Describe the processes which cause a cell to become specialised
idea of correct stimulus e.g. chemical
2. (stimulus) { activates some genes / inactivates genes
3. { transcription / mRNA produced } at active genes
4. translation of mRNA produces { protein /polypeptide
5. idea that this protein either permanently modifies cell or
determines { cell structure / function
Explain what is meant by the term pluripotent.
idea that cells can divide
2. these cells are { undifferentiated / unspecialised } / these
cells can undergo { differentiation / specialisation
3. idea that they give rise to { most cell types / all cell types
except extra-embryonic tissues } ;
Explain what is meant by the term polygenic inheritance
- more than one gene (for a characteristic) / eq ;
- on more than one locus ;
- idea of continuous variation ;
- idea of cumulative effect of genes
state what is meant by the term species
(a group of) organisms that are capable of {(inter)breeding/mating /reproducing} and producing fertile offspring
name structures present in animal cells that are not present in plant cell
-cilia, glycogen (granules, flagella, centrioles and lysosomes
compound needs to be extracted from trees and used to make a drug
compounds tested on Y. pestis in vitro
tested on {animals / human cells}
(phase 1 / preliminary) (small scale) tests on healthy {people / volunteers}
review by independent {scientists / medics} to see if work can progress to stage 2
(phase 2) - drug tested on {small / 100 to 500} groups of {patients / people} who have the {plague / disease}
appropriate concentrations identified
(phase 3) - drug tested on {larger groups of / 1000 to 3000} {patients / people} who have the plague
placed randomly in two groups - one group receives {treatment / drug containing the chemical compounds} and the
other receives placebo
double blind test
analyse results with (appropriate) statistical test / test for significant difference
what is meant by the term polygenic inheritance
- genes at different loci
- code for the same characteristic
what happens in double fertilisation
-
what does in happen after the sperm cell enters and egg cell
- fusion of cortical granules with cell membrane and release of enzymes - hardening of zona pellucida
- fusion of two haploid nuclei
what xylem vessel transport
- calcium ions from stem to the leaves
how does standard deviation affect reliability
- as SD increase the reliability decreases
how to calculate the heterozygosity index
- analyze the DNA/determine the number of heterozygotes
- divide the number of heterozygotes by the total number of organism population
describe the role of zoos in the conservation of endangered species
- genetic diversity identified as the variety of alleles in a population
- genetic analysis of the endangered organism in zoo and the organism in their island
- increase gene pool
- breeding in zoos or natural habitat
- use of stud books
- increase of habitat
- raising awareness of need for protected area
- recreating similar habitat in zoos/ protection from predators/ food provision
- treatment of diseases
- reintroduction of organisms form captive breeding
- education of local population in country where zoo is located
how scientists could confirm that two different species of this domain
- molecular evidence
- comparison of biological molecules
- analysis of phenotype
- to identify similarities and differences between the two organisms
what is meant by the term organ system
group of organs together to preform one function
what is meant by the term tissue system
group of cells that together to preform one function
compare and contrast the structures of phloem sieve tubes and xylem vessels
Similarities:
* both (fibres) contain cellulose (in the cell wall)
* both have tubular structures
* both do not contain a nucleus
Differences:
* phloem (sieve tubes) have {sieve plates / (perforated) end walls} whereas xylem (vessels) have no end walls/ sieve plates}
* phloem (sieve tubes) {contain cytoplasm / are not
hollow} whereas xylem (vessels) {do not contain
cytoplasm / are hollow}
*phloem (sieve tubes) contain no {lignin / secondary
thickening} whereas xylem contain {lignin / secondary
thickening}
* phloem have plasmodesmata whereas xylem have
pits
Explain how the arrangement of cellulose molecules and secondary thickening in
xylem vessels contributes to the physical properties of the cell wall
cellulose molecules can be organised into microfibrils. (1)
- (due to layers of) {cellulose / microfibrils} arranged in
{different directions / a mesh} (1) - {hydrogen bonds in cellulose molecules / hydrogen bonds in
microfibrils / layers (of microfibrils) / lignin / secondary
thickening / pectate} add {strength / support / stability} (1) - {(cellulose) microfibrils / mesh} held together by {pectin /
pectate} (1) - lignin makes {outside of xylem vessels / cell wall}
impermeable (to water) (1) - the structure of lignin described (1)
describe the function of the tube nucleus
explain how seed banks would prepare , store and assess viability of these seeds
seeds would be (prepared by being) dried
seeds would be treated with an antimicrobial
seeds would be stored in suitable conditions
samples of seeds would be {germinated / x-rayed /
scanned} (to check viability)
replacement seeds would be collected from (these plants)
(1)
describe the structure of blastocyst
- outer cell layer
- inner mass cell
hollow
what does happen in DNA methylation and histone modification
- DNA methylation is the addition of methyl group to cytosine
- histone modification is the (methylation/phosphorylation/acetylation) of histone
- which will cause the DNA to be wrapped more tightly around the histone
- resulting in the inhibition of RNA polymerase binding
- therefore preventing gene expression
what is the function of pits in xylem vessels
- allows movement of water/inorganic ions/mineral ions or communication
- between cells/to other tissues / out of xylem or into xylem
why is water needed for bacterial growth
for hydrolysis/ solvent/ prevent dehydration
