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Biology Y13 > Energy and Ecosystems > Flashcards

Energy and Ecosystems Flashcards

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1
Q

explain simply how energy is transferred from plants to animals?

A

plants gain enrrgy from the sun, and animals get their energy by eating other plants and animals. Some energy is lost as heat along the way.

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2
Q

what are the 3 groups organisms can be grouped based on how they obtain their energy?

A

consumer, producer and decomposers/ saproboints

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3
Q

what is a producer?

A

photosynthetic organisms that obtain their energy through the photosynthesis of light energy, water and Carbon dioxide. (to make organic substances)

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4
Q

what is a consumer?

A

Organisms that obtain their energy by feeding off of other organisms

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5
Q

what are the three types of consumers and what are the differences?

A

primary consumers - feed directly off plants/producers
secondary consumers - feed off of primary consumers
tertiary consumers - these are usually predators and feed of secondary consumers

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6
Q

what are Saproboints / decomposers?

A

they feed off dead organic matter to obtain energy which is trapped inside them by breaking down the complex materials in dead organisms into more simpler ones.

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7
Q

Saproboints can either be..?

A

fungi or bacteria or even be animals such as earthworms

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8
Q

what is an autotroph?

A

organism that makes it’s own food

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9
Q

What is a food chain?

A

describes a feeding relationship by showing the transfer of energy between producers and consumers.

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10
Q

what is each stage referred to as?

A

a trophic level

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11
Q

what do the arrows in a food chain represent?

A

the direction of energy flow

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12
Q

what is a food web?

A

Shows how different food chain within a habitat interact with each other. As most organism in a community do not just feed up on one animal, and one animal can be fed upon by many other animals.

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13
Q

Why are food web’s just a model?

A

food webs are too complex and not all relationships can be shown, so we can use food webs as a model

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14
Q

all the relationships between organisms is almost impossible to record because they also change depending on..?

A
  • Time of year
  • Age
  • Population size
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15
Q

why are food webs still better than food chains?

A

more realistic, as animals do not have a single food source

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16
Q

Why is most energy not converted by plants?

A
  • most of the sun’s light energy is reflected back into the atmosphere by clouds.
  • not all wavelength’s can be absorbed
  • light may not fall on the chlorophyll molecules
  • a limiting factor may stop the rate of photosynthesis e.g low CO2 levels
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17
Q

How do plants use the glucoses and sugars they make?

A

some used for photosynthesis, to release energy for growth. the rest of the glusocse is used to make other biological molecules such as cellulose.And these biological molecules make up biomass.

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18
Q

What is net production?

A

the rate at which plants store energy.

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19
Q

How can we calculate Net production?

A

Net production = Gross production - respiratory loss

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20
Q

Why might there be a low % of energy transferred at each stage of the food chain? - MSA

A
  • not all parts of the organism is eaten
  • so parts of the organism can not be digested, so lost in faeces
  • lost in excretory materials e.g in urine
  • lost as heat, maintaining body temp.
  • energy lost in movement during hunting
  1. Heat (loss) from respiration;
  2. (Food) not digested
    OR
    Not all eaten;
  3. Excretion;
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21
Q

why do most organisms not have more than 4-5 trophic levels?

A

because a lot of energy is lost in heat

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22
Q

when is the total mass of organism less?

A

at high trophic levels

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23
Q

when is the total amount of energy stored low?

A

at each trophic levels

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24
Q

How can energy transfer at each trophic level be calculated?

A

energy available after the transfer/ energy available before the transfer x100

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25
Q

What is Biomass?

A

Biomass is the mass of living material in an organism in a specific area (at a given time)

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26
Q

How is biomass made?

A

some energy is used for, respiration for growth. the rest of the glucose is used to make other biological molecules such as cellulose. And these biological molecules make up biomass.

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27
Q

How can biomass be measured?

A

Biomass can be measured in terms of mass of carbon or dry mass of tissue per given area per given time.

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28
Q

what is dry mass?

