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Biology Unit 3 > Population Size and Ecosystems (DONE) > Flashcards

Population Size and Ecosystems (DONE) Flashcards

1
Q

What is an Ecosystem?

A

Balanced biological system made up of biotic and abiotic elements.

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2
Q

What is a Habitat?

A

A particular area occupied by a population.

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3
Q

What is a community?

A

The different populations of species that live in a habitat.

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4
Q

What is a niche?

A

An organisms role in the ecosystem.

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5
Q

What is Ecology?

A

A branch of Biology that studies the relationship between living organisms and their environment.

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6
Q

What is the environment?

A

The complex of physical, chemical and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival.

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7
Q

What is population?

A

The number of organisms of the same species in a certain place at a certain time, which can reproduce.

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8
Q

What factors will increase populations?

A

Birth rate and Immigration.

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9
Q

What factors will decrease populations?

A

Death rate and Emigration

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10
Q

Give the description and example of a fugitive species (r), which is a strategy for population growth.

A

Rapid reproduction and rapid Invasion of habitations, however cannot tolerate competitions. Examples include sea palm and dandelions.

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11
Q

Give the description and example of a equilibrium species, which is a strategy for population growth.

A

They balance the population and the growth pattern is sigmoidal.

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12
Q

What happens at the lag phase (1st part)?

A

Little or no cell growth. Organisms adapt and prepare for growth.

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13
Q

What happens at the log/exponential phase (2nd part)?

A

Numbers increase rapidly, so more individuals are available for reproduction. There is a lack of environmental resistance, e.g.
lots of resources (food).

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14
Q

What happens at the stationary phase (3rd part)?

A

Birth rate and death rate are equal. There are some limiting factors, but the population has reached its maximum (carrying capacity).

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15
Q

What happens at the death phase (4th part)?

A

Death rate is now bigger than birth rate. This could be due to environmental resistance/ food sources or toxin build up.

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16
Q

What is carrying capacity and what are the 2 effects on it when it has been exceeded?

A

The limit to the number of organisms the environment can support. Population crash is a sudden drop in population number due to significantly exceeding the carrying capacity. As a result the subsequent carrying capacity is greatly reduced due to environmental damage.

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17
Q

What are the factors in the environment that may prevent population growth?

A

Predators, disease and shortage of any of the various requirements for survival such as food, water, shelter and light (plants).

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18
Q

Describe the predator/prey relationship.

A

Due to resources being plentiful, prey start to reproduce and population increases. As a result predator population increases as they move into the habitat. Prey population decreases as they are eaten by predators. Predator population decreases as they have moved to find more prey.

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19
Q

What is Interspecific competition?

A

Competition for resources between members of different species and in general one will out compete another one.

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20
Q

What is the competitive exclusion principle?

A

When two species occupy the same niche, there will be competition and one species will out compete the other.

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21
Q

What is intraspecific competition?

A

Competition for resources between members of the same species. This tend to have a stabilising influence on population size.

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22
Q

What are some abiotic factors?

A

Temperature, water/humidity, pH, light/shade, soil (edaphic) factors, mineral supply, current (wind/water), slop, aspect, catastrophes and pollution.

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23
Q

What is density dependent and give some examples?

A

The effect of these factors increase as the population density increases. These factors limit the maximum size of a population.
Examples include: competition, toxic waste, disease and parasitism.

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24
Q

What is density independent and give some examples?

A

These factors have exactly the same affect irrelevant of the population size (they are abiotic factors).
Examples include: Ice age, flood, earthquakes, tsunami.

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25
Q

What is biodiversity?

A

The number of species and the number of individuals within each species.

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26
Q

What is abundance?

A

The number of organisms of a particular species in a given area or volume.

27
Q

Describe the capture recapture technique for motile organisms.

A
  1. Capture, count and mark a sample of organisms in an area and release them.
  2. Recapture and count in the same area at a later date.
  3. Count recaptured organisms in sample 2.
28
Q

What assumptions are made for the capture recapture technique?

