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Biology Unit 4 > 5 - Energy and ecosystems > Flashcards

5 - Energy and ecosystems Flashcards

1
Q

EQ

How would you calculate percentage efficiency of energy transfer between producers and primary consumers? (2)

Measure bars in?

A

PE = energy avail after/energy avail before x 100

mm

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2
Q

EQ

The average efficiency of energy transfer between producers and primary consumers in pyramids of energy is around 10 %.
Suggest why the efficiency of energy transfer from producers to primary consumers in this food web is higher than 10 %. (2)

A
  1. Single-celled producers are more digestible / contain less cellulose (than plants) / less energy lost in faeces;
  2. All of producer eaten/parts of plant not eaten;
  3. Less heat/energy lost / less respiration;
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3
Q

EQ

Energy from the sun may ultimately end up in dead plant matter. Describe how. (2)

A
  1. Photosynthesis/light dependent reaction/light independent reaction;
  2. Carbon-containing substances;
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4
Q

EQ

The gross productivity of the plants in the field was highest in July (highest temp). Use the data in the table to explain why. (2)

A
  1. High temperature allows enzymes to work faster/allows more collisions/ allows more e-s complexes to be formed
    OR
    A lot of light so light not limiting;
  2. Photosynthesis reactions are faster/more photosynthesis;
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5
Q

EQ

Give the equation that links gross productivity and net productivity. (1)

A

Gross productivity = net productivity - respiratory loss/respiration;

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6
Q

EQ

The net productivity of the plants in the field was higher in August than in July. Use the equation in part (b)(i) and your knowledge of photosynthesis and respiration to suggest why. (2)

A
  1. Respiration slower /less respiration;
  2. Light-dependent reaction/photosynthesis less affected by temperature increase;
  3. Lower (energy) loss;
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7
Q

EQ

A horse was kept in the field from March to October. During the summer months,
the horse was able to eat more than it needed to meet its minimum daily requirements.
Suggest how the horse used the extra nutrients absorbed. (1)

A
  1. Stored as fat/glycogen/biomass;

2. Used for growth/movement/reproduction / process involved in growth/movement/reproduction;

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8
Q

EQ

The horse’s mean energy expenditure was higher in March (colder)than it was in August. Use information in the table to suggest why. (2)

A
  1. More heat/energy is lost (in March)/colder (in March);

2. Maintain/regulate body temperature/more heat generated; 3. By respiration/metabolism;

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9
Q

EQ

Suggest appropriate units for gross productivity. (1)

A

KJm-2year-1

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10
Q

EQ

Explain the decrease in gross productivity as the woodland matures. (2)

A
  1. Less light / more shading / more
    competition for light;
  2. Reduced photosynthesis;
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11
Q

EQ

Use the information in Figure 3 and your knowledge of net productivity to explain why
biomass shows little increase after 100 years. (2)

A 
1. Net productivity = gross productivity
minus respiratory loss;
2. Decrease in gross
productivity/photosynthesis /
increase in respiration
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12
Q

EQ

Rather than use chemical pesticides or biological agents, farmers often use an integrated system of chemical pesticides and biological agents to control agricultural
pests. Explain the advantages of using an integrated system to control agricultural pests. (6)

A 
(Biological Agents)
1. Only needs one application/
reproduces;
2. Specific;
3. Keeps/maintains low population;
4. Pests do not develop resistance;
5. Can use less chemicals /
reduces chemical residues / no
bioaccumulation;
(Chemical pesticides)
6. Acts quickly;
7. Can apply to specific area;
8. Kills all/most/greater variety of
pests;
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13
Q

EQ

Explain how the intensive rearing of domestic livestock increases net productivity. (4)

A 
1. Slaughtered when still
growing/before maturity/while
young so more energy
transferred to biomass/tissue;
2. Fed on concentrate /controlled
diet / so higher proportion of food
absorbed/digested/assimilated /
used for biomass/tissue / lower
proportion lost in faeces;
3. Movement restricted so less
heat/energy/respiratory loss;
4. Heating/Kept warm/ inside so less
heat/energy/respiratory
loss/maintain body temperature;
5. Genetically selected / selective
breeding (for high productivity);
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14
Q

