On the wild side

Question 1

What is a climax community?

Answer 1

A community of organisms, where the populations stay relatively stable over time.

Question 2

Describe how pollen grains can be used to evidence climate change.

Answer 2

• pollen can become trapped in peat.
• arranged in layers, and the depth correlates to when the pollen grain was formed.
• Plant species can be identified from their pollen grains.
• Certain plants thrive in certain climates, so can tell the climate at that time
• any changes in pollen over time may be used to evidence climate change.

Question 3

define what is meant by a dynamic ecosystem

Answer 3

• a constantly changing ecosystem where habitats are followed by periods of succession

Question 4

Describe the process of succession

Answer 4

1. Starts with pioneer species - like bacteria which are adapted to living in extreme conditions.(fast life cycle, rapid growth, abundant seed dispersal)
2. pioneer specis chang e soil/environmental conditions that make it more suitable for other species to inhabit the area (humus, decomposition of their bodies)
3. forms climax community

Question 5

What effects distribution and abundance?

Answer 5

• abiotic and biotic factors

Question 6

Define the term ‘density dependant’

Answer 6

effects relating to the size of the population and the area availible.
eg larger population in a given (smaller) area is likely to have more competition

Question 7

define succession

Answer 7

the gradual, directional change of an ecosystem over time, in which pioneer species change conditions, making them more suitable for adapted organisms to colonise the area.

Question 8

Explain how soil if formed on newly formed land

Answer 8

• pioneer speicies such as lichens colonise the area, as they are adapted to those conditions.
• they break down rocks to their grain
• this releases humus, an organic component of soil.
• forms soil, making the environment more suitable for complex organisms.
• over time, larger and larger organisms can colonise the area, forming a climax community.

Question 9

define deflected succession

Answer 9

• a community that remains stable only because humans influence it - prevent succession from running its course.

Question 10

Describe how starch is formed from the products of the light-independent reactions of
photosynthesis.

Answer 10

• 2 GALP molecules used to make hexose sugars, like glucose
• glucose monomers join via condensation reactions, forming glycosidic bonds
• this forms amylose and amylopectin.

Question 11

Describe the light-dependent reactions of photosynthesis.

Answer 11

• light energy excites electrons
• photolysis of water produces H+ ions, O2 and electrons
• electrons used in the ETC
• this releases energy to make ATP
• NADP is reduced to NADPH.

Question 12

In some commercial glasshouses, the concentration of carbon dioxide in the atmosphere is
increased.
Explain why this increase in carbon dioxide concentration affects the growth of plants in
glasshouses

Answer 12

• high concentration of CO2 = faster rate of photosynthesis, as it may be considered a limiting factor.
• so more glucose can be produced
• this can be used to make amino acids to increase rate of growth.

Question 13

state the location of chlorophyll in a chloroplast.

Answer 13

• granum

Question 14

Describe the roles of the products of the light-dependent reactions in the Calvin cycle.
(3)

Answer 14

• ATP and reduced NADP are products of the light dependant reaction
• NADPH is oxidised in order to reduce GP to GALP
• ATP is used to provide energy for the calvin cycle.

Question 15

Explain the importance of RUBISCO to the productivity of an ecosystem.

Answer 15

• fixes Carbon to RubP
• This helps form complex organic molecules, which need to be transferred to the next trophic level.

Question 16

Explain the relationship between the structure and functions of a granum in
photosynthesis.

Answer 16

• granum is a stack of thylakoid membranes which increases surface area
• thylakoid membranes contain chlorophyll to absorb light
• the electron carrier molecules in the thylakoid are involved in ATP synthesis.

Question 17

Explain why the value for GPP is lower than the light energy available to the ecosystem.
(3)

Answer 17

• Some light may be reflected off the surface of the leaf
• light may be delivered to other parts of the plant, eg the branches.
• Not all wavelengths of light are absorbed by the leaf.

Question 18

Climate change has been linked to the release of carbon dioxide from some power stations.
Net primary productivity (NPP) is a measure of the increase in biomass of a plant.
Explain why respiration affects the production of biomass.

Answer 18

• respiration uses up organic materials, such as glucose, so less are available for producing biomass.
• NPP = GPP-R

Question 19

The ratio of net primary productivity to gross primary productivity is a measure of the
ability of forests to transfer carbon from the atmosphere into biomass.
Scientists concluded that temperate deciduous forests would reduce levels of carbon
dioxide in the atmosphere more than boreal forests.
BF= 0.32
DF= 0.6
Justify this conclusion.

