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topic 5 Flashcards

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Biology 101 flashcards
1
Q

what is a biosphere?

A

part of the earth and its atmosphere inhabited by living organisms

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2
Q

what is the definition of abiotic factors?

A

abiotic factors- physical + chemical/ non living factors e,g climate

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3
Q

what are biotic factors?

A

biotic factors- determined by organisms e.g competition

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4
Q

what is an ecosystem?

A

contains a community of organisms that interact with each other + their physical environment in a way that makes it self sustaining
within an ecosystem there are many different habitats

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5
Q

what is a habitat

A

a place with a distinct set of conditions where an organism lives

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6
Q

what is a population

A

a group of organisms of the same species that can interbreed that are found in the same area

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7
Q

what happens when two species have the same niche

A

competition

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8
Q

recall the abiotic factors

A

solar energy input
climate
topography
oxygen concentration
edaphic factors
pollution
catastrophes

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9
Q

what factors affect solar energy input and what is it needed for?

A

affected by latitude, season, cloud cover, changes in the earths orbital
light needed for photosynthesis + initiating flowering for seed germination (for some)

behaviour of many animals

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10
Q

what is topogrophy?

A

altitude, slope, aspect, direction in which land faces, drainage

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11
Q

what are edaphic factors and what is their effect?

A

connected with soil pH, mineral ion conc. (which is affected by geology), soil texture
underlying geology of an area can have significant effect on plant distribution

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12
Q

recall the biotic factors

A

competition
grazing, disease, predation + parasitism which are examples in which one organism benefits at the others expense
mutualism

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13
Q

what is interspecific competition

A

competition for resources between species

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14
Q

what is intraspecific competition

A

competition within a species

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15
Q

what is mutualism

A

relationship in which both organisms benefit

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16
Q

how does population density affect biotic factors

A

effects are related to size of population relative to area available
larger population density= greater competition for food, space etc

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17
Q

what do biotic and abiotic factors affect?

A

abundance + distribution of organisms in a habitat

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18
Q

what are anthropogenic factors

A

arise from human activity which can be biotic or abiotic

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19
Q

what happens when conditions become more stable in an ecosystem?

A

diversity of organisms increase
more mineral ions are available

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20
Q

what is succession

A

a series of predictable changes in the composition of species in an ecosystem

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21
Q

what is primary succession and what is its purpose

A

occurs in newly formed habitats where there’s never been a community (aka colonisation)
may occur on bare rock
purpose: allow there to be life where there was no life before

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22
Q

for how long does succession continue?

A

until a stable community is established unless prevented

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23
Q

what is a pioneer species

A

first organisms to colonise bare rock (lichens and algae)

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24
Q

what is the role of pioneer species

A

change in conditions in habitat enough to make them suitable for other species
when pioneer species die + decompose, the organic mater/ nutrients are recycled back into the soil → soil will eventually be able to hold more nutrients

  • allow soil to develop
  • release nutrients
  • change soil pH
  • allow soil to hold more water
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25
Q

what are the adaptations of pioneer species

A
  • seeds widely dispersed by the wind
  • rapid growth
  • short life cycle
  • abundant seed production
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26
Q

what happens when succession continues after the first colonisation

A

seeds + small rooted plants can germinate + survive
biomass inc
conditions improve so larger plant species can colonise and compete and replace existing community
eventually stable climax community is reached and remains unchanged unless disturbed
as succession progresses the number of species and therefore niches inc.
its not unusual for climax community to have less biodiversity than previous stages of succession

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27
Q

what is the dominant species

A

(largest + most abundant plant species)
has an influence on all of the other species
co-dominant= sometimes several species share this role

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28
Q

what is secondary succession

A

occurs on bare soil (where existing community has been cleared)
seeds lie dormant in soil or brought by wind or animals
type of succession that happens when a disturbance (wipe out of organisms there) occurs but soil still remains

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29
Q

what is deflected succession

A

a community that remains stable only because human activity prevents succession from running its course
humans interfere with the landscape
humans introduce the organisms
purpose is to manage biodiversity

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30
Q

why may a small amount of light reaching a plant actually used in photosynthesis?