A

Assumes that marked individuals distribute themselves evenly in the population.
Assumes no immigration, emigrations, births or deaths.

29
Q

Describe the kick sampling technique for measuring biodiverity

A
  • Hold a fine-mesh net in the direction you’re facing, downstream of where you’re standing.
  • Use one foot to kick the bottom of the stream dislodging the substrate in the direction of the net.
  • Work upstream from first sample so that uncaught organisms will flow downstream. This prevents more organisms being caught that would actually be present.
30
Q

Describe the quadrat sampling method for measuring biodiversity.

A
  1. Form a measured grid.
  2. Select random coordinates using a random number generator.
  3. Place a quadrat at the co-ordinates and count the number of individuals in the quadrat.
  4. Repeat so the number of replicates is representative of the whole population.
  5. Find the mean number per unit area.
  6. Multiply the total area of grid to obtain total density of population.
31
Q

What is a line transect used for?

A

To see how the distribution of different species changes along a habitat.

32
Q

Describe the three different types of transects.

A

Line transect - Any species touching the tape are recorded.
Belt transect - Quadrats are placed along the transect one after another
Interrupted transect - Quadrats at regular intervals along the transect.

33
Q

What is succession?

A

The sequence of changes in a community over time. Each stage of successions is called a sere. Changes in abiotic conditions due to the species present.

34
Q

What limits the population size in a climax community?

A

Maximum availability of light. Maximum light for any abiotic factor. Available space. Competition for resources.

35
Q

Describe pioneer community. (5 marks)

A
  • Not able to compete for resources e.g. light
  • Able to fix nitrogen and build up soil nutrients
  • Can tolerate extreme conditions (low nutrients levels)
  • Not influenced by/or dependent on animals species
  • Species which are early on arrival
36
Q

Describe the species/organism found at the climax community (6 marks)

A
  • Species found in the end point
  • Strongly influenced by other organisms
  • Are unable to tolerate great fluctuation in the water content of soil
  • Have large seed (large energy store), so seedings can survive low light intensity.
  • Have very good means of dispersal, usually by wind
  • Specialised niche
37
Q

What do humans do that affect succession? (6 marks)

A
  • Sheep grazing
  • Controlled burning
  • Extinguishing natural forest fires
  • Soil erosion
  • Deforestation
  • Coppicing
38
Q

What are producers?

A

Autotrophic organisms (plants and algae) which absorb light energy to convert simple inorganic compounds into more complex organic compounds.

39
Q

What are detritivores?

A

(Earthworms, woodlice and maggots) Feed on dead organic matter.

40
Q

What are decomposers?

A

Bacteria and fungi, break down organic compounds into simpler inorganic compounds, which can be absorbed by plant roots.

41
Q

How is energy lost in producers (plants)? (4 marks)

A
  • Light is reflected from the leaf surface
  • Wrong wavelength of light which cannot be absorbed by the photosynthetic pigment
  • Light passes through the leaf and doesn’t hit the photosynthetic pigments
  • Lost as heat during photosynthesis/ respiration
42
Q

How is energy lost from consumers?
(4 marks)

A

-Heat from respiration
- Indigestible material to decomposers (lignin and cellulose)
- Urine from biomass broken down
- Egestion and Excretion

43
Q

How do you calculate photosynthetic efficiency?

A

Quantity of light energy incorporated into biomass / Quantity of light energy hitting the leaf *100

44
Q

What is Gross Primary Production (GPP)?

A

The rate of production of chemical energy in biological molecules by photosynthesis

45
Q

What is Net Primary Production (NPP)?

A

The energy in plant biomass which could pass to the primary consumers.

46
Q

How do you calculate NPP?

A

GPP - R, where R = respiration

47
Q

What is Secondary Productivity?

