Topic 4 Flashcards
(155 cards)
1
Q
how has variety of life changed over time
A
generally increases as new species form
human activity threatens it
2
Q
define biodiversity
A
variety of living organisms
can be measured in terms of number of species within a habitat, or by genetic variation within a species
3
Q
what is endemism
A
when a species is found in one geographical location and is unable to be found elsewhere
4
Q
who formulated the natural selection theory
A
charles darwin and alfred wallace
5
Q
what is the definition of species
A
a group of organisms capable of reproducing to create fertile offspring
6
Q
what is a population
A
a group of interbreedig individuals of the same species found in an area
7
Q
what is a community
A
various populations in a habitat
8
Q
what is a niche
A
the way an organism exploits/uses its environment
functional role that it plays within an ecosystem
9
Q
what happens if there are 2 species fulfilling the same niche - use an example
A
they will compete directly with each other and the better adapted organism will out-compete the other and exclude it from its habitat
grey squirrels and red squirrels
red squirrels have now been out-competed and replaced by the grey squirrel
10
Q
what is the hardy-weinberg equation
A
p^2 + 2pq + q^2 = 1
p + q = 1
11
Q
what are the 3 types of adaptations
A
behavioural
physiological
anatomical
12
Q
what is the difference between physiology and anatomy
A
physiology is the features of the internal workings of organisms that help them to survive
anatomy is the structures we can see when we observe or dissect an organism
13
Q
definition of behavioural adaptations and give an example
A
any actions by organisms that help them to survive or reproduce
agoutis burying Brazil nuts which ensures a future food source
14
Q
define physiological adaptations
and give an example
A
features of the internal workings of organisms that help them to survive or reproduce
Danish scurvy grass - able to tolerate very high salt concentrations
15
Q
define anatomical adaptations and give an example
A
the structures we can see when we observe or dissect an organism
bumblebees have very long tongues to suck nectar
16
Q
define co-adaptation
A
when the plant and pollinator become dependent on each other, and more closely adapted
17
Q
what kind of adaptation is knocking body to signal food
A
behavioural
18
Q
what kind of adaptation is a stinger
A
anatomical
19
Q
One type of joint injury is a torn ligament. This may be treated by adding a piece of
tendon to the ligament. This is because after a period of time, the tendon tissue changes and responds in the same way as a ligament.
describe changes in piece of tendon
A
it shows a change in its phenotype
and is an anatomical and physiological adaptation
20
Q
The Scottish wildcat can interbreed successfully with domestic cats.
Explain the effect this could have on the genetic diversity of the Scottish wildcat
A
increase in genetic diversity
because of introduction of new alleles into the population
21
Q
what is the diversity index equation
A
D = N (N-1) / Σn (n-1)
22
Q
Describe what needs to be measured in order to compare the biodiversity of two
rainforests.
A
counting number of different species
counting number of individuals per species
23
Q
Explain how two species of snake could have arisen from a common ancestor.
A
mutation leads to variation in population of snakes
natural selection led to those snakes which were better camouflaged surviving to reproduce
therefore giving rise to two populations with differing allele frequency
the 2 populations become reproductively isolated
sympatric speciation
24
Q
Name the process that could lead to the Brownsea Island population of
squirrels becoming a new species
A
natural selection
25
Describe the features that could be used to identify the prokaryotic cells in the blood sample.
presence of a cell wall
circular DNA
small/70s ribosomes
flagellum
capsule
26
Explain how molecular phylogeny can be used to show that these two populations are reproductively isolated.
comparing similarities and differences in DNA/proteins
comparison of nucleotides
the greater the number of differences, the more likely they are to be reproductively isolated
27
Describe how mutations in badgers to the east of the Bosphorus Strait may lead to this population becoming a separate species.
mutations result in production of new alleles
selection pressure can cause the mutations to be advantageous
more individuals with advantageous allele survive and reproduce
after time, population won't be able to reproduce with other badger species to produce fertile offspring
28
define species richness
measures number of species in a population
29
define heterozygosity index
a measure of genetic diversity within a species
30
Explain why the frequency of this allele may change from one generation to the next
bc allele may undergo mutation
gene flow may cause the allele to be lost or gained from population
due to natural selection
because people with the condition may not have children
31
Explain how the Hardy-Weinberg equation can be used to show that natural selection is occurring in a population.
shows the allele frequency in a population
if natural selection is occurring there would be a change in allele frequency over time
32
production of anti-freeze proteins is an example of
a physiological adaptation
33
The bee orchid, Ophrys apifera, is pollinated by a species of bee, Eucera longicornis, that is
found in parts of the UK.