A
  • energy lost as heat
  • wavelength of light absorbed by photosynthetic pigments varies for each pigment
  • reflection
  • light could go straight through
  • light may reach non photosynthetic parts of the plant
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31
Q

what is the equation for photosynthesis

A

6CO2 + 6H2O -> C6H12O6 + 6O2

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32
Q

where does photosynthesis occur

A

occurs in chloroplast in the palisade mesophyll cell in a leaf

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33
Q

Recall the structures of a chloroplast

A
  • Thylakoid membranes
  • thylakoid space
  • outer membrane
  • inner membrane
  • granum
  • starch grain
  • stroma
  • DNA loops
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34
Q

what are the adaptations of the thylakoid membrane

A
  • photosystems which contain chlorophyll
  • electron carrier molecules in membrane such as ATP synthase
  • contain specialised enzymes
  • large surface area due to stacks
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35
Q

what two cycles occur in the light dependent reaction

A

non cyclic photophosphorylation
cyclic photophosphorylation

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36
Q

what two reactions are involved in photosynthesis

A

light dependent
light independent
Both of these occur at the same time as part of the light dependent reaction

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37
Q

recall the process of non cyclic photophosphorylation and what is it responsible for

A
  1. Light is absorbed by PS2 which causes for electrons to excite to a higher energy level
  2. The excited electrons are passed onto one electrons carrier molecule
  3. Electrons go down electron transport chain to PS2
  4. Light hits PS2 and electrons are excited and are passed onto another electron transport chain
  5. Release of energy when electrons go along the electron transport chain which fuels the production of ATP
    • energy is used to pump H+ ions to the thylakoid space
    • chemiosmosis → name of the process where the movement of H+ ions across a membrane generates ATP (also occurs in respiration)
  6. Electrons are used in the reduction of NADP to NADPH
  7. Photolysis of water to form H+ ions and electrons
  8. The electrons that are used need to be replaced. They are replaced by the electrons from the photolysis of water

responsible for reducing NADP and producing ATP

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38
Q

recall the process of cyclic photophosphorylation

A
  1. Light hits PS1 and electrons excite to a higher energy level to a an electron acceptor molecule
  2. The electrons then go along the electron transport chain to another electron acceptor molecule and then goes along the electron transport chain again and goes back to PS1

Its used as another way to generate ATP

Doesnt involve PS2

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39
Q

what is the role of NADP

A

Prevents hydrogen reacting with oxygen gas released in photolysis

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40
Q

how is ADP formed

A

Third phosphate group loosely bonded to 2nd in ATP + is easily removed
ATPase catalyses breakdown of ATP to ADP- phosphorylation

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41
Q

how is ATP produced and how does this provide energy

A

ATP produced from ADP when P1 is added
which can be used to drive energy requiring reactions

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42
Q

recall the calvin cycle aka light independent reaction

A
  1. CO2 combines with RuBP which is a 5 carbon compound which is catalysed by RUBISCO which forms a 6 carbon compound
  2. 6 carbon compound immediately breaks down into two x3 carbon molecule called GP
  3. GP reduced to form 3 carbon sugar phosphate called GALP and ATP is required for this reaction and NADPH provides hydrogen ions for reduction
  4. 1 carbon out of 6 (from the two molecules produced) saved for production of glucose
  5. the leftover 5 carbons is used to form RuBP so the cycle can continue which also requires ATP
  6. cycle needs to be repeated x6 to produce one molecule of glucose
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43
Q

what are the uses of glucose

A
  • used in respiration
  • make sucrose + transported around + transported around the plant
  • polymerised to form polysaccharides- starch + cellulose
  • production of lipids, amino acids + nucleic acid
    inorganic carbon CO2 incorporated into organic molecules → carbon fixation
    carbon fixed in organic molecules is available for other organisms
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44
Q

what is chemiosmosis

A

name of the process where the movement of H+ ions across a membrane generates ATP (also occurs in respiration)

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45
Q

what is the definition of primary productivity

A

the rate at which energy is incorporated into organic molecules in an ecosystem

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46
Q

what are producers

A

aka (autotrophs) - can make their own organic compounds from inorganic compounds which can be transferred to other organisms in the ecosystem

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47
Q

what are heterotrophs

A

organisms that obtain energy ready-made organic matter by ingesting material from other organisms

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48
Q

what are the different types of consumers

A
  • primary consumers→ herbivores
  • secondary consumers→ carnivores/ feed on primary
  • tertiary(also carnivores)→ eat other consumer
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49
Q

what is the order of energy transfer in an ecosystem and how can their relationships be shown

A

producer → primary→ secondary→ tertiary
there relationships can be a shown on a food chain

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50
Q

how does an energy transfer/food chain diagram work?