Answer 19

• ratio is higher for deciduous forests
• so deciduous forests are taking in more CO2 than they are giving out.
• so NPP is higher for DFs.

Question 20

Give two biotic factors, other than cutting down trees, that could affect the number of bird
species observed in a forest.

Answer 20

• availability of food
• predation

Question 21

Explain what happened to the bare rock to allow the growth of these trees.

Answer 21

• colonised by pioneer species
• they broke through rock
• which added humus to the rock, breaking down into grain.
• made conditions more suitable for hemlock trees to grow - soil becomes more permeable to water eg.

Question 22

Bare rock is exposed as the glacier retreats. Two hundred years ago, bare rock was
exposed after a glacier retreated. A study has been made of the long-term changes
in vegetation on that area of rock after the retreat of the glacier.
Plants such as lupin are often found in the early stages of glacial retreat. Lupin
plants have nodules on their roots containing nitrogen-fixing bacteria that
convert atmospheric nitrogen to ammonium ions. Plants can use ammonium ions
as a source of nitrogen.
Explain why lupin plants are able to grow in the early stages of glacial retreat.

Answer 22

• in its early stages, the rock may lack nitrates
• but lupin can convert atmospheric nitrogen to use as a source of nitrate ions through making ammonium ions
• so these can then be used to make amino acids for growth.

Question 23

The pigment content of mountain plants can be affected by various environmental factors.
These factors include altitude (height up a mountain), exposure to ultraviolet radiation
(UV-B) and temperature.
These pigments include chlorophyll, found in chloroplasts, and flavonoids that are found in
sap vacuoles.
Flavonoids can protect plants from ultraviolet radiation (UV-B) that can damage DNA.
The altitude at which a plant grows on a mountain affects its flavonoid content.
Devise a procedure to show that an increase in altitude increases the flavonoid content of
one species of plant found growing on a mountain. (6)

Answer 23

• test at least 5 different altitudes
• place the same type of plant at altitudes with a set variance (eg 5, 10, 15 m)
• Keep them there for the same amount of time.
• Collect each sample from leaves of the plants
• extract flavonoids using a solvent - eg ethanol
• use colourimeter to determine absorbance - higher the reading, the higher the conc of flavonoids.

Question 24

Explain why the ‘anaerobic oxidation of methane’ could be a ‘key climate regulator’

Answer 24

methane is a greenhouse gas, so it will absorb infrared radiation, thus warming up the atmosphere.
the breakdown of methane could produce less harmful products, which could contribute to reducing global warming.

Question 24

Large areas of land may need to be cleared in order to produce biofuels. This might involve
deforestation.
Discuss why the production of biofuels may not be carbon neutral. (6)

Answer 24

• carbon neutral refers to the fact that the carbon taken in by trees is the same as they give out.
• However, burning of biofuels may also produce CO2, which contributes to the Carbon given out by biofuels
• Decomposition of biofuels may also produce CO2
• However, Trees may take in CO2 for photosynthesis, reducing CO2 in the atmosphere, making them carbon sinks
• However, if the CO2 produced through burning, deforestation and decomposition is more than taken in for photosynthesis, production of biofuels may not be carbon neutral.

Question 24

Explain how the combustion products, from the burning of fuels, may lead to global warming.

Answer 24

• combustion may produce greenhouse gasses such as CO2 and methane
• these increase the levels of these gasses in the atmosphere, in which they trap more heat that is reflected by the earth.
• This could increase the greenhouse effect, leading to a higher average global temperature.

Question 25

Suggest why using first generation ( eg crops) biofuels instead of petrol and diesel could reduce
global warming.

Answer 25

• burning of CO2 and diesel produces greenhouse gasses like CO2, and so does burning of biofuels
• ## however, crops take in CO2 for photosynthesis, making the process potentially carbon neutral, meaning there is no net change in the levels of CO2 in the atmosphere.

Question 26

Explain the effect of temperature on the rate of photosynthesis in wheat.