Males of this species of bee mistake the flower for a female bee.
The bee orchid can also self-pollinate.
The niche of E. longicornis is that it
pollinates the orchid
34
what is the hierarchy if groups
kingdom phylum class order family genus species
35
what are the 5 kingdoms
Animalia Plantae Fungi Prokaryotae and Protoctista
36
what does the animalia kingdom consist of
multicellular eukaryotes that are hetertrophs; organisms thar obtain energy as 'ready-made' organic molecules by ingesting material from other organisms
37
what does the plantae kingdom consist of
multicellular eukaryotes that are autotrophs, organisms that make their own organic molecules by photosynthesis
38
what does the fungi kingdom consist of
multicellular eukaryotes that are heterotrophs that absorb nutrients from decaying matter after external digestion
39
what does the Protoctista kingdom consist of
eukaryotes that photosynthesis or feed on organic matter from other sources but are not included in the other kingdoms; includes single-celled protozoa, such as amoeba and algae
40
what does the Prokaryotae kingdom consist of
prokaryotic organisms; includes bacteria and cyanobacteria
41
what are the 3 domains
Bacteria, Archaea and Eukaryota
42
what are some features of a plant cell
ribosomes, tonoplast, chloroplasts, smooth ER, pit, plasmodesma, middle lamella, rER, chromatin, nucleus, nucleolus, nuclear envelope, mitochondria, cell surface membrane, cell wall, amyloplast, golgi
43
what is tonoplast
vacuolar membrane
44
what is the function of plasmodesma
form a living bridge between them to allow specific molecules to pass through.
45
what is the function of the middle lamella
Cementing together the primary cell walls of adjacent plant cells.
Providing structural support and integrity to plant tissues.
Forming barriers that prevent the movement of substances between cells.
Stabilizing cells and forming plasmodesmata between them.
Being the first layer to form during cytokinesis.
46
what are the plant basics of building strong and tall structures
produce strong cell walls out of cellulose
build columns and tubes rom specialised cells
stiffen some of special cells with lignin
47
what is cellulose
polymer made out of glucose
48
how do trees build up wood
they add a ring of stiffened lignin tissue each year - tree rings
49
what are the fundamental differences between plant and animal cells
plant cells have rigid cell walls and contain chloroplasts
50
what is the function of the pit in plant cells
Pits are depressions on the cell walls that act as channels for the transport of water and minerals between adjacent cells.
They form a morphological and functional unit called the pit pair.
Pit-pairs allow for communication and transport of substances between adjacent cells, especially in xylem and phloem tissues.
51
what does the ability of a population to adapt to new conditions depend on
strength of selection pressure
size of gene pool
reproductive rate of the organism
52
what are the fundamentals of evolution by natural selection
1. population has some naturallt occurring genetic variation with new alleles created through mutations
2. a change in the environment causes a change in the selection pressures acting on the population
3. an allele that was previously of no particular advantage now becomes favourable
4. organisms with the allele are more likely to survive, reproduce and so produce offspring,
5. offspring are more likely to have allele so becomes more common in population
53
what contains cellulose in a plant cell
cell wall
54
what is cellulose made out of
beta glucose monomers
55
what bonds are in cellulose
beta 1,4 glycosidic bonds
56
how do you join 2 beta glucose monomers
condensation reaction and 1 monomer is flipped upside down
57
what are bundles of neighbouring cellulose chains called
microfibrils - bundles of about 60-70 cellulose molecules
58
what are the components of microfibril glue
hemicelluloses and pectins
they bind to the surface of cellulose and to each other the microfibrils together
59
where else are pectins important and what is the function of them
important components in the middle lamella and they act as a cement and hold cells together
60
what bonds form between OH groups in neighbouring cellulose chains and describe their strength
hydrogen bonds
individually weak but collectively strong
61
why are pectins annoying in fruit juice industry
they thicken the juice and make it difficult to extract
62
what are the narrow fluid-filled channels between plant cells called
plasmodesmata
63
Describe how nitrate ions are transported from the root to the leaves
through xylem vessels in water solution
64
These microfibrils are embedded in a matrix containing calcium pectate.
