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Biology - Unit 5 > Chapter 13 - Energy & Ecosystems > Flashcards

Chapter 13 - Energy & Ecosystems Flashcards

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1
Q

Define population

A

All organisms of a single species in a habitat

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2
Q

Define community

A

All organisms of all species in a habitat

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3
Q

Define habitat

A

Where a organism lives

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4
Q

Define niche

A

The role of the species in an ecosystem and how it interacts

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5
Q

Define trophic level

A

Each stage of the food chain

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6
Q

Define gross primary productivity

A

The total amount of energy made my producers per unit of area per unit of time

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7
Q

What is net primary productivity?

A

The amount of chemical energy a producer stores as biomass per unit of area per unit of time and is the total amount of energy available to the next trophic level

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8
Q

Give the equation for NPP

A

NPP = GPP - RL

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9
Q

Give the equation for NP

A 
NP = I - (R+F)
I = Ingestion
R = Respiration
F = Shit
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10
Q

Why do trophic levels lose energy?

A
  • Energy lost as heat due to respiration
  • Not all is consumed
  • Indigestible parts shat out
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11
Q

How do you calculate energy transfer efficiency?

A

Net productivity/Ingestion X 100

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12
Q

Summarise the general food chain

A

Sun - Producer - Primary Consumer - Secondary Consumer

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13
Q

How much energy is transferred to the producer from the sun and why?

A
  • Approx 2%
  • Not right wavelength
  • Does not strike chloroplast
  • Reflect by leaf or molecules in air
  • Lost as heat
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14
Q

How much energy is transferred to the primary consumer from the producer?

A
  • Approx 10%
  • Respiratory loss for metabolism/ATP
  • Lost as heat
  • Not all plant is eaten
  • Some food indigestible and shat out
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15
Q

How much energy is transferred to the secondary consumer from the primary producer?

A
  • 10-15%
  • Respiratory loss for metabolism/ATP
  • Lost as heat
  • Not all of animal is eaten
  • Some foot indigestible so shat out
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16
Q

Give reasons as to why energy transfer efficiency is low

A
  • Old animal has stopped growing
  • Herbivores so more excretion
  • Endotherms lose more energy as heat
17
Q

How can we increase energy transfer efficiency in plants?

A
  • Shorten food chain to reduce competition so more energy to create biomass
  • Fertilisers to add phosphate/nitrogen to stop limiting growth
18
Q

How can we stop the effect of fungi, weeds and insects and how does this help?

A
  • Herbicide to kill weeds
  • Fungicide to reduce fungus
  • Insecticide to kill insects (either chemical or biological)
    There is less competition so crop receives more light energy and creates more biomass
19
Q

How can we increase energy transfer efficiency in animals?

A
  • Reduce respiratory and excretion loss (R+F)
  • Restrict movement so less respiration/less energy
  • Keep warm so less respiration required
  • Slaughter animal while still growing
  • Keep predators away
  • Controlled diet with antibiotics to ensure all digested
  • High yield organisms
20
Q

How can we measure biomass?

A

Take dry biomass by hearting on a scale until mass becomes constant, but low enough to ensure combustion does not occur (this will lose biomass)

21
Q

Why do we remove water in biomass samples?

A

Different plants contain different water amounts and so different samples are not representatives

22
Q

What is biomass measured in?

A

KG per M^2

23
Q

How do we use calorimetry to estimate dry biomass?

A
  • Burn substance completely to heat known volume of water
  • Measure temperature change
  • Calculate energy released
24
Q

How do estimate dry biomass using mass of carbon?

A
  • Organisms made from organic compounds with carbon
  • Mass of carbon good indicator for biomass
  • Difficult to measure but carbon is usually 50% of the dry biomass
25
Q

Summarise the nitrogen cycle

A
  • Inert N2 gas in atmosphere
  • Fixed into ammonium ions (NH4+) by NFB
  • Freeliving NFB in soil, mutualistic in leguminous roots
  • NH4+ converted into NO3- by nitrification (NH4+ into nitrite ions NO2- into nitrate ions NO3-)
  • NO3- absorbed by plants to make AA, proteins and nucleotides
  • Consumers eat plant to obtain AA
  • Organic material broken down by saprobiotic decomposers that secrete extracellular enzymes
  • NO3- converted back into nitrogen gas by denitrifcation in anaerobic conditions
26
Q

Summarise the phosphorus cycle

A
  • Phosphorus present in rock as phosphate ions (PO4^3-)
  • Erodes and leaves PO4^3-
  • Plants absorb phosphorus
  • Consumers eat plants
  • Saprobiotic decomposers break down organic material and release phosphate ions back into soil
  • Mycorrhizae fungus help uptake of these minerals
27
Q

How do microorganisms play a role in the nutrient cycles?

A
  • Saprobionts use extracellular enzymes to break down large organic compounds into smaller ones
  • These are absorbed by producers
  • Microorganisms also absorb inorganic ions across their membrane
  • Mycorrhizae fungi has a mutualistic relationship: fungi increases SA for absorption for plants and the fungi receives organic compounds from plant
28
Q

How does eutrophication occur?

A
  • Soluble compounds washed off the land by rain
  • Runs into water sources
  • Algae bloom
  • Blocks light so plants underneath cannot photosynthesis
  • Plants die, so broken down by sapribioptic decomposers and use oxygen to respire areobically
  • Fish die
  • Hence bad
29
Q

Why is fertiliser needed when crops are harvested?

A

Nitrogen and phosphorus removed from the cycle so replaced with fertiliser

30
Q

Why is too much fertiliser a negative?

A

Changes water potential so less water absorbed and harder to absorb other molecules

31
Q

What is good/bad about natural fertilisers?

A
  • Aerate soil
  • Contain wide range of substances
  • Less leaching
  • Consume less energy to create
  • Still require the breaking down by saprobionts so slow release of N and P

Biology - Unit 5 (4 decks)

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