Energy transfers

section 5

nitrogen cycle

• nitrogen gas is turned into ammonium ions

• then into nitrite then into nitrate

• which are then absorbed by plants

• when consumers eat the plants this nitrogen is transferred into their body

• when they die or excrete its decomposed by saprobiontics

• then back into n2 gas

why is nitrogen cycle important

nitrogen is limited availability in usable form so its important to recycle

why is nitrogen important

it is used to make DNA,RNA,ATP and other biological molecules

how does plants take up nitrogen

the take in nitrate ions through the roots by active transport

explain the process of nitrogen fixation

• nitrogen gas from atmosphere is reduced into ammonium ions by free living nitrogen fixing bacteria in the soil

• the nitrogen gas can directly taken in by plants by mutualistic nitrogen fixing bacteria in their root nodules

describe the process of nitrification

• ammonium ions are oxidised into nitrites then into nitrates by nitrifying bacteria in aerobic conditions so soil with air spaces

describe the process of ammonification

production of ammonium ions from the organic matter from dead organisms and wate products like urea by saprobiontics

describe the process of denitrification

• conversion of soil nitrates into nitrogen gas by denitrifying bacteria in anaerobic conditions its worst for the farming as plants wont have enough nitrates

what is the main form of phosphorus found in environment

it occurs mainly as phosphate ions in rocks, soils and ocean

why is phosphorus important

it is a component of ATP, phospholipids and nucleic acids

how do phosphate enter the soil

through weathering or erosion of sedimentary rocks

how does plants and animals obtain phosphorus

• plants absorb via their roots

• animals gain phosphate by feeding on plants

what happens to phosphorus when organisms die or excrete

decomposers break down organic matter releasing phosphate ions back into soil

what process returns phosphorus back into rocks

sedimentation forms new phosphate containing rocks

how can human activity affect the phosphorus cycle

use of fertilisers increase phosphate that can cause eutrophication

show phosphorus cycle and describe it

1. Saprobionts decompose organic molecules such as DNA/ATP/phospholipids in dead remains and waste products which releases phosphate ions; 

2. Phosphate ions (in water/soil) are absorbed by producers and used to make molecules such as DNA/ATP/phospholipids; 

3. Phosphorus in phosphate is passed to consumers when they eat producers;  

4. Weathering of rocks releases phosphate ions into soil/water; 

what are mycorrhizae

they are associations between fungi and plant roots forming a symbiotic relationship

how do mycorrhizae benefit plants

they act as extensions of the root system increasing the surface area for the absorption of water and minerals

how does the mycorrhizae benefit from this

a mutualistic relationship so in return they get organic compounds such as sugar and amino acid

why are fertilisers needed in agriculture

crops remove mineral ions from soils once they are harvested and those ions wont return to the soil so soil nutrient decrease and plant growth limits

two main types of fertilisers

• organic

• inorganic

what are organic fertilisers

• its made from dead and decaying animals and plants

• slower - saprobiontics need to ammonification and nitrifying bacteria to nitrification

• they are water soluble

• less chance of leaching

what are inorganic fertilisers

fertilisers made from inorganic materials

• quicker as immidiate supply of nitrate

• water soluble

• more chance of leaching

how can fertilisers reduces species diversity

• fertilisers causes crops to grow quicker

• these species outcompetes the slower growing species for light,water and space

• as a result only few plant species survive

what is leaching

leaching is the removal of soluble mineral ions from soil by water, rainwater dissolves the nutrients in soil and carry them into streams, lakes etc

why is leaching harmful

the soluble nutrients ions can contaminate the drinking water which can be harmful for health

describe the process of eutrophication

• mineral ions leached into lakes, streams

• which cause rapid algae growth forming a algal boom

• it blocks sunlight from reaching the deeper water

• so aquatic plants below cant photosynthesis and they die

• the dead plants cause increase in the number of decomposers and carry out aerobic respiration

• which reduces the oxygen content in water and cause the aerobic organisam to die

• decreasing the biodiversity

what are producers

plants or autotrophs they can make their own food using the energy from sun

plants only take in 1-3 percent of suns energy where does the rest goes

• absorbed by clouds

• reflected back to atmosphere

• some just pass through the leaves

how are producers releasing energy

they take heat energy from sun and carbon dioxide from atmosphere to make glucose and other sugar which is used in respiration to release energy

equation linking net production

net production = gross production - respiration

what is the meaning of gross production and net production

net primary production is the energy that is left and gross primary production is the all the energy from the sun

State and explain the equation that links GPP and NPP. 

1. NPP = GPP – R 

2. NPP is net primary production, GPP is gross primary production and R is respiratory losses; 

3. GPP is the total chemical energy store fixed by producers in photosynthesis in a given area or volume; 

4. NPP is the chemical energy store in plant biomass after respiratory losses to the environment (R); 

5. NPP is the energy available for plant growth and subsequently, to other trophic levels; 

what is biomass

Photosynthesis produces sugars, Sugars that are not used in respiration are used to make other biological molecules which become the biomass of the plan

Biomass is the mass of carbon or dry mass of tissue in a given area; 

how is biomass measured

• dry mass

• mass of carbon per unit of area

State and explain the equation for net production (N) of consumers. 