Calcium pectate can be found in the
middle lamella
65
Compare and contrast the structure of cellulose and amylopectin.
both are ploysaccharides/ monomers of glucose
both contain 1,4 glycosidic bonds
cellulose contains beta glucose whereas amylopectin contains alpha glucose
cellulose is unbranched
66
Describe how the tensile strength of these fibres could have been measured.
add 50g bamboo fibre to resin
tensile strength tested by adding masses until fibre breaks
calculate tensile strength by dividing force by cross sectional area
control bamboo species
67
State one difference between the hexose in cellulose and the hexose in amylopectin.
amylopectin contains alpha glucose
cellulose contains beta glucose
68
Name the bond between adjacent cellulose molecules in a cellulose microfibril.
hydrogen bonds
69
Explain why the seedling needs a supply of magnesium ions.
magnesium is needed to make chlorophyll
because chlorophyll is required for photosynthesis
because shoots need to carry out photosynthesis in order to grow
70
Devise an investigation to determine the effect of nitrate ion concentration on the growth of young peanut plants.
use of plants that are clones of each other
range of at least 5 different nitrate concentrations
use a buffer to control pH
grown for a set period of time
measure height
repeat to calculate mean values
71
'The growth of seedlings is affected by the concentration of magnesium ions whereas germination of seeds is not.'
Devise an investigation to obtain valid evidence to support this statement.
range of Mg ion concentrations
measurement of germination rate
use of seedlings germinated in solutions containing all mineral ions
measurement of seedling growth
control temperature
72
Name a plant tissue that has lignin in its cell wall
xylem
sclerenchyma
73
Explain the role of the middle lamella when a plant cell completes mitosis.
produced between 2 adjacent new cells
because they hold cells together
74
explain function of plasmodesmata
cytoplasmic connection in between cells
which allows transport/communication between cells
75
Explain the effects of a shortage of magnesium ions on a plant.
limits production of chlorophyll
lack of glucose and cellulose due to photosynthesis
plant leaves may be yellow/plants may be small
76
Give two reasons why a sieve tube element does not require rough endoplasmic reticulum
and ribosomes.
there will be no transcription and no proteins will be synthesised to be processed in endoplasmic reticulum
77
Cystic fibrosis is a genetically inherited condition. A couple who are both carriers for the condition have a 25% chance of having a baby with cystic fibrosis. In the UK, 1 in 2500 babies born have cystic fibrosis.
Use the Hardy-Weinberg equation to calculate the probability of babies born in
the UK being carriers for cystic fibrosis
(val of q) √1/2500 = 0.02
(val of p) = 1-0.02 = 0.98
(2pq) = 2(0.98 x 0.02) = 0.0392
0.0392 x 100 = 3.92% of population = carriers
78
Muscular dystrophy is a group of disorders that gradually cause muscles to weaken. One type of muscular dystrophy, caused by a recessive allele, affects 10 people in 100 000 of the population.
Calculate the number of carriers in a population of 17.02 million.
Use the Hardy-Weinberg equation, p2 + 2pq + q2 = 1
p = 0.99 q = 0.01
2pq = (0.99x0.01) x 2 = 0.0198
0.0198 x 17020000 = 336996 carriers
79
what is the definition of habitat
a place where an organism lives
80
Pond B is close to a farm and some houses. Chemicals and waste from the farm and houses have increased the levels of pollutants in pond B. The biodiversity index for pond A is 4.81.
