Topic 4 Flashcards
(112 cards)
1
Q
List the organelles that are only found in a plant cell?
A
- cellulose cell wall
- middle lamella
- plasmodesmata
- pit
- amyloplast
- tonoplast, vacuolar membrane
- vacuole
- chloroplast
2
Q
What is the function of a chloroplast
A
Site of photosynthesis
3
Q
What is the function of amyoplasts?
A
Storage vacuoles containing starch
4
Q
What is cellulose made of?
A
Beta glucose monomers joined by 1,4 glycosidic bonds in a condensation reaction
5
Q
Describe microfibrils
A
- make up the cell wall
- made of cellulose chains joined by hydrogen bonds between side groups
- arranged at angles, in net shape, for strength
- laid parallel for flexibility
- microfibrils are held together by hemicellulose and calcium pectate (pectins)
6
Q
Describe plasmodesmata
A
Narrow cytoplasm filled channels that cross cell walls
7
Q
What is the difference between a pit and plasmodesmata?
A
A pit has a thin cell wall, plasmodesmata don’t
8
Q
Is cellulose a branched molecule/
A
No
9
Q
What is secondary thickening?
A
When lignin is added to the cell wall
10
Q
What is found in a vascular bundle/
A
- xylem vessel
- phloem sieve tubes
- sclerenchyma fibres
- cambium - unspecialised stem cells
11
Q
Describe the xylem structure
A
- lignified, lignin found in spirals and strings for strength and flexibility, water proofs the cell, secondary strengthening
- have absent cell walls
- have pits, allows lateral movement of water
- hollow, no cytoplasm
12
Q
What does xylem transport
A
Water and mineral ions
- via transpiration ONE WAY
13
Q
Describe autolysis
A
Cell organelles are broken down by the action of enzymes, leaves dead empty cells that form a tube
14
Q
Describe the 5 stages of transpiration
A
- water vapour diffuses out through the stoma down a diffusion gradient
- water evaporates from the surface of cells lining the substomatal cavity, water moves by osmosis across the leaf, from cell to cell
- water replaced by Dan’s of capillary action within the cell walls
- water is drawn out of the xylem
- a continuous column of water is drawn up through the xylem
15
Q
Define the transpiration stream
A
Unbroken chain of water molecules
16
Q
Describe cohesion
A
- attraction between like molecules
- hydrogen bonds between the water molecules
17
Q
Describe adhesion
A
- attraction between unlike molecules
- hydrogen bonds form between water molecules and the OH groups of the cellulose cell wall
18
Q
Describe cohesion-tension theory
A
Water is linked by cohesion and is pulled up under tension
19
Q
Water moves thorugh the xylem tube by ___________.
A
Mass flow system
20
Q
Describe the phloem
A
- comprised of sieve tubes and companion cells
- a sieve tube element is a section of phloem with sieve plats at the end
- is alive
- TWO WAY
21
Q
The phloem transports ________ via __________
A
- sucrose and water
- translocation
22
Q
describe the movement of sucrose in a plant
A
- sugars are produced at source
- transfer cells actively pump sucrose into phloem against concentration gradient
- water is drawn into phloem via osmosis due to increased solute concentration, increasing hydrostatic pressure
- diffusion- down a conc.gradient by mass transport
- sucrose is then actively unloaded into transfer cell then sink
- water osmoses back into xylem
23
Q
The plant stem relies on ________, fully ____________ parenchyma cells to maintain its shape and keep it upright
A
- tightly packed
- turgid
24
Q
What is the plant stem comprised of?
A
- parenchyma- provide support
- vascular bundles
- epidermis
- collenchyma tissue- strength
25
What are calcium ions used for?
- calcium pectate in cell wall
- middles lamella
26
What are magnesium ions used for?
- chlorophyll
- nucleic acid synthesis
27
What are nitrate ions used for?
- making amino acids
- chlorophyll, nucleic acids, atp, growth hormones
28
What are phosphate ions used for?
- nucleic acid
- ATP
- phospholipids
- NADP- co enzyme
29
Why do phloem have companion cells/
Provide metabolic support
30
What can starch from seeds be used for/
- stiffening agents
- thickening agents
- super absorbants
- starch foam
31
Define sustainable
-a resource that can be renewed and will not run out for future generations
32
Plants are renewable as the can be _________
Regrown
33
Plants _________ so wont contribute to _________
Biodegrade/decompase
Landfill
34
35
How do bacteria reproduce?
Binary fission
- asexual reproduction resulting in identical cells
36
What are the conditions required for growth?
