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55 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Explain speciation |
- geographical isolation (physical barrier) - different selection pressures e.g. climate, disease, predation, competition - mutations > natural selection - advantageous allele = ^ chances of survival & reproduction - lack of allele = death > less competition for resources - allele frequency increases > becomes more common - species becomes GENETICALLY DISTINCT - X reproduce to create fertile offspring > no longer the same species (reproductive isolation) |
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How do seed banks & zoos contribute to scientific research |
(Reintroduction into the wild - both) Zoos: - studying animal behaviour (increases our knowledge of animals’ physiological & nutritional needs) Seedbanks: - medicine, disease resistance - new crops used for new materials |
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What is the role of water in plants |
- photosynthesis > creating it own food - maintaining structural rigidity (> water exerts pressure in vacuhole) - to regulate temperature (> evaporation from leaves helps cool plants down) > maintaining internal conditions - to transport minerals in xylem |
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Similarities between the xylem & phloem |
- contain dead & living cells - form a part of the vascular bundle - show primary & secondary growth - complex tissues composed of more than one cell type - involved in transporting substances |
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Differences between sclernchyma & phloem |
- S is for support P is not - S cells are thickened w/ lignin whilst in P this is not the case - P is for transport of organic solutes S X involved in transport - P contains dead & living cells whilst S only contains dead cells |
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Similarities between xylem & Sclerenchyma |
- both provide support - both contain cells thickened w/ lignin - both are a part of the vascular bundle - both contain dead cells |
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Differences between xylem & phloem |
- X transport water & minerals whilst P transports organic solutes e.g. glucose - X contains mainly dead cells whilst P does not - X provides support whilst P does not |
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Similarities between sclerenchyma & phloem |
- both are a part of the vascular bundle - both contain dead cells |
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Differences between xylem & sclerenchyma |
- X transports water & minerals whilst the P does not - Only X has pits - Only X can do autolysis (breaking down) |
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Importance of nitrate ions in plants |
- to create DNA (proteins & enzymes) - to create chlorophyll - required for growth + fruit & seed production |
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Importance of calcium ions in plants |
- for growth - important component of the plant cell wall > calcium pectate forms a part of the middle lamella + maintains cell membrane permeability |
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Importance of magnesium ions in plants |
production of chlorophyll (> photopigment needed for photosynthesis) |
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What conditions are required for bacterial growth |
- energy source e.g. glucose > respire & grow - moist > water available for bacterial cell functions - oxygen > aerobic respiration > energy - warm > temperature increases rate of reactions in bacteria (temperature & pH > effects enzyme activity > effects metabolic processes) |
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How do seedbanks store seeds |
Dry cold conditions |
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4 problems with re-introducing species into the wild after captive breeding (4 marks) |
- cruel to keep animals in captivity - may find it difficult to communicate & reproduce w/ members of the same species - may introduce a new disease into the habitat |
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Xylem |
- dead cells (no cytoplasm) joined end to end to create long, hollow, uninterrupted tubes (Have no end walls) - thickened with lignin > strength (thick walls) - support - transports water & minerals - pits > no lignin - transports upwards only (from the roots) |
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Phloem |
- dead & living cells - translocation of organic solutes (e.g. sucrose) - sieve tube elements - companion cells - sieve plates (has holes wall extending across the sieve tube elements) allow organic solutes through |
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Sieve tube elements |
Structure: no nucleus, thin cytoplasm, few organelles - living cells (> but unable to carry out ‘living processes’) - joined end by end to form sieve tubes - have holes in them allowing solutes through - paired with a companion cell |
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Companion cells |
- carries out living functions for BOTH itself & sieve tube element e.g. respiration - provide energy for active transport |
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Sclerenchyma fibre |
- dead cells - long tube like structure with hollow lumen & end walls - provides support - thickened with lignin > strength |
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How can you measure species diversity in 2 different areas? |
- species richness (count no. of dif species in the area) - Index of diversity (calculate abundance/ count no. of individuals in species) |
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What is genetic diversity? How can genetic diversity be measured? |
- variety of alleles within a species - Hardy Weinberg principle, heterozygosity index |
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Explain the classification system |
- grouping together based on similarities - 8 levels: domain, kingdom, phylum, class, order, family, genus, species - down hierarchy > fewer organisms in each group - species > reproduce to make fertile offspring - genotype & phenotype |
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Naming a species |
‘Homo sapiens’ First word = genus name (homo) Last word = species name (sapiens) Binomial (two-word) system Unique Latin name for each species |
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When is the Hardy Weinberg principle valid/true? |
- large population - no emigration, immigration, mutations, natural selection - random mating is required |
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Why is the hardy Weinberg principle not true at these times? |
- It predicts allele frequency will stay constant across generations (from one generation to the next) - all these factors do not allow for this statement to be true |
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What is the difference between geographic and reproductive isolation? |
- Geographic isolation is a type of reproductive isolation - reproductive isolation is the major mechanism that leads to speciation |
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Why was the classification system changed |
new evidence from molecular phylogeny > suggested organisms had more in common > archae, bacteria & eukaryota |