Comment on the effect of pollutants on the biodiversity of pond B
species richness is lower
because fewer species can survive in polluted conditions
adaptations are required for conditions
lack of competition allows for a large presence of certain species
81
Describe how the seeds are preserved for long periods of time in a seed bank.
seeds are cleaned and surface sterilised
seeds are then died
and stored at cold temperatures
82
Seed banks obtain seeds collected from a number of plants of each species. Explain the advantages of this for the conservation of a plant species.
ensures genetic diversity/ large gene pool of genetic variation
therefore greater of survival/ adaptation
if plants are reintroduced, conditions may have changed/ may be in different habitats
83
what are the methods are used before the three-phased testing of clinical trials?
testing on animals, isolated cells and tissues
84
Describe the stages of a three-phased clinical trial.
stage 1 involves testing on healthy individuals to assess the side effects and effects on metabolism on healthy humans
stage 2 - testing on patients with the condition to see if drug is effective
stage 3 - double-blind testing on large groups
85
the myoglobin in these shrews has a different, tertiary structure than in other
species of shrew. This allows larger quantities of myoglobin to be stored in their muscles.
Describe how these species of semi-aquatic shrew may have evolved.
genetic mutation leads to some shrews having different myoglobin
shrews with mutation able to feed in water and therefore more likely to survive and reproduce
advantageous allele passed on to offspring
the frequency of the advantageous allele increases over time
86
Explain why the increase in greenhouse gases is leading to a decrease in the
growth of seagrass.
carbon dioxide dissolves in the sea
increasing acidity of the water
increased global warming could increase the water temperature
therefore change in temperature causes
the enzymes to denature so less seagrass survives
87
discuss the possible effects of a reduction in seagrass on animals living in the
Mediterranean Sea.
number of aquatic animals will decrease
les food for primary consumers
due to decrease in photosynthesis
less oxygen for respiration of aquatic animals
more competition between species for food
88
Explain why maintaining a healthy population of seagrass reduces the release of carbon dioxide into the atmosphere
seagrass takes up carbon dioxide during photosynthesis
less decomposition
seagrass is a carbon sink
89
Explain why specialist butterfly species may find it more difficult to adapt to the
changes in spring temperatures
specialist species feed on one type of plant, they may have nothing to feed on
food may not be available at all due to climate change
other species may be competing with specialists for food
generalist species more likely to survive as they can feed off other plants too
90
Golden snub‑nosed monkeys live in areas with very cold winters.
The seeds in their diet contain lipids and carbohydrates.
Climate change is reducing seed production by plants in their habitat.
Discuss the impact of climate change on the monkey population
fewer seeds will lead to a decrease in the plant population
fewer seeds means that there is less food
lipids and carbohydrates contain (large amounts) of stored
energy
the monkeys will not be able to generate enough heat to
survive the cold winters the monkey population will decrease in size (1)
91
the wall of the sieve tube element contains what
microfibrils, pectin and hemicellulose
92
give 2 reasons why a sieve tube element does not require rough endoplasmic reticulum and ribosomes.
no nucleus - no genes to transcribe and translate
no proteins will be synthesised to be processed in endoplasmic reticulum
93
Describe the structure that connects the cytoplasm of the companion cell to the sieve tube element.
plasmodesma
the cell wall has only one layer
94
electron micrograph shows a difference in the number of mitochondria in the sieve tube element and in the companion cell. Explain the difference in the number of mitochondria.
the CC has many mitochondria
whereas the ST has none
the role of the ST is to provide a channel, so cellular
contents are kept to a minimum
the ST has no ability to carry out (aerobic)
respiration
energy is supplied to the ST from the CC
95
Which compounds, found in plants, contain nitrogen from nitrate ions?
DNA Amino Acids and enzymes
96
Describe how nitrate ions are transported from the root to the leaves
through xylem vessels in water
97
The concentration of magnesium ions in the soil was found to be very low.
Explain the effects of a shortage of magnesium ions on a plant.
a shortage of magnesium ions ) limits the
production of chlorophyll
lack of glucose due to less photosynthesis
plant leaves may be yellow / plants may
be small
98
Devise a laboratory investigation to determine the tolerance category of tomato plants to lead ions
use of similar, healthy plants grown in the same conditions up to the start of the experiment
control of the growing environment, e.g. light intensity, temperature
use of growth medium with an adequate concentration of all other necessary ions
measurement of an appropriate specified dependent variable, over the same growing period for all plants
data collection from at least five plants at each concentration of lead, used to calculate mean values
use of different concentrations of lead ions, and a control with no lead
lead concentrations to include 300, 999/1000 and 2000 ppm (boundary concentrations for tolerance categories)
99
Describe two aseptic techniques that should be used when working safely with
bacteria.
