biology- component 1 > populations > Flashcards

populations Flashcards

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1
Q

what is ecology

A

the study of the relationship between living organisms, including humans and their physical environment

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2
Q

what is an ecosystem

A

a balanced biological system where all the organisms and the non-living componenets interact in a particular location
this is energy flow and nutrient cycling within the ecosystem

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3
Q

what is a habitat

A

the palce where an organism lives

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4
Q

what is a niche

A

the role and position of an organism within its environment, inclusing all interactions with the biotic and abiotic factors of its environment

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5
Q

what is an enviornment

A

the factors in a habitat which affect an organism- both living and non living

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6
Q

what is biotic and abiotic factors

A

biotic- living factors - eg pathogens, predators
abiotic- non living factors- eg oxygen, temperature, light

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7
Q

what is a limiting factor

A

aspects of the environment which restrict populations size

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8
Q

what is a species

A

a group of organisms which share a large number of common characteristics and which can interbreed to produce fertile offspring

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9
Q

what is a population

A

a group of organisms of a single species, interbreeding and occupying a particular habitat

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10
Q

what is a community

A

interacting populations of two or more species in the same habitat at the same time

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11
Q

ecosystems are dynamic, so what are the changes that are constantly happening

A
  • intensity of energy flow
  • biological cycles eg nitrogen cycle
  • successional change in habitats
  • species composition and population sizes- arrival of new species or presence no longer detected
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12
Q

why do populations fluctuate

A
  • birth rate
  • death rate
  • immigration into the population
  • emigration away from population
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13
Q

what is the popualtion size equation

A

constant if
birth rate + immigration = death rate + emigration

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14
Q

what are the stages in an animal population curve and their explanations

A
  1. lag phase
    - may last from several days to months or years
    - only a few individuals present initially- growth rate is slow
    - period of adaptation to new environment
  2. log/exponential phase
    - plentiful resources, population grow rapidly at maximum rate
    - no limiting factors/lack of environmental resistance
  3. stationary phase
    - rate of growth slows as organisms start to compete with each other
    - birth rate = death rate
    - environmental resistance/intraspecific competition
    - carrying capacity has been reached
  4. death phase
    - death rate exeeds production rate
    - may occur when all plants are eaten leading to population crash
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15
Q

what are the stages in an bacterial/yeast population curve and their explanations

A
  1. lag phase
    - bacteria are synthesising new enzymes and proteins
    - rate of cell divison is slow
  2. exponential phase
    - plenty of nutrients- no other limiting factors
    - cells divide at their maximum rate
    - doubling in a unit time
  3. stationary phase
    - cells are dying at the same rate as they are being produced
    - there are limiting factors- nutrients running out
  4. death phase
    - cell death is greater than the rate of production of new cells
    - build up of toxic waste eg ethanol- yeast, acid - bacteria
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16
Q

what is the carrying capacity

A

the maximum population size that can be sustained over a period of time in a particular habitat/environment

the maxiumum number around which a population fluctuates about this set point in a given environment

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17
Q

why do populations sometimes go above or below the carrying capacity

A

the influnence from limiting factors
eg food supply changes
eg predators can suffer disease

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18
Q

what is environmental resistance

A

environmental factors that slow down population growth
combined with effects of limitimg factors that prevent further increase of popultion

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19
Q

factors that contribute to environmental resistance for bacterial culture

A
  • avaivable food
  • overcrowding
  • competition
  • accumulation of toxic waste
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20
Q

factors that contribute to environmental resistance for animal/plant population

A

biotic factors
- predation
- parasitism/disease
- competition (intra/interspecific)
abiotic
- light intensity
- water availability
- water mineral content
- tempertaure
- pH
- amount of space available

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21
Q

if environmental resitance increased, how would this effect the carrying capacity

A

carrying capacity would decrease as its more difficult for organisms to survive and breed
fewer organisms can be supported by the environment

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22
Q

what is a density dependent factor

A

affect a higher proportion of the population if the population is denser

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23
Q

exampes of density dependent factors

A

mainly biotic factors
- predation
- competition
- parasitism
- disease
- food availabiloty
- accumulation of toxic waste
- availability of territory/shelter

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24
Q

what is a density independent factor

A

the effect of these factors doesnt not depend on population size
- all members of species are equally affected

