Biology Unit 4 Model Answers Flashcards

Question

M- How does an increase in carbon dioxide levels in the atmosphere affect yield of grain?

Answer 1

Causes an increase in rate of photosynthesis therefore increases the amount of glucose made which increases growth rate - due to an increases rate of respiration and there ATP prodction- and yield Increase in carbon dioxide levels usually causes an increase in climate temperature which would cause faster reaction rate hence higher yield

Answer 2

breaks down macromolecules into smaller ones Produces hydrogen atoms that are carried by NAD to the ETC for oxidative phosphorylation (and the subsequent production of ATP) Regenerates the 4C compound which would otherwise accumulate Source of intermediate compounds used in the manufacture of other substances

Answer 3

Low carbon dioxide during the day As plants are photosynthesising and taking in carbon dioxide Plants respire all the time but do not photosynthesise at night so carbon dioxide concentrations increase at night Carbon dioxide levels are increased at the forest floor Because ground level has less photosynthesising tissue, less light and more respiring animals

Answer 4

Glucose is activated - phosphorylated - by the addition of inorganic phosphate Produced by the breakdown of ATP into ADP and Pi Glucose splits into 2 molecules of triose phosphate NAD co enzyme accepts hydrogen from triose phosphate and becomes reduced Inorganic phosphorus is removed from triose phosphate to make pyruvate 4 molecules of ATP are produced by substrate level phosphorylation to give a net gain of 2 ATP per glucose molecule

Answer 5

Specific Biodegradeable cost effective will not accumulate in the food chain

Answer 6

Pyruvate is oxidised to the 2C compound acetyl coA CO2 is released NAD accepts hydrogen from pyruvate and so is reduced

Answer 7

2C acetyl coA combines with 4C compound 6C compound loses CO2 5C compound loses CO2 One molecule of ATP is produced by substrate level phosphorylation FAD and NAD accept hydrogen and electrons And becomes reduced (FADH and NADH) 4C compound combines with another 2C compound and the cycle begins again

Answer 8

To avoid bias

Answer 9

Some of the carbon dioxide produced in respiration is used in photosynthesis

Answer 10

Carbon dioxide joins with ribulose bisphosphate (RuBP) a 5 carbon compound- this gives an unstable 6 carbon compound This quickly breaks down to 2 molecules of a 3 carbon compound glycerate 3-phosphate (GP) This reaction is catalysed by the enzymes ribulose bisphosphate carboxylase (Rubisco) ATP from the light dependent reaction is used to provide energy for the reduction of GP into TP - triose phosphate The reduction reaction needs H+/reducing power H+ are provided by reduced NADP (NADPH)from the light dependent stage Two TP join up to form hexose which can combine to form starch and cellulose, 1 in every 6 TP molecules is used to make hexose TP regenerates RuBP and so the cycle continues, 5 in every 6 TP molecules form RUBP TP also forms amino acids, fatty acids, glycerol, DNA, RNA, glucose and starch.

Answer 11

C6H12O6 --> 2CH3CH2OH + CO2 ( glucose --> ethanol and carbon dioxide) Anaerobic conditions Optimum temperatures/pH Only glycolysis can take place Glucose --> pyruvate (NAD -->NADH) Pyruvate --> Ethanol + CO2 (NADH --> NAD) Nad is recycled/regenerated

Answer 12

Pyruvate takes up hydrogen ions from the reduced NAD To produce lactate and NAD This ensures that glucose can still be respired Even in the absence of oxygen

Answer 13

Nitrates Nitrites Ammonium

Answer 14

Larger surface area to carry out oxidative phosphorylation producing more ATP

Answer 15

NAD accepts hydrogen during glycolysis, link reaction and Kreb's cycle NAD is reduced NADH releases hydrogen ions during the electron transport chain, which are pumped across the mitochondrial membrane Electrons released from the co enzymes are passed along a series of carrier proteins in the membrane Energy lost from the electrons is used to make ATP from ADP and Pi