A
  • position of a species in a food chain is called its trophic level
  • energy transferred from one trophic level to the next trophic level by consumers
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51
Q

what are detrivores

A

primary consumers that feed on dead organic material

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52
Q

what are decomposers

A
  • species of bacteria/ fungi that feed on the dead remains of organism/ faeces
  • secrete enzymes + digest food externally
  • play a role in recycling organic matter
  • organic compounds are broken down into inorganic substances (absorbed by algae to grow and reproduce)
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53
Q

how efficient is the transfer of energy through the system

A
  • depends on how much energy is captured by producers + transferred to higher trophic levels
  • only about 40% energy reaching leaf is absorbed by chlorophyll + used to make organic molecules (some lost during photosynthesis + transferred to environment)
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54
Q

what are the limiting factors of photosynthesis

A

temp in cool conditions, light, CO2 conc.

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55
Q

what is the definition of GPP

A

rate at which energy is incorporated into organic molecules in plants by an ecosystem

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56
Q

how do you calculate %efficiency of photosynthesis

A

GPP/ amount of energy from light arriving at plant surface x 100

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57
Q

what happens when carbs are broken down and what are they used for

A
  • carbs produced are broken down by respiration which provides energy for the plants processes, incorporated into proteins + organelles and components of new cells
  • becomes new plant biomass
  • examples of biomass:
    proteins fats cell wall new cells
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58
Q

what is the definition of NPP and how is it calculated + units

A

the rate at which energy is transferred into the organic molecules that make up the new plant biomass
NPP= GPP - R (plant respiration)
units-> kj m-2 yr-1

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59
Q

why are the units kj m-2 yr-1

A
  • over a year because it takes into account changes/ fluctuations
  • whole year also gives as overall value
  • biomass includes all organic material
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60
Q

why should you always refer back to photosynthesis in questions involving energy transfers

A
  • cant have NPP without GPP
  • cant have GPP without photosynthesis
    • therefore in questions refer back to factors affecting photosynthesis
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61
Q

why is transfer of energy from producers to primary consumers not very efficient

A
  • not all available food gets eaten due to limitations of animal feeding methods
  • some undigested food remains in faeces such as cellulose as theres no enzyme to break it down so the energy it contains isnt transferred
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62
Q

why is the transfer of energy from primary to secondary consumers more efficient

A

herbivore may be eaten by carnivore + protein diet is easily digested
less biomass is lost in faeces

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63
Q

why is energy transferred to the surroundings and decomposers in respiration

A

there are no more than 4/5 trophic levels, so there comes a point where there is insufficient energy remaining to support the trophic levels

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64
Q

how do you calculate energy efficiency

A

energy efficiency= (net productivity/energy received) x 100
or
NPP of this level/ NPP of previous level x 100

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65
Q

what is biomass

A

all of the living matter in an area

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66
Q

what is the thylakoid membrane

A

a system of flattened fluid-filled sacs

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67
Q

what is the thylakoid space

A

fluid in thylakoid membrane sacs→ contains enzymes for photolysis

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68
Q

what is the outer membrane of the chloroplast

A

freely permeable to CO2 + H2O

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69
Q

what is the inner membrane of the chloroplast

A

contains many transport molecules + regulate passage of substances in/out of cell

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70
Q

what is the granum

A

stack of thylakoids joined to one another

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71
Q

what does the starch grain do in a chloroplast

A

stores product of photosynthesis

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72
Q

what is the stroma

A

fluid surrounding thylakoid membrane which contains all the enzymes needed in light-independent reactions

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73
Q

what does the DNA loop in the chloroplast do

A

contain genes for some of their proteins

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74
Q

when would you use a transect as a sampling method?

A

when there is a gradient of abiotic conditions across the habitat

75
Q

when would you use random sampling?

