Anaerobic Respiration, Energy Transfer, Nutrients Cycles

Question 1

Anaerobic respiration?

Answer 1

• absence of oxygen, occurs in cytoplasm only
• pyruvate produced in glycolysis reduced to form ethanol and CO2 (in plants and microbes) or lactate (in animals) by gaining hydrogen from reduced NAD
• NAD can be reused in Glycolysis and ensures more ATP is produced

Question 2

Energy Transfer?

Answer 2

• in any ecosystem, plants are producers - able to produce own food (carbs) using CO2 and water
• majority of energy lost between each tropic level via respiration and excretion. Remaining used to form biomass.
• amount of biomass remaining in organism measured in mass of carbon or dry mass of tissue per given area

Question 3

Net Primary Production and Gross Primary Production?

Answer 3

• GPP - chemical store in plant biomass in given area. Total energy resulting from photosynthesis
• NPP - chemical energy store in plant biomass taking into account energy lost from respiration. (R)
• NPP = GPP-R

Question 4

Net Production of Consumers (animals)?

Answer 4

• N=I-(F+R)
• I - chemical energy store in ingested food
• F - chemical energy lost to environment in faeces and urine
• R - respiratory losses

Question 5

Nitrogen Cycle?

Answer 5

1. Saprobiotic nutrition and microbes
2. Ammonification
3. Nitrification
4. Nitrogen Fixation
5. Denitrification

Question 6

Importance of Nitrogen Cycle?

Answer 6

• plants and animals cannot obtain nitrogen through gas exchange
• Nitrogen gas (N2) contains a triple bond
• microorganisms needed to convert N2 into nitrogen containing substances that plants and animals can absorb - proteins, ATP and nucleic acids all contain nitrogen.

Question 7

Phosphorus Cycle?

Answer 7

• phosphorus Cycle used for DNA/RNA, ATP, Phospholipid bilayer - essential element for life
• different to carbon and nitrogen cycle as it is not found in gas (atmosphere)
• mainly found as phosphate ions, in mineral form in sedimentary rocks

Question 8

Mycorrhizae?

Answer 8

• fungal associations between plant roots and beneficial fungi
• beneficial for plant growth:
  1. Increases surface area for water and mineral absorption
  2. Acts like sponge - holds water and minerals around the roots
  3. Makes plants more drought resistant and able to take up more inorganic ions.
• role in nutrient cycles - improving uptake of relatively scarce ions (phosphate ions)
• mutualistic relationship

Question 9

Fertilisers?

Answer 9

• added to soil to replace nitrate and phosphate ions lost when plants are harvested and removed from nutrient cycles as crops
• either natural (manure) - cheaper, but minerals and proportions can’t be controlled
• artificial (inorganic chemicals) - exact proportions of minerals, more water soluble so more ions dissolve in water surrounding the soil

Question 10

Leaching?

Answer 10

• water soluble compounds washed away, often into rivers/ponds
• causes eutrophication

Question 11

Eutrophication?

Answer 11

• nitrate leached from fertilised fields stimulates growth of algae in ponds (algal bloom)