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QCE Biology Unit 3&4 Externals > QCE Biology - Unit 3 Topics 1 and 2 > Flashcards

QCE Biology - Unit 3 Topics 1 and 2 Flashcards

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1
Q

What is biodiversity?

A

describes the number and variety of organisms living in a geographical area, measures at the level of species/ecosystem - includes genetic variation

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2
Q

What is an ecosystem?

A

A biological community of interacting organisms and their physical environment

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3
Q

What are some positive attributes to the water ecosystem?

A

stable (doesn’t change temperature/composition easily), very buoyant (organisms can grow big), sexual reproduction occurs easily

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4
Q

What are some adaptations fish have developed to live well in water?

A

salt water fish have adaptations to remove excess salt and retain water, fresh water fish have adaptations to remove excess water and retain salt.

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5
Q

Why does sexual reproduction occur more easily in water?

A

the sperm won’t dry out on its way to the ova

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6
Q

What are some disadvantages to living in water?

A

O2 doesn’t dissolve well, disturbance limits light penetration, organisms tend to compete for light and oxygen

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7
Q

What are the advantages to living on land?

A
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8
Q

Explainthe transfer and transformation of solar energy into biomass as it flows through biotic components of an ecosystem?

A

Solar energy is transformed into chemical energy via photosynthesis.

This chemical energy flows through the ecosystem as organisms consume plants and each other.

Energy stored in biomass is transferred from one organism to another, fueling growth, reproduction, and maintenance of living organisms.

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9
Q

what is the process of photosynthesis?

A

Photosynthesis is the primary method through which solar energy is captured and converted into chemical energy by plants, algae, and certain bacteria. This process occurs in the chloroplasts of plant cells, where chlorophyll pigments absorb sunlight.

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10
Q

What is the chemical reaction of photosynthesis?

A

The basic equation for photosynthesis is:
6CO2 + 6H2O + light energy → C6H12O6 + 6O2

Here, carbon dioxide (CO₂) and water (H₂O) are converted into glucose (C₆H₁₂O₆) and oxygen (O₂) using light energy.

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11
Q

What is the process of Light Energy Absorption?

A

Chlorophyll and other pigments absorb photons of light, which excite electrons to higher energy states.

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12
Q

What is the process of the Electron Transport Chain?

A

These excited electrons move through an electron transport chain, creating a proton gradient that powers ATP synthesis.

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13
Q

What is the process of the Formation of Glucose?

A

ATP and NADPH produced in the light-dependent reactions are used in the Calvin cycle to convert CO₂ into glucose, a form of chemical energy stored in the plant.

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14
Q

What is the process of biomass?

A

Glucose Utilization: The glucose produced during photosynthesis is used as a building block for more complex organic molecules such as carbohydrates, proteins, and lipids. These molecules make up the plant’s biomass.

Growth and Development: Plants use these organic molecules to grow, develop, and produce new cells and tissues, increasing their overall biomass.

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15
Q

What is Carbon Fixation?

A

During photosynthesis, plants fix atmospheric CO₂ into organic molecules, effectively capturing carbon and incorporating it into their biomass.

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16
Q

What are the primary producers role in the transfer and transformation of solar energy into biomass ?

A

Primary producers capture solar energy through photosynthesis, converting it into chemical energy stored in organic molecules like glucose.

This forms the base of the food web, supplying energy to herbivores and higher trophic levels.

Primary producers also play a crucial role in the carbon cycle by fixing atmospheric CO₂ into biomass, produce oxygen as a byproduct, contribute to soil formation and stability.

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17
Q

What are the secondary consumers role in the transfer and transformation of solar energy into biomass ?

A

Secondary consumers

consume primary consumers (herbivores), transferring the chemical energy from plants up the food chain.

Biomass Conversion: They convert the biomass of primary consumers into their own biomass.

Nutrient Cycling: Their waste and decomposition ( pooping) return nutrients to the soil, supporting primary producers ( fertilisation).

Population Control: They regulate herbivore populations, preventing overgrazing and supporting plant growth.

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18
Q

What are the primary consumers role in the transfer and transformation of solar energy into biomass ?

A

Energy Transfer: They consume plants, converting the chemical energy into their own biomass, supporting higher trophic levels.

Nutrient Cycling: Their waste and decomposition return nutrients to the soil, aiding plant growth.
Supporting

Food Webs: They provide energy for secondary consumers, maintaining the ecosystem’s food web dynamics.

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19
Q

What are the tertiary consumers role in the transfer and transformation of solar energy into biomass ?

A

Energy Transfer: They consume secondary consumers, transferring the energy stored in their biomass up the food chain.

