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biology updated > nutrient cycles topic 5 > Flashcards

nutrient cycles topic 5 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what does an ecosystem include?

A

all the organisms living in an area, and all the abiotic conditions

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2
Q

what is a producer?

A

organism that makes its own food, eg a plant in photosynthesis

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3
Q

what is a consumer?

A

organism that consumes on another organism to obtain its energy, rather than directly using the energy of sunlight

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4
Q

what is a primary consumer?

A

organism that directly eats a producer

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5
Q

what is a secondary consumer?

A

organism that eats a primary consumer

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6
Q

what is a tertiary consumer?

A

organism that eats a secondary consumer

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7
Q

what is a saprobiont?

A

decomposer that breaks down complex material in dead organisms into simple matter

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8
Q

what is biomass?

A

the mass of living material

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9
Q

what does a food chain do?

A

describes a feeding relationship where producers are eaten by consumers

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10
Q

what is a stage in a food chain called?

A

a trophic level

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11
Q

what does an arrow on a food chain represent?

A

the direction of energy flow

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12
Q

what does a food web represent?

A

how many food chains in a habitat often link together

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13
Q

how can you estimate the chemical energy stored in biomass?

A

by burning biomass in a calorimeter

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14
Q

what can biomass be measured in terms of?

A

the mass of carbon an organism contains, or the dry mass of its tissue per unit area

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15
Q

what is dry mass?

A

the mass of an organism with all of the water removed

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16
Q

how can you find the dry mass of an organism?

A

sample of an organism is dried in a low temperature oven, weighed at regular intervals, when the mass becomes constant all water has been removed, scale up to the total population/area being investigated

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17
Q

how much carbon is present in dry mass?

A

50%

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18
Q

how does a calorimeter find the chemical energy given off?

A

sample of dry biomass burnt
energy released used to heat a known volume of water
change in temperature of water used to calculate the chemical energy of the dry biomass

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19
Q

what is gross primary production?

A

the total amount of chemical energy converted from light energy by plants, in a given area

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20
Q

how much of the GPP is lost to the environment as heat when plants respire?

A

50%

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21
Q

what is respiratory loss?

A

GPP lost to environment when plants respire

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22
Q

what is the net primary production equation?

A

the gross primary production-respiratory loss

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23
Q

what is NPP?

A

the energy available to the plant for growth and reproduction/ energy stored in a plant’s biomass, as well as the energy available to organisms at the next stage of the food chain

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24
Q

what is primary productivity?

A

the total amount of biomass in a given area in a given time

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25
Q

where do consumers store chemical energy?

A

in their biomass

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26
Q

how do consumers get energy?

A

by ingesting plant material, or animals that have eaten plant material

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27
Q

around how much energy is lost between trophic levels?

A

90%

28
Q

why is energy lost between trophic levels?

A

not all of the organism is consumed, some parts of an organism are lost in faeces if they cannot be digested, some energy lost in excretory materials eg)urine, heat loss during respiration

29
Q

what is the formula for net production of consumers?

A

net production = chemical energy in ingested food - (chemical energy lost in faeces and urine+energy lost through respiration)

30
Q

what can the net production of consumers also be called?

A

secondary production, or secondary productivity when expressed as a rate

31
Q

why do most food chains only have 4/5 levels?

A

insufficient energy available to support a large enough breeding population at a higher trophic level than this

32
Q

is the mass or organisms higher or lower at higher trophic levels?

A

lower

33
Q

how does energy available change the higher up the food chain you go?

A

energy available decreases

34
Q

what is the equation for percentage efficiency?

A

(energy available after the transfer/energy available before the transfer) x 100

35
Q

what are two methods farmers use to increase the efficiency of energy transfer?

A

reduce the energy lost to other organisms, reduce the energy lost through respiration

36
Q

how can a food web be simplified?

A

by getting rid of pests

37
Q

what are methods of pest control?

A

use chemical pesticides, (which simplifies the food web and means less biomass is lost from crops), and biological agents can reduce the number of pests (less energy and biomass lost from crops)

38
Q

how can respiration loss be reduced?

A

keep animals in pens which restricts their movement, keep pens indoors and warm so less energy is lost by generating body heat

39
Q

how do pens increase the energy conversion rate?

A

movement restricted so less energy used in muscle contraction
environment kept warm to reduce heat loss from the body
feeding controlled so maximum growth with no waste
predators excluded so no loss to other organisms in the food web

40
Q

what is a natural ecosystem?

A

ecosystem that hasn’t been changed by human activity

41
Q

how do saprobionts perform extracellular digestion?

