topic 4 Flashcards
species richness
the number of species in a habitat
biodiversity
variety of species in a habitat
variety of alleles in a population
diversity index
higher index, greater biodiversity
record number of species and the number of individuals of each species
describe how the scientific community critically evaluates new theories
communicating theory to specific community
peer review
checking of evidence to ensure its validity
explain the relationship between the structure and functions of a granum in photosynthesis
- granum is formed from many layers of thylakoid membranes to increase surface area
- thylakoid membranes contain chlorophyll to absorb light
- electron carrier molecules in thylakoid membrane involved in ATP production
how are nitrate ions transported from the root to the leaves
through the xylem in water
monomer that makes cellulose
beta - glucose
Every other molecule is inverted
6 carbons
how are monomers in cellulose held together
by 1,4 glycosidic bonds in an unbranched chain
Alternative monomers are inverted
why do seeds need magnesium ions
magnesium is needed to make chlorophyll
because chlorophyll is required for photosynthesis
because shoots need chlorophyll to carry out photosynthesis to grow
(produce glucose during photosynthesis whcih is needed to produce cellulose for cell walls)
plant tissue that has lignin in its cell walls and the position
xylem on inside of vascular bundle. sclerenchyma on outer side of vascular bundle
role of middle lamella when plant cell completes mitosis
produced between adjacent new cells
because the middle lamella holds cell walsl together
Contains calcium pectate
effect of magensium defficiency on plants
limits production of chloroplasts
lack of glucose due to less photosynthesis
plant leaves may be yellow and plants may be small
why does sieve tube element not require RER and ribosomes
no transcription/mRNA so ribosomes not required for translation
no proteins will be synthesised to be processed in ER
polygenic meaning
a characteristic showing variation
caused by multiple genes at different loci
explain how epigenetic chanegs affect development of tissues in embryo
dna is wrapped around histones
histone modification affects binding of rna polymerase
methylation of dna affects transcription of genes
therefore gene expression is altered
difference between organ and tissue
tissue made up of one type of cell
organ made of different tissues
decisions society had to make about embryonic stem cells
they are totipotent
source of them has to be considered
moral issues as embryos destroyed
research establishments to be regulated
totipotent
a cell that has the ability to differentiate into all cell typesd
how do cells become specialised
chemicals cause some genes to be activated
only atcivated are transcribed producing specific mrna
mrna translated to produce specific proteins. this determines cell structure
causing cell modification/different types of cells being produced
amylopectin
alpha glucose
bonds between cellulose molcules in microfibril
hydrogen
role of middle lamella
produced between adjacent new cells becasue they hold cell walls togethr
starch
Polysaccharide made from alpha glucose
Monomers in the chains joined by 1.4 glycosidic links
Contains amylopectin which is branched, so it is rapidly hydrolysed
Insoluble so has no osmotic effect
Branches are joined to chains by 1,6 glycosidic links
Contains amylose which is coiled making starch making
sieve tube
provide a channel
positions in stems of schlerenchyma fibres and xylem vessels
schlerenchyma fibres on the outsid eof vascular bundels
xylem vessels on the inside of vascular bundeles
what contains nucelus
companion cell
the wall of the sieve tube contains
microfibrils, pectin, cellulose
if cells arent totipotent
some genes have already been aciutvated/deactivated
so cant specialsie
as we grow older
fewer mesenchymal stem cells
to replace cells in tissues
stem cells
undifferentiated cell that can give rise to sepcialsiec cells that can divide to produce more cells
Why use stem cells from patient than donor
Genetically identical cells to patient
No risk of rejection
Less risk of infection
No need to take immunosuppressant drugs
Difference between pluripotent and totipotent
Totipotebt can give rise to any cell
Pluripotent can not give rise to extra embryonic tissues
Only totipotent cells can give rise to other totipotent cells
Totipotent cells can give rise to an entire human being while pluripotent cells can’t
Explain why a second sperm cell cannot fertilise the egg cell.
cortical reaction
thickening/hardening of zona pellucida
so sperm cells cannot reach egg cell membrane
Explain why DNA is replicated before mitosis begins
to ensure daughter cells are genetically identical
to ensure diploid number of chromosomes in eac daughter cell
Describe how each gamete receives only one allele of each gene.
homologous chromosomes are separated from one another
sister chromatids are also separated from one another
spindle fibres pull the chromatids to opposite poles of the cell
Describe how the acrosome is involved in the digestion of the zona pellucida
membrane of acrosome fuses with plasma membrane of sperm
releasing enzymes by exocytosis
Explain how large numbers of cells with the same phenotype can be produced in a
tissue.
phenotype is determined by genotype and effect of environment
mitosis produces cells with the same genotype
Describe one advantage and disadvantage of using ropes made from plant fibres rather than ropes from oil-based plastics
Advantage - being sustainable
Disadvantage - less strong
Describe two aseptic techniques that should be used when working safely with bacteria
Boiling culture medium before use
‘Flaming’ of the instruments
Keeping lids off for the minimum time
Disinfecting the bench
Explain why some bacteria can grow rapidly in skin wounds
The temperature is warm, increasing the rate of reactions in bacteria
Availability of energy source from blood
Availability of water for bacterial cell functions
Oxygen availability is good, allowing aerobic respiration
Explain how breeding programmes in zoos maintain 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
Explain why healthy volunteers were give different doses of the drug or placebo
Check for side effects
Different doses to determine safe dose
Placebo to make sure that any side effects described were due to the drug
Compare modern clinical trials with William Withering when he tested digitalis soup
Both trials used different doses
William withering didn’t use healthy volunteers and this drug trial did
William withering did not use a placebo while his trial did
Describe how clinical trials of a vaccine would be conducted.