Biomass Conversion: They convert the biomass of secondary consumers into their own biomass, contributing to their growth and maintenance.

Regulation of Trophic Levels: By preying on lower trophic levels, they help regulate population sizes ( “kill them off one by one”) and maintain ecosystem balance 🙏.

Supporting Energy Flow: Their feeding behavior ensures the continued flow of energy through the food web, sustaining the ecosystem’s structure and function

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20
Q

What are biotic factors?

A

living factors - competition, predation, symbiosis, disease

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21
Q

What are abiotic factors?

A

nonliving factors - temperature, sunlight, O2

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22
Q

What are the 2 types of species interactions?

A

Intraspecific and interspecific

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23
Q

What are intraspecific interactions?

A

interactions between the same species (mate competition)

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24
Q

What are interspecific interactions? How many types?

A

interactions between different species, 5 types

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25
Q

What are the 5 types of interspecific interactions and what are they?

A
  1. mutualism (both species benefit - needed for survival)
  2. co-operation (both species benefit - not essential for survival)
  3. commensalism (one benefits and other unaffected)
  4. amensalism (one species causes harm to the other, species causing harm is unaffected)
  5. parasitism (parasites benefit but host harmed)
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26
Q

What is genetic variation?

A

differences that occur in individuals within a species (according to alleles they have for certain genes)

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27
Q

What is symbiosis?

A

a type of interspecific interaction where two organisms live in close association over a long period of time

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28
Q

What is an example of mutualism, co-operation and commensalism?

A

mutualism - yucca plant and moth (yucca moth pollinates the plant, in return the yucca flower is a safe space to lay eggs)

co-operation - clownfish and anemone

commensalism - bird making a nest in a tree

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29
Q

What is an example of amensalism and parasitism?

A

amensalism - cows trampling on grass (grass crushed, cattle unaffected)
parasitism - malaria in humans

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30
Q

What is ecosystem diversity?

A

the different habitats, communities and ecological processes within a geographical location. contains both abiotic and biotic components

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31
Q

What are the 4 main categories that make terrestrial environments more variable than aquatic ecosystems? (mnemonic in case you can’t remember this;) - crazy goats push ballerinas 🐐)

A
  1. chemical (nature of soil)
  2. geographical (altitude, topography)
  3. physical (buoyancy or lack of)
  4. biological
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32
Q

What are some measures of biodiversity? (name 4:))

A

percentage cover, percentage frequency, species evenness and richness

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33
Q

Infectious pathogens have the ability to reduce population numbers significantly when __________ _______ increases. why?

A

population density.
this is because individuals living in close proximity and sharing resources have higher transmission rates of infectious disease. this leads to a high rate of infection, therefore, high mortality can reduce the population over time

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34
Q

What is mortality?

A

ratio of deaths to the total population of a species

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35
Q

What does the terrestrial ecosystem ultimately depend on?

A

the producers (vegetation)

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36
Q

What is vertical stratification?

A

A multitude of vertical layers which contain many niches due to varying environmental conditions

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37
Q

What is a biosphere?

A

portion of earth that supports life

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38
Q

What are the 5 levels of ecology? (mnemonic for everyone: beautiful engineers chased purple orangutans)

A

biosphere, ecosystem, community, population, organism

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39
Q

What is a population?

A

the same species living in the same habitat at the same time

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40
Q

What is a community?

A

different species living in the same habitat at the same time

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41
Q

What does ‘distribution’ refer to?

A

where a particular species is found

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42
Q

What are the 3 types of distribution?

A

random (no pattern)
uniform/evenly spaced
clumped (clustered in particular parts of an area)

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43
Q

What is abundance vs relative abundance?

A

abundance is the population of a species in a selected area. useful for comparing populations of one species across multiple sites.

relative abundance compares the abundance of a species to the abundance of other species living in the same area. useful for determining the most dominant/rare species in an area.

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44
Q

increases in salinity reduce the ability of freshwater plants and fish to obtain water through _______

A

osmosis

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45
Q

The Holdridge Life Zone System is mostly _______ based

A

climate

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46
Q

what is the specht’s classification system?

A

a system of classifying ecosystems by using the foliage cover of the plants and the MEDIAN height of the plants

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47
Q

What is species richness?

A

measure of number of species in an area, measured by number of species and evenness in relation to one another

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48
Q

Environments with a high species richness not only have many __________ _________ but also many _________ _______

A

individual organisms, different species

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49
Q

Environments with a low species richness may have many ___________ but only a few _________ _______

A

individuals, different species

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50
Q

How to calculate species richness using the Menhinick Index? What does each letter stand for?