Answer 26

• higher temp = higher rate of photosynthesis, as more kinetic energy, so frequency of enzyme-substrate complexes increases
• 30 is optimum temp though, and after 30 enzymes denature
• so they might change shape, meaning that the active site is no longer complimentary to the substrate, decreasing rate of photosynthesis.

Question 27

Explain why the data may not be useful for predicting future climate change.

Answer 27

• cannot assume that a trend will continue
• not enough data collected- only 40 years, need more to effectively conclude info
• data only collected from one location, so cant generalise to others.
• data fluctuates a lot - means that it may stay the the same in the future, or just not gonna be able to conclude.

Question 28

How do electrons in the ETC move across it?

Answer 28

• through a series of redox reactions

Question 29

what happens to electrons once they leave the ETC?

Answer 29

• combine with H and NADP to form NADPH

Question 30

why do anaerobic and acidic soil conditions slow decay rate in peat?

Answer 30

• Low pH might mean that enzymes denature
• bacteria may not be able to reproduce in low pH due to this.

Question 31

Outline how Global warming may increase rates of global inequality.

Answer 31

• crop production in already cooler regions may benefit from high temps, as this may increase photosynthesis rates, and therefore, yield
• but regions near the equator may face low yield rates due to temperatures getting too high that enzymes involved in photosynthesis denature.
• Overall, this may increase inequality in terms of food availability - most poorer countries are located near the equator, while wealthier ones are not.

Question 32

Using the information given, explain the relationship between GPP and NPP.

Answer 32

• NPP = GPP - R
• Energy is lost through respiration, ie to make biomass or for active transport.
• so NPP is how much energy will be transferred to the next trophic level

Question 33

Suggest why NPP values would be of use to a farmer who wanted to use this land for cattle

Answer 33

• since cattle are primary consumers,
• NPP is the amount of energy they will gain through consumption of grass
• therefore, this may benefit the farmer to ensure good yield of milk or meat from cattle.

Question 34

The units (kJ m−2 year−1) used in the diagram show a rate of energy production. Suggest why
this is more useful than measurements of biomass in the grassland on a particular day.

Answer 34

• it is a per year measurement, so would most likely take averages from each day or month into account
• more likely to give a more reliable value as there may be variation per season or month etc.

Question 35

Explain the meaning of the term gross primary productivity (GPP).

Answer 35

• the rate at which chemical energy is converted to biomass in an ecosystem
• in producers.

Question 36

The total GPP for this sea is 8.40 × 10^6
kJ m−2 y−1

Explain how GPP for the phytoplankton could be calculated

Answer 36

• take percentage from pie chart
• multiply that by 8.4 x 10^6

Question 37

Suggest why GPP for this sea is very high.

Answer 37

• high light intensity
• optimum temperature

Question 38

explain why NPP is lower than GPP

Answer 38

• NPP = GPP- R
• energy is lost through things like making biomass or movement.

Question 39

Suggest an explanation for the effect of depth of water on the NPP in this
freshwater lake (4)

Answer 39

• As depth increases, light intensity may decrease as well
• therefore less photosynthesis takes place, or at a lower rate
• so less glucose will be made to be turned into biomass.
• so GPP will decrease, even though R will stay the same, thus reducing NPP.

Question 40

Describe the role of the group of membrane proteins represented Y in the
diagram.

Answer 40

• the electron transport chain
• is involved in ATP production.

Question 41

Describe the role of RUBISCO in the production of GALP in the light-independent reaction

Answer 41

• an enzyme
• fixes carbon to RuBP
• in the calvin cycle
• forms GP
• which is then reduced to GALP by

Question 42

Describe how the membranes inside the chloroplast are involved in photosynthesis.

Answer 42

• thylakoid membranes contain PS1 and PSII, which absorb light and excite electrons
• ATP synthase located in membranes, to help synthesis ATP from ADP and Pi
• site of the light dependant reaction.

Question 43

Explain how the data demonstrate the process of succession. (5)

Diveristy index of dunes 1 -4:
1: 1.1
2: 1.75
3: 3.35
4: 3.48

Answer 43

• succession is the process of species replacing each other with time
• no species of plant inhabits all 4 dunes
• Biodiversity index increases from dunes 1-4, so plant diversity increases with time
• so dune 4 is older than dune 1
• large increase of biodiversity index from dune 2-3 (increase of 1.6)

Question 44

Describe and explain how global warming could affect plant species. (4)

Answer 44

• Could affect distribution, as there may be a change in rainfall patterns.
• could affect abundance or plants could go extinct - due to too high temp denaturing enzymes from photosynthesis - so less amino acids for growth.