Answer 16

Enzymes catalyse respiration reactions Rate of reaction decreases as particles have less kinetic energy So fewer collisions between enzyme active site and substrate So fewer ES complexes can form

Answer 17

Respiration is catalysed by enzymes which are proteins Hydrogen bonds in the tertiary structure break Active site is denatured Substrate can no longer bind to the active site so fewer ES complexes can form

Answer 18

Plants take up nitrate ions (NO3^-) from the soil The nitrates then form amino acids which are used to synthesise proteins which are organic nitrogen containing compounds in plants and animals The plants are eaten by animals and the proteins are digested Both plants and animals die, leaving a collection of dead materials (detritus) which contains nitrogen containing compounds Decomposers decay the excretory products and detritus, releasing ammonia (NH3) and ammonium ions (NH4^+) into the soil Nitrifying bacteria oxidise the ammonia into nitrites (NO2^-) Then the nitrites are oxidised into nitrates which are taken up by the plants Lightning and nitrogen fixing bacteria in the soil and in nodules on the roots of legumes fix nitrogen gas (N2) into ammonia (NH3) which is dissolved into ammonium Denitrifying bacteria reduce nitrate to nitrogen, in anaerobic soil conditions that escape from the soil and returns to the atmosphere

Answer 19

Anaerobic respiration produces less ATP so more glucose is respires to generate the same amount of ATP

Answer 20

The plant will be using more glucose than it is producing. Therefore the plant will not grow as quickly because there is less ATP produced for reactions such as DNA replication and protein synthesis - this will have an impact of total plant biomass and therefore lower yield

Answer 21

Some of the organism is not eaten Some parts are not digested Some energy is lost in excretory material e.g. urine energy is lost as heat from the organisms Energy is lost in repsiration

Answer 22

The non-living part of the environment

Answer 23

Movement is restricted therefore less energy used in muscle contraction Warm environment to reduce heat loss from the body No wastage in feeding as animals receive optimum amount Predators are excluded

Answer 24

No account is taken of size of the organism | Number of individuals may be so great as to not be able to represent them accurately

Answer 25

Metabolism Movement - energy for muscle contractions Active transport - change shape of carrier proteins Cell division Production of enzymes or hormones - energy needed to form lysosomes for secretion Maintenance of internal body temperatures

Answer 26

Some light is reflected off the plant or is the wrong wavelength to be absorbed by chlorophyll Efficiency of photosynthesis is low - less than 2% energy lost during respiration/excretion or some parts of the plants/animal are not eaten Heat loss efficiency f transfer increases with increasing trophic level (along food chain) so efficiency of consumers is greater than efficiency of producers Efficiency is lower in older animals, primary consumers, warm blooded animals (endotherms) Carnivores use more of their food than herbivores

Answer 27

Loss of trees means less photosynthesis Therefore less CO2 removed from atmosphere Unwanted trees often burned releasing CO2 into the atmosphere The concentration of CO2 in the atmosphere increases leading to increased global warming Reduced input to nitrogen cycle as less recycling of nitrate ions occurs Increases loss of nitrates by leaching roots of trees hold fertile part of soil= topsoil together. With no trees, wind erosion occurs causing removal of topsoil Soil loses fertility so can only support lower numbers and fewer species of plants, giving lower biodiversity

Answer 28

The number of individuals of a species in a given place

Answer 29

The efficiency of the crop | The area of ground covered by the leaves of the crop

Answer 30

always have some effect on non target species must be re applied therefore expensive pests may develop resistance

Answer 31

An estimate of the area within a quadrat that a particular plant species covers

Answer 32

Natural - lower producivity; higher species diversity; more genetic diversity; nutrients recycled naturally; populations controlled by competition or climate; solar energy only; reaches a natural climax community Artificial - higher productivity; lower species diversity; less genetic diversity within a species; nutrients cycling supplemented by use of fertilizers; population controlled by pesticides and cultivation; energy from food and fossil fuels as well as solar; prevented from reaching a natural climax community

