Biol4 Exam Q's

Front 1

Nitrogen gas is the usual substrate for nitrogenase. Name the product

Back 1

Ammonia/ammonium;

Front 2

Nitrogenase also catalyses reactions involving other substances. What does this suggest about the shapes of these molecules.

Back 2

Similar shape/tertiary structure/complementary;

bind to active site/form E-S complex;

Front 3

Azotobacter has a very high rate of aerobic respiration compared with non nitrogen-fixing bacteria. Nitrogenase only works in the absence of oxygen. Suggest 2 advantages of this

Back 3

ATP used for nitrogen fixation;

more nitrogenase produced/produced quicker;

removes oxygen for enzyme;

Front 4

If gene for nitrogenase transferred to cereal plants, they would grow more slowly than those given fertiliser. Why?

Back 4

ATP needed for nitrogen fixation;

less ATP for growth/protein synthesis/production of new cells/production of biomass;

Front 5

In June, young birds leave their nest and join adults. Why would mark-release recapture not be reliable?

Back 5

Population changes;

as young birds join population;

Front 6

In March, each pair of adult birds forms a separate territory. The pair stays in this territory while breeding. Why would mark-release recapture not be reliable?

Back 6

Would catch all birds in second sample;

birds not mixing with population;

only estimates/territory not representative;

Front 7

You could use information about the base sequence to estimate the size of a pop. using mark-release-recapture. Explain why.

Back 7

Recording DNA sequence is like marking

Finding identical sequence shows animal has been caught;

Front 8

What does the Hardy-Weinberg principle predict?

Back 8

The allele frequency of a gene

Will remain constant from one generation to the next;

providing no mutation/selection/population large/genetically isolated/mating at random/no migration

Front 9

If white cats are deaf, does the Hardy-Weinberg principle hold true?

Back 9

White cats selected against/unlikely to survive;

will not pass on allele/will reduce frequency of allele;

Front 10

Describe and explain how intensive rearing affects the energy absorbed from he gut by mammals.

Back 10

Increases

Fed concentrates/controlled diet with high digestibility/less egested

Front 11

Describe and explain how intensive rearing affects respired energy of mammals.

Back 11

Decrease;

movement restricted/heat loss reduced

Front 12

Are values predicted by a model supported by actual measurements?

Back 12

Yes: positive correlation;

Yes: most points close to line;

No: lower values less close to line;

No: generally, values are higher

Front 13

Ecologists investigated succession. Explain the increase in soil nitrate conc.

Back 13

Increase in dead organisms/humus;

increse in nitrification/ammonia to nitrate;

nitrogen fixation

Front 14

Pioneer plants had seeds that germinate better when the temp fluctuates. Explain the advantage of this to the pioneer plants.

Back 14

Bare soil temp fluctutaes NOT ENVIRONMENTAL TEMP;

More bare soil at start of succession/when few plants;

Front 15

Explain the advantage to a plant that colonises after 50 years of having a high rate of photosynthesis at low light intensities.

Back 15

Will grow when receiving less light

Front 16

Conservation of grassland involves management of succession. Why?

Back 16

Grassland consists of small/annual plants;

will be outcompeted by taller plants;

taller have to be removed/growth checked;

Front 17

Describe the part played by the inner membrane of a mitochondrion in producing ATP. (3)

Back 17

Electrons transferred down ETC (reduce carriers);

provide energy to take protons into inter-membranal space;

protons diffuse back into matrix through ATPase;

Energy used to combine ADP and Pi to produce ATP;

Front 18

Why do mitochondria need to be suspended in an isotonic solution?

Back 18

Prevent damage by water/osmosis

Front 19

Explain why the glucose was not used as the respiratory substrate for mitochondria. (2)

Back 19

Glucose broken down during glycolysis;

in cytoplasm;

cannot cross mitochondrial membrane/only pyruvate can;

Front 20

Question about probability and chance?

Back 20

Whole shebang

null hypothesis

significance

Front 21

Why would you incubate seaweeds at 80 and not higher to get dry biomass.

Back 21

Combustion/loss of substances and dry mass

Front 22

The ratio of dry biomass of animals to dry biomass of seaweeds is always <1. Why?

Back 22

Seaweeds are producers;

energy lost between trophic levels;

due to respiration/as heat

Front 23

The conc of CO2 in the air at diff heights in a forest changes over 24 hours. Describe and explain. (5)

Back 23

Highest at night;

no photosynthesis (no LDR);

plants respire;

in light, net uptake/rate of photosynthesis>respiration;

decreased CO2 at greater heights;

less light at ground/fewer leaves;

Front 24

In LIR, carbon in CO2 becomes carbon in triose phosphate. Describe how.

