amount of blood flowing close to the skin, therefore less heat lost from radiation. [Often why you look pale(whiter) when your cold.
Controlling body temperature (when its cold)
- Vasoconstriction
- Sweat glands stop producing sweat so no heat is lost by evaporation.
- In cold weather, hair muscles contract to trap air adding an extra layer of insulation to prevent heat loss, by radiation and convection.
- Shivering is when muscles start to contract spontaneously and release heat from respiration. As blood flows through the muscles it is warmed by this
heat.
Negative feedback
Negative feedback is the process where a change in a condition from a set level causes a series of actions that return the condition to the set level. It is how the body keeps conditions within it constant at the optimum level (homeostasis).
How to increase rate of anaerobic respiration of yeast
- Increase temperature
2. Increase the concentration of glucose
why a mixture of yeast and water would not produce carbon dioxide
it is glucose that breaks down to form carbon dioxide