boiling culture medium before use
boiling instruments
keeping lids off for minimum time
100
Explain why some bacteria can grow rapidly in skin wounds.
the temperature is warm, increasing the rate of reactions in bacteria
availability of energy source from tissue
availability of water for bacterial cell functions
101
Describe how scientists, after testing the salve on mice, could test whether the salve is an appropriate treatment for humans with wounds infected with S. aureus.
salve must be applied to healthy humans treat one group of patients with the salve and another group with an existing treatment
neither the doctors nor the patients involved in the trial should know which treatment is being used
participants must be monitored for side effects
compare the outcomes of patients treated with the salve and the control group
102
State suitable conditions for keeping seeds in a seed bank
cold and dry
103
Why does the food store in seeds contain starch rather than cellulose
starch is branched and supplies energy more quickly than cellulose
104
Explain why starch must be broken down before it can be used by the cells of
the growing plant
to produce glucose
which is soluble
105
The tensile strength of plant fibres can be tested using different methods.
One method is to attach both ends of a fibre to clamps horizontally and hang
increasing numbers of masses until the fibre breaks.
A second method is to attach one end of a fibre to a clamp and the other to a
forcemeter, pulling on the forcemeter until the fibre breaks.
Explain which method will give more accurate results
the second is more accurate as number is shown on the forcemeter
first is less accurate as the true value will be between 2 masses
106
n modern drug testing protocols, side effects such as nausea will first be
identified in healthy volunteers during
phase 1
107
n modern drug testing protocols, the first stage that patients with an illness
are involved is
phase 2
108
explain the role that a placebo will have in producing valid
conclusions.
bc it provides a control group for comparison
therefore ensuring that the active ingredient/ drug is causing the effect
109
explain the role that a double blind trial will have in producing valid
conclusions.
because neither doctor nor patients know who is being given the drug
therefore bias is completely removed from the trial
110
Drug trials may last 15 years before the drug is licensed. The results of each stage
are analysed before the drug trial can progress.
The results of a trial of a drug for lowering blood pressure are shown in the table.
mean reduction in blood pressure / mmHg
people given drug = 7 ± 12
placebo = 4 ± 8
Deduce why the drug trial was stopped at this stage
drug doesn't show significant improvement when compared with the placebo
ranges overlapped
because some people in trial had increased blood pressure
111
The growth of seedlings is affected by the concentration of magnesium ions
whereas germination of seeds is not.’
Devise an investigation to obtain valid evidence to support this statement
range of magnesium ions
measurement of germination rate
use of seedlings germinated in solutions containing all mineral ions
measure seedling growth
environmental variables controlled - temperature/humidity
112
Herbicides are sprayed on lawns to kill unwanted plants.
Explain how the calculated value of diversity index would change if a herbicide was used on a lawn
value would decrease as fewer species present
113
Explain how the changes in the relative abundance of bee species in the UK may
result in the development of a new species of bee orchid.
The diversity will reduce due to increased self-pollination
Populations that self-pollinate will still produce some variation in their offspring
This variation will be reduced as only one parents’ alleles are used
Genetic drift may occur
Similarities to E. longicornus may not be as obvious
Because there is no advantage / selection pressure to look like a bee
Chance of different gene pool
Leading to formation of two new species
The lack of E. Longicornus in areas of the UK will increase the chance of new species of bee orchid developing there
114
Describe the importance of nitrate ions to plants
nitrates are used to make proteins
plant growth is stunted
if nitrates are lacking
needed to make DNA
115
Devise a laboratory experiment to measure the effect of magnesium ion
concentration on the growth of pea plants
use of plants that are clones/ variety
use a range of magnesium ions
control temperature and mineral concentration
grown for the same time period - 6 weeks
measure growth by height of shoots/ length of roots
repeat at each concentration to calculate a mean
116
Before the 1960s, all of the hedgehogs on this island were dark coloured.
It has been suggested that the blonde hedgehogs are less likely to be killed
by cars at night.