Back 24

CO2 combines with RuBP;

to produce 2 molecules of GP;

reduced to triose phosphate;

requires reduced NADP;

energy from ATP;

Front 25

Microorganisms make the carbon polymers in a dead worm available to cells in a leaf. Describe how.

Back 25

microorganisms are saprobionts;

secrete enzymes/extracellular digestion;

absorb products of digestion/smaller molecules;

respiration produces carbon dioxide;

taken into leaves;

through stomata

Front 26

A large size results in gesse being adapted fro breeding in colder conditions. How?

Back 26

Small SA:V ratio;

lose less heat to environment;

when sitting on eggs;

Front 27

The further north, greater the risk of snow. How might natural selection have resulted in more white geese further north? (3)

Back 27

Snow lying longer/longer to melt;

white geese better camoflaged;

less predation/better reproductive success;

Front 28

In terms of geese, how do you know that there is stabilising selection?

Back 28

Few geese survive at the extremes, most survive from the middle of the range

Front 29

Dead leaves contain starch. Explain how microorganisms make carbon in starch available to plants

Back 29

Release enzymes/extracellular digestion;

starch into monosaccharides;

respire product of digestion;

produce carbon dioxide;

Front 30

Explain what is meant by the term population.

Back 30

All organisms of one species in a habitat at one time

Front 31

Explain the shape of a survival curve from 1750.

Back 31

More disease/poor food supply/poor sanitation/poor medical care;

high death rate among young;

Front 32

Describe how you would decide the number of quadrats to use to collect representative data.

Back 32

Calculate running mean;

enough results and this levels out;

enough for a statistical test;

a large number for reliable results

Front 33

The rate of CO2 production was higher when apple slices were in nitrogen than when in air.

Back 33

Aerobic respiration air;

anaerobic produces less ATP/less efficient;

more anaerobic to produce same ATP, so more CO2;

Front 34

With a graph showing light intensity against rate of photosynthesis, which species is likely to grow at start of succession?

Back 34

vegetation consists of annual/low-growing species;

high rate of photosyntheiss at high light intensity;

grow fastest at high light intensity;

will outcompete other species;

Front 35

Why random?

Back 35

Avoid bias, allow statistical test

Front 36

Explain why it is important to check the repeatability of measurements

Back 36

Improve reilability

diff less likely to be due to measurements/identify anomalies

Front 37

Explain why setting traps immediately after using hair tubes is more reliable

Back 37

rules out differences due to environmental conditions/change in population;

as change in environmental conditions affects births/deaths in a specific way

Front 38

In the LDR, light energy generates ATP. How? (5)

Back 38

Light energy raises energy (excites) electrons in chlorophyll;

electrons pass down electron transfer chain;

reduce carriers;

ETC in thylakoid membranes

release energy/carriers at decreasing energy levels;

used to make ATP from ADP and Pi (phosphorylation)

Front 39

Energy is transferred through an ecosystem. Describe and explain why the efficiency of energy transfer is different at different stages of the food chain.

Back 39

Light does not strike/is reflected/not of right wavelength;

efficiency of photosynthesis is low around 2%;

respiratory losses/excretion/not eaten/faeces;

lost as heat;

effiency of transfer to consumers greater - 10%;

efficiency lower in older animals/herbivores/endotherms;

carnivores use more of their food;

Front 40

Explain how the intensive rearing of livestock increases net productivity

Back 40

Slaughtered while still young so more energy transferred to biomass;

fed on concentrates/controlled diet so higher prop of food absorbed/lower prop excreted;

movement restricted so less eneryg used/less respiratory loss;

kept inside so less heat loss/no predators;

genetically selected for high productivity;

Front 41

What info is required to calculate the growth rate of a population?

Back 41

Birth rate and death rate

Front 42

Describe evidence for population being at an early stage in demographic transition?

Back 42

High birth rate/high prop of young/wide base

high death rate/low life expectancy/low prop of elderly/narrow at top

Front 43

Why would you use percentage cover rather than frequency for algae?

Back 43

difficult to count/too many to count

Front 44

Describe the process of succession.

Back 44

Pioneer species;

makes conditions less hostile;

new species better competitor/outcompetes

Front 45

Explain what is meant by the term phenotype?

Back 45

Expression of genotype;

appearance due to enviornment

Front 46

How do you explain that a diseae is recessive?

