topic 4 - biodiversity and natural resources Flashcards
how can the physical properties of xylem and sclerenchyma fibres be used by humans
in materials that require strength eg ropes and fabrics
relate the structure of xylem and sclerenchyma fibres to their function
-cellulose microfibrils form net like arrangement in cell walls of the fibres
- secondary thickening further strengthens the fibres by adding lignin
- fibres are suited to their function of structurally supporting the plant
relate the structure of cellulose to its function
- long beta glucose chains held together by hydrogen bonds to form microfibrils
- hydrogen bonds very strong, so cellulose suited to providing structural support within cell walls
- high tensile strength makes it possible for cell walls to withstand turgor pressure
- cellulose fibres and lignin found in cell wall form a matrix which increases the strength
differentiate between xylem, phloem and sclerenchyma fibres
- xylem vessels transport water and minerals, and provide structural support. long cylinders made of dead tissue with open ends. thickened with lignin
- phloem are tubes of living cells involved with translocation
- sf provide structural support. short structures made of dead cells with hollow lumen and end walls. thickened with lignin
why is water required in plants
-photosynthesis
- maintains structural rigidity (turgidity)
- transport of substances
- thermoregulation
magnesium ions
- involved in chlorophyll production which is necessary to produce glucose during photosynthesis. this allows glucose to be available for respiration and ATP production
-activate some of plants enzymes
nitrate ions
supply nitrogen for making DNA,RNA and chlorophyll
calcium ions
- component of cell wall - the form calcium pectate
- essential for plant growth
function of pith
act as packing between other cells and tissues
Xylem
- function
- structure
- transport water and mineral ions, provide support
- long, tube like structure formed from dead cells. Found in bundles
- hollow lumen and no end plates which makes an uninterrupted tube so flow of water is not slowed
- walls thickened with lignin to withstand water pressure
- small unlignified regions in the wall called pits which allow for lateral movement of water and minerals between xylem vessels
- no protoplasm to not impede the mass flow of water
- small diameter of vessels to prevent water column from breaking
How do water and mineral ions move into xylem
Through pits in the wall where there is no lignin
Sclerenchyma fibres
- function
- structure
- provide support
- made of dead cells, hollow lumen and HAVE end walls
- lignin but no pits like xylem
Phloem
- function
- structure
- transport organic solutes and sugars: this is translocation
- not used for support, only transport.
- contains sieve tubes and companion cells
- sieve tubes are living cells joined end to end. The ‘sieve’ parts are the end walls which have holes to allow solutes to pass through. They have no nucleus, thin layer of cytoplasm and few organelles. Lack of nucleus means they can’t survive on their own so need a companion cell
- companion cells carry out the living functions for themselves and sieve tubes. Eg energy for active transport
Biodiversity definition
The variety of living organisms in an area
Species diversity definition
The number of different species and the abundance of each species in an area
Genetic diversity
The variation of alleles within a species
Endemism definition
When a species is unique to a single place
What has human activities done to biodiversity
Natural selection, has increased biodiversity, but human activities such as farming are having the opposite affect
What are the right conditions for bacterial growth
- A source of nutrients to provide them with the materials needed for growth and respiration
- Supply of oxygen for aerobic respiration
- Correct temp and pH
Explain how drug testing used to occur - william witherings digitalis soup
- He discovered an extract of foxgloves could be used to treat dropsy
- Withering made a chance observation - a patient suffering from dropsy made good recovery through traditional remedy containing foxglove
- He then tested different versions of the remedy with different concentrations
- Too much positioned his patients
- Through trial and error he discovered the correct dosage
Describe modern drug testing
- Computers used to model potential effects and tests done on human tissues, then live animals
Phase one: drug tested on group of healthy individuals to find out safe dosage and side affects
Phase two: tested on larger group of people
Phase three: compared to existing treatments. Double blind study
What makes clinical trials more valid. And explain why
Placebos: in phase two patients split into two groups. One given a placebo to see if drug actually works
Double blind study: phase 2 and 3 are usually double blind - neither doctor or patient knows which patient has been given drug or placebo. Reduces bias in the results.
what measures biodiversity and what is the equation
heterozygosity index
H= number of heterozygotes/number of individuals in the population
index of diversity equation
D = N(N-1)/the sum of n(n-1)
what is ecological niche
- the species role within the community
- the species which share the same niche compete with each other, the better-adapted species will outcompete the other forcing it to alter its niche or die.