A

the mass of an organism with the water removed

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29
Q

why does the Biomass have to be dry?

A

because water content varies in living tissue

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30
Q

Why can we not heat the Biomass dry?

A

it will die.

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31
Q

what is Biomass measure in?

A

gm-2 or gm-3

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32
Q

how is the dry mass carried out?

A

a sample of an organism is dried, often in an oven set to a very low temperature. the sample is then weighed at regular intervals. once the mass becomes constant you know that all the water has been removed. the mass of carbon present is usually taken to be 50% of the dry mass.

33
Q

How is dry mass then used in calculations for biomass?

A

once you have measure the dry mass of a sample, you can scale up the result to give the dry mass (biomass) of the total population or the area being investigated.

34
Q

Why do we use calorimetry?

A

The chemical energy stored in dry biomass can be estimated using calorimetry.

35
Q

How can we calculate the chemical energy of heather in calorimetry?

A

we can measure the energy released as heat

36
Q

An oxygen supply is connected to the apparatus, what is the advantage of burning the heather in oxygen and not in air?

A

so that the sample is burned completely and in a plentiful supply of oxygen, prevents incomplete combustion occurring

37
Q

A copper spiral is attached to the top of the combustion chamber. what is the function of this copper spiral?

A

the copper spiral provides a large surface area for heat exchange with the water

38
Q

the water jacket contains a large volume of water. the total rise in temperature of the water in this jacket when the heather is burned is only small. explain the advantage of the small rise in temperature.

A
  • makes it easier to measure the temperature change, so a more precise and accurate reading can be measured. However, there are also safety advantages for example, without the temperature would rise high and become really hot.
    furthermore, there is less heat loss to the environment
39
Q

Why is the stirrer in calorimetry?

A

the stirrer moves the water so, the water get equally heated up and decrease in experimental error occur .

40
Q

Do a Calorimetry exam question?

A
41
Q

Go over photosynthetic efficiency.

A
42
Q

what does the law of conservation of energy state?

As energy is transferred, the amount of usable energy …?

A

Energy cannot be created or destroyed, only
transferred and converted from one form to another.

The amount of usable energy in a system
decreases as energy is transferred.

43
Q

Energy transfer in plants/producers

A
44
Q

What is productivity?

A

amount of energy input to the trophic level that is converted into BIOMASS

Can be in a given time period (yr) Or a given area of ecosystem (m2)

45
Q

primary productivity involves..?
secondary productivity involves?

A

plants
animals

46
Q

what is gross primary production (GPP)?

A

The chemical energy store in a plant biomass, in a given area or volume, in a given time.

47
Q

What is net primary production (NPP)?

A

the chemical energy store in a plan biomass after respiratory losses to the environment have been taken into account.

also the energy available to the plant for growth and reproduction - the energy is stored in the plants biomass.

it is also the energy available to organisms at the next stage in the food chain.

48
Q

What is NPP available for?

A
  • plant growth
  • reproduction
  • Other trophic levels in ecosystem (herbivores and
    carnivores)
49
Q

approximately how much gross primary production is lost?

A

approximately 50% is lost to the environment as heat when the plants respire

50
Q

What is this called (above)?

A

respiratory loss

51
Q

how can we calculate (net) primary production?

A

NPP = GPP - R

52
Q

what is primary production called when expressed as a rate?

A

primary productivity

53
Q

What are the factors affecting primary production?

A

Directly related to photosynthesis so:

Intrinsic capabilities of a particular species

Light intensity

Duration of light each day

Water availability

Temperature

Atmospheric carbon dioxide concentration

Availability of inorganic ions (eg nitrates)

Competition for light and other resources

Damage to the plants by fungi, insects and other pests

54
Q

Energy transfer in consumers

A
55
Q

how do consumers get their energy?

A

by ingesting plant material or animals that have eaten plant material

56
Q

But what is the downside?

A

no all energy is transferred to the next rophic level

57
Q

how much energy is lost?