- optimum temperature
- optimum pH
- optimum oxygen (if needed)
- optimum concentration of glucose
- moisture/water- for hydrolysis
- no build up of waste products
37
Describe the phases of bacterial growth
Lag phase
- no increase in cell number as cells adjust to conditions
Log/exponential phase
- cell number increases exponentially at the fastest rate possible
Stationary phase
- no change n cell number, when cell formation=cell death
Death phase
- cell number decreases as cells die due to change conditions of run out (of space)
38
Define antimicrobial
The ability to kill microorganisms
39
Define generation time
Hw long it takes between new cells forming and cell division
40
What did William withering do?
- found foxglove/ digitalis
- did no test on healthy volunteers
- did not have placebo or double blind
41
What happens in pre-clinical testing
- tissue cultures and animal testing
- assess safety and efficiency
- several years
42
Describe phase one of clinical trials
- small group of healthy volunteers
- safer y and doses
43
Describe phase II clinical trials
- on volunteer patients
- 100-300
- look at effectivnss
44
Describe phase 3 clinical trials
- patients in two groups
- 1000-3000
- placebo and double blind used
- control group for comparison
- efficacy
45
Describe phase 4
- after licensing
- trial continue of wider public
46
Define placebo
An inactive compound or the original drug
47
Define double blind trial
When neither the doctor of the patient know if the drug is being taken or if the placebo is
48
Define natural selection
The mechanism by which organisms change over time as they adapt to their changing environment
49
Differential survival is _____________ sometimes called _________
- natural selection
- survival of the fittest
50
Define evolution
A change inn allele frequency in a population over time/generations
51
Describe the fundamental theory of natural selection/ evolution
- population has naturally occurring **genetic variation** with new alleles created through **random mutations** in DNA
- change in environment creates selective e pressure
- a previously neutral allele has a selective advantage/becomes favourable
- there is competition for survival
- organisms with the allele are MORE LIKELY to survive ,reproduce, produce offspring- pass on the allele
- offspring likely to have advantageous allele so increased allele frequency i gene pool/population
- allow species to become better adapted to a niche
52
What efffects adaptation
- strength of selection pressure
- size of gene pool- greater genetic diversity
- reproductive rate of the organism
53
Define allele frequency
The relative frequency with which an alele is found in a population
54
Define selection pressure
A change in the environment that can affect the organism ability to survive in a given environment
55
Define struggle for existence
Competition between members of a species for resources e.g…… for survival and reproduction
56
Define gene pool
All the alleles of all the genes present in a population of a species
57
Bigger gene pool =
Greater genetic diversity
58
Define genetic diversity
The variety/number of different alleles in a gene pool/population
The frequency of different allels in a particular species
59
What is the hardy-Weinberg equation
P*2* + 2pq + q*2* =1
60
What does p*2* stand for
The frequency of homozygous dominant individuals
61
What does q*2* stand for
Frequency of heterozygous individuals
62
What does 2pq stand for
Frequency of heterozygous individuals
63
In the equation p + q = 1, what does p stand for
Frequency of dominant allele
64
In the equation p + q = 1, what does q stand for
Frequency of recessive allele
65
Hardy-Weinberg principle states….
Allele frequency won’t change if
- population size is large enough to prevent genetic drift
- mating is random
- there is no gene flow
- no mutations/mutation ae rare
- no natural selection
66
Hardy -Weinberg equation can be used to see
Changes is allele frequency over time
- see if evolution has occurred
67
How does genetic diversity arise
- crossing over in meiosis
- independent assortment of chromosomes in meiosis
- random fertilisation
- mutations which change thw base sequence of DNA
68
How can you measure genetic diversity
- observed in external phenotype
- DNA sequencing to detriment what alleles are present
- gel electrophoresis to produce DNA fragments and a **heterozygosity index** cna be calculated
69
How do you calculate a heterozygosity index
Number of heterozygous / total number of individual in population
- measure of genetic diversity
70
Genetic diversity is important as…
The population is more likely to be able to adapt and survive as it is more likely that an advantageous allele is present
71
Define species
A group of closely related individuals that can interbreed to produce fertile offspring
72
For speciation to occur there must be
as isolation mechanism
73
An isolation mechanism will prevent..