1. N = I – (F + R) 

2. I is the energy ingested, F is energy in faeces, R is energy lost in respiration; 

3. Of the energy ingested by a consumer, some is lost in faeces, some in lost in respiration; 

4. The remainder is used for growth/biomass and is available to the next consumer/trophic level; 

how is dry mass obtained and why is wet mass not used

• dry mass used as water content can varies in each organisms

• heat in the oven at low temperature and weigh until you get a constant mass

how do you find the energy in biomass

by a calorimetery - the amount of energy released from burning biomass is used to heat the known vol of water

describe the features of calorimetry

• termometer to measure the temperature change

• stirer to distribute the heat evenly

• insulated air to prevent heat loss to the surroundings

what is respiration

its process by which cells produce ATP from glucose

two types of respiration and where does it takes place

• aerobic respiration - takes place in mitochondria

• anaerobic respiration - takes place in cytoplasm

whats the difference between aerobic and anaerobic respiration

• aerobic requires oxygen, completely oxidises the glucose and produce large amount of ATP

• anaerobic does not require oxygen, incomplete oxidation of glucose and a small yield of ATP produced

what are coenzyme and whats their function

it is an organic molecule that assists enzyme catalysed reaction and it works by transferring chemical group from one molecule to another and it is regenerated at the end

what are the stages of aerobic respiration

• glycolysis

• link reaction

• krebs cycle

• oxidative phosphorylation

where does glycolysis occur

in cytoplasm

what is the first step of glycolysis

phosphorylation

describe the process of phosphorylation in glycolysis

• glucose is phosphorylated using a phosphate from ATP this creates 1 molecule of glucose phosphate and a ADP

• another ATP is hydrolysed and addition of 2nd phosphate forms hexose biphosphate

• which is then split into two triose phosphate

describe the process of oxidation in glycolysis

• triose phosphates are oxidised, releasing hydrogen

• they hydrogen is accepted by the coenzyme NAD and it becomes reduced NAD

• ATP is produced by substrate level phosphorylation

• and it forms 2 pyruvate (3C)

what are the products of glycolysis

• 2 pyruvates

• 2 NADH

• 2 ATP - 4 ATP produced but 2 are used up in the early stages

where does link reaction take place

in mitochondrial matrix

describe the process of link reaction

• pyruvate enters the mitochondrial matrix by active transport

• pyruvate get oxidised to acetate (2C)

• one CO"2 is removed and H+ are accepted by NAD to form NADH

• acetate combines with a coenzyme A to form acetyl coenzyme A

products of link reaction

• 2 acetyl coenzyme A

• 2 CO”2

• 2 NADH

• for one glucose molecule as it has 2 x pyruvates

where does krebs cycle take place

in mitochondrial matrix

describe the process of krebs cycle

• acetyl coenzyme A combines with a 4 carbon chain to form citrate (6C)

• decarboxylation and dehydrogenation occurs to form 5 carbon molecule and a co2 is removed and NAD accepts hydrogen to form NADH

• this happens again to form a 4 carbon molecule from 5 carbon molecule also CO2 and NADH formed

• FAD is reduced by accepting hydrogen to form NADH

• ATP is produced by substrate level phosphorylation from ADP also another NADH formed

• so citrate is converted to oxaloacetate (4C)

what are the products of krebs cycle

it happens twice as two pyruvate per glucose

• 4 CO2

• 6 NADH

• 2 FADH

• 2 ATP

what is the importance of krebs cycle

• breaks molecules into smaller ones

• production of hydrogen ions that are carried by NAD/FAD providing energy for the next step electron transmission chain

• regeneration of oxaloacetate prevents the accumulation and allows cycle to continue

where does oxidative phosphorylation/ ETC takes place

in the inner membrane of mitochondria - cristae

how is mitochondria adapted for the oxidative phosphorylation

• the folding of cristae - increases the surface area for electron carriers and ATP synthases enzyme

• ETC is embeddded in the the inner membrane - it contains a series of electron carriers that transfer electron from reduced NAD/FAD to release energy to pumps

• intermembrane space - narrow space allows rapid accumulation of hydrogen ions to create a steep electrochemical gradient

describe the process of oxidative phosphorylation/ETC

• hydrogen atoms are released from reduced NAD/FAD and each hydrogen atom splits into a proton(H+) and electrons (e-) and turning reduced NAD/FAD to just NAD/FAD

• electrons move down the electron transport chain, losing energy at each carriers and h+ moves into intermembrane of mitochondria

• energy from e- is used to pump h+

• the accumulation of H+ creates a electrochemical gradient

• so they diffuses into the matrix down the conc gradient via ATP SYNTHASE

• this movement drives the production of ATP from ADP + pi

• at the end of the chain electrons combines with H+ and oxygen to form water it is the final electron acceptor

why is oxygen so important in ETC and its role

because it is the final electron acceptor

so if it doesn’t accept the electrons it accumulate and stops the flow of electrons it can stop the pumping of H+ ions so no gradient established so it cant pass via ATP synthase and no ATP production

it combines with electron and proton to form water

how is ATP made in mitochondria

1. ATP is produced by substrate level phosphorylation in Krebs cycle which occurs in the matrix of mitochondria

2. Link reaction produces reduced NAD in the matrix of mitochondria

3. Krebs cycle produces reduced NAD and reduced FAD

4. Electrons are released from reduced NAD and reduced FAD (reduced coenzymes)

5. Electrons pass along carriers on the inner mitochondrial membrane

6. Redox reactions occur OR oxidation/reduction reactions occur; 

7. Energy is released as electrons pass between carriers; 

8. Protons/hydrogen ions move from matrix into intermembrane space; 

9. ATP is made from ADP and P_i as protons/hydrogen ions pass through ATP synthase from intermembrane space to matrix 

10. ATP synthase in the inner membrane catalyses the formation of ATP;