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Biology IB HL > C4.1 > Flashcards

C4.1 Flashcards

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1
Q

What is a population?

A

Group of species that live in the same area
Can interbreed, interbreed less or never
Geographically separated

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2
Q

What is a community?

A

A group of many different species populations live in the same area

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3
Q

What are some examples of non-breeding interactions?

A

Competition -.> resources
Cooperation -> avoid predation

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4
Q

What is the use of random sampling?

A

Used to estimate the size of a population.
Estimations based on evidence
Rare to count reliably (camouflage, movement)

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5
Q

sampling

A

Small portion
Not a representative of whole population -> use multiple samples
Every individual should have an equal chance of inclusion -> random sampling

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6
Q

Estimate

A

Based on evidence, assumptions
For population size -> sampling

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7
Q

What is random sampling?

A

Every member of a population -> equal chance of selection
Unconscious bias avoided
Use of random numbers for this reason -

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7
Q

quadrats

A

Square sample areas -> marked with frame
Quadrat sampling -> place frame -> random positions in habitat -> record no. organisms present
Random coordinates generated -> place quadrat in area sampled -> each area must have equal chance

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8
Q

how to calculate a population estimate?

A

Population estimate = mean count per quadrat x area of whole site / area of one quadrat

Only suitable for sessile organism (fixed positions)

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9
Q

What is the capture-mark-release-recapture method? To estimate population sizes?

A

Capture as many -> in area occupied with netting, trapping, searching
Mark each, without making them visible to predators
Release back into habitat
After a day/two, recapture as many, count the marked and unmarked

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10
Q

What is the Lincoln Index

A

used to estimate population sizes
M x N / R

M=no. individuals caught+marked

N = total number recaptured

R = total number recaptured with marks

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11
Q

What are some assumptions from the period of time from capture to recapture?

A

No migration in/out
No deaths/births
Marked individuals mix back -> same chance of being captured second occasion as non marked
Marks remain visible

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12
Q

What is carrying capacity?

A

Maximum population size of an environment can support
- resources are needed, e.g food, limited

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13
Q

What happens when a resource becomes scarce?

A

-Competition for it by members of a population
-if population is too large, some are unable to attain

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14
Q

Examples of resources that will limit carrying capacity?

A

Animals
- water
- space for breeding
- food/territory to obtain food
- dissolved oxygen in water

Plants:
- water
- light
- soil nitrates and phosphates

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15
Q

What factors cause changes in population size?

A

Density dependent factors
Density independent factors

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16
Q

What are density independent factors

A

Same effect whatever populations size (e.g frost vs plants, forest fires)

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17
Q

what are density dependent factors?

A

Increasing effect as population becomes larger
Negative feedback mechanisms -> reduce larger populations/smaller populations increase
Tend to bring back to carrying capacity

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18
Q

What are the three groups of density dependent factors?

A

Competition - resources are limited
Predation - if the predator population is denser, they are easier to find. If scarce, this is less intense
Infectious disease, parasitism, pest infection -> increase with density, transfer to host to host is easier if closer

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19
Q

What factors contribute to a change in the number of individuals in a population?

A

Natality - offspring produced+added
Mortality - individuals die+lost
Immigration - individuals move into area from elsewhere
Emigration - individuals move from area to elsewhere

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20
Q

How can we calculate the overall change in the size of a population?

A

Natality + immigration - Mortality + emigration

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21
Q

What is a sigmoid (S-shaped) population growth curve:

A

To show increased population size over time
phases:
exponential
transitional
plataeu

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22
Q

Explain the exponential part of the Sigmoid population growth curve?

A

population is established in an ideal environment -> follows exponential growth pattern -> increase rapidly
-> natality rate > mortality -> Resources abundant
pred/diseases rare -> Immigration > emigration

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23
Q

Explain the transitional part of the Sigmoid population growth curve?

