topic 4 Flashcards by Eda Ozkaramanli

features of cellulose

-polysaccahride of beta-glucose
-1,4-glycisidic bond
-every other monomer is inverted
-hydrogen bond between each chain of beta-glucose molecules to form a microfibril
-strong and insoluble, high tensile strength

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primary cell wall

-microfibrils laid down in a criss-cross manner, mesh like str.
-cellulose, pectin and hemicellulose present
-inner to the middle lamella

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secondary cell wall

-thicker and more rigid
-lignin present
-microfibrils arranged in parallel and at right angles
-inner to the primary cell wall

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middle lamella

-formed from vesicles containing calcium pectate during cytokinesis
-holds adjacent plant cells together

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plasmodesma

-forms cytoplasmic bridges between cells
-cell-to-cell transport
-areas of no cell wall

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pits

-secondary cell wall is absent
-no lignin
-involved in cell-to-cell transport
-allow flow of water and dissolved minerals

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lignin

-provide support to the plant
-waterproof
-present in xylem and sclerenchyma

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vacuole

-stores pigments, hydrolytic enzymes and waste products
-keeps the plant cell turgid

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chloroplast

-own loop of DNA
-70s ribosomes
-filled with stroma
-double membrane
-stack up to form granum
-site of photosynthesis

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xylem

-long and hollow tubes with no cytoplasm
-no end walls
-lignin present to help withstand the hydrostatic pressure
-both structural and transport function
-cellulose fibres in spirals or rings
-has secondary cell wall
-dead cells with pits
-impermeable
-one way only

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phloem

-thin with only primary cell wall
-sieve plates
-two way movement
-living cells with no nucleus
-companion cells present

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sclerenchyma

-dead cells with pits
-tapered ends
-thick with cellulose and lignin
-pits

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explain how the arrangement of cellulose molecules and secondary thickening in xylem vessels contribute to its physical properties

-cellulose molecules form microfibrils
-these are arranged in a mesh like structure
-cellulose chains are connencted via hydrogen bonds
-lignin is present in secondary cell wall which makes it impermeable to water
-lignin is arranged in spirals
-the structure is held together by pectate so that microfibrils cannot slide over each other

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why choose plant-based products rather than oil-based products

-sustainable, can be regrown, renewable
-biodegradable
-carbon-neutral

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how to detect a change in frequency of an allele

-use hardy-weinberg’s equilibrium
-DNA analysis to identify differences
-compare allele frequency in previous generations with current generation

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how to determine if an organism is part of a specific species

-molecular phylogeny to establish evolutionary relationship between organisms by looking at their DNA fragments
-morphology, comparing physical appearances
-breed them together to see if fertile offspring is produced

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discuss how beneficial asexual reproduction is

+genetically identical individuals produced in a shorter time
+no need for finding mate
+increase in population
-low genetic diversity can lead to wiping out of most of the population in a changing environment
-more pollens collected from more plants

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discuss storing seeds in a seedbank

-expensive as regular check for viability via X-ray is needed
-time-consuming
+seeds are stored for a longer time and it does not affect wild population
+does not take up much space
+less likely to get damaged by disease
+stay dormant for longer
+needs less maintenance

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how can a suitable dose be found in human trials?

-use a range of doses
-select the minimum conc. with most effective outcomes and least side -effects

describe how a double blind trial can be carried out

-select patients with that disease
-one group is given the new drug, the other is given a placebo
-neither patient nor the doctor knows which treatment they have received
-compare effectiveness of new drug with placebo or existing methods

suggest why a tree species may be endangered

-deforestation
-(fungal) disease
-increased grazing
-reduced pollination
-reduced genetic diversity

differences between distribution of xylem and phloem in the root compared with the stem