A

If the population size is small or the size of the individual samples and their number are relatively small

76
Q

what is climate change

A
  • climate change → the term used to describe a significant change in the weather over a region over a period of several decades
    • includes natural variation in climate but is commonly used to refer to the changes caused by humans
77
Q

what is global warming

A
  • global warming → a type of climate change
    global warming is an increase in global mean surface temperature
78
Q

what does global warming cause

A
  • global warming causes other types of climate change
    • e.g changes in rainfall patterns and seasonal cycles
79
Q

what is thought to cause climate change

A

believed that current global warming is due to anthropogenic burning of fossil fuels due to raised CO2 conc of the atmosphere leading to the enhanced greenhouse effect

80
Q

recall what factors can be used as evidence for climate change

A

temp records
dendrochronology
pollen in peat bogs

81
Q

how can temperature records be used as evidence for climate change

A
  • since 1850s, the temp has been measured around the world using thermometers
  • gives a reliable but short-term record of global temp changes
  • look at the general trend of global temperature
82
Q

what are the advantages for using temperature records for climate change

A
  • scientific
  • temp recorded accurately
  • line/curve of best fit
  • may identify patterns with the general trend
83
Q

what is the disadvantage for using temperature records for climate change

A

only goes back 200-300 years → no info before that

84
Q

what is dendochronology

A
  • dendrochronology → a method used to figure out how old a tree is using tree rings
85
Q

what are tree rings and how do they form

A
  • tree rings are the rings formed within their trunks as it grows
  • most trees produce one ring within their trunks every year
  • thickness of the ring depends on the climate when the ring was formed
    • when its warmer→ rings are thicker as conditions for growth are better
86
Q

how can dendrochronology be used as evidence for climate change

A

most trees produce one ring within their trunks every year
- can use this to see what the climate was like each year
- you can take the cores through tree trunks and then date each ring by counting them back from when the care was taken

87
Q

what are the advantages of using dendrochronology as evidence for climate change

A
  • ring positions can be used to determine the specific age of each ring
  • trees can be many hundreds of years old
88
Q

what are the disadvantages of using dendrochronology as evidence for climate change

A
  • time data is accurate but the climate data isn’t accurate as it’s not measured with scientific equipment
  • other factors might affect ring size
89
Q

what is a peat bog

A
  • pollen in peat bogs can be used to show how temp has changed over thousands of years
  • a peat bog is acidic wetland areas
90
Q

how can observing pollen in peat bogs be used as evidence for climate change

A

pollen is often preserved in peat bogs
peat bogs accumulate in layers so the age of the preserved pollen increases with depth
scientists can take cores from peat bogs and extract the pollen grains from the different aged layers
they then identify the plant species the pollen came from

91
Q

what does it mean if pollen from a certain species is found in a core sample from a peat bog

A

only fully grown plant species produce pollen → so samples only show the species that were successful at the time
when scientists find preserved pollen from similar plants it indicates that the climate was similar to when that pollen was produced
since plant species vary with climate, the preserved pollen will vary as climate changes over time
the gradual increase in pollen from a plant species thats more successful in warmer climates would show a rise in temperature
. a decrease in plant pollen from a plant that needs cold conditions would show the same thing

92
Q

what are the advantages of using pollen in peat bogs as evidence for climate change

A
  • can go back to 12,000 years ago
  • also provides info about soil conditions
93
Q

what are the disadvantages of using pollen from peat bogs as evidence for climate change

A
  • no info before 12,000 years ago
  • temp not determined accurately
  • other factors affect species present such as humidity, nutrients etc
  • age not accurately determined
94
Q

what is the greenhouse effect

A
  • the greenhouse effect is the effect of greenhouse gases absorbing energy reflected from earth so that less is lost to space
    • its essential to keep the planet warm
    • however too much greenhouse gas causes the planet to warm up
95
Q

what is a greenhouse gas

A

a greenhouse gas is a gas that absorbs the re-radiated radiation, trapping it in the earths atmosphere so its not lost to space

96
Q

what are the two main greenhouse gases contributing to global warming

A

methane and CO2

97
Q

why is methane conc. inc

A
  • methane conc is increasing due to the increase in the number of cattle which gives off methane as waste gas, decaying waste from the extraction of fossil fuels
  • methane can also be released from natural stores e.g frozen ground
    • as temperatures increase its thought that these stores thaw and release large amounts of methane into the atmosphere
98
Q

why are CO2 levels increasing

A
  • this is due to increased use/burning of fossil fuels such as coal, oil which releases CO2
  • CO2 conc. also increased by the destruction of natural sinks
    • natural sinks keep CO2 out of the atmosphere by storing carbon
    • example of natural sink → trees
      • they store carbon as organic compounds
    an increase in human activities such as farming, deforestation, and burning fossil fuels has increased CO2 and methane levels
99
Q

what is global warming potential

A

global warming potential is a relative measure of how much mass a greenhouse gas traps in the atmosphere. it compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped in a similar mass of carbon dioxide