Explain the role of natural selection in the increase in the number of blonde
hedgehogs on the island of Alderney.
cars running over and and killing hedgehogs
hedgehogs with lighter coats survive and reproduce
passing on allele for blonde spines
alleles for advantageous characteristic become more common in population over time
117
the effectiveness of these extracts was tested against the bacteria
Staphylococcus aureus grown in agar jelly in Petri dishes.
Describe how valid results could have been obtained for this investigation.
flame inoculating loop and other instruments
volume of culture added is controlled
same size disc of paper
same mass of plant material used
same incubation temperature and time to incubate
118
Explain the pre-clinical trials that will be carried out when testing a new drug.
tissue samples/ tested on animals
to determine toxicity and safe dosage
119
Explain what is meant by the term double‑blind trial
a trial using a placebo
where the patients and doctor do not know who has been given the drug and who hasn't
to prevent bias
120
Explain how molecular phylogeny could be used to identify the
microorganisms as Archaea and not Bacteria
molecular phylogeny compares DNA
compare sequences of bases
to determine if sequences more similar to Archaea than Bacteria
121
State what is meant by the term niche
the role an organism plays within its habitat
how an organism exploits its habitat
122
Discuss the factors that need to be taken into account when zoos carry out
captive breeding and reintroduction programmes for the greater flamingo.
maintenance of genetic diversity
by selection of mates
to prevent inbreeding
habitat protected
presence of warm water
123
what happens in phase 1 of clinical trials
small group of healthy volunteers to confirm that the drug works as expected within the body
124
what happens in phase 2 of clinical trials
small group of volunteer patients with the condition are treated to test drugs' effectiveness
125
what happens in phase 3 of clinical trial
a double blind trial in which neither the doctors nor the patients know who receives the drug to remove bias from the trial
126
Explain why starch must be broken down before it can be used by the cells of
the growing plant.
to produce glucose
which is soluble
127
Give reasons why the use of fibres from plants is sustainable.
more plants can be grown plants are a renewable resource
128
Six people, who were given the drug, became ill and had to be treated in hospital.
Explain why healthy volunteers were given different doses of the drug or a placebo
check for side effects different doses to determine safe dose placebo to make sure that any side effects described were due to the drug
129
Compare and contrast modern drug testing protocol with that used by William
Withering when he tested digitalis soup
both trials used different doses to determine safe dose
William Withering did not use healthy volunteers and modern drug trials do
William Withering did not use a placebo while this trial did
130
A nucleus will be found in a
A companion cell
B sclerenchyma fibre
C sieve tube
D xylem vessel
A
131
why does the cell wall forms a greater percentage of the total mass of the sclerenchyma fibre than of a phloem sieve tube.
sclerenchyma fibres have thickened, lignified cell walls
132
sloths are slow moving and use their hooked claws to hold onto branches.
They sleep for over 15 hours a day. During this time, their slow metabolism
processes their diet of low nutrition vegetation.
what are the physiological, anatomical and behavioural adaptations
physiological = slow metabolism
anatomical = hooked claws
behavioural = moving slow
133
Explain why they are now classed as different species
no longer able to interbreed to produce fertile offspring
because the populations are reproductively isolated
134
There are currently two major populations of C. hoffmanni in South America.
B. pygmaeus (critically endangered) is restricted to an island off the coast of Central America.
Each population occupies different habitat
Discuss why the number of sloth species may change in the future.
species number may increase due to:
geographical isolation
different selection pressures on the different populations of C. hoffmanni resulting in different allele frequencies
evolution leading to formation of new species
Species numbers may decrease due to:
B. pygmaeus being critically endangered
and there's only one population
therefore vulnerable to inbreeding
at risk of disease
leading to extinction
135
Explain the advantages of drying seeds before storage
extends storage time by preventing germination
136
Justify the benefits of conserving seeds from Boyacá.
prevent species from becoming extinct conserving species with (potential) medicinal properties
safeguarding genes that may prove useful in the future
allow for reintroduction of species (in the future)
137
Explain how tensile strength is related to the arrangement of cellulose in plant fibres.