A

secrete enzymes, digest food externally, absorb nutrients that they need

42
Q

what is a symbiotic relationship?

A

close relationship between 2 species where at least one benefits

43
Q

what are mycorrhizae?

A

symbiotic relationships that fungi form with plant roots

44
Q

how do fungi form symbiotic relationships with plant roots?

A

fungi are made of long thin strands (hyphae) that connect to a plant’s roots
hyphae increase the surface area of a plant’s root system, which helps the plant to absorb ions from the soil that are usually scarce
hyphae increase the uptake of water by a plant
in turn the fungi obtains organic compounds from the plant

45
Q

what percentage of the air is made of nitrogen?

A

78%

46
Q

how can plants and animals obtain nitrogen?

A

microorganisms convert nitrogen gas into nitrogen containing substances which can be absorbed, plants and animals cannot absorb directly through gas exchange

47
Q

what biological molecules are nitrogen found in?

A

proteins, ATP, nucleic acids

48
Q

what is nitrogen fixation?

A

when nitrogen gas in the atmosphere is converted into nitrogen containing compounds

49
Q

where can nitrogen fixation occur?

A

in nitrogen fixing bacteria in legume root nodules, and nitrogen fixing soil bacteria

50
Q

what are the stages of the nitrogen cycle?

A

nitrogen fixation occurs where nitrogen gas is converted into a nitrogen containing compound, such as an amino acid, by nitrogen fixing bacteria

ammonification occurs when saprobionts break down organic matter into ammonium

then nitrification occurs where nitrifying bacteria converts ammonia to nitrite ions, then to nitrate ions, using nitrifying bacteria in the process

finally, dentrification occurs, where nitrate ions are converted into nitrogen gas by dentrifying bacteria

51
Q

how can the process of dentrification be less wasteful?

A

keep the soil well drained and aerated

52
Q

how do plants obtain nitrate ions?

A

by active transport

53
Q

how do animals obtain nitrate ions?

A

by eating and digesting plants

54
Q

what are examples of molecules where phosphorus is found?

A

DNA, RNA, ATP, phospholipid bilayer

55
Q

what form is phosphorus found in?

A

not a gas like most cycles- found in phosphate ion mineral form in sedimentary rocks

56
Q

why is mycorrhizae beneficial?

A

increases the surface area for uptake of water and mineral ions
acts as a sponge to hold water and minerals
makes plants more drought resistant
able to take up more inorganic ions

57
Q

how do mycorrhizae impact the phosphorus cycle?

A

improve uptake of scarce ions such as phosphate

58
Q

what are the stages of the phosphate cycle?

A

1) phosphate ions in the rocks are released into the soil by weathering
2) phosphate ions are taken into the plants through the roots
3) mycorrhizae increase the rate at which phosphorus can be assimilated
4) phosphate ions are transferred through the food chain
5) phosphate ions are lost from animals in waste products
6) when plants/animals die, saprobionts are involved in breaking down organic compounds, which releases phosphate ions into the soil for assimilation by plants
7) weathering of rocks releases phosphate ions into seas, lakes and rivers, which is taken up by aquatic producers
8) waste produced by sea birds= guano- conatins a high proportion of phosphate ions
9) guano retruns phosphate ions to the soil, and is often used as a natural fertiliser

59
Q

how are nutrients lost when crops are harvested?

A

crops take in minerals from the soil as they grow, when they are harvested removed from where they are grown rather than dying and deomposing, minerals are not returned to the soil by decomposers, when animals are taken elsewhere to be slautered nutrients aren’t replaced by their remains/waste products

60
Q

what are artificial fertilisers?

A

inorganic- contain pure chemicals

61
Q

what are natural fertilisers?

A

organic-include manure, composted vegetables and sewage sludge

62
Q

what is leaching?

A

water soluble compounds in the soil are washed away

63
Q

when is leaching more likely to occur?

A

if fertiliser is applied just before heavy rainfall

64
Q

why do fertilisers leach?

A

more fertiliser is applied than the plants need/can use at a certain time

65
Q

when are fertilisers used?

A

to replace the nitrate and phosphate ions when plants are harvested and removed from the nutrient cycles as crops

66
Q

what are the stages of eutrophication?

A

mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds and rivers

large amounts of algae block light from reaching the plants below

plants die as they cannot photosynthesis enough

bacteria feed on dead plant matter- more bacteria reduce the oxygen concentration by carrying out aerobic respiration

fish/aquatic organisms die if there isn’t enough dissolved oxygen

biology updated (10 decks)

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