A

around 90% of the total energy is lost in various ways

58
Q

How is energy lost in consumers?

A
  • not everything is eaten, so roots of a plant, bones, so the energy they contain are not taken in.
  • Lost in Excretion - some is indigestible, so egested out as faeces and urine. the chem energy is lost to environment
  • some energy is also lost to respiration In the form of Heat
59
Q

how can the net production of consumers be calculated?

A

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

60
Q

state how the energy transfer of a trophic level can be calculated

A

net production of trophic level / net production of previous trophic level x100

61
Q

as we move up a food chain why does energy transfer usually become more efficient?

A

this is because plant (producers) contain more indigestible matter than animals (consumers)

62
Q

Productivity and Farming

A
63
Q

what is productivity?

A

amount of energy input to the trophic level that is converted to biomass
9can be given in a time period yr or given area of an ecosystem m2)

64
Q

What happens to energy in a trophic level?

A
  • Photosynthesis stores energy in organic form
  • Respiration releases energy in form of ATP
  • ATP is used:
    Muscle contraction
    Growth
    Reproduction
    Excretion
    Active transport
  • Feeding transfers chemical energy to next level

Eventually all energy escapes as HEAT

65
Q

how can we figure out if a food chain is more efficient?

A

if there are less trophic levels, more efficient.

66
Q

How can the efficiency of food production be improved?

A

Simplify food webs to reduce energy losses to non-human food chains

Reduce respiratory losses within a human food chain (farm animals)

67
Q

By simplifying food webs how can we make food production more efficient?

A

Food production is more efficient if the food
chain is short, because a higher percentage of
energy is available (by reducing energy losses
to non-human food chains)

68
Q

give an example of this

A

1 hectare of land can either farm crops or animals, more efficient to farm crops because it feeds more people and more crops can grow

69
Q

What are the other ways of maximising primary production?

A

Removing factors that inhibit plant growth, such as predators and disease used.

Improving the conditions for photosynthesis, by increasing light, water, carbon dioxide concentration, temperature and available nutrients.

Increasing ground coverage. This allows the maximum amount of the available energy from the sun to be used.

70
Q

What is a pest?

A

a pest is an organisms that competes for the energy in our food chain, or reduced productivity.

71
Q

How can pests be controlled?

A

pests can be controlled using chemical agents, biological control or a combination of both

72
Q

Maximising secondary productivity

A
73
Q

Main ways to maximise secondary productivity

A

Animals are often culled when they are young, as they have a higher secondary productivity rate than that of adults.

Antibiotics are used to avoid any unnecessary loss of energy to pathogens. Also given growth hormones

Selective breeding allows farmers to produce livestock with faster growing rates and increased production of milk, eggs, etc.

Some animals are kept in confined
spaces to reduce energy loss.

74
Q

What is factory farming?

A

Keeping animals in small enclosures such as barns or cages can help to reduce energy loss.

75
Q

How does factory farming conserve energy?

A

keep animals in confined spaces to restrict movement, decreasing the energy lost in muscle contraction.

a warm environment, reducing the amount of energy lost as heat from the body so more energy available to be incorporated into new tissue.

Feeding is controlled to prevent wastage and provide the animals with the optimum amount of concentrated food (less un-digestible food so less faeces).

The enclosure also helps to exclude predators.

76
Q

What are the advantages of increasing secondary productivity?

A

efficient energy conversion

produces low cost food

uses less space

easier to prevent disease

being introduced

easier to isolate ill animals

77
Q

what are the disadvantages of increasing secondary productivity?

A

animals vulnerable to rapid spread of disease

use of drugs can lead to antibiotic resistance

unnatural conditions may cause stress to the animal

restricted movement may cause osteoporosis and joint pain

produces large concentration of waste in a small area: rivers and ground waters may become polluted and pollutant gases may be produced

reduced genetic diversity due to selective breeding

the burning of fossil fuels that lead to increased global warming

78
Q

FINISH

A

Biology Y13 (13 decks)

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