Back 46

2 unaffected individuals have affected children;

individuals are carriers/hetero

Front 47

How do you show that a disease is not X-linked if recessive?

Back 47

unaffected father has affected daughter;

father does not have recessive allele on his X chromosome (has 2 copies)

Front 48

The actual % of carriers of a disease is likely to decrease. Why?

Back 48

Affected individuals do not reproduce/pass on allele

Front 49

An inhibitor stops a reaction that occurs in the Krebs cycle. When inhibitor is added, why does O2 uptake decrease?

Back 49

Krebs cycle inhibited;

NAD/FAD not reduced;

hydrogens not passed to ETC;

oxygen used as final acceptor

Front 50

Explain why its important to grow plants in the same conditions before an experiment.

Back 50

Any diff due to independent variable

Front 51

Iron deficiency redcuces electron transport. Explain the decrease in production of TP in iron-deficient plants

Back 51

Less ATP produced

Less NADP produced;

both produced during LDR;

less GP to TP

Front 52

Forest split, and diff plant communities developed in each forest. Explain why there is a high diversity of bird species in forest when it reformed.

Back 52

No interbreeding/geographical isolation/separate gene pools;

mutations;

diff selection pressures/food sources/niches/habitats;

adapted organisms survive and reproduce/differential reproductive success;

change in allele frequnecy

Front 53

Why might speciation be infrequent?

Back 53

no isolation/Gene flow/same gene pool/interbreeding can occur/similar environemntal and biotic factors/similar selection pressures

Front 54

What causes population size to vary?

Back 54

Availbality of water;

food;

predators;

breeding

Front 55

Explain the advantages of integrated pest control

Back 55

Biological:

reproduces;

specific;

maintains low pop;

no resistance;

no accumulation

Chemical:

quickly;

specific area;

kill all pests

Front 56

Explain how nitrate entering ponds and lakes may cause the death of fish.

Back 56

Growth of algae blocks light;

plants die as no photosynthesis;

saprobiotic microorganisms decompose dead plant matter;

use of oxygen by aerobically respiring;

less oxygen for fish to respire/fish die due to lack of oxygen

Front 57

2 reasons for the differences in UK pop between 1700 and 2010

Back 57

contraceptives/birth control;

improved health care/lower infant mortality;

diet/food suply;

sanitation/water supply;

education;

financial considerations of having children;

government policy;

war

Front 58

Describe the role of microorganisms in producing nitrates from dead organisms

Back 58

Saprobiotic microorganisms;

break down proteins/DNA;

into ammonia/ammonium;

extracellular digestion;

ammonia/ammonium into nitrite and then into nitrates;

by nitrifying bacteria;

oxidation;

Front 59

Upwelling (movement of nutrients) results in high primary productivity and highly productive fishing. Why the fishing?

Back 59

Nitrate used by plants;

more producers so more fish

Front 60

Explain the increase in the diversity of birds as the woodland developed

Back 60

Greater variety of plants;

more food sources;

greater variety of habitats/niches

Front 61

Explain why CO2 uptake is a measure of net productivity

Back 61

Shows how much photosynthesis exceeds respiration

Front 62

Why are sex-linked characteristics more common in males?

Back 62

Recessive allele always expressed/females could be heterozygous

Front 63

Malaria affects those those with an allele less. Explain why this allele has a high frequency.

Back 63

Individuals with the allele reproduce;

pass on allele.frequency increases;

homozygous for toher allele less likely to survive/reproduce

Front 64

Explain why yeast would produce less gas after an hour

Back 64

Glucose used up (is a limiting factor)/toxins build up/cells die/increase in ethanol

Front 65

Respiration produces more ATP per molecule of glucose when oxygen is present. why?

Back 65

Oxygen is final electron acceptor/combines with electrons and protons;

ETC provides ATP;

only glycolysis otherwise

Front 66

Why might a non-native species become dominant?

Back 66

Favourable environment/better competitor/ideal niche;

no predators/pathogens;

Front 67

Describe how CO2 is converted into organic substances in the LIR

Back 67

Combines with RuBP;

producing 2 GP

reduced into TP;

using reduced NADP

energy from ATP;

triose phosphate converted to glucose

Front 68

Explain how human activities have contributed to global wariming.

Back 68

CO2 is a greenhouse gas;

deforestation so less CO2 removed;

combustion produces CO2;

methane is a greenhouse gas;

rice fields/landfills/cattle

Front 69

Suggest one reason for the change in life expectancy since 1990.