3 versions of adaptation
- anatomical
- behavioural
- physiological
anatomical adaptations
physical adaptations, either external or internal
behavioural adaptations
changes in behaviour which improve the organisms chance of survival
physiological adaptations
processes that increase an organisms chance of survival
natural selection definition
the process in which fitter individuals who are better adapted to the environment survive and pass on the advantageous alleles to future generations
evolution definition
the process by which the frequency of alleles in a gene pool changes over time as a result of natural selection
explain why offspring may be genetically different even if they have same mother and father
- each gamete contains different combination of alleles
- there is a different combination of alleles due to crossing over during meiosis
Magnesium deficiency
stunted growth, yellowed leaves (because chlorophyll
cannot be synthesised).
Nitrate deficiency:
yellowed leaves with red-brown cast (because chlorophyll
cannot be synthesised as protein synthesis is restricted).
Calcium deficiency
stunted growth, weakened stem (because the support
from the cell wall is reduced and metabolism is restricted due to decreased membrane permeability)
investigation for plant mineral deficiencies
- Use the measuring cylinder to fill test tubes with each of the nutrient solutions.
- Cover the top of the test tube with tinfoil. Poke a hole through the tinfoil.
- Push the roots of the Bryophyllum plantlets through the hole in the tinfoil into
the solution. - Wrap the test tubes in tinfoil (to prevent light getting in) and place them under a
sunny window.
how can molecular phylogeny be used to show populations are reproductively isolated
comparing similarities and differences in { DNA / proteins }
(1)
comparison of { nucleotide sequences / amino acid
sequences } (1)
the greater the number of differences, the more likely
they are to be reproductively isolated (1)
why do we need standard deviation
standard deviation gives an indication of the spread
of the data (1)
standard deviation indicates validity of mean (1)
overlapping standard deviation values would
indicate no difference between the means (1)
Describe the arrangement of glucose monomers in a cellulose molecule.
monomers are connected by 1-4 glycosidic links (1)
alternate monomers are inverted (1)
if ATP production was inhibited how would this affect transport within plant tissues
translocation inhibited but transpiration stream not
inhibited (1)
• phloem contains cytoplasm but xylem does not (1)
• cytoplasm has organelles/mitochondria involved in
metabolism (1)
It is thought that this difference may cause epigenetic changes.
Explain how these changes might affect the functioning of the genome.
methylation of DNA base, therefore the expression of the
gene is changed (1)
if histones are modified, this may affect binding of other
proteins to DNA because DNA is wrapped around
histones (1)
therefore genes may become activated or repressed (1)
what temp should be used for bacterial incubation
25 degrees to prevent production of human pathogens
lower temperatures would inhibit growth
why are plant fibres useful to humans and more sustainable
- sustainable and renewable as can be regrown
- biodegradable, as can be broken down by microbes
- very strong so can be used to make ropes etc
- cheaper than oil production
how do captive breeding programmes work
- endangered species are carefully bred to increase genetic diversity and population size
- genetic diversity is maintained via exchange of organisms
- reintroduction programmes release animals into natural habitats to restore lost ones
how do seek banks work
- store large no of seeds to conserve genetic diversity and prevent species becoming extinct
- cheaper than storing plants as takes up less space
- stored in cool dry conditions as this maximises time they can be stored and they are periodically tested for viability
how do education programmes work
- aim to educate people about the importance of maintaining biodiversity, captive breeding and illegal trade of animal products
- national parks and sites of specific scientific interest aim to conserve habitats and biodiversity
sustainability definition
using resources in such a way that the requirements of the current generation are met without depleting the resources for future generations
renewable resources definition
can be used without the resource running out
how can starch be used for sustainability
- can be used to make bioplastics which is more sustainable than oil based plastics
- does not require as many fossil fuels to be burned to produce them and the crop plants can be replanted
- starch can also be used to make bioethanol
antimicrobial definition
the substance will either kill microbes or prevent their growth
what is the modern method of drug testing
- The first step is modelling the potential effects of the drug using computers
- Next, the drug will be tested on human tissues in a laboratory, before being tested on animals