100
Q

how do you calculate the relative contribution of a gas t the greenhouse effect

A

% abundance of the gas x global warming potential

101
Q

what is a controversial issues

A

a controversial issue is one when alternative points of view can be held

102
Q

why is climate change contreversial

A

scientific methods can only disprove theories
- there is no way to measure precisely how much CO2 is added to the atmosphere by fossil fuel combustion
- numbers reported are estimated
– political and economic considerations may affect how individuals, organisations and countries interpret the evidence for climate change
- if cuts in CO2 emissions to reduce global warming may harm then businesses, countries may not accept the causal link between the 2CO2 levels doesn’t cause global warming

103
Q

what is the widespread concensus on global warming

A

a widespread consensus that temperatures are rising, the climate is changing and that rising conc. of greenhouse gases are at least partly responsible

104
Q

what do some people think the changes in temp are due to if not anthropogenic activity

A

some people think that the changes in temps observed are a part of a natural cycle of climate variations or due to changes in the suns activity

105
Q

what are the ethical issues with global warming

A
  • we all have the right choose whether we use fossil fuels to achieve a good standard of living
  • we have a duty to allow others to improve their standard of living
  • we have a duty to preserve the environment for the next generation
106
Q

how can future climate change be predicted

A

extrapolation is often the basis for predictions
- smooth line of best fit added to graph
- this is when you extend the line

107
Q

how can you evaluate using extrapolated data to make predictions

A
  • predictions based on this model arent very accurate
  • the present trend for increasing CO2 may not continue
108
Q

when extrapolating a graph what can you assume

A
  • we have enough data to establish the trend accurately
  • present trends continue
109
Q

what may cause the predictive accuracy on future climate change to reduce

A
  • many factors are involved in climate change
  • if one or more factors are missed out then the predictive accuracy will be reduced
110
Q

recall the factors affecting climate change

A
  • greenhouse gases such as methane, CFCs and nitrous oxide
  • aerosols
  • the degree of reflection from those parts of the earth’s surface that are free of ice and snow
  • the fraction of the earth covered with ice and snow
  • changes in the suns radiation
111
Q

what are the limitations with future climate change models

A
  • limited data
  • limited knowledge of how the climate system works
  • limitations in computing resources
  • failure to include all factors affecting the climate
  • changing trends in factors included
112
Q

how can models used to predict future climate change be tested

A
  • the models are continually improving, using bigger data sets and incorporating more factors
  • taking past data and putting them into the model and seeing if the predictions match what actually happened can test climate models
113
Q

how can climate change models be evaluated

A

climate change models can be evaluated by comparing their outcomes with each other and with observations, increasing the scientific community’s confidence in their predictions

114
Q

recall the effects of climate change

A
  • animals may migrate to avoid the changing conditions
  • plant distribution can change over time even though they are rooted in one spot
  • changes already being attributed to climate change can be divided into two categories
    • changing distribution of species
    • altered development and life cycles
115
Q

how can climate change cause changes in the distribution of species

A
  • some species may benefit from the new conditions from climate change and become dominant
  • other species may be lost from the community due to competition with existing or invading species
    if the species are mobile or have good seed dispersal they may migrate to more favourable conditions → distribution changes
116
Q

what happens to organisms that are under pressure from climate change

A

organisms under pressure from climate change may find it impossible to reach new areas and their populations simply die out

117
Q

why are trees vulnerable when it comes to climate change

A

trees are vulnerable as they are unable to grow, reproduce and disperse their seeds quickly enough to cope with rapidly changing climate conditions
scientists have found that towards the equator the trees are dying off probably due to drought conditions

118
Q

what may be a problem for animals when species of animal or plant mve areas

A
  • a problem for some communities may be the invasion of exotic animal or plant species from other regions of the world → may push out the current inhabitants
  • pests and diseases may also spread to new areas if they favour warmer temperatures and may reduce crop yield such as witchweed
119
Q

what do pests and diseases do and why are they bad. What may happen if global temps increase

A
  • these pests and diseases absorbs nutrients and moisture from the host plant
  • as a result the host plant is less productive
  • if global temperatures increase it may spread to cereal crops in new areas and cause more damage
120
Q

why are invertebrate pests likely to change their distribution

A
  • warmer temperatures may allow them to produce more new generations in a single year, increasing their effect on crops
  • however, its hard to predict what the impact will really be due to interactions with other animals and any change in the life cycle of the host plant
121
Q

what other factors may effect species distribution (other than temperature)