-xylem and phloem are contained in (separate vascular) bundles in the stem
-more equal phloem:xylem in stem
-vascular bundles are
arranged in outer part of
stem
-the phloem is closer to the epidermis than the xylem in the
stem

explain how the structure of starch relates to its function

-polymer of glucose because it is an energy source
-branched therefore can be rapidly hydrolysed to release glucose
-compact so more glucose can be stored
-insoluble therefore does not affect osmosis

compare and contrast structure of xylem vessels and phloem sieve tubes in short

-both have primary cells wall
-both do not have a nucleus
-xylem has no end walls, phloem has perforated end walls
-phloem has companion cells wherease xylem does not
-xylem has lignin, phloem does not
-xylem has pits, phloem doesnt
-xyleam has no cytoplasm, phloem does

features and role of phloem

-has companion cells, primary cell wall, perforated end walls, cytoplasm, no secondary thickening, no nucleus -translocation of sucrose and amino acid -from site of production to site of storage

describe the methods of trialing a drug containing these compounds

-compound needs to be extracted from trees and used to make a drug -compounds tested on Y. pestis in vitro -tested on human cells -phase 1> tests on healthy volunteers -review by independent scientists to see if work can progress to stage 2 -phase 2> drug tested on small groups of patients with the disease -appropriate concentrations identified -phase 3> drug tested onlarger groups of patients with plague -placed randomly in two groups - one group receives treatment -double blind test -analyse results with statistical test / t-test

reasons why seed bank store seeds instead of growing whole plants

-takes up less space -needs less maintenance -can survive longer than plants

difference between genetic diversity and species richness

-genetic diversity considers one species whereas species richness considers different species -genetic diversity considers alleles whereas species richness is within a habitat and considers whole organism

suggest why some organisms have long flagellums

-increased chance of fertilisation -as it can swim faster -competition with sperm from other mice

conditions for max bacterial growth

-humidity for hydrolysis and to prevent dehydration -pH for optimum activity of enzyme -temp for optimum enzyme activity -minerals to make own amino acids -amino acids to make proteins

species

a group of organisms with similar characteristics that interbreed to produce fertile offspring

define molecular phylogeny

analysis of molecular similarities and differences between base sequence of DNA and RNA or a. a sequence of proteins of organisms to establish evolutionary relationship between organisms

how can molecular phylogeny be used to determine evolutionary relationship between organisms

-obtain blood sample -compare base seq. of DNA -compare a. a in their proteins -the more similarities they have the more closely related they are -more recently evolved from common ancestor

DNA profiling>fingerprinting

-analyzing non-coding parts in DNA to identify patterns -isolate DNA from organism -cut with restriction enzyme -gel electrophoresis -compare size and position of bands -the more similar bands, the more related the organisms are

DNA sequencing

process by which base sequences of all or part of genome is worked out

how can organisms be classified into taxonomic groups

-similar organisms are put into the same group -observable characteristics -behavioral chr. -similarities in DNA and RNA fragments and proteins

how can organisms be classified into taxonomic groups

-similar organisms are put into the same group -observable characteristics -behavioral chr. -similarities in DNA and RNA fragments and proteins

gene pool

the total of all alleles in a population

species richness

number of different species in a habitat

species evenness

relative abundance of each species

genetic diversity

number of different alleles in a gene pool

endemism

species found in only one area

how to measure biodiversity

-record number of different species in a habitat -calculate biodiversity index -determine genetic diversity by number of different alleles in a gene pool -calculate heterozygosity index

how is wild life threatened by human activity?

-deforestation, pollution lead to habitat destruction -hunting reduces population size -no food or shelter found -introducing new predator by human -fragmentation of habitat by human> harder to find mate -

allele frequency

proportion of one allele within a gene pool

why are cells in morula identical?

-it is formed when zygote divided by mitosis -in interphase of mitosis, DNA is replicated -each daughter cell receives same no of chromosomes

how does the arrangement of molecules contribute to physical pr. in sclerenchyma fibres

-lignin in helices -pectate holds the structure together and prevents microfibrils from sliding over each other -lignin for lateral water movement -microfibrils for reduced flexibility