- clinical trial stage which includes three phases
Phase 1 involves a small group of healthy individuals to determine how the body will react to the drug, side effects of the drug and the correct dosage that
should be taken
Phase 2 will be done on a larger group of patients (non-healthy individuals who require the drug) to determine the effectiveness of the drug
Phase 3 involves comparing the drug to existing drugs to see if it works any better. A large number of patients are split into two groups, each of which receives either the new drug or the existing one
explain the structure and adaptations of sieve plates
cellulose cell wall: strengthens the wall to withstand hydrostatic pressure
no nucleus, vacuole or ribosomes: maximises space for translocation
thin cytoplasm: reduces friction to allow movement
explain the structure and adaptations of companion cells
- nucleus and other organelles present: provides metabolic support to sieve tube element and helps with loading and unloading of assimilates
- transport proteins in plasma membrane: moves assimilates into and out the sieve tube elements
- large amount of mitochondria: to provide ATP
- plasmodesmata: allows organic compound to move from companion cells into sieve tube
advantages and disadvantages of seed banks
advantages:
- more cost effective to store seeds compared to fully grown plants
- seeds take up less space, so more can be stored
- less labour intensive
- can be stored anywhere in the world
- less vulnerable to disease or natural disaster
disadvantages:
- testing seeds for viability is expensive and time consuming
- challenging to collect seeds from plants growing in remote habitats
pros and cons of zoos
pros:
1. provides greater understanding of species needs and aids conservation efforts in the wild
2. scientists can carry out studies that would be hard with wild populations
3. contribute to educating the public about endangered species
cons:
1. captive breeding of small species populations can reduce genetic diversity
2. zoo animals may not behave how they do in the wild studies could be invalid
3. not all zoos provide adequate habitats for animals
what are the three domains
archaea
bacteria
eukarya
what are the main factors affecting biodiversity today
- habitat destruction
- when land is cleared for human resources this leads to habitat loss and habitat fragmentation - overexploitation
- hunting
- agriculture (fertilisers and pesticides)
- climate change
how does skin in humans allow bacteria growth
temp is warm, increasing rate of reactions of bacteria
availability of water for bacteria cell functions
oxygen is available allowing aerobic respiration
explain the role of the middle lamella when a plant cell completes mitosis
produced between adjacent cell walls
because the middle lamella holds cell walls together
why should starch be broken down before being used by the plant
- to produce glucose
- which is soluble
tensile strength definition
force the fibre can withstand before breaking
describe the positions in the stem of the tissues that contain lignin
sclerenchyma fibres on the outer side of the vascular bundle
xylem vessels on the inner side of the vascular bundle
standard deviation definition
spread of data around the mean
experiment for observing the stages of mitosis
- cut a 5mm sample of a root tip using a scalpel
- transfer root tip to sample tubes containing HCl and leave for 5 minutes
- transfer to watch glass containing cold distilled water. leave for 5 minutes
- dry root tips on filter paper
- place tip on a microscopic slide. macerate with a needle to spread the cells out
- Add a drop of toluidine blue to the slide and leave to stain for 2 minutes.
- Lower the cover slip down carefully onto the slide.
- place under microscope and adjust focus
mitotic index equation
number of cells with visible chromosomes/ total number of cells in sample
method for identifying plant stems
- Calibrate the eyepiece graticule by placing both on the stage and lining up the divisions of the stage micrometer
- Cut transverse sections of the plant stem as thinly as possible
- Place one section on a microscope slide. Draw a line in wax crayon from top to
bottom of the slide either side of the specimen to prevent the dye from spreading. Add
a few drops of concentrated phloroglucinol and lower the cover slip down carefully
onto the slide. Make sure there are no air bubbles in the slide which may distort the
image. - place under microscope and adjust focus
investigating plant mineral deficiencies
- Use the measuring cylinder to fill test tubes with each of the nutrient solutions.
- Cover the top of the test tube with tinfoil. Poke a hole through the tinfoil.
- Push the roots of the Bryophyllum plantlets through the hole in the tinfoil into
the solution. - Wrap the test tubes in tinfoil (to prevent light getting in) and place them under a
sunny window.
antimicrobial properties method
- Carry out aseptic techniques
- Crush 3g of the garlic and mint (separately) with methylated spirit. Shake occasionally.
