The importance of energy transfer within and between organisms

Question 1

list of topics

Answer 1

• photosynthesis
• energy transfer through ecosystems
• nerve impulses
• respiration

Question 2

photosynthesis: The importance of energy transfer within and between organisms

Answer 2

• Plants use the transfer of energy during photosynthesis to generate glucose.
• Energy is transferred to the stroma of the chloroplast in the form of ATP during the Calvin cycle.
• The Calvin cycle consists of carbon fixation where CO2 is combined with ribulose bisphosphate and is catalysed by rubisco creating an unstable 6C intermediate which is broken down into 2 molecules of glycerate-3-phosphate, during the reduction stage hydrolysis of ATP releases energy to reduce glycerate-3-phosphate into triose phosphate
• The transfer of ATP into the Krebs cycle therefore provides energy for the reduction of glycerate-3-phopshate into triose phosphate.
• Triose phosphate is then used to synthesise glucose which is a main component of cellulose.
• If no glucose is produced due to the transfer of ATP during photosynthesis, the plant cell walls would be unsupported due to lack of cellulose and unable to withstand turgor pressure, turning them flaccid.
• Therefore the transfer of energy via ATP in the plant is essential in photosynthesis to synthesise glucose used to support plant cell walls.

Question 3

energy transfer through ecosystems: The importance of energy transfer within and between organisms

Answer 3

• Energy is transferred between organisms in ecosystems via biomass.
• Energy from the sun is absorbed by the chlorophyll pigment in plants for photosynthesis which produces glucose used for plant growth, and becomes biomass.
• Primary consumers eat the plants, and the energy within the biomass of the plant is transferred to the next trophic level.
• This energy is eventually transferred onto secondary, then tertiary consumers as their biomass is also consumed.
• This is significant to all organisms, specifically animals as it provides them energy in the form of ATP for metabolic processes such as muscle contraction.
• If energy would not be transferred between trophic levels, animals would not have enough ATP to move the myosin head to its resting position, therefore the muscles would be constantly contracting which can cause spasticity in animals.
• In conclusion, the importance of energy transfers between ecosystems is that it generates energy in the form of ATP which allows for continuous contraction in the muscles of animals.

Question 4

nerve impulses: The importance of energy transfer within and between organisms

Answer 4

• Animals transfer energy within their organisms the maintenance of a resting potential via the sodium-potassium pump.
• Carrier protein actively transport 3 sodium ions out of the axon for every 2 potassium ions that are actively transported in, against the concentration gradient via active transport.
• The movement of ions via the sodium-potassium pump establishes an electrochemical gradient where there is a larger concentration of positive ions outside the axon than there is inside the axon.
• Energy is transferred to the sodium potassium pump via the hydrolysis of ATP as active transport requires energy.
• Failure to maintain the resting potential via the transfer of energy by ATP would cause the cell to become depolarised, resulting in faulty action potentials.
• If the neurone has prelonged depolarisation due to the failure of a sodium-potassium pump an epileptic seizure can occur.
• Therefore it is important that animals transfer energy in the form of ATP during resting potential to avoid prelonged depolarisation that can cause epilepsy.

Question 5

respiration: The importance of energy transfer within and between organisms

Answer 5

• Animals transfer energy during aerobic respiration which includes the Krebs cycle that is a series of redox reactions occurring in the matrix of the mitochondria.
• This involves the binding of acetyl coenzyme A with a 4C compound, to generate a 6C molecule and releasing acetyl coenzyme A back into the link reaction.
• The 6C molecule is decarboxylated andhydrogenated producing a 5C molecule, the 2H+ ions released are used to reduce NAD.
• 5C molecule, a phosphate is removed and used togenerate ATP,substrate level phosphorylation.
• 5C is decarboxylated and hydrogenated again to produce 4C andCO2 and reduced NAD as well as 2x ATP.
• The ATP produced from the Krebs cycle is used to power homeostatic processes such the control of blood water potential in the Loop of Henle.
• The transfer of ATP made during aerobic respiration to the Loop of Henle in the form of energy allows for the reabsorption of water into the blood created by the water potential gradient via the active transport of Na+ ions (active transport requires ATP).
• This is important as it prevents dehydration which would cause the cells in our body to shrink, which presents itself via dry skin and sunken eyes.
• Therefore the transfer of energy in the form of ATP from respiration to the Loop of Henle is important in preventing dehydration.