Answer 33

Activity increases rate of respiration which uses glucose and depletes food reserves This is why some animals hibernate - they reduce their activity so reduce their rate of respiration so they do not use food stores

Answer 34

Specific Control organisms reproduces itself and does not need to be reapplied Pests do not become resistant

Answer 35

Can be collected rapidly | No need to define individual plants

Answer 36

time lag as control does not act quickly | control organism itself may become a pest

Answer 37

Slaughtered when young so more energy transferred to biomass Fed on controlled diet so higher proportion of nutrients are absorbed Movement restricted so less lost by respiration Kept inside and heated so less energy lost as heat Genetically selected for high productivity

Answer 38

Nutrient is taken up by producers as simple, inorganic molecules Produces incorporates nutrient into complex organic molecules Nutrient passes into consumers when producer is eaten Nutrient passes along food chain when producers and consumers die their complex molecules are broken down by saprobiotic microorganisms that release the nutrient in its organic simple form

Answer 39

Combustion of fossil fuels releases carbon dioxide | Deforestation means there are less plants to tae in carbon dioxide during photosynthesis

Answer 40

They would need to adapt Their niche would change If plants couldn't adapt its niche, the it would die our and become extinct An animals may be forced to migrate

Answer 41

Prevents growth of woody plants Decreases plant diversity Less habitats and niches for animals Lower variety of food sources

Answer 42

These organisms are saprobiotic Release (secrete) enzymes Hydrolyse starch to glucose; products are absorbed by the microorganisms Respire Release carbon dioxide which is taken into leaves by stomata

Answer 43

Melting ice caps could cause extinction of some species Rise in sea levels could flood low-lying land Higher temperature and less rainfall could lead to the failure of crops Intense storms would be prevalent in some areas leading to changes in wildlife distributon Life cycles and populations of insects pests would alter and increase spread of tropical diseases towards the poles

Answer 44

A group of interbreeding organisms of one species in one particular habitat

Answer 45

Pyruvate is actively pumped into the matrix Pyruvate is decarboxylated to produce acetyl coA and CO2 NADH is also produced, as pyruvate loses hydrogen Acetyl coA combines with 4C compound to produce 6C compound which is then decarboxylated One molecule of ATP is produced by substrate level phosphorylation NADH carries hydrogen and electrons to the crisae Electrons are passed along the series of carrier proteins in the membrane Electrons lose energy which is dissipated as heat Hydrogen ions are pumped into the inter membrane space Hydrogen ions diffuse back into the matrix down an electrochemical gradient Via ATP synthase Electrons at the end of the transport chain bind with H+ ion and are accepted by oxygen, the final acceptor, to make water

Answer 46

Mutualistic bacteria in the root nodules of leguminous plants fix nitrogen to ammonium, the plant then uses this to create amino acids, proteins, DNA etc

Answer 47

Sandy soil contain lots of oxygen | Denitrifying bacteria are anaerobic

Answer 48

Leads to interspecific competition | One may outcompete the other

Answer 49

The likelihood of a particular species occurring within a quadrat

Answer 50

respiration

Answer 51

``` DNA RNA ATP Protein Amino acids Urea ```

Answer 52

Ethical, economica, cultural, aesthetics

Answer 53

Biological agents - Only needs one application (reproduces); specific; maintains a low population; pests do not develop resistance; can use less chemicals (no bioaccumulation) Chemical pesticides - acts quickly; can apply to a specific area; kill greater variety of pests

Answer 54

Leaching of fertilisers causes algae to grow exponentially at the surface of water This absorbs light and prevents it penetrating to lower depths Light is limiting factor for plant growth at lower depths and so aquatic plants die Saprobiotic bacteria feed on dead plant mater And use oxygen for respiration Oxygen becomes limiting factor for aerobic organisms e.g. fish and so they die

Answer 55

``` Produce lots of wind-dispersed seeds/spores Rapid germination Ability to photosynthesise Ability to fix nitrogen Tolerance to extreme conditions ```