A

S = s/√N - S is species richness, s is total number of different species, N is total number of individual organisms

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51
Q

When calculating species richness, the response will always be between 0 and 1. what response is considered ‘rich’?

A

a response close to 1

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52
Q

What is species evenness (relative species abundance)?

A

how common a species is relative to all other individuals in a defined location

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53
Q

How to calculate species evenness/relative species abundance? What is the alternative method?

A

RSA = no. of individuals in a species / total no. of organisms × 100. or, you can calculate the range (higher range = more even)

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54
Q

What is species diversity?

A

the number and abundance of species in a community

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55
Q

What is Simpson’s Index?

A

measures the probability 2 randomly selected individuals wil be of the SAME species.

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56
Q

How do you calculate D (Simpson’s Index)? What does each letter stand for?

A

D = ∑n(n-1) / N (N-1) n stands for all individuals in a species, N stands for total organisms for all species

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57
Q

How to calculate Simpson’s Diversity Index?

A

1 - D

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58
Q

What are the 3 ecosystems related to the ecosystem management chapter?

A

coral reefs, old growth forests, productive soils

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59
Q

What is random sampling?

A

Sampling an area in such a way that every part of the area has an equal chance of being picked

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60
Q

What is percentage cover?

A

an estimate of the amount of a selected area covered by living organisms

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61
Q

What is percentage frequency?

A

number of times a species occurs within a survey of quadrat samples

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62
Q

How to calculate percentage frequency?

A

% freq. = number of occurrences/number of samples × 100

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63
Q

What are some examples for the measurement of biotic factors?

A

plot method (quadrat used to measure a specific point) transects (belt (rectangular shaped), line (only things along the line), strip census (looking both sides of the line))

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64
Q

What is the capture-recapture method?

A

measurement for things that move around a lot, good for measuring density of organisms. used with Lincoln index

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65
Q

What is the Lincoln Index? What does each letter stand for?

A

part of the capture-recapture method - N = M x n / m
N is estimated size of population
M is no. originally marked
n is total gotten in recapture
m is number in recapture who were marked

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66
Q

What is divergent and convergent evolution?

A

divergent - species with common ancestor change to become different over time
convergent - unrelated species developing similar characteristics

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67
Q

What are homologous structures?

A

similar structures but with different functions (whale flippers /human arms)

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68
Q

What are analagous structures?

A

Different structure but same function (flippers of penguins and dolphins)

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69
Q

What are vestigial structures?

A

remnants of structures (evolutionary ‘leftovers’) that served important functions in the organism’s ancestors (appendix, wings of flightless birds). they are homologous structures to other functional ones in closely related organisms.

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70
Q

What are the 8 stages of hierarchical arrangement in the Linnaean system? (mnemonic time!! Doctor Karl Peters Comes Over For Good Spaghetti)

A

Domain, Kingdom, Phylum/division, Class, Order, Family, Genus, Species

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71
Q

What does the Linneaen taxonomy classify organisms by?

A

physical differences, cell structures, reproductive structures in plants

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72
Q

What does cladistics classify organisms by?

A

classifies organisms by grouping them according to evolutionary relatedness through common ancestors. separated by shared/derived characteristics

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73
Q

In cladograms, what are shared and derived characteristics?

A

shared - characteristics which all members of the group have

derived - characteristic which separates on group (clade) from another

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74
Q

What is cladogenesis/bifurcation?

A

splitting of an evolutionary lineage into 2 lineages through divergent evolution

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75
Q

What are the 3 assumptions of cladistics?

A
  1. any group of organisms are related by descent from a common ancestor
  2. cladogenesis (bifurcating pattern - new organisms may arise when populations divide into exactly 2 groups)
  3. change in characteristics occurs in lineages over time
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76
Q

⭐multi-choice question time!⭐
cladistics differs from Linnaen classification because it…

A) focuses on homologous structures.

B) is more technologically complicated.

C) does not consider derived characteristics.

D) focuses on phylogenetic analysis

A

the answer is D:)
phylogenetic analysis is a method used to infer the evolutionary relationships between different species or groups of organisms based on their genetic characteristics. phylogenetic trees can be made by analysing data from DNA sequencing, or by comparing DNA nitrogen bases of two species, including other methods. sorry for the long answer:))

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77
Q

What is a clade?

A

group of organisms on a cladogram believed to comprise a common ancestor and all its evolutionary descendants

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78
Q

What are molecular clocks?

A

models that use mutation rates to measure evolutionary time

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79
Q

Why is mitochondrial DNA used to trace genetic lines?