EQ

In some countries, pigs are reared in intensive units in which the temperature is controlled. Agricultural scientists investigated the effect of temperature on pig growth
and on the efficiency with which the pigs converted food to biomass.
In the investigation, the scientists used pigs of the same breed, with similar genotypes. Explain why. (2)

A
  1. Same breed so similar alleles;
  2. Controls/removes variable/so
    genes not a factor / only
    temperature affects results /
    rate of growth affected by
    genes;
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15
Q

EQ

The pigs were allowed to eat as much food as they wanted.
How could this have decreased the reliability of any conclusions drawn from the
investigation? (2)

A 
1. Different growth rates / gained
different biomass / grew
different amount;
2. Not due to temperature / the
independent variable;
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16
Q

EQ

10=0.80
20=0.85
30=0.45

A student concluded from these data that the mean growth rate of the pigs was fastest
at 20 oC. Do you agree with this conclusion? Explain your answer. (2)

A 
1. Temperature may be between
10 and 30/10 and 20/20 and
30;
2. Intervals are 10 C/large/not
small/should be smaller/should
be intermediates;
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17
Q

EQ

Pigs can survive at temperatures above 35. Use the data to suggest why scientists did not carry out any investigations at temperatures higher than 35 (2)

A 
1. Growth rate decreasing /
conversion staying same/
decreasing;
2. (Scientists would be) looking
for high growth rate/
conversion / data shows
unlikely to improve
growth/yield;
3. Wastes time/resources/would
not relate to farming
conditions;
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18
Q

EQ

The scientists isolated the fungus from the tissue of Hydrilla growing in its country of origin. Suggest two possible advantages of using this fungus as the biological
control agent. (2)

A 
1. Is specific / grows/survives in
Hydrilla/habitat;
2. Can reproduce / only one application
required;
3. Does not become a pest;
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19
Q

EQ

The treatment in experiment 4 was the most effective. Use your knowledge of integrated pest control systems to suggest why the treatment in experiment 4 was the
most effective (2)
A 
1. Fluridone/chemical acts quickly /
quickly reduces Hydrilla;
2. Fungus/biological control keeps
Hydrilla in low numbers;
3. Fungus/biological control works over a
long time/can reproduce
4. Resistance does not develop against
fungus/biological control;
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20
Q

Define producer

A

a (photosynthetic) organism that synthesises complex organic molecules from simple inorganic ones.

21
Q

Define consumer

4 types?

A

an organism that obtains its energy by feeding on other organisms.

Primary, secondary, tertiary, quaternary

22
Q

The efficiency of conversion of food to biomass is lower at 0 oC than it is at 20 oC. Suggest an explanation for the lower efficiency (2)

A 
1. Will lose more heat / not as
much energy used to maintain
body temperature;
2. Heat resulting from
respiration/more respiration;
3. More food used in respiration;
23
Q

Define decomposer

2 types with examples?

Nutrients released in what form?

A

An organism that breaks down complex organic molecules into simple organic molecules or ions by secreting enzymes onto them.

Decomposer - fungi and bacteria, detritivore e.g. earthworms

One that can be absorbed by producers

24
Q

Define food chain

A

a feeding relationship

25
Q

Define trophic level

A

the position of an organism in a food chain.

26
Q

Food webs:

Most animals?
In single habitat?

Problems? (2)

A

Rely on multiple food sources.
Many food chains linked together to form food web.

Impossible to show feeding interrelationships of all of species - too many.
Relationships change - time of year, age and population size.