Answer 56

Some are free living nitrogen fixing bacteria They reduce N2 gas to NH3 which dissolves to form NH4+ ions Some are Mutualistic ( symbiotic) nitrogen fixing bacteria They are found in root nodules of leguminous plants, like peas and clover This is mutualism because both species benefit from the relationship due to bacteria being protected and the plant being provided with nitrates They reduce nitrogen gas into ammonia Lightning also reduces nitrogen gas into ammonia

Answer 57

Not all wavelengths can be absorbed Light may not fall on chlorophyll molelcule Other factors may limit the rate Most light is reflected back by clouds

Answer 58

Pioneer species with appropriate adaptations colonise bare land and interact with the environment Members of pioneer species die and are decomposed by bacteria and fungi This adds humus to the soil which improves water holding capacity of the soil Changes in the soil make environment less hostile Larger plants replace smaller plants (competition) new niches/habitats produced for new species to form new communities Increases biodiversity New communities will form and be replaced by later communities until a climax community is established. Biotic factors are more important than abiotic factors, biodiversity remains constant due to competitions making a stable climax community

Answer 59

A feeding relationship in which the producers are eaten by primary consumers which in turn are eaten by secondary consumers

Answer 60

Correlation does not establish a cause | There may be another factor

Answer 61

The position along the chromosome where genes occur

Answer 62

Selective breeding so animals are more efficient at converting food into body mass Using hormones to increase growth rates

Answer 63

photosynthetic organisms that manufacture organic molecules using light enregy, water and carbon dioxide

Answer 64

That the frequency of alleles will stay constant over time providing no mutations/selection etc

Answer 65

An allele that affects the phenotype of an organism only when the dominant allele is absent

Answer 66

``` No mutations Population is isolated No selection - all alleles are equally likely to be passed on Large population Mating within the population is random ```

Answer 67

Variation within the original population Random spontaneous mutation Adaptation coded by mutated allele may give survival advantage/disadvantage Survival to reproduce - differential reproductive success Pass on alleles for favourable characteristics/adaptation to offspring Allele frequency increases in population Moe of the new variants in population

Answer 68

Accuracy is being free from error, making no mistakes with instruments Reliability means that there is little variation from the true value i.e. results are concordant when repeated

Answer 69

Organisms that obtain energy by feeding on other organisms

Answer 70

Identifies anomalies and increases reliability - differences likely to be due to personal error

Answer 71

Plot a scatter graph of X verses Y Look for overlying points i.e. points should lie close to the line of best fit in both cases

Answer 72

Plants take in carbon dioxide This is used for photosynthesis Sugar/starch (carbon compounds) synthesised Carbon compounds then passed along food chain when primary consumer eats producer, secondary consumer eats primary consumer etc Organism dies Decomposers, use extra cellular enzymes to digest and break down organism and use their carbon compounds in respiration All the living organisms (plants, animals and the decomposers) give off CO2 from respiration and CO2 is returned into the atmosphere this way Plants take in CO2 again for photosynthesis Burning trees and fossil fuels releases CO2 also Burning coal also releases sulphur dioxide (SO2)

Answer 73

Determines the probability of results being due to chance Determines whether results is biologically significant Enables null to be accepted or rejected

Answer 74

The living part of the environment

Answer 75

There is a probability of less than 0.05 (5%) that the difference was due to chance OR There is a probability of more than 0.95 (95%) that the difference was not due to chance i.e. was biological

Answer 76

A self contained unit made up of all the biotic and abiotic features in a specific area

Answer 77

Reduces nitrates to nitrogen In anaerobic soil conditions Which escapes from the soil and returns to the atmosphere

Answer 78

An organism that feeds on another organism

Answer 79

economic conditions/ cultural background/ social conditions/ birth control/ political factors

Answer 80

All the population of different organisms living and interacting in a particular place at the time

Answer 81

The place where a community of organisms lives

Answer 82

How an organism fits into an environment referring to where it lives and what it does there

Answer 83

Within a particular species - when referring to competition

Answer 84

Between 2 or more different species- when referring to competition

Answer 85