healthy volunteers are given the vaccine to test for side effects
they are tested for presence of antibodies to the virus
a group of people at risk of contracting the disease is given the vaccine
the number of people who develop the viral disease are monitored
justify the use of vaccine, if clinical trials have not been done
large numbers of people died
health workers are in close contact with people suffering from the disease
side effects of the vaccine will not be worse than contracting the disease
vaccinating immediate family will help to reduce the spread of disease
if health workers were vaccinated they could care for more people
suitable conditions for keeping seeds in a seed bank.
cold and dry
Describe how aseptic techniques are used when handling bacterial cultures.
working near a bunsen burner to provide a convection current
sterilising work surfaces
sterilising equipment with heat
limiting time containers are open
Explain the role that a placebo has in producing valid conclusions
provides a control group for comparison
ensuring that the active ingredient is causing the effect
Explain the role that a double blind trial has in producing valid conclusions
neither doctors nor patietns know who has been given the actual drug
bias has been removed
Explain why the agar plate was incubated at 25 °C.
allow bacteria to multiply
without encouraging pathogenic organisms
Describe roles that zoos play in animal conservation
Protection - from hunting, poachers, vet care
Repopulation - increase numbers, breeding programmes, release back into wild
Education - conservation
Role in research - improving health
Explain advantages of drying seeds before storage
Extends storage time of seeds
Because drying prevents germination of seeds
Prevents damage to seeds
Benefits of conserving seeds
Prevent species from becoming extinct
Conserves genetic diversity
Protected from effects of climate change
Ensures future food security
Conserving species with medical properties
Safeguarding genes that may prove useful in the future
Allow reintroduction of species
Explain why bacteria are able to multiply in bloodstream when they enter body
Warm conditions/water/glucose/ideal pH available
Suitable temperature/pH for bacterial enzymes
Glucose used for respiration
Amino acids used for growth
Advantage of washing seeds
Washing with disinfectant will kill any microorganisms
Why use of fibres from plants is sustainable
More plants can be grown
Plants are renewable source
Available to future generations
Inbreeding effect on genetic diversity
Increases genetic diversity
Introduction of new alleles
Explain how two species may have risen from a common ancestor
Mutation leads to variation within the population
Species with better adaption survive to reproduce
Giving rise to population with differing allele frequency
Populations become reproductively isolated
Explain how molecular phylogeny shows populations are reproductively isolated
Comparing differences in DNA
comparison of amino acid sequences
Greater differences number, more likely they are reproductively isolated
Heterozygosity index
Measure of genetic diversity within a species
Species
Group of organisms that can interbreed to produce fertile offspring
Explain how Hardy Weinberg equation shows natural selection occurring in the population
The equation shows allele frequency in a population
If natural selection is occurring there would be a change in allele frequency over timr
Effect of calcium ion deficiency
Without calcium for the middle lamella new leaves cannot grow fully
Lignin
Strength and waterproofing
Why starch must be broken down before it can be used by cells
Produce glucose
Which is transported easily/soluble/used in respiration
Companion cells
Contain nucleus
Why are plant fibres strong
Cell wall made of strong cellulose microfibrils in a net like arrangement
Secondary thickening, cell wall which is thicker and has more lignin
Why is plastic material only partially sustainable
Starch comes from plants that can be regrown
Not 100% starch so some oil-based products needed
what happens during telophase
spindle fibres break aparrt
chromosomes decondense
nuclear envelope forms
two separate sets of chromosomes
the importance of nitrate ions for plants
used to mkae amino acids
makes DNA
if lacking,growth is reduced
how does dna methylation affect thr activation of a gene
methyl groups attahced to dna
prevents transcription
transcription factors cannot bind to dna
deactivating a gene
compare and contrast the sturcture of unfertilised egg cell with zygote
both contain mitochodnria/rer in the cytoplasm
both possess cell cytoplasm/cell membrane
unfertilised egg has a haploid nucleus whereas zygote has a diploid nucleus
unfertilised egg cells contains cortical granules
Ecosystem
All the organisms living in a particular area
Habitat
Place where an organism lives
Population
All the organisms of one species in a habitat
Community
All the organisms of different species that live in the same habitat and interact with each other
What happened to bare rock to allow growth of trees
- rock colonised by pioneer species
- break up the rock
Dead plants add organic matter as they decompose
Trees able to grow as soil becomes deeper and can retain more water
Test for comparison
T test
What infection control practices have hospitals introduced
Hand wash
Doctors not to wear long sleeves
Disinfection of beds/surfaces
Isolation/quarantine of infected patients
explain how microorganisms in soil break down stems
- stems contain starch or cellulose
- enzymes are secreted by microorganisms
they break down glycosidic bonds
which releasse glucose that is used by microorganisms in respiration
describe how mineral ions are taken up by root hair cells
low to high conc. through carrier proteins, active transport
explian how protection of hotspots can affect global biodiveristy
prevents extinction
loss of these species will decrease global biodiversity
which population is more likely to adapt to changing conditions
the population with more genetic diversity
frequency of allele increases
more likely to have an allele that gives advantage
those with advantageous allele survive and reproduce
Role of products of LDR in Calvin cycle
ATP used to convert GP to GALP
Reduced NADP converts GP to GALP