A

The mitochondrial DNA is inherited from the mother only, and has a higher rate of mutation than nuclear DNA making it easier to compare differences between closely related individuals.

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80
Q

Why are there multiple definitions for species?

A

because some species definitions cannot be applied to organisms that don’t reproduce sexually. For example, many organisms reproduce asexually (producing clones), undergo parthenogenesis or transition between sexual and asexual.

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81
Q

What are K-strategists?

A

species whose populations fluctuate at or around carrying capacity (K) of the environment in which they live, occupy a stable environment, have a long gestation period and offer their offspring lots of care, competitive for resources

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82
Q

What are r-strategists?

A

produce a large number of offspring without parental investment, live in unstable, unpredictable environments, they have an advantage to reproducing quickly, produce many offspring when conditions are favourable, not competitive for resources

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83
Q

What is an example of an interspecific hybrid that doesn’t produce fertile offspring and why?

A

Lions and tigers producing a liger. Serological tests involve studying the antigens and antibodies in the blood of different species. Lions and tigers have distinct proteins and other molecules in their blood that are detected through serological tests. Hybridization can result in an altered combination of these molecules, potentially leading to issues in reproductivity or fertility.

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84
Q

What is a microhabitat?

A

a small, specialised habitat within a larger habitat

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85
Q

What is a biome?

A

A large geographical area that is defined by its predominant vegetation and climate

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86
Q

What is an ecozone?

A

a large area where organisms have been evolving in isolation for a long period of time. separated from each other by geographical barriers and can contain multiple biomes for this reason

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87
Q

What is an ecoregion?

A

subdivision of an ecozone. geographically distinct community based on geology, soils, climate and predominant vegetation

88
Q

Why is important to manage the coral reef?

A

The coral provides a home for many organisms and protects the coast from storms, and there have been increased reports of coral bleaching (coral dies and decrease in biodiversity)

89
Q

Why is important to classify ecosystems before managing them?

A

provides a general understanding of soil type, climate, vegetation and topography, which defines the fauna of the area. therefore a better understanding of the area is provided giving better management strategies for the ecosystem

90
Q

Why should productive soils be managed, and how can they be managed?

A

the health of a soil is directly related to its ability to support the growth of plants. can be managed by rotating monoculture crops with legumes to fix nitrogen-fixing bacteria into the soil, mulching the soil to reduce erosion and water loss.

91
Q

Why should old-growth forests be managed?

A

they store a large amount of carbon and if released will be detrimental to pollution levels, many species are dependent on the hollows for shelter and the microclimates, high biodiversity levels will decrease if not protected

92
Q

What is zonation?

A

breaking of a biome into habitat zones (horizontal separation)

93
Q

What is stratification?

A

division of physical environment into smaller components for sampling (vertical separation)

94
Q

What is a niche?

A

its ecological role (or ‘job’), which is defined by the set of conditions, resources, and interactions it needs

95
Q

What is the competitive exclusion principle (Gause’s Law) ?

A

no two species can occupy the same niche in the same habitat at the same time

96
Q

What is resource partitioning? Give an example.

A

two species that adapt because it can’t have it’s ideal/fundamental niche. this can be done by looking for food at different times/places.

the hummingbird is active during the day, feeds on insects and lives solitarily. the sparrow is active during the day, feeds on seeds, generally solitary but can be found in groups. although the sparrow and the hummingbird live in the same tree, the feeding habits and interactions mean they occupy different niches.

97
Q

Can species whose niches overlap partly be able to coexist? If the niches overlap more, what will happen?

A

yes, however, the more the niches overlap (the more resources in common) the stronger the competition will be

98
Q

What sort of ecological communities are more resilient and resistant to change?

A

diverse ones, because of high species richness and evenness

99
Q

What is a foundation species?

A

species that play a unique, essential role in creating and defining a community. usually primary producers

100
Q

What is a foundation species?

A

species that play a unique, essential role in creating and defining a community. usually primary producers

101
Q

What is a keystone species?

A

a species that has a disproportionately large effect on its environment relative to its biomass/abundance. differ from foundation species by being more likely to be in a higher trophic unit (top predator). its presence helps determine the other organisms present.

102
Q

What is photosynthesis?

A

the process by which plants use sunlight, water, and carbon dioxide to create oxygen and glucose for cellular respiration

103
Q

What is biomass?

A

the total mass of living matter in an ecosystem

104
Q

What is a trophic level?

A

a level in the food chain of the ecosystem

105
Q

What are autotrophs?

A

producers - make their own energy

106
Q

What is photosynthetic efficiency?

A

how well a producer converts light energy into carbohydrates

107
Q

What does photosynthetic efficiency depend on?