A

its not only changing temperature that affects species distribution→ changing rainfall patterns, soil moisture, winds and rising sea levels are all likely to influence species and communities

122
Q

what is the effect of changing intensities of rainfall on plant distribution

A

the changing intensities of rainfall will affect plant distribution → conditions become drier and species sensitive to drought may be excluded if theyre unable to adapt to the change

123
Q

what is the effect of climate change on photosynthesis

A

in cooler climates → photosynthesis is temperature limited, a rise in temperature will result in faster photosynthesis as the enzyme catalyst reaction of photosynthesis occurs more quickly

124
Q

why may warmer temperatures increase rate of photosynthesis

A
  • this is because more heat= greater kinetic energy → molecules move faster
    • enzymes more likely to collide with the substrate molecules
125
Q

what happens if temperatures increase too much to the rate of photosynthesis

A
  • above the optimum temp, plant enzymes work more slowly
    • as the active site changes shape and can no longer fit its substrate → enzyme denatured
126
Q

what is metabolism

A
  • the metabolism of an organism is all the chemical reactions that take place in its cells in order to keep it alive
  • metabolic reactions are controlled by enzymes
127
Q

what is the effect of an inc in temp on the metabolism of some animals

A
  • inc in temp means that the metabolic reactions in some organisms will speed up → so rate of growth will increase
  • this means they’ll develop and progress through their life cycle faster
128
Q

what is the effect of a dec in temp on the metabolism of some animals

A

if temp becomes too high for some organisms, their metabolic reactions will slow down so their rate of growth will decrease → so they’ll progress through their life cycle slower

129
Q

what is the effect of global warming on seasons

A
  • global warming is thought to be changing the timing of the seasons → will affect the development and life cycles of some organisms and the distribution of some species
  • organisms are adapted to the timing of the seasons and the changes that happen
130
Q

why does an increase in CO2 concentration affect the growth of plants

A

CO2 is a limiting factor of photosynthesis
carbon dioxide is fixed to produce GP
therefore increased CO2 concentration results in more glucose being poduced
this leads to a greater rate of growth

131
Q

how do you calculate the temperature coefficient Q10

A

Q10= rate of reaction at (x+10) °C / rate of reaction at °C
or
higher temp rate value / lower temp rate value
- use the rate at the temperature given in the question that they want you to find Q10 for

132
Q

recall what information can be used as evidence for evolution

A

genomics

133
Q

recall what information can be used as evidence for evolution

A

genomics
proteomics

134
Q

what is genomics used for

A

determines the base sequence of an organisms genome and the functions of its genes

135
Q

what does genomics allow scientists to do

A

allows scientists to make comparisons between organisms’ DNA

136
Q

what does the theory of evolution suggest

A

theory of evolution suggests that all organisms have evolved from shared common ancestors

137
Q

how can genomics be used as evidence for evolution

A
  • closely related species diverged (evolved to become different species) more recently
    • so should have more similar DNA
    • this is because less time has passed for changes in the DNA sequence to occur
138
Q

what is evolution caused by

A

evolution is caused by gradual changes in the base sequence of organisms’ DNA

139
Q

what is proteomics

A
  • is the study of proteins
    • size, shape, amino acid sequence of proteins
140
Q

how can proteomics be used as evidence for evolution

A
  • related organisms have similar DNA sequences and therefore similar amino acid sequences in their proteins
  • organisms hat have diverged away from each other more recently should have more similar proteins as less time has passed for changes to occur
141
Q

what is the role of a scientist

A
  • job of scientist → collect data and use it to test theories
  • the data either support the theory or doesn’t
142
Q

what is the scientific community composed of

A

scientific community is all of the scientists around the world → researchers, technicians and professors

143
Q

why do scientists accept the theory of evolution

A

they’ve shared and discussed the evidence for evolution to make sure its valid and reliable

144
Q

what are scientific journals

A

are academic magazine where scientists can publish articles describing their work

145
Q

what can scientific journals be used for

A
  • used to share new ideas, theories, experiments, evidence and conclusions
  • they allow other scientists to repeat experiments and see if they get the same results using the same methods
146
Q

how can scientific journals increase the scientific communities confidence

A

if the results are replicated then the scientific community can be confident that the evidence collected is reliable