(many) cellulose molecules held together in microfibrils
hydrogen bonds hold cellulose chains together
criss cross arrangement of cellulose provide strength in both directions
embedded in hemicellulose
prevents cellulose from sliding over each other
138
Explain why the use of bamboo fibres to make coffee cups is sustainable
available to future generations
bamboo is a renewable resource
more bamboo plants can be grown
139
Describe how aseptic techniques are used when handling bacterial cultures.
working near a Bunsen burner (to provide a convection current
sterilising work surfaces
sterilising equipment with heat
limiting time containers are open
140
Explain why the agar plate was incubated at 25 °C.
to allow bacteria to multiply
without encouraging pathogenic organisms
141
Describe how mutations in badgers to the east of the Bosphorus Strait may
lead to this population becoming a separate species.
mutations result in production of new alleles
selection pressures cause the alleles to be advantageous
more individuals with the advantageous alleles survive and reproduce
after time, the population would not be able to reproduce with other badger species to produce fertile offspring
142
Explain why lions that eat antelopes were not released into this game reserve until 2004.
to allow the antelopes time to reproduce
therefore providing a sustainable food source for the lion
143
Explain why choosing lions from different regions increased the genetic diversity
of the lion population
increases chances of mating of unrelated lions
lions will be from different gene pools
maintain range of alleles in offspring
144
Describe the importance of magnesium ions in the production of plant fibres.
magnesium is essential to produce chlorophyll
chlorophyll is necessary to produce glucose during photosynthesis
glucose needed to produce cellulose for the cell walls
145
Explain why the standard deviations were calculated for data
standard deviation gives an indication of the spread of the data
standard deviation indicates validity of mean
overlapping standard deviation values would indicate no difference between the means
146
Describe the arrangement of glucose monomers in a cellulose molecule
monomers are connected by 1-4 glycosidic links
alternate monomers are inverted
147
Devise a method to find the relationship between the actual diameter and the
tensile strength of kapok fibres
isolation of single fibre
diameter of fibre measured microscopy
control of relevant named variable
clamping fibres and hanging masses from the fibre adding increased mass at regular intervals until fibre breaks
repeat to find a mean at each diameter divide the force by the cross-sectional area
148
it is possible to investigate the location of xylem tissue in a plant stem by
using a microscope.
The following method is used:
1. cut the stem of a broad bean plant just above soil level
2. place the cut end of the stem in a beaker of coloured dye for 30 minutes
3. cut thin sections of the stem to view using the microscope.
Explain why the plant is left in the dye for 30 minutes before cutting sections
through the stem.
to allow dye time to travel through and stain the xylem
making the xylem visible under the microscope
149
Explain why captive breeding programmes are important for maintaining biodiversity.
increases population size of species
maintains genetic diversity
therefore prevents extinction of species
150
When these two cubs became adults, they were separated and sent to zoos in
Poland and Italy.
Explain why these offspring were not allowed to remain in the same zoo.
to prevent related animals from breeding to prevent inbreeding depression
to increase genetic variation within the offspring
151
give two reasons why snow leopard cubs born in captivity have not been
released into the wild.
they are needed to maintain breeding programme
not enough suitable habitat
they are not prepared for reintroduction
152
Describe the structure of a cellulose microfibril
cellulose is a polymer of beta glucose
glucose molecules held together with glycosidic bonds
beta monomers for a straight chain
cellulose molecules are held together by hydrogen molecules
microfibrils are composed of many cellulose molecules
153
devise an investigation to provide further, valid evidence that there is a significant
correlation between fibre diameter and tensile strength
extract fibres with a range of diameters including fibres less than 0.09mm
control length of fibre
attach fibres to clamp stand and add masses to it until fibres break
repeat to calculate a mean
calculate tensile strength by dividing force by cross sectional area
plot values on a graph to establish if there is a positive correlation
154
Explain why the area covered by Pando shows less biodiversity than a similar
area of mixed forest.
more species in mixed forest
therefore species richness is low in Pando
low genetic diversity as all Pando plants are genetically identical
fewer animals species as there are fewer habitats/ food sources
155
Explain why the Pando colony is unable to adapt to changing environmental conditions.
they reproduce by asexual reproduction and produces genetically identical clones
and a lack in genetic variation
do not have characteristics is more suitable to the environment
leading to no evolution occurring