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Describe the arrangement of cellulose in a plant cell wall & explain how this relates to the properties of plant fibres (2) |
- net like arrangement of cellulose microfibrils - strength of microfibrils in this arrangement increases plant strength |
microfibrils |
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Describe secondary thickening of plant cell walls and explain how this relates to the properties of plant fibres (2) |
- secondary thickening = production of another cell wall between the plant cell wall and cell membrane - secondary cell wall is thicker (& has more lignin than a normal cell wall) giving plant fibres lots of strength |
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Starch (structure) |
- amylose (1-4, unbranched, coiled > compact) - amylopectin (1-4,1-6, branched, long) > easily releases energy - alpha glucose |
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Bond joining cellulose chains/molecules |
Hydrogen bonds |
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Cellulose (structure) |
- beta glucose (inverted from the previous molecule at each binding point > stops it cooling) - long, unbranched chains - 1-4 glycosidic bonds - straight chains |
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Starch (function) |
- amylose > storage > compact > more can fit into a smaller space - amylopectin > branched (& 1-6 bonds)> glucose can be easily hydrolysed |
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Cellulose (function) |
- unbranched, long straight chains > stronger intermolecular bonds > rigid - microfibrils formed due to h bonds between chains > strength - net like arrangement of microfibrils (cross over each other) > strength |
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How would you identify sclerenchyma fibres phloem sieve tubes and xylem vessels and their location within stems through a light microscope? |
- use a mounted needle to remove vascular bundle from (rhubarb) tissue - place on microscope slide - cover with methylene blue (leave for 5 minutes) - place dilute glycerol on fibres - mount under coverslip - look at under microscope (changing the magnification) |
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What bonds are there between monomers within cellulose |
Glycosidic bonds as the monomers are beta glucose |
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Investigate plant mineral deficiencies |
- IV: minerals present in solution - DV: physical characteristics of the plant e.g. growth - control variables: exposure to sunlight, type of plant, time growing, volume of solution - fill test tube with solution > cover top with cling film > put seed on top - repeats & mean |
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Investigate tensile strength of plant fibres |
- IV: type of plant - DV: amount of mass needed for fibre to break (strength) - Control variables: length of fibre, size of (same) individual masses, thickness of plant fibre - Connect between 2 clamp stands > record when breaks - repeats & mean
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Contemporary drug testing (pre-clinical) |
animal & human cells/tissues |
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Why is it tested on healthy volunteers first? |
- establish if there are dangerous side effects - different doses to determine safe dose |
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Outline historic drug testing methods |
- tested on ppl with the disease - trail & error > determine correct dosage - extract (not pure drug) |
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Contemporary drug testing (clinical phases) |
1) small sample of healthy individuals 2) small sample of ppl with disease 3) large sample of ppl with disease (+one grp receives new treatment & other grp receives existing treatment > see if better) (3 stage process) |
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How to increase validity of drug tests |
- use placebo (see if the treatment has an effect > accounts for psychological effects i.e. improvement shown because the patient thinks they’re being treated) - use a double blind trial (neither patient nor doctors know who has the drug/ placebo > reduces bias > attitudes of patient & doctors x effect results) |
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What is the difference between historic and contemporary drug testing? (Min 5) |
1) pure drug vs extract > valid 2) larger samples > reliable 3) tested on animals and human cells before on humans (pre clinical trials) > safer 4) double blind trials/ placebo used > validity 5) control over factors in tested cohort e.g. age > valid 6) regulated by legislation > safer 7) results analysed statistically > reliable |
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Investigate the antimicrobial properties of plants |
- IV: type of plant (garlic, mint, control) - DV: antibiotic properties > size of zone of inhibition - control variables: temperature of petri dish, volume of plant extract, - disc of absorbent paper dipped into extract, petri dish, inverted & incubated at 25 degrees (for 1/2days), - aseptic techniques used to prevent contamination (e.g. sterilising equipment) - repeats & means |
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How to ensure contamination doesn’t occur on agar plates? |
- sterilised equipment/ disinfect work spaces (destroys microbes) - work under a Bunsen burner (> hot air rises so microbes in the air move away from the plate) |
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Why may plant extracts be soaked in ethanol (antimicrobial practical) |
This will extract the antimicrobial substances as they are soluble (dissolve) in ethanol |
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Why are plant materials more sustainable? |
- renewable > plants can be re-grown > future generations have access to same materials - biodegradable > can be broken down by microbes > dnt remain in the earth |
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How can the use of plant fibres contribute to sustainability? |
- less fossil fuels used to make materials - renewable > can be regrown - biodegradable > can be broken down by microbes - easier to grow & process > cheaper |
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How can the use of starch contribute to sustainability? |
- makes bioplastics & bioethanol - less fossil fuels used to make materials - renewable > can be regrown - biodegradable > can be broken down by microbes |
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Advantages of seedbanks |
- cheap (less space) - little maintenance - stored in dry & cool place (dnt need very specific conditions) - less likely to be damaged by disease, natural disaster |
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Disadvantages of seedbanks |
- test for viability > expensive & time consuming - seeds in remote locations > hard to acquire + costly - expensive to store many seeds |
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Why are organisms re-introduced into the wild? |
- unethical for them to live in a cage - no.s of that species are critically low in the wild > endangered > to conserve the species - restoring habitats that have been lost > helps organisms relying on these plants |
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How do zoos educate people on conservation? |
- empathy > allowed to touch the animals - more likely to support conservation |
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