Back 69

improved medical care/improved nutrition/improved sanitation/less disease

Front 70

What is a recessive allele?

Back 70

Only expressed in the phenotype when homozygous/when no dominant allele/not expressed when heterozygous

Front 71

What are codominant alleles?

Back 71

Both alleles are expressed in the phenotyp

Front 72

How do you explain that a disease is dominant?

Back 72

2 affected have unaffected child

parents are heterozygous/if recessive all children have disease

Front 73

How do you explain that a disease is not X-linked if dominant?

Back 73

Unaffected mum has affected son;

affected son would only receive unaffaceted allele/could not receive disease allele

OR
affected dad has unaffected daughter;

daughter would receive dominant allele

Front 74

Urea broken down by urease secreted by bacteria and converted into ammonia. ammonia released. why does ammonia level increase when urea fertiliser applied?

Back 74

Increase in urease;

more bacteria;

more E-S complexes;

Front 75

DNP inhibits a proton gradient gradient being maintained. When added to isolated mitochondria, less ATP was produced, more heat was given off, oxygen uptake was constant. Why?

Back 75

Less proton movement so less ATP produced;

heat released from electron transport chain/energy not used to make ATP released as heat;

oxygen used as final electron acceptor

Front 76

Why do you need to control type of food when measuring RFI of cattle?

Back 76

may vary in protein/carb/fibre/vitamins/minerals;

affects

digestibility/absorption/energy value

Front 77

Why do you need to control environmental temp when measuring RFI of cattle?

Back 77

Affects heat loss/respiration;

need to maintain body temp;

more energy for growth

Front 78

What do farmers need to know aside from methane released before deciding on a treatmsent?

Back 78

may affect yield/damage on crops;

cost of applicaiton/labour/substance;

treatment may affect other organisms;

method/amount of substance required

Front 79

Methane is produced by anaerobic microorganisms. Rice fields that aren't flooded prodcue less methane. Why?

Back 79

Not flooded = aerobic conditions/more oxygen/or flooded = anerobic;

not flooded = fewer anaerboic microorganisms/respiration

Front 80

Describe and explain how succession occurs.

Back 80

Colonization by pioneer species;

change in environment;

enables other species to colonise;

change in diversity/biodiversity;

stability increases/less hostile environemnt;

climax community

Front 81

What are the disadvantages of biological pest control agents?

Back 81

Slow acting/lag phase/take time to reduce pest population;

may become a pest itself;

does not get rid of pest completely

Front 82

Describe the process of speciation.

Back 82

Geographical isolation;

separate gene pools/no interbreeding;

variation due to mutation;

diff selection pressures/environmental conditions;

selection for different/advantageous characteristics/alleles;

differential reproductive success;

leads to change in allele frequency;

over a long period of time

Front 83

Explain what is meant by a community

Back 83

All the species/all the organisms

Front 84

How can the mark-release recapture method be used to estimate the number of fish in a lake.

Back 84

Capture sample, mark and release;

appropriate way of marking (attaching a tag/mark/cutting a fin) without harming fish;

count number of marked individuals in second sample;

pop = N1*N2/M

Front 85

During the fish-breeding season, mark release recapture may not be accurate. Explain why

Back 85

population increases/changes between samples OR population has to remain constant

Front 86

Each species of fish had adaptations to its niche. Describe how the shape of the mouth of a fish is an adaptation to its niche

Back 86

Different mouth eats different food;

interspecific competition reduced

Front 87

Stickleback feeds on freshwater shrimp feeds on single celled producer which is also fed on by mayfly larva. Explain effect of a decrease in stickleback pop. on mayfly larva

Back 87

reduced predation/less eaten so more shrimp;

more competition for food/resources/more producers eaten by shrimp;

less food/resources for mayfly

Front 88

Why is the transfer of energy of single-celled producers to primary consumers higher than normal transfer of energy from producers?

Back 88

single-celled more digestible/have more cellulose/less energy lsot in faeces;

all producer eaten/not all of plants eaten;

less energy lost as heat/in respiration

Front 89

Energy from the sun may eventually end up in dead plant matter. Describe how.

Back 89

Photosyntheiss/LDR;

carbon containing/organic substances

Front 90

Describe how you would investigate the distribution of marram grass from one side of a sand dune to the other

Back 90

Transect/lay line/tape measure;

place quadrats at intervals along line;

count plants/percentage cover/abundance scale (in quadrats)

Front 91

Why is marram grass good at preventing damage and allowing other species to colonise?