A

Slows, carrying capacity is reached -> max population -> natality falls -> mortality rises -> natality is still larger but by a lowering amount

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24
Q

Explain the Plateauing part of the Sigmoid population growth curve?

A

factor limits -> population
-> shortage + more predators + disease + pests
-> negative feedback mechanism, as population rises, density dependent factors are more intense
- emigration > immigration

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25
Q

Outline a test to model the sigmoid population growth curve

A

1) Test whether model -> fits growth real population
2) Small no. individuals -> given abundant resources -> numbers counted at regular intervals + repeats
3) Floating plants (e,g duckweed) -> grown on water in beakers
4) contain nitrate, phosphate + mineral ions needed
5) placed in bright light -> warm temp -> suitable rapid growth
6)No. counted on surface -> Exp continued until one resource needed is limiting

26
Q

What is an intraspecific relationship?

A

One that exists between individuals of the same species + usually in same population

27
Q

Intraspecific competition

A

Members, population -> same ecological niche -> same resources required
If abundant -> no competition -> vise versa
Some more successful -> gain more resource -> survive + reproduce
Natural selection over generations for traits -> for individuals to compete effectively.

28
Q

Intraspecific cooperation:

A

Individuals, population -> cooperate -> extent varies -> e.g termites
All individuals benefit

29
Q

interspecific relationships

A

One that exists between individuals of different species
Divided in two groups

30
Q

What are the relationships between species not living in close association?

A

Herbivory
Predation
Interspecific competition:

30
Q

Herbivory

A

Primary consumers -> feed -> producers (may/not be killed
Bison feeding on grasses

31
Q

Predation

A

One consumer species kills/eats another consumer species (prey)
Anteaters feeding on ants

32
Q

Interspecific competition:

A

two/more species use the same resources, rivalrous
Ivy competing with oaks

33
Q

What are the Relationships between species living in close association:

A

Mutualism
Pathogenicity:
Parasitism

34
Q

Mutualism

A

Two species -> close association -. Benefit from this
Zooxanthellae in hard corals
Usually from different taxonomic kingdoms -> different capabilities + different services.

35
Q

Pathogenicity

A

One species (pathogen) lives inside another species (host) -> disease
Anthrax bacteria in kudu (african antelope)

36
Q

Parasitism

A

One species (parasites) lives in/on another species (host) -> obtains food -> host harmed, parasite benefits
Black legged ticks on white tailed deer

37
Q

Examples of mutualism

A

Root nodules in Fabaceae (legumes)
Mycorrhizae in orchids (orchidaceae)
Zooxanthellae in hard corals

38
Q

Root nodules in Fabaceae (legumes)

A

Mutualistic relationship -> rhizobium bacteria
grows a root nodule -> bacteria can safely live
Provide sugars + low o2 environment -> rhizobium convert nitrogen -> ammonium ions -> some supplied to plant -> promoting growth in low nitrogen soils

39
Q

Mycorrhizae in orchids (orchidaceae)

A

Hyphae of Russula + other mycorrhizal fungi -> grow -> roots -> penetrate root cell walls
Fungus -> extension of root system -> absorbs water + mineral nutrients -> passed to orchid
Orchid -> supplies sugars + carbon compounds -> photosynthesis

40
Q

Zooxanthellae in hard corals

A
  • Cells of reef-building hard corals -> zooxanthellae (algae) -> absorbed from seawater
  • In safe environment gain co2 (aerobic respiration) from coral cells
  • Use in photosynthesis, coral -> gain o2, carbon compounds + aminos -> produced from photosynthesis
41
Q

Endemic versus alien species?

A

Species that occur naturally in an area vs species that were introduced by humans are alien.

42
Q

What happens if alien species are not effectively regulated?

A

pests/predators in their native habit are absent
If they increase in number, and spread rapidly -> invasive .
Alien species -> successful -> competition of resources

43
Q

What is the competitive exclusion principle?