Successful interbreeding between populations of species
- reproductive isolation
74
Reproductive isolation prevents…
Gene flow between populations
75
What are the two types of speciation
- allopatric
- sympatric
76
Describe allopatric speciation
- 2 population of same species separated by GEOGRAPHICAL BARRIER
- the two populations are subject to different selection pressures
- will accumulate different random mutations and different allele frequencies will arise/ different alleles selected
- become reproductively isolated so no gene flow between populations
- populations become genetically different
- 2 populations can no longer interbreed to produce fertile offspring
- separate species
77
Define allopatric speciation
Occurs where 2 populations of the sae species are geographically isolated preventing the groups from interbreeding so are now reproductively isolated
78
Define sympatric speciation
Two populations become reproductively isolated in the same environment=ent without any geographical barrier
- due to other isolation mechanisms
79
Give examples of isolating mechanisms
- ecological/habitat - different parts of habitat
- temporal - exist in same area but reproduce at different times
- behavioural- exist is same area but don’t respond the each others’ courtship behaviour
- physical incompatibility - species co-exist but physically can copulate
- hybrid in viability- hybrids produce don’t live long enough to reproduce
- hybrid sterility - hybrids produced can’t reproduce
80
describe the binomial system
- made by Carole’s Linnaeus
-gives every species a unique two-part Latin name
- first part gives genus
- second part gives species
- written in italics
81
Taxonomy is
The science of classifying living organisms
82
How are organisms placed in taxonomic groups
Based off of similarities in pho type and genotype
83
What are the 5 kingdoms
- animalia
- plantae
- fungi
- protocista
- prokaryotae
84
Describe animalia
- multicellular eukaryotes
- heterotrophs
85
Describe plantae
- multicellular eukaryotes
- autotrophs
86
Describe protocista
- eukaryotes
- includes single called Protozoa and algae
87
Describe prokaryotae
- prokaryotic organsisms
- bacteria
88
Describe fungi
- multicellular eukaryotes
- heterotrophs - external digestion
89
what is a taxonomic heirarchy
A series of taxa in which the members all share one or more common features/homologies and ancestors
90
What are the levels of classification
Kingdom, phylum, class, order, family, genus, species
91
What are the 3 domains
Archaea, bacteria, eucarya
92
Who cam up with domains
Carl woese
- identified **methanogens**
-had different RNA sequence to bacteria
-had no peptidoglycans in walls
-had different membrane lipids
93
Define phylogeny
The evolutionary history of a species
94
Define convergent evolution
Unrelated organisms evolving a similar appearance as they adapt tot the same conditions
95
Define molecular phylogeny
Using the sequence of DNA or RNA bases, sequence of amino acids in a protein, or other information about molecular structures to analyse evolutionary relationships and group organisms together based on shared/similar features
96
Define phylogenetic trees
A diagram that shows the evolutionary relationship between organsisms based n molecular differences, they show where species shared and branched off from common ancestors
97
What is the process of critical evaluation
- scientist communicate findings in scientific journals and conferences
- other scientists **peer review** findings to check reliability and validity
98
what is the primary threat to most species and habitats?
human activity
e.g.
- land development- habitat destruction/degradation/fragmentation
- over exploitation
- introduction of alien species
- pollution
99
describe in situ conservation
when speries are protected at the site of the threatened species
- includes protecting and maintaining habitats
100
describe ex situ conservation
when species are protected away from the site of the threatened species
- populations supported in zoos and conservation centres
101
describe captive breeding programmes
- increase population numbers of species whichare at risk
- protect animals from predators/poachers
- will move animals between zoos and use **stud books** to keep record of breeding
-this is important in maintaining/increasing geneitic diversity
- DNA profiling can be used to moniter genetic diversity and decide breeding pairs
- may breed using IVF, artificial insemination or surrogates
102
describe reintroduction programmes
- habitats and carefully chosen to release animals into
- animals are prepared via reinforcing wild behaviour, encouraging hunting
- will raise awareness and educate the local population to protect animals further
103
what is genetic drift
some alleles are lost/not passed onto offspring purely by chance
- happens in small populations
- allele frquency will change overtime
104
what is inbreeding
when closely related individuals reproduce
- offspring more likely to have harmful homozygous recessive alleles
- affects small populations
- results in **inbreeding depression**, lower yield, lower fertility
105
what are plants threatened by
- habitat destruction
- climate change
- over-harvesting
106
how can plants be protected in situ
protecting/managing habitats
107
how can plants be conserved ex situ
seed banks and botanic gardens
108
What is an example of a seed bank
The Millennium seed bank
109
what are the roles of a seed bank
- store many seeds from many plant species
-conserves endangers species, genetic diversity and protects plants
-seeds may contain alleles that prove to be advantageous in the future
- to conduct scientific research (storage/germination conditions)
- work with governments to safeguard threatened habitats
- educate people about the importance of conserving plants
110
how are seeds prepared for storage
- cleaned and dried
- sterilised- prevent decomposition due to microorganisms
- x-rayed to make sure seed contains viable embryo and no parasites
- stored in -20c and dry conditions to extend life span
- subjected to germination checks every 10 years
111
what are the advantages of using seeds
- seeds survive for a longer time
- seeds can be frozen
- seeds are smaller so more can be stored (greater genetic diversity)
- seeds need less maintenance, cheaper
- seeds contain full genetic make up of plant
112
why are cold storage temperatures used
- stops bacterial/fungal growth
- lowers/inhibits enzyme activity
- prevents germination
TO INCREASE SEED LIFE SPAN
