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biology paper 2 & 3 > topic 4 > Flashcards

topic 4 Flashcards

1
Q

features of cellulose

A

-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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2
Q

primary cell wall

A

-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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3
Q

secondary cell wall

A

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

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4
Q

middle lamella

A

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

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5
Q

plasmodesma

A

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

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6
Q

pits

A

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

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7
Q

lignin

A

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

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8
Q

vacuole

A

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

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9
Q

chloroplast

A

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

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10
Q

xylem

A

-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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11
Q

phloem

A

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

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12
Q

sclerenchyma

A

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

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13
Q

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

A

-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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14
Q

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

A

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

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15
Q

how to detect a change in frequency of an allele

A

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

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16
Q

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

A

-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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17
Q

discuss how beneficial asexual reproduction is

A

+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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18
Q

discuss storing seeds in a seedbank

A

-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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19
Q

how can a suitable dose be found in human trials?

A

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

20
Q

describe how a double blind trial can be carried out

A

-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

21
Q

suggest why a tree species may be endangered

A

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

22
Q

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

A

-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

23
Q

explain how the structure of starch relates to its function

A

-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

24
Q

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

A

-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

25
Q

features and role of phloem

A

-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

26
Q

describe the methods of trialing a drug containing these compounds

A

-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

27
Q

reasons why seed bank store seeds instead of growing whole plants

A

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

28
Q

difference between genetic diversity and species richness

A

-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

29
Q

suggest why some organisms have long flagellums

A

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

30
Q

conditions for max bacterial growth

A

-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

31
Q

species

A

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

32
Q

define molecular phylogeny

A

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

33
Q

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

A

-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

34
Q

DNA profiling>fingerprinting

A

-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

35
Q

DNA sequencing

A

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

36
Q

how can organisms be classified into taxonomic groups

A

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

37
Q

how can organisms be classified into taxonomic groups

A

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

38
Q

gene pool

A

the total of all alleles in a population

39
Q

species richness

A

number of different species in a habitat

40
Q

species evenness

A

relative abundance of each species

41
Q

genetic diversity

A

number of different alleles in a gene pool

42
Q

endemism

A

species found in only one area

43
Q

how to measure biodiversity

A

-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

44
Q

how is wild life threatened by human activity?

A

-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
-

45
Q

allele frequency

A

proportion of one allele within a gene pool

46
Q

why are cells in morula identical?

A

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

47
Q

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

A

-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

biology paper 2 & 3 (4 decks)

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