147
Q

what ways can scientists discuss their work

A

scientific journals
peer review
conferences

148
Q

what has to happen before a scientist can get their work published

A

before a scientist can get their work published in journal it has to undergo the peer review process

149
Q

what is peer review

A
  • this is when other scientists who work in that area read and review the work
  • the peer reviewer has to check that the work is valid and that it supports the conclusions
150
Q

what is the aim of peer review

A

is used by the scientific community to try and make sure that any scientific evidence that’s published is valid + that the experiments are carries out to the highest possible standards

151
Q

what are scientific conferences

A
  • scientific conferences are meetings that scientists attend so they can discuss each others work
  • those with important or interesting results may be invited to present their work by poster presentation or lectures
152
Q

why are conferences used as a way for scientists to discuss their results

A
  • other scientists can then ask questions and discuss their work with them face to face
  • conferences are valuable as they’re an easy way for the latest theories and evidence to be shared and discussed
153
Q

recall the process of the carbon cycle

A
  1. carbon in the form of CO2 is absorbed by plants when they carry out photosynthesis → becomes carbon compounds in plant tissues
  2. carbon is passed onto animals when they eat the plants and then to decomposers when they eat dead organic matter
  3. carbon is returned to the atmosphere as all living organisms carry out respiration which produces CO2
  4. if dead organic matter ends up in places where there arent any decomposers such as deep oceans or bogs then the carbon compounds can be turned into fossil fuels over millions of years by heat and pressure
  5. the carbon in fossil fuels is released as CO2 when they’re burnt in combustion
154
Q

to reduce CO2 concentrations in the atmosphere what would need to be done

A

→ amount of CO2 going into the atmosphere due to respiration and combustion needs to be decreased

or

→ amount of CO2 being taken out of the atmosphere by photosynthesis needs to be increased

155
Q

why is it difficult to find ways to reduce atmospheric concentrations of CO2

A
  • as there is a conflict between human needs and conservation
  • this is because humans use energy from fossil fuels for transport, cooking, electricity etc
  • they also use land to build on and for growing crops or grazing animals → leads to deforestation and therefore reduces photosynthesis
156
Q

what two methods can be used to manage the conflict between human needs and conservation to reduce atmospheric CO2 emissions

A

biofuels
reforestation

157
Q

how are biofuels produced

A
  • biofuels are produced from biomass (material that is or was living
  • can be made from crops which can be replanted after harvesting so is a sustainable resource
158
Q

how do biofuels reduce atmospheric CO2

A
  • biofuels are burnt to release energy which produces CO2
  • there is no net increase in atmospheric concentration when biofuels are burnt because the amount of CO2 produced is the same as the amount of CO2 taken in when the material was growing → is carbon neutral
  • so this stops the increase in CO2 conc. in the atmosphere caused by burning fossil fuels
159
Q

how can reforestation be used to reduce atmospheric concentrations of CO2

A
  • when new trees are planted in existing forests that have been depleted
  • more trees means more CO2 is removed from the atmosphere by photosynthesis
  • CO2 is converted into carbon compounds and stored as plant tissues in these
  • this means more carbon is kept out of the atmosphere → so less CO2 is contributing to global warming
160
Q

recall the reasons why some people disagree with the methods used to reduce climate change

A

increased use of biofuels
increase the use of wind turbines

161
Q

why do some people disagree with the use of biofuels

A
  • some farmers support this strategy as some governments fund the farming of crops for biofuels
  • drivers may support this as the price of biofuels is usually lower than oil-based fuels
  • consumers may oppose this strategy because using farmland to grow crops for biofuels could cause food shortages
  • conservationists may oppose this strategy as forests have been cleared to grow crops for biofuels
162
Q

why do people disagree with the use of wind turbines

A
  • companies making the wind turbines would support this as their sales would increase
  • environmentalists may support this strategy as wind turbines produce electricity without increasing atmospheric CO2 conc
  • local communities might oppose this strategy as some people think wind turbines ruin the landscape
  • bird conservationists may oppose this as many birds are killed by flying into wind turbines
163
Q

what is the definition of evolution

A

when the frequency of an allele in a population changes over time which occurs by natural selection