``` Environment becomes less hostile Greater number of variety of habitats Increased biodiversity More complex food webs Increased biomass ```

Answer 86

Organisms that obtain energy by feeding on primary consumers

Answer 87

Organisms that obtain energy by feeding on producers

Answer 88

Increases variety of food sources Increase number of niches Increased number of habitats

Answer 89

The position of an organism in a food chain

Answer 90

Total quantity of energy that the plants in a community convert to organic matter

Answer 91

Plot a scatter graph and draw a line of best fit OR Conduct Spearmans Rank Correlation Test - look for figures close to +1 or -1

Answer 92

Microorganisms e.g. bacteria and fungi, that break down complex organic molecules into simple components and release minerals and elements into the soil

Answer 93

Small organisms e.g. woodlice and earthworms, that breakdown the complex organic molecules in dead and decaying plant and animal matter

Answer 94

One alternative form of a gene occupying a specific position on a chromosome

Answer 95

Total mass of plants and/or animals in a particular place

Answer 96

Mass of plants and/or animals in a particular place minus their water content

Answer 97

A section of DNA coding for the synthesis of a single polypeptide

Answer 98

An organism that is consumed by another organism

Answer 99

Individuals of one species can freely interbreed and have a single gene pool Climate change over time causes a split in the area with different conditions - geographical isolation Variation within the original population Random spontaneous mutation Adaptation coded by mutated allele may give survival advantage/disadvantage Survival to reproduce - differential reproductive success Pass on alleles for favourable characteristics/ adaptations to offspring Allele frequency increases in population more of the new variants in population Type of alleles and their frequency in each area/each gene pool changes And becomes so different that they become a separate species If species are reunited, they will not be able to interbreed to produce fertile offspring- reproductive isolation

Answer 100

Rate at which plants store energy

Answer 101

A diploid organism that has inherited the same allele for a single gene from both parents

Answer 102

The genetic constitution of an organism

Answer 103

A diploid organism that has inherited different alleles for the same gene from each parent

Answer 104

The characteristics or appearance of an organism ( the way the gene is expressed)

Answer 105

An allele that affects the phenotype of an organism, whether present in the homologous or heterozygous condition

Answer 106

An individual with a recessive allele of a gene that does not affect their phenotype

Answer 107

Pairs of alleles that both affect the phenotype when present in a heterozygote

Answer 108

proportion of marked to unmarked in the second sample if equal tot he proportion of marked to unmarked in the whole population Marked individuals from the first sample distribute themselves evenly with enough time to do so Population has a boundary so no emigration or immigration Few births and deaths Method of marking does not make it more liable to predation Mark is not lost during the investigation

Answer 109

Produce a grid and select coordinates using a random number generator by using a calculator. Place a quadrat at the intersection of each pair of coordinates and record the species within it. Record a mean and the scale up to the entire area.

Answer 110

Saprobiotic microorganisms like fungi and bacteria, break down organic nitrogen and release ammonium ions into the soil Fertilisers contain urea and ammonium phosphate. Urea is converted into NH3 by enzymes in the soil and then converted into ammonium ions by bacteria

Answer 111

Effect of temperature - at low temperature, enzymes work slowly due to having less kinetic energy therefore less movement and less successful collisions between active site and substrate leading to decreased formation of ES complexes; at high temperatures enzymes are denatured - hydrogen bonds break, tertiary structure unfolds leading to less ES complexes forming Light - rate of photosynthesis increases as light intensity increases; plants grow faster and produce more spores/seeds; animal population that feeds on producers can grow larger pH - enzymes working in extremes of pH above and below the optimum can denature and tertiary structure unfolds leading to less ES complexes forming Humidity - affects transpiration rate in plants and rate of evaporation in animals

Answer 112

Thylakoid stacks in the grana

Answer 113

Nitrifying bacteria- free living soil microorganisms Oxidise ammonium to nitrites(NO2-) The oxidises nitrites to nitrates This is an exothermic reaction which means it releases energy