A

availability of nutrients in soil, sunlight levels, temperature and the nature of the organism itself

108
Q

What is GPP (Gross Primary Productivity)? what unit is it measured in?

A

the rate of light energy conversion to biomass with unit kJ/m²/year

109
Q

What are specialist feeders? Give an example

A

a heterotroph that can thrive on a limited diet, like koalas who only eat eucalyptus leaves

110
Q

What are generalist feeders?

A

a heterotroph that can eat a varied diet

111
Q

What is NPP (Net Primary Productivity)? what unit is it measured in?

A

amount of organic matter available to herbivores (subtracting the energy it takes to digest the plants). unit: kJ/m²/year

112
Q

write the NPP formula

A

NPP = GPP - R (where R is energy used up by plant to do cellular work (respiration))

113
Q

What are heterotrophs?

A

Organisms that obtain food by consuming other living things

114
Q

What is detritus? What are detritivores?

A

detritus is a mixture of dead plants, skin, undigested food and dead organisms, detritivores are organisms who eat the detritus

115
Q

What is the rule in ecology regarding energy passed to trophic levels?

A

about 10% of the energy at one trophic level is passed to the next level (80-90% is lost as heat or waste to the environment)

116
Q

Where is the most energy stored in a food chain?

A

at the producer level

117
Q

What is the difference between a food chain and a food web?

A

food chain is a linear series where each organism is completely dependent on a single source, a food web is a graphical representation of the many food chains that are linked in an ecosystem

118
Q

Can an organism be part of multiple trophic levels at once?

A

yes

119
Q

What is productivity?

A

the rate at which energy is added to bodies of organisms in the form of biomass

120
Q

What is % efficiency?

A

% efficiency - compares how well a trophic level creates biomass compared to what was available

121
Q

Why do ecologists calculate transfer energy efficiency?

A

to identify energy ‘bottlenecks’ and to identify species that contribute to ecosystem sustainability

122
Q

what is the formula for % efficiency? (NOTE: remember to put % at the end of your answer, otherwise you lose marks 😬)

A

% efficiency = (net productivity of the organism / net productivity of the previous trophic level) × 100.

123
Q

Why are insects more efficient (40% or more) than birds or mammals (1-3%)?

A

lower respiration rate, being smaller and no thermoregulatory losses being cold-blooded

124
Q

the more ___________ the transfer of energy, the more ____________ can be sustained in a particular ecosystem

A

efficient, trophic levels

125
Q

What are ecological pyramids?

A

diagrams that show the relationships between trophic levels in an ecosystem

126
Q

What are the three types of ecological pyramids?

A

pyramid of numbers - numbers of organisms at each trophic level of a food chain

pyramid of biomass - amount of living matter transferred through a food chain

pyramid of energy - amount of energy transferred through a food chain

127
Q

What are 2 reasons why a biomass pyramid shows a larger amount of biomass in the primary consumer level?

A

producer is REALLY efficient (passes lots of energy to primary consumer level)

OR…

in marine ecosystems, even though phytoplankton (producer) has a short lifespan, they can reproduce very quickly to fulfil increased demand of primary consumers

128
Q

What do energy flow diagrams do?

A

illustrate movement of energy through ecosystems

129
Q

total heat energy lost (in energy flow diagrams) must equal…..

A

the amount of chemical energy brought into the system by producers

130
Q

Does energy need to be recycled, and if not, why? What about matter?

A

no, because the sun is constantly applying energy unto the earth. matter needs to be recycled as it’s not constantly added

131
Q

What are the 3 nutrient cycles?

A

water cycle, carbon cycle, nitrogen cycle

132
Q

What 2 components make up any nutrient cycle?

A

biological - (cycling through organisms)
geochemical - (cycling through rock, water, atmosphere etc)

133
Q

Explain the carbon cycle. (clue for you: plants → food webs → decomposing → fuel → atmospheric)

A

Plants take in atmospheric carbon dioxide, go through photosynthesis and produce chemical carbon via cellular respiration. The fixed CO2 in the plant (biomass) is then passed along food webs to animals and other consumers. after they die, most carbon breaks down (carbon available in soil for example), the remaining carbon becomes fossil fuels. these fossil fuels are burnt (atmospheric CO2) or forms sedimentary rock (unavailable for nutrients).

134
Q

Does the carbon cycle include decomposers? Does it require decomposers?

A

yes, but the carbon cycle is unique as it is not dependent on them

135
Q

What are the two cycles that form the nitrogen cycle?