A

Predicts that two species cannot occupy the same ecological niche indefinitely (no two species can exploit in the same way)
COMPETITION -> same/overlapping ecological niches

44
Q

Consequences of invasive species?

A

Endemic species -> occupy smaller realized niche
Decline in pop
Lose its niche entirety
Extinction
Widespread -> humans transport high no. (species) to new areas -> not enough/no limiting factors to control populations of alien species.

45
Q

Approaches to test interspecific competition:

A

Field manipulation -> one of two species removed from quadrats -> evidence of interspecific competition -> if increase in no. or biomass
Laboratory experiments -> under controlled conditions -> species grown together + apart -> investigate if they compete
Tests for association between species -> random sampling

46
Q

What is the chi squared test?

A

Test for association -> are twos pieces found in same/diff quadrats, or are they randomly distributed?

47
Q

outline the chi squared test…

A

1) Define two alternative hypotheses:
2) Draw a contingency table of observed frequencies (containing/not containing species)
3) Calculate expected frequencies for the 4 species combinations, assuming independent distribution
4) Calculate number of degrees of freedom (df)
5) Find critical region using table of chi-squared values and probability = 0.05 (5%)
6) calculate chi squared
7) If the calculated value is in critical region, there is evidence at the 5% level -> association between two species

48
Q

expected frequency formula

A

Expected frequency = row total x column total / grand total

49
Q

number of degrees of freedom

A

Df = (m-1)(n-1)
m=rows
n= columns

50
Q

what happens if df = 1?

A

the critical value is 3.83 or larger

51
Q

calculate chi squared

A
52
Q

what happens If the calculated value is in critical region

A

there is evidence at the 5% level -> association between two species
- reject null hypothesis
- Species are found more/less frequently -> than if randomly distributed
- Tend to occur together in quadrats when they have same habitat requirements -> or interspecific relationship -> encourages co-location.
- Tend to occur in different quadrats -> may be competition for resources or different habitat req.

53
Q

what are predator prey relationships?

A

Population of prey does not change much due to predation -> new individuals born at same rate as lost
Rates are stable for both predator+prey
Dynamic equilibrium
Some do not have dynamic equilibrium -> cyclical oscillations in numbers -> possibly due to habitat weather conditions varying

54
Q

What are the 4 types of density dependent interactions?

A

Rise in prey -> increase prey availability -> predator rise
Fall in prey -> fall in availability -> pred falls
Rise in pred -> prey falls -> pred increase
Fall in predator -> prey rise -> pred decreases

55
Q

What are Two Types of interactions operating in control of populations?

A

Top down control acts -> higher trophic to lower
- increase in pred -> decrease in prey in lower trophic levels

Bottom up control -> lower to higher
- Population of producers limited by mineral nutrient availability

56
Q

What are secondary metabolites?

A

Substance produced by a pathway, exists in some taxonomic groups
Not essential for cell growth -> wider range of functions
Released to environment -> toxic to other organisms and deter potential competitors

57
Q

What are antibiotics?

A

Secreted by microorganisms -> kill -. inhibit/prevent growth of other species of microorganism.
E.g penicillium

58
Q

What is penicillium?

A

Fungi inhabits natural habitats -> saprotrophic
the food they digest -> may be absorbed by bacteria
Penicillium -> secrete penicillin -> Reducing competition
Interferes with cross-linking of peptidoglycan molecules -> cell wall of gram-positive bacteria
Walls -> weak -> eventually burst and die

59
Q

What is allelopathy:

A

the chemical inhibition of one organism due to another
-> chemical release into the environment of substances acting as germination or growth inhibitors.

60
Q

What are allelopathic agents?

A

Secreted to soil -> plants -> to kill/deter growth of neighbouring plants
Reducing competition for water/mineral ions

61
Q

What is ailanthus altissima (tree of heaven)

A

Native to China
Invasive species across NA
Released Ailanthone -> soil -> inhibits germination, growth, survival -> Of other trees

Biology IB HL (14 decks)

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