27
Q

Why is most energy from the Sun not converted? (4)

A

Reflected back to space by clouds/dust or absorbed by atmosphere
Not all wavelengths absorbed
May miss chlorophyll molecule
Limiting factors of photosynthesis

28
Q

Why is most energy not transferred between trophic levels? (4)

A

Some of organism not eaten.
Some parts not digested
Some excreted
Some lost as heat in respiration/radiation

29
Q

Inefficient transfer between trophic levels means? (3)

A

Most food chains have no more than 5 trophic levels - insufficient energy to support larger population.
Biomass less at higher levels.
Gross productivity less at higher levels.

30
Q

Percentage efficiency/energy transfer calculation

Units?
Equation?

A

Unit = kJm-2year-1

Percentage efficiency/energy transfer = (energy available after the transfer/energy available before the transfer) x 100

31
Q

Why are ecological pyramids useful?

A

Provide quantitative information

32
Q

Pyramids of number:

Problems? (2)

A

Size of organism not taken into account

Number of individuals may be too great to fit scale

33
Q

Pyramids of biomass:

Problems: (2)

A

Seasonal differences not taken into account

Same biomass does not necessarily mean same energy - 1g fat 2x energy as 1g carb

34
Q

Pyramids of biomass:

Define biomass (3)

Units? (2)

A

the total mass of living material in a specific area at a given time.
Fresh mass unreliable - varying water content
Dry mass reliable - requires killing organism, small scale, not representative

Area being sampled - grams per square metre (gm-2).
Volume being sampled - grams per cubic metre (gm-3)

35
Q

Pyramids of energy:

Most?

Unit?

A

Most accurate

kJm-2year-1.

36
Q

Problems? (2)

A

Collecting energy information difficult

Not representative - taken from small area

37
Q

Define productivity

A

the rate at which something is produced.

38
Q

Define gross productivity

A

total quantity of energy that producers convert to organic matter ( kJm-2year-1)

39
Q

Define net productivity

Affected by? (2)

A

Net productivity = gross productivity - respiratory losses
(energy available to next trophic level)

Photosynthetic efficiency
Area of ground covered by crop leaves.

40
Q

Energy input:

Why do agricultural systems have a higher energy input? (3)

A

Suppressing climax community requires additional energy (e.g. ploughing, removing weeds) from:
Food - energy expended by farmers comes from food
Fossil fuels - energy used by machinery comes from fuels

42
Q

Productivity:

Why do agricultural systems have higher productivity? (2)

A

Competition reduced so effect of limiting factors reduced (e.g. for light, carbon dioxide)
Fertilisers and pesticides

44
Q

Define pest

A

an organism that competes with humans for food or space, or could be a danger to health.

45
Q

Define pesticide

A

Poisonous chemical that kill pests.

46
Q

Biological control aims to… not….

Because… due to…

A

Control so pest has no adverse effect, not eradicate

Predators would die - no food

47
Q

Biological control:

Advantages (5)

Disadvantages (3)

A 
Adv:
Specific
Only needs one application/reproduces
Keeps/maintains low population
Pests do not develop resistance
Reduces chemical residues/no bioaccumulation

Disadv:
Acts slowly
Does not kill all pests
May become pest itself

48
Q

Chemical control:

Advantages (2)

Disadvantages (3)

A

Adv:
Acts quickly
Kills all pests

Disadv:
Needs multiple applications
Pests develop resistance
Chemical residues/bioaccumulation

49
Q

How does each reduced productivity?

Weeds?
Insect pests? (2)
Monoculture?

A

Weeds - compete for limited resources so reduce photosynthesis
Insect pests - predators/damage leaves so reduce photosynthesis
Monoculture - enables pests to spread rapidly

49
Q

Economics of pest control:

Important to balance?

Often conflicting interests between? why? (4)

A

Balance cost of pest control with benefits

Farmer - economic (cheap prices but profit)
Conservationists - environmental (food for future)

49
Q

How does intensive rearing increase productivity? (6)

A

Movement restricted - less heat lost in respiration
Slaughtered when still growing - more energy transferred to biomass
Fed on concentrate - higher proportion of food absorbed
Heating - less heat lost maintaining body temperature;
Genetically selected
No predation/competition

Biology Unit 4 (29 decks)

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