A

the elemental cycle - atmospheric, relies on nitrogen fixing bacteria

the ionic cycle - fixed nitrate and ammonia, passes nitrogen between organisms

136
Q

Explain the nitrogen cycle. (clue for you: atmospheric → plants → animal → waste → atmospheric)

A

Nitrogen fixing bacteria converts N2 (atmospheric N) into ammonia (NH3) which is taken up by plants. this is nitrogen fixation. plants are eaten (herbivores) organisms who eat plants are eaten (carnivores/omnivores). can be incorporated in the organisms body or excreted (as urea for example). nitrogenous wastes are converted by bacteria to ammonia, then by bacteria to nitrates. denitrifying prokaryotes convert this to N2 gas.

137
Q

Explain the water cycle (no clues:) )

A

liquid water turns into water vapour via evaporation and transpiration (water lost as vapour from plants), water vapour condenses into a cloud and precipitates back (as liquid or solid). water goes to ocean or land, where it will be stored for the cycle to begin again.

138
Q

write the formula for photosynthesis.

A

6CO2 + 6H2O ⇌ C6H12O6 + 6O2

139
Q

What is an ecological niche?

A

an organisms ‘profession’ (what they eat, active at night/day, all the environmental abiotic and biotic factors and interspecies interactions that influence the organism

140
Q

How are niches and habitats related?

A

the niche of the predator (hunting) will take place in the prey’s habitat. feeding relationships impact niche and habitat in this way.

141
Q

What is a fundamental/ideal niche?

A

the niche occupied by a species if there was no competition/predators/parasites.

142
Q

What is the realised niche? What does this sometimes mean for the organism?

A

niche occupied in response to interspecific competition and relationships. sometimes the organism may not be able to fully express its ‘profession’ because of this

143
Q

Why is a narrow realised niche good for biodiversity?

A

they allow space, time and resources for a larger number of species

144
Q

Identify two roles that keystone species play in maintaining the structure of a community

A

maintains biodiversity and control populations of some harmful organisms to allow other populations of species to thrive

145
Q

What is functional redundancy? (think niche!)

A

where a fundamental niche of one species overlaps with the fundamental niche of another species in the ecosystem

146
Q

Do keystone species have a high or low functional redundancy? Why?

A

Low, because if the species disappeared from the ecosystem, no other species would be able to fill its niche. the ecosystem would be forced to radically change, allowing new (possibly invasive) species to populate the ecosystem.

147
Q

What is an umbrella species?

A

A species which, when protected, indirectly protects many other species occupying habitats within its microhabitat

148
Q

What is a flagship species?

A

A species that acts as an ambassador for the protection of an ecosystem

149
Q

Why are populations of species regularly fluctuating?

A

populations depend on the amount of resources available to each individual

150
Q

What is carrying capacity?

A

the maximum number of individuals of a population that an ecosystem can support

151
Q

What is a limiting factor? (carrying capacity)

A

any abiotic or biotic factor that impacts the abundance of individuals/populations in an environment

152
Q

Are limiting factors the same for every population? why? (clue: think niche)

A

no, because each species/organism occupies a different niche so they will have different limiting factors and therefore, different adaptations to conduct their niche

153
Q

Why is calculating and tracking population changes helpful?

A

because it helps to understand the key influencing factors on an ecosystem. solutions can therefore be implemented to maintain diversity

154
Q

What are the four main indicators that scientists use to track population changes?

A
  1. Immigration (individuals into population)
  2. Emigration (individuals out of population)
  3. Birth rate
  4. Death rate
155
Q

⭐ GET UR CALCULATOR OUT!! ⭐

Calculate the growth rate of a population of 1000 individuals where, every year, 100 individuals are born, 65 individuals immigrate into the population, 37 individuals die and 25 individuals emigrate to another population.

A

PGR (population growth rate) = (birth + immigration) - (death + emigration) = (100 + 65) - (37 + 25) = 103
increased by 103 individuals per 1000. in percentage form, +10.3% increase

156
Q

What is a J-shaped curve?

A

the exponential growth of a population’s density (increases rapidly then stops suddenly)

157
Q

What is an s-shaped curve?

A

change in population density when it increases slowly, then rapidly, then decreases and levels off as the carrying capacity is reached

158
Q

How much of the sun’s energy do plants take in when doing photosynthesis?

A

1.3 to 1.6%

159
Q

Explain how decomposers get energy from producers/consumers

A

When a producer or consumer dies, the carbon and other molecules in its body are broken down by decomposers like fungi and bacteria, which releases energy that the decomposers can use. also happens to parts of the organism that drop off (dead skin cells, leaves) during its life

160
Q

What is ‘succession’?

A

The progressive change of communities over time

161
Q

What are some examples of small-scale disturbances to an ecosystem?