A

The rate at which heterotrophs accumulate energy in the form of new cells and tissues.
Carnivores are more efficient at energy conversion than herbivores.

48
Q

What is biomass?

A

The mass of biological tissue.

49
Q

What are pyramids of energy and what are their use?

A
  • Shows the quantity of energy transferred from one trophic level to another
  • They allow comparison of the efficiency of energy transfers in different communities
50
Q

What is the role of photosynthesis in the carbon cycle?

A

Fixes carbon dioxide from the atmosphere into carbohydrates.

51
Q

What is the role of respiration in the carbon cycle?

A

In plants and animals, releases carbon dioxide into the atmosphere.

52
Q

What is the role of combustion in the carbon cycle?

A

From fossil fuels, releases carbon in the form of carbon dioxide into the atmosphere

53
Q

What is the role of decomposition in the carbon cycle?

A

Decomposers will decay animal and plant waste/ dead material and release carbon dioxide due to respiration.

54
Q

What is the role of feeding in the carbon cycle?

A

Carbon is fixed into organic molecules which are passed from producers to the next trophic levels along a food chain.

55
Q

How does human activity disrupt the balance of the carbon cycle?
(3 marks)

A
  • Deforestation as less carbon is fixed into carbohydrates by photosynthesis
  • Burning fossil fuels on a massive scale leads to more carbon released due to combustion
  • Increase in decomposition leads to more carbon released in landfill sites
56
Q

Describe (2 marks) the green house effect and explain the results of it (4 marks)

A
  • increased atmospheric CO2 leads to enhanced greenhouse effect
  • Leads to global warming/ climate change
    As a result:
  • Polar ice melts and rising sea levels
  • Increased frequency of extreme weather
  • Soil erosion
  • Increased extinction rate
57
Q

What is nitrogen fixing and how does it occur?
What are the conditions needed?

A

Atmospheric nitrogen is fixed into soluble compounds (NO3- and NH4+) via rhizobium/azotobacter.
Anaerobic conditions

58
Q

Where are azotobacter and rhizobium found? What does rhizobium include in its structure?

A

Azotobacter - Free living in soil
Rhizobium - root nodules of legumes. Uses nitrogenase, which is inhibited by oxygen. Surrounded by a layer of leghaemoglobin to prevent oxygen reaching rhizobium.

59
Q

What relationship does rhizobium and legumes show? Describe who and what benefits.
(4 marks)

A
  • Symbiotic relationship.
  • Plant gets access to soluble nitrogen to use in the synthesis of amino acids/ proteins.
  • Plant can grow in low nitrogen soils.
  • Rhizobium gets access to glucose, sucrose and amino acids.
60
Q

What is decomposition/putrefaction/ammonification?

A

When bacteria and fungi release nitrogenous compounds from large organic molecules during decomposition. This includes NH4+ ions

61
Q

What is nitrification and how does it occur?

A
  • Nitrifying bacteria and chemoautotrophs converting ammonium into nitrite and then nitrate
  • Nitrosomonas convert ammonium into nitrite
  • Nitrobacter converts nitrite into nitrate
62
Q

How can human activity improve the availability of soluble nitrate and therefore soil fertility?
(4 marks)

A
  • Adding fertilizers (ammonium nitrate)
  • Adding manure or treated sewage
  • Planting legumes such as clover
  • Ploughing or draining soil to improve aeration
63
Q

Describe and explain the effects of eutrophication.
(7 marks)

A
  • Eutrophication occurs when chemicals from fertilizers such as nitrogen, phosphorus leak into waterways.
  • This results in an increase in soluble nitrate content in waters and increases algae and plant growth
  • Algae bloom forms, covering the surface of the water and blocks light to plants at lower depths
  • Plants die as photosynthesis cannot take place
  • Aerobic bacteria decompose dead plants and use up oxygen
  • Other organisms die due to suffocation
  • Water becomes anaerobic, where denitrifying bacteria will thrive

Biology Unit 3 (7 decks)

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