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25
examples of density independent factors
- suddent violent change in abiotic factors- temperature, water, flood, fire - soil pH, light intensity
26
what do plants compete for
light water space nutrients
27
what do animals compete for
food and water shelter space reproductive partners
28
what is intraspecific competition
competition between individuals of the same species with the same niche - limits population size- density dependent - important in natural selection
29
what is interspecific competition
competition between individuals of different species - two species cant occupy the same niche in a specific habitat, the more the niche overlaps, the more competition there is
30
what is an example of population fluctuations due to prey and predators (lynxs and hares)
- in a season where weather conditions are favourable, theres a lot of plant growth, so lots of food for hares- increase population as many of yooung survive - in subsequent years, the larger hare population (prey) provide more food for the lynx (predator)- more lynx young survive so population increases - more predators means that more hare are eaten, causing the prey population to decline - in subsequent years, theres less prey as food so lynx population declines and intraspecific competition for food means that some animals (young and sick) starve
31
what is niche overlap avoidance
the process where coexisting species use different strategies to reduce competition for shared resources, allowing them to live in the same ecosystem without one driving the other to extinction.
32
what is competitive exclusion principle
no two species can occupy the same niche in a specific habitat
33
what do food webs show
how energy is transferred through a community the relationship between producers and consumers in a community
34
what do producers do
capture light energy and use it to make their own food carry out photosynthesis
35
how is chemical energy stored
stored within the bonds of organic/biological molecules especially carbon-carbon bonds and carbon-hydrogen
36
what can only a producer do
create these C-C and C-H bonds (food) from inorganic ions and molecules
37
what is photosynthesis efficiency and its units
a measure of ability of a plant to trap light energy percentage
38
what is the photosynthesis effiency equation
(quantity of light energy incoroparted into product (GPP) / quanity of light energy falling on plant ) x100
39
what is gross primary productivity and unit and on average GPP
the rate of production of chemical energy in organic molecules by photosynthesis in a given areas in given time KJ m-2 year-1 average GPP= 0.2 %
40
what is net primary productivity and unit and on average GPP
energy in plants biomass which is available to primary consumer. represnts potential food/chemical energy available to heterotrophs in ecosystem KJ m-2 year-1 average GPP= 0.1%
41
what is primary productivity
the rate at which energy is converted by rpoducers into biomass
42
what is secondary productivity
the rate at which consumers covert the chemical energy of their food into biomass
43
why is energy transfer between plants and herbivores very inefficient
plants are made out of a large amount of cellulose which is difficult to digest alot of energy is used during the digestive process of this- bacteria in stomach produce cellulase alot of energy lost in undigested waste in faeces
44
why is energy transfer between herbivores and carnovires more efficient
protein and fat are easier to digest less energy is lost in faeces
45
what is biomass
the mass of biological materialin living or recently living organisms
46
what is trophic level
feeding level an organisms position in a food chain, indicating how it obtains energy
47
what is a saprotroph
a microorganicm that secretes enzymes onto dead or decaying remains and carries out external digestion
48
what does the arrow in the food chain show
direction of energy flow
49
what is the order of trophic levels/food chain
primary producers- primary consumers- secondary consumer- tertiary consumer- quaternary consumer
50
Why is photosynthesis efficiency typically only 1-2%
- light is reflected from leaf - some light passes through leaf - some light is absorbed by non photosythetic parts - much of light is of the wrong wavelength- absorb blue and red best
51
why is energy lost between trophic levels
- some of tissue is inedible so its not eaten - some of food is indigestible - respiration losses- energy needed for active transport, muscle contraction, keeping warm - lost in excretory products
52
what is succession
the change in strucure and composistion of species in a community over time
53
where does primary succession occur
occurs in a habitat that had never been colonised beacause there is no established soil eg bare rock, sand dune, pavement
54
what are pioneer species
the first plants to grow in a new habitat eg lichens and mosses
55
what do pioneer species have to be
adapted to be successful in very harsh enviornments eg extreme temperatures, low water availability, high winds, low nutrients
56
what is seral stage 1 using pioneer species
lichens - a slow growing symbiotic re;ationhsip between fungi and algae - able to tolerate total desiccation and low nutrients - algae photosythesise and fungal hyphae grip the rock and trap soil fragements/nutrients released by weathering mosses - able to root into the first soil formed by decomposing lichen and still tolearte desiccation - couldnt survive on bare rock
57
what is seral stage 2/grassland community
- decomposing mosses and lichens from soil - seeds are carried into habitat by the wind and germinate in the soil - soil allows low growing plants eg grasses and herbaceous plants, to establish
58
what is seral stage 3/ shrubs
- growth of perennial woody plants eg heather - shade out lower growing species - outcompete low growing plants by blocking light - outcompete exisiting plants fro water and nutrients and replace them in the habitat
59
what is the seral stage 4/ climax community
- final stable community in an ecosystem (equilibrium) - usually woodland made of large trees - a waide variety of both plants and animals exist at the variety of heights within the ecosystem
60
what are seral stages/seres
the different stages in a succession when particular communities dominate between the pioneers and the climax community
61
what is a climax community
the final stage of succession, in which species composistion remains relativle stable community has reached equilibrium
62
what are some of the gradual changes overtime due to succession
- depth of soil increases - humus content of soil increases - conc of nirtrates and phosphates in soil increases - number of woody plants increase - biodiversity increases - number of niches increase - pioneer plants are lost as they die as their space is occupied by perennials
63
why does the climax community may have a lower biodiversity than the stage before it
climax community is dominated by one type of organism so there are fewer niches and so biodiversity is lower
64
why are pioneer plants often xerophytes that can fix nitrogen
bare rock has little or no available for use in protein synthesis any nitrate are quickly washed away by rain
65
what is secondary succession
repopulation of an areas that had been previously colonised, often due to the habitat being disturbed or damaged
66
why is secondary sucession much quicker than primary succession
- soil is already present - seefs from previous plants already present - undisturbed root systems in soil, stumps and other plants parts from previously existing plants can rapidly regenerate - available nitrates and phospahtes in soil as well as more water
67
what are factors that affect succession
- migration - seed dispersal in flowering plants - seed dispersal in fungi
68
how does interspecific competition affect succession
- at each seral stage, organisms are competing with each other for resources - larger plants outcompete smaller plants for light which leads to changes in the community - grasses outcompete mosses at the end of the pioneet stage - shrubs outcompete grasses at the end of the grassland stage
69
how does facilitation affect succession
the conditions created by one species, eg soil depth, helps the growth of a larger species which would otherwise not be able to grow there - the invasion of later species depends on condition created by eralier colonists - earlier species modigy the environmnet so as to increase the competitive ability of species which are then able to displace them
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