A

a tree falling, or an animal digging a burrow

162
Q

What are some examples of large-scale disturbances to an ecosystem?

A

catastrophic events like volcanic eruptions, cyclones, landslides etc

163
Q

What is nudation?

A

the clearing of an ecosystem from a large-scale disturbance, leaving bare rock

164
Q

Briefly explain how an ecosystem goes from bare soil to a climax community

A

many environments start with bare soil before being colonised by grasses. over time, they are replaced by a succession of larger plants/trees until a stable climax community is formed

165
Q

What is a sere?

A

a stage in succession with recognisable characteristics

166
Q

What are pioneer species?

A

the first species to colonize barren areas

167
Q

List the 4 characteristics that make pioneer species effective colonisers
(fyi:) this is v. important bc its a syllabus requirement:) )

A

tolerant to extreme conditions, rapid seed/spore germination, have ability to fix nitrogen from the air, can photosynthesise

168
Q

What is secondary succession?

A

The succession of an area where the dominant species of a plant community is removed (by natural disasters)

169
Q

What can polar ice cores determine?

A

the age of each layer of ice, the depth of each layer (therefore duration of extreme cold period), level of CO2 in each layer (high temp = more carbon)

170
Q

What are the two oxygen isotopes in the sea?

A

O18 and O16

171
Q

What do higher levels of O18 in the collected ice core sediment mean?

A

a cold period, as O16 was able to evaporate

172
Q

What do higher levels of O16 in the collected ice core sediment mean?

A

a warmer period

173
Q

What can fossilised pollen give insight to in regard to ecosystems in the past?

A

the number and type of species of pollen present gives insight into human impacts on ecosystems. these fossils also show the degradation or succession of an ecosystem

174
Q

The age of a fossil can be determined by…

A

how close to the surface it was when found

175
Q

The adaptations observed in plant and animal fossils reveal abiotic factors, such as…

A

atmospheric oxygen concentration, ocean salinity, sea levels and soil pH

176
Q

How can ecosystem changes and environmental pressures be determined using fossils?

A

The kind of conditions organisms adapted to and how diverse/abundant they are in certain areas given insight to ecosystem changes and environmental pressures.

177
Q

What is the impact of land clearing for human settlement?

A

loss of trees impacts birds, insects and mammals, reduced vegetation, soil compaction increases runoff and erosion

178
Q

What is habitat fragmentation?

A

the process by which human activity results in the division of large, continuous habitats into smaller, more isolated remnants.

179
Q

What is the impact of land pollution?

A

waste is placed in a landfill where it is burned (air pollution) or forms acid as it breaks down. decomposition of waste also produces methane

180
Q

What are the effects of fertilisers?

A

too much can increase concentration of nutrient ions in water, called eutrophication

181
Q

What are the effects of eutrophication?

A

Increase in nutrients cause an algal bloom. when the algae dies, microbes digest it and use oxygen, leading to O2 deficiency, killing organisms

182
Q

What is the impact of dams on the environment?

A

erosion of banks caused by dredging of rivers, decreased biodiversity (waterways are destroyed, no fertile silt deposited)

183
Q

What must be considered before using pesticides?

A

biodegradability: if it can be broken down

biological magnification: each trophic level accumulates more and more of the chemical as it passes along a food chain

half life: time it takes for HALF of the quantity to break down

persistence: length of time that residues of the pesticide remain in the environment

184
Q

give some examples of biotic limiting factors

A

food competition, parasites, disease, mates

185
Q

give some examples of abiotic limiting factors

A

shelter, light, temperature, oxygen levels

186
Q

ecological succession proceeds if…

A

simpson’s diversity index approaches 1

187
Q

molecular phylogenetics determines evolutionary relatedness of organisms using…

A

comparison of DNA fragments from different species.

188
Q

what is molecular phylogenetics?

A

Cladistics using molecular sequence data, looking at differences and similarities in the sequence of specific genes or proteins

189
Q

What are dichotomous keys?

A

dichotomous keys are used to classify a sample species according to its taxonomic rank. they are made up of dichotomous branches according to the presence/absence of a feature until only one possibility of a genus and species is determined using physical characteristics present

190
Q

the upward movement of water from the soil through the roots to the leaves of a plant is called…

A

transpiration

191
Q

What is an ecosystem?

A

An ecosystem includes everything: that’s all of the living and nonliving factors in an area and how they interact.

192
Q

Why do fish die during eutrophication?

A

Fish die during eutrophication because decomposers respire aerobically and use up all of the oxygen in the waterway.

193
Q

What is each level of grouping in a classification system called?