Question 45

Explain how the effects on plant species could affect animal species

Answer 45

• change in distribution of plants could change distribution of animals too
• or could decrease populations of herbivores
• could also increase habitat loss if plants start to go extinct
• thi may cause decrease in predation if populations of primary consumers start to decrease (less food for secondary and tertiary consumers)

Question 46

Using the information in the diagram, describe and explain the changes in the distribution of
organisms with distance from the front edge of this glacier.
(3)

Answer 46

• succession takes place
• algae an lichens are first pioneer species that colonise bare rock
• break down rock and release humus to make conditions suitable for moss, trees etc.

Question 47

Epilobium latifolium is a plant that occupies a niche in an area once covered by this glacier.
It is a short flowering plant that grows in clumps.
Explain what is meant by the term niche, using the plant Epilobium latifolium as an example.
(3)

Answer 47

• a role of an organism in its ecosystem
• E. Latifolum is a producer
• so it provides as a food source for primary consumers,

Question 48

Suggest one abiotic factor that might affect the abundance of Epilobium latifolium and
describe how this factor could be measured.

Answer 48

• Temperature could affect it
• can be measured using thermometer at different lengths of the glacier
• count number of E Latifolium at different lengths along the transect and calculate mean by counting at different areas long the same length

Question 49

name 3 characteristics of a pinoeer species

Answer 49

• need to withstand harsh conditions
• have fast life cycles
• have relatively low requirements for minerals.

Question 50

Explain why succession occurs in stages.(2)

Answer 50

• because pioneer species need to make conditions more suitable for other species
• eg making soil richer in mineral ions.

Question 51

When this volcano erupted, sulfur dioxide and particles of ash were released
into the atmosphere.
Sulfur dioxide and particles of ash cause less light to pass through
the atmosphere.
Explain the results shown in the graph.

Answer 51

• initially, ash will block IR radiation reflected from the earth’s surface
• so less light reaching the earth will result in cooler temps
• but over time, the ash and cloud will clear
• allowing more light, and thus, heat to reach the earth, increasing temp

Question 52

Discuss the possible effects of volcanic eruptions on climate change.
Use all the information in part (b) to support your answer.
(3)

Answer 52

• shows that volcanoes do release CO2
• which is a greenhouse gas, and therefore could lead to the green house effect, and global warming
• might be offset by ash and SO2 though

Question 53

define sympatric speciation

Answer 53

anything but geographical isolation

Question 54

allopatric speciation

Answer 54

geographical isolation

Question 55

define genetic drift.

Answer 55

• random change in allele frequency within a species.

Question 56

name 2 factors that are likely responsible for the carbon cycle not being in cycle

Answer 56

• combustions
• deforestation

Question 57

Define evolution

Answer 57

• the change in allele frequency over a long period of time

Question 58

Describe the process of natural selection

Answer 58

• variation within the population due to potential mutation.
• a selection pressure arises, such as an environmental change.
• individuals with an advantageous allele will survive this selection pressure, while those without it may die out.
• therefore, these individuals survive long enough to reproduce, passing these alleles onto their offspring.
• the frequency of this allele then increases over a long period of time in the population.

Question 59

What can evolution eventually lead to? what is needed for this to happen?

Answer 59

• speciation - forming of a new species all together as difference in species becomes too great to breed and produce fertile offspring.
• need reproductive isolation of some kind
• gene flow needs to be disrupted.

Question 60

Define allopatric speciation

Answer 60

speciation that is a result of geographical isolation

Question 61

Define sympatric speciation

Answer 61

• speciation that is a result of other isolation forms - eg temporal or behavioural.

Question 62

name 3 effects of climate change

Answer 62

• changes in distribution - species moving to cooler areas - could lead to extinction due to extra competition.
• changes in development: temp determined sex etc - could affect sex ratio, could lead to extinction
• disrupted life cycles.

Question 63

name 2 ways in which climate change can be reduced by using knowledge of the carbon cycle.

Answer 63

• reforestation: increases rate at which CO2 is removed from the atmosphere, (putting O2 into the atmosphere)
• growing plants to use as biofuels - carbon neutral.