- Use a sterile pipette to transfer plant extract to paper disc.
- Leave paper discs to dry for 10 minutes.
- Use sterile forceps to place the paper disc onto a petri dish.
- Lightly tape a lid on, invert and incubate at 25°C for 24 hours. DO NOT tape around the entire dish as this prevents oxygen entering and so promotes the
growth of more harmful anaerobic bacteria. - Sterilise equipment used to handle bacteria and disinfect work surfaces.
- Measure the diameter of the inhibition zone (clear circle) for each plant. DO
NOT remove lid from agar plate. - Work out the area of the inhibition zone
investigating photosynthesis (the hill reaction) practical
- Remove stalks from leaf samples. Cut into small sections. Grind sample using a
pestle and mortar and place into a chilled isolation solution. - Place several layers of muslin cloth into funnel and wet with isolation medium to
filter sample into a beaker. - Suspend the beaker in an ice water bath to keep sample chilled.
- Transfer to centrifuge tubes and centrifuge at high speed for 10 minutes. This
will separate chloroplasts into the pellet. - Remove supernatant and add pellet to fresh isolation medium.
- Store isolation solution on ice.
- Set the colorimeter to the red filter. Zero using a cuvette containing chloroplast extract and distilled water
- Place test tube in rack 30cm from light source and add DCPIP. Immediately take
a sample and add to cuvette. - Measure the absorbance of the sample using the colorimeter
10.Take a sample and measure its absorbance every 2 minutes for 10 minutes.
11.Repeat for different distances from lamp up to 100 cm. This will vary the light
intensity.
advantage and disadvantage of ropes made from plant fibres rather than oil-based plastics
-sustainable and biodegradable
- less strong
Explain how breeding programmes in zoos maintain the genetic diversity of captive
populations.
animals are selected to prevent breeding between closely related individuals
a stud book is used to select individuals for mating
exchange of animals between zoos
Compare and contrast modern drug testing protocol with that used by William Withering
- both use different doses to determine safe dose
- ww did not use healthy volunteers
- ww did not use placebos
why is a placebo and a double blind trial used…
placebo:
- provides a control group for comparison
- ensuring that the drug is causing the effect
double blind:
- neither doctors nor patietns know who received actual drug
- therefore removes bias from the trial
why is agar incubated at 25 degrees
to allow bacteria to multiply without encouraging pathogenic organisms
Explain the advantages of drying seeds before storage.
- extends storage time of the seeds
- because drying prevents germination
justify the benefits of conserving seeds
- prevent species from becoming extinct
- conserves species with potential medicinal properties
- allows for reintroduction of species in the future
- conserves genetic diversity
- helps to ensure future food security
- crops protected from natural disasters
washing the seeds with disinfectant
allowing the seeds to dry.
Explain the advantages of these two stages in regards to seed banks
-washing with disinfectant will kill any microorganisms
- drying reduces chance of germination
- therefore preventing decay/damage to the seeds
taxonomy definition
practice of biological classification
characteristics and features of Archaea
prokaryotic
circular chromosome
cell membrane lipids: glycerol - ether lipids
ribosomes : 70s
cell wall always present
histones
sometimes introns
characteristics and features of eubacteria
prokaryotic
circular chromosome
cell membrane lipids: glycerol - ester lipids
70s ribosomes
cell wall always present
no histones
rarely introns
characteristics and features of eukaryotes
eukaryotic
linear chromosomes
cell membrane: glycerol - ester lipids
80s ribosomes
cell wall sometimes present
histones
introns
what assumptions does hardy weinburg make
- the population is large
-mating is random - no new mutations have arisen
- no natural selection
how does lignin form
- during a process called secondary thickening
- when xylem and sf have finished growing they produce a secondary cell wall between the normal cell wall and the cell membrane
- this second cell wall is thicker than the first and contains a higher proportion of lignin
how does a lack of nitrate ions affect processes in the plant
photosynthesis : translation of proteins such as chlorophyll and photosynthetic enzymes will be reduced so less photosynthesis takes place. leaves will be yellow, and the lack of glucose synthesised results in reduced respiration, leading to stunted growth
cell division: since cell division relies on dna replication, nitrate deficiency reduces cell division and growth. this contributes to stunted growth and also results in reduced seed and fruit production