A

Each level of grouping is called a taxonomic group!

194
Q

What happens to the biodiversity of an area following habitat destruction?

A

Habitat destruction causes biodiversity to decrease. This is because it reduces the area of habitat available to organisms that live there, which reduces sources of food and shelter.

195
Q

Approximately what percentage of energy is transferred between trophic levels?

A

Around 10% of the energy from one trophic level is transferred to the next.

196
Q

What is Linnaeus’ classification system largely based on?

A

Old Linnaeus classified organisms mainly according to their physical characteristics or morphology!

197
Q

What information about an organism can be directly gained from a phylogenetic tree?

A

Phylogenetic trees show us the evolutionary relationships between organisms. They’re kind of like a family tree!

198
Q

Compared to the centre of a rainforest, the abiotic conditions at the edge of a rainforest are…

A

Humid

It’s far less humid at the edge of a rainforest compared to in the centre.

This is because the edge of the forest is cooler and far more exposed to the wind, which will quickly remove moisture. Plus, there are fewer trees releasing moisture through transpiration.

199
Q

What is an example of a marine ecosystem?

A. Lake
B. Swamp
C. River

A

Lakes, swamps and rivers are all examples of freshwater aquatic ecosystems, not marine ones! Marine ecosystems are characterised by large amounts of saltwater.

200
Q

Water plays an important role in which cellular process?

A. Digestion
B. Photosynthesis
C. Maintaining cell shape

A

Water is important in digestion and photosynthesis, and for maintaining cell shape… and lots of other processes.

All the more reason to stay hydrated!

201
Q

Biotic factors often focus on the dominant species and the…

A

It’s the distribution of species! This is like the density of the species in the area they inhabit. For example, really densely packed trees would be a biotic factor in forests but not in deserts.

202
Q

What is NOT a terrestrial ecosystem?
Atomi Question
A. Desert
B. Rainforest
C. Swamp
D. Tundra

A

Swamps are not terrestrial ecosystems! They’re dominated by water, so they would be classified as an aquatic ecosystem.

203
Q

True or False??
Human activities are the key selection pressures responsible for extinction of animals today.

A

It’s true! Human activities are creating selection pressures on a large number of species. If these species are unable to adapt to the selection pressures, they go extinct.

204
Q

True of False??
All plants have a higher carrying capacity in higher light intensities.

A

It’s false! Although plants usually love high light intensity because it allows them to maximise photosynthesis, some plants are damaged if they’re exposed to too much light, like ferns for example.

205
Q

What is the first step in ecosystem management?

A

Ecosystem classification is the first step in effectively managing an ecosystem! It sets out the requirements of the ecosystem, so the best management strategies can be used!

206
Q

What term describes the rapid growth of algae on the surface of a waterway?

A

An algal bloom is the rapid growth of algae on the surface of a waterway.

207
Q

True or False??
An abiotic factor in marine ecosystems is fresh water.

A

It’s false! Marine ecosystems have salt water, like seas and reefs. Lakes, streams and rivers are examples of freshwater ecosystems.

208
Q

In what type of symbiotic relationship do both organisms benefit?

A

Both organisms benefit in mutualism, even if those benefits are slightly different things. It’s a win-win! 🎉

209
Q

Which directions are species migrating as a result of climate change?

A

In general, species are migrating towards the North in the Northern Hemisphere and South in the Southern Hemisphere. This is because it’s cooler towards the poles, and so it’s more similar to the temperatures that species adapted to.

210
Q

What does the length of a branch on a phylogenetic tree represent?

A

The length of a branch in a phylogenetic tree represents the time that passed between when a species was formed and when it underwent a divergence event.

211
Q

Which is used to represent all of the interactions in a community?

A

A food web shows all of the interactions in a community, whilst ecological pyramids just show one food chain.

212
Q

Why is ammensalism not an example of a symbiotic relationship?

A

In a symbiotic relationship, at least one organism must benefit. But, in ammensalism, one organism is harmed, and the other isn’t affected at all! Where’s the fun in that?

213
Q

What name do we give a community that will see no further succession?

A

We call a community that will see no further succession a climax community, since it’s the end of the process of succession!

214
Q

Which ecosystem is most likely to have an ‘inverted’ pyramid of biomass?

A

In marine ecosystems, phytoplankton have really short life cycles and low biomass.

So a pyramid of biomass will have a small primary producer component, giving it an inverted shape!

215
Q

What are endemic species?

A

Endemic species are only found in a specific area. For example, the giant otter and the golden lion tamarin are only found in the Amazon rainforest.

216
Q
A

QCE Biology Unit 3&4 Externals (2 decks)

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