Back 91

Stabilises sand;

makes conditions less hostile/improves soil - water retention/adds nutrients

Front 92

What is an abiotic factor?

Back 92

Non-living/physical/chemical/non biological factor

Front 93

Conc of CO2 in air higher at ground level than among leaves, and increases from 15.00 to 22.00 to 06.00 (when it is at a peak). Explain why?

Back 93

No photosynthesis at night/only respiration;

net uptake of CO2 during day;

At ground level more respiration/more photosynthesis in leaves;

CO2 produced at ground level/taken up by leaves

Front 94

Population of trees adapted to mountain environment. Use knowledge of selection to explain how.

Back 94

Variation in colonisers/mutations took place;

some better adapted for survival in mountains;

greater reproductive success;

allele frequency changes

Front 95

Scientisits investigated the effect of temp on pig growth and efficiency of conversion of food to biomass.

Why did they use pigs of the same breed, with the same genotypes?

The pigs were allowed to eat as much as they wanted. How would this decrease reliability?

Back 95

Similar alleles;

control variables so genes not a factor/only temp affects results/genes affect rate of growth

Diff growth rates/diff conversion to biomass/more food for growth;

not due to temp;

Front 96

The efficiency at which pigs convert food into biomass is lower at 0 degrees than at 20 degrees. Why?

Back 96

Lose more heat;

heat energy released in respiration;

more food used in respiration

Front 97

ATP is useful in many biological processes. Explain why?

Back 97

ATP releases small manageable amounts of energy;

good immediate energy source;

releases energy in a single (hydrolysis) reaction;

reformed/made again;

phosphorylates;

makes phosphorylated substances more reactive/lowers activation energy

Front 98

Describe how ATP is made in mitochondria/

Back 98

Krebs cycle/substrate-level phosphorylation;

Reduced coenzymes made in Krebs cycle/link reaction;

electrons released from reduced coenzymes;

pass down carriers/through electron transport chain/redox reactions;

energy released;

ATP from ADP and Pi;

protons move into intermembrane space;

ATP synthase

Front 99

Explain why it is important for plants ro produce ATP through respiration as well as photosynthesis

Back 99

In the dark no ATP production occurs in photosyntehsis;

some tissues unable to photosyntehsis/produce ATP;

ATP cannot be moved from cell to cell/be stored;

Plants use more ATP than produced in photosyntehsis;

ATP needed for active transport;

synthesis of named substance

Front 100

Why is ATP a suitable energy source for biological processes

Back 100

Soluble;

releases energy in small/suitable amoutns;

involves a single/simple reaction

Front 101

Humans syntheisse more than body mass of ATP a day. Why is this necessary?

Back 101

ATP is unstable;

cannot be stored;

used in active transport/muscle contraction/glycolysis;

ATP releases small amoutns of energy

Front 102

Explain why the net productivity of plants may be higher when the temp is lower?

Back 102

Rate of respiration is lower;

photosyntheiss affected less by temp;

less energy loss/respiratory loss

Front 103

Suggest how a horse may use extra nutrients absorbed?

Back 103

Store as fat/glycogen;

use for growth/movement/reproduction

Front 104

Why does an anaerobic digester containing microorganisms need a cooler?

Back 104

Respiration causes temp increase;

enzymes would be denatured/microorganisms killed

Front 105

One advantage of natural fertiliser over artificial fertiliser?

Back 105

Less leaching/slow release of nutrients;

acts as soil conditioner/increases organic content of soil/aerates soil;

contains other nutrients such as phosphates;

production of artificial is energy-consuming

Front 106

What is meant by birth rate?

Back 106

Births per thousand per year

Front 107

Why do females live longer than males?

Back 107

Wars;

males more affected by CVD;

smoke/drink to excess

Front 108

Explain why actual phenotypic ratio differs from predicted?

Back 108

Random fertilisation;

small sample;

offspring ratios are random/due to chance;

gametes not produced in equal numbers

Front 109

Feather mites eat pathogenic bacteria on birds. Explain how birds may have greater breeding success with more mites.

Back 109

Improves health of bird/less disease;

healthier birds find more food for young/do not pass on disease/have longer breeding life

Front 110

The species that are present cahnge during succession. Explain why?

Back 110

Species change environment/add humus/nutrients;

make less hostile;

others better competitiors

Front 111

Pine trees have leaves all year, explain how this results in low species diversity.

Back 111

Only plants which can photosynthesise with less light survive

Front 112

Suggest and explain one advantage to the fish of occupying different depths.