164
Q

why do individuals within a population vary

A
  • individuals within a population vary as they have different alleles
  • different alleles are due to gene mutations → means that some individuals are better adapted to their environment than others
165
Q

why does the frequency of the beneficial allele increase over generations

A
  • individuals that have an allele that increases their chance of survival are more likely to survive, reproduce and pass on the beneficial allele compared to individuals that don’t have this beneficial allele
  • therefore the frequency of the beneficial allele increases over generations
166
Q

how does speciation occur

A
  • isolation reduces gene flow leading to speciation
  • speciation occurs when populations of the same species become reproductively isolated which reduced the gene flow (transfer of genes) between two populations
    • this means that natural selection acts on each population separately → new species can develop
167
Q

how may allopatric speciation

A

reproductive isolation may occur due to geographical isolation (which is also known as allopatric speciation)

168
Q

how may sympatric speciation occur

A

reproductive isolation may also occur because of random mutations which may produce changes in phenotype which prevents populations from mating (which is known as sympatric speciation)

169
Q

describe how allopatric speciation occurs

A
  • populations that are geographically separated will experience slightly different conditions/ selection pressures
    • so different changes in allele frequency could occur
    • different alleles will be more advantageous in different populations e.g those with long fur in cold climates
  • allele frequencies will also change as mutations occur independently in each population
  • the changes in allele frequency will lead to differences accumulating in the gene pools of the separated populations, causing changes in phenotype frequencies
  • eventually the different populations will have become genetically distinct → their DNA will have become significantly different
  • individuals from the different populations will have changed so much that they have become reproductively isolated as they arent able to breed to produce fertile offspring → so they will have become separate species
170
Q

what changes occur in reproductive isolation that prevents two population from successfully breeding together

A
  • seasonal changes- individuals of the same population develop different flowering or mating seasons
  • changes in genitalia which prevent successful mating, changes in the number of chromosomes
  • behavioural changes such as different courtship rituals that may not be attractive to the main population
171
Q

describe how sympatric speciation occurs

A
  • doesn’t have to become geographically isolated to become reproductively isolated
    • speciation without geographical isolation is called sympatric speciation
  • random mutations could occur within a population which results in the changes mentioned here * which prevent members of that population breeding with other members of the species
172
Q

what is the origin of genetic variation

A

mutation
sexual recombination

173
Q

how is mutation an origin of genetic variation (what sources of mutation are there)

A

deletion
insertion
substitution
addition
change triplet code due to a frameshift and therefore protein produced
deletion of translocation of part of a chromosome
loss or gain of a single chromosome
the addition of a whole chromosome sets

174
Q

how is sexual recombination an origin of genetic variation

A

meiosis -> independent assortment, crossing over
random fertilisation

175
Q

what are darwins observations and conclusions made from these observations on survival / how evolution can occur

A

if there is a struggle for existence more offspring are made than survive
when populations remain stable over time -> competition for limited resources maintains a stable population size
there is variation in a population so differences between individuals may affect their competitiveness
variable is inheritable -> adaptations can be passed on letting species evolve gradually

176
Q

what is DNA hybridisation

A

DNA strands are split and taken from two different species and recombined as a hybrid
the more heat it takes to split this hybrid the more closely organisms are related

177
Q

what is DNA molecular clocks

A

how regularly the gene mutates
figure out what point the gene mutates and see where this occurs for other organisms

178
Q

what is the molecular evidence for evolution

A

all living organisms use ATP for energy storage
cell membranes of organisms (all have a phospholipid bilayer)
all have some form of genetic material -> universal code
all have proteins (similar proteins), similar amino acids
all use processes such as protein synthesis, respiration
early stages of life look similar

179
Q

why are mature trees not net absorbers of CO2

A
  • CO2 absorbed in photosynthesis = CO2 released when the tree decays through respiration
  • this is because they arent rapidly growing as they arent accumulating biomass
180
Q

give some examples of biofuels

A

methane
straw
wood
vegetable
biogas

181
Q

what are the advantages of using biofuels

A

renewable as it comes from plants
sustainable
carbon neutral
less use of fossil fuels

182
Q

what are the disadvantages of using biofuels

A

transportation releases CO2
land for growing crops for biofuels could be used for food instead -> clearing land for growing plants -> cutting down trees
needs water, fertilisers -> pollute water sources -> eutrophication

183
Q

why may the production of biofuels not be carbon neutral

A

less trees and plants = less photosynthesis, less carbon sinks is less CO2 removed
if the wood from trees is unused it will be burnt which will release CO2
there may be some decay of the wood due to microorganisms using the glucose in trees and when they respire they release CO2
clearing forests -> net increase in CO2
transportation using fossil fuels releases CO2

[OBSELETE] S - Bio (5 decks)

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