Back 112

Food/prey/oxygen;

less competition;

Front 113

DMCU inhibits electron transfer during photosyntehsis. How would it reduce CO2 uptake

Back 113

less ATP produced;

less reduced NADP produced

Front 114

Why might you not use biological agents.

Back 114

Expensive;

may become pest itself;

take a long time;

not completely remove pest;

Front 115

Chemical pesticide was sprayed on a field that was biologically controlled. Explain why pest population rises

Back 115

Pesticide kills predator/pest is resistant;

pest reproduces

Front 116

Why is it important to carry out experiments involving respriation at same temp

Back 116

Affects enzymes;

affects respiration;

affects volume/pressure;

affects readings

Front 117

Seeds kept in flask connected to tube with coloured liquid. CO2 is absorbed. Explain why level of coloured liquid decreases

Back 117

Oxygen taken up in respiration;

decrease pressure in flask

Front 118

Petroleum is used as a comparison when comparing NLPs of biofuels. Explain why.

Back 118

Widely used;

used as a standard/benchmark;

produces a lot of CO2;

could be replaced by biofuel

Front 119

Why is it important government environmental scientists test NLPs of biofuels produced by companies?

Back 119

Independent;

non-profit making;

focused on environment

Front 120

Ethanol can be produced from cellulose. It is produced by anaerobic respiration ofcellulose-based biomass by microorganisms. The cellulose is pre-treated by addingcellulose-digesting enzymes before it is used in anaerobic respiration. Suggest whypre-treatment is necessary

Back 120

Microorgamisms dont have enzymes;

cellulose is a polysaccharide;

insoluble;

broken down into glucose/simple sugars;

converted into pyruvate;

more ethanol produced/produced quicker

Front 121

Explain how farming practices increase productivity of agricultural crops.

Back 121

Fertilser;

supply nutrients (nitrates for proteins);

genetically modified crops/selective breeding;

biological control/predators prevent damage/consumption;

herbicides remove competition;

irrigation removes limiting;

ploughing aerates soil/improves drainage;

ploughing allows nitrification/decreases denitrification;

greenhouse enhance temp/CO2/light;

crop rotation improves soil fertility/nutrients/pest reduction;

protection of crops from birds using netting

Front 122

Explain how the use of pesticides can result in resistant strains of pests.

Back 122

Variation in pest population;

due to mutation;

allele for resistance;

selection;

differential reproductive success;

increase in frequency of allele;

Front 123

Legumionous plants have nitogen fixing bacteria in root nodules. They grow better on soils with low conc of nitrate. Why?

Back 123

Nitrogen into ammonia;

produce protein/amino acids

Front 124

Applying very high conc of fertiliser can reduce plant growth. Why?

Back 124

Lowers water potential in soil;

osmosis FROM plant/less water taken up BY plant

Front 125

2 factors which decrease death rate.

Back 125

Improved health care;

nutrition;

sanitation;

less disease;

improved living conditions;

improved economy;

war ends

Front 126

The fruit fly is a useful organism for studying genetic crosses. Female fruit flies areapproximately 2.5 mm long. Males are smaller and possess a distinct black patch ontheir bodies. Females lay up to 400 eggs which develop into adults in 7 to 14 days.Fruit flies will survive and breed in small flasks containing a simple nutrient mediumconsisting mainly of sugars.

Explain why they are useful for genetic crosses.

Back 126

Produce large number of offspring - representative/statistical analysis/reduces sampling error/improves reliability/large sample;

small size/simple nutrient medium - reduce cost/easy to store;

Markings - easy to identify males/females;

reproduce quickly - results produced quickly/saves time

Front 127

Suggest why observed ratios are often not the same as expected ratios.

Back 127

Fertilisation is random;

small popilation/sample;

selection advantage/disadvantage

Front 128

Male fruit flies are more likely to have recessive phenotype of X linked characteristic. Why?

Back 128

Only have one allele;

females must be homozygous

Front 129

Explain how data shows succession has occured.

Back 129

Decrease in bare soil/surface water as more plant coverage/species of plants;

change in diversity as environment less hostile/more soil/competition;

increase in depth of soil as humus formed

Front 130

2 conditions for mark-release-recapture;

Back 130

Marking not removed/not increase predation;

no immigration/emigration;

large population;

sufficient time to mix;

Sampling method is the same;

no deaths/births/breeding

Front 131

Explain why yield is lower at high conc of oxygen, when oxygen inhibits Rubisco.

Back 131

Less GP formed;

less TP converted into glucose/organic compounds/proteins;

less RuBP regenerated