Topic 4 Flashcards
Give 3 differences between plant and animal cells
Plants contain chloroplasts
Plant cells have a vacuole
Plants have a rigid cells wall
What are amyloplasts
They are in the cytoplasm and it’s where starch is found in storage vacuoles
What is parenchyma
Plant tissue that help in supporting plants as well as filling in spaces between speculated tissue,they may have specialised functions
What is cellulose
A polysaccharide that give cell walls there strength
What is cellouse made out of and how is it formed
It’s made out of beta glucose as a result of condensation reactions and it contains 1,4 glycosidic bonds
What’s the difference between beta and alpha glucose
The OH group are on opposite sides on the first carbon
Ie beta high and alpha low
What do cellulose form bundles of
They form microfibriles which is when cellouse chains develop hydrogen bonds between them
State the structure of microfibres and what holds them together
They are wound in helical arrangement around a cell wall and a polysaccharide glue sticks it together parallel chains
What are the two branches polysaccharide that hold microfibrils together called
Pectins and hemicellolses
What are plasmodesmata
They are fluid channels that cross cell walls which enable the transport of substances and communication between cells (enable cytosplasm of cells to link
What is the pit in a cell wall
The thin part within a cell wall enables transport of substances between cells
What are the 3 specialised cells for transport in a cell
Xylem vessels
Sclenrencyma fibres
Phloem sieve tube cells
What are xylem vessels
They form tubes that aid in transporting water and minerals and they stiffen cell walls
What are sclerencyma fibres
They provide support for the plant as they stiffen cell walls
What are phloem sieve tubes
They form lung tubes that aid in transportation of sugars and amino acids and organic solute
What about the cell walls of xylem vessels enables them to carry water
They are water proof which allows them to carry water
How do cell walls of xylem vessels become water proof
The plant produces lignin which impregnate the cell wall making it water proof
What is autolysis
The action of enzymes which means they break down cell organelles,cytoplasm and cSM and its leads to dead empty cells forming xylem vessels
What is transpiration
The evaporation of water from the surface of leaves
How is water lost form leaves replaced
By xylem vessels carrying water from the roots
How do xylem vessels carry water up through the plant
They contain minute channels that act like capillaries and by capillary action they draw to water by surface tension between it and water and it’s a continuous process
What is the transpiration stream
The process of s steam of water passing through a plant
What is the middle lamella
It sticks adjacent plant cells together which gives them stability
What is the function of vacuole and tonoplast
The vacuole contains cell sap which keeps the cells turgid
Tonoplast controls what enters and leaves the vacuole
When being carried up a plant why doesn’t water break down
They have cohesive forces between them due to hydrogen bonding
What is cohesion tension theory
The concept of water movement that it’s pulled under tension and molecules are linked cohesively
What are nitirate,magnesium and calcium ions used for in a plant
Nitrate ions are used to make amino acids which enable the plant to grow
Magnesium ions are needed to make chlorophyll which allows the plant to photosynthesis
Calcium ions are needed in the plant cell wall to allow it to grow
Give 4 properties of water
Solvent
Thermal
Density and freezing cohesive
How is water a solvent and why is this useful In a plant
It can dissolve substances as a result of hydrogen bonding
Means substances can be easily transported around the xylem
What thermal properties do plants have
The strength of hydrogen mean its difficult to raise temperate of water
It enables plants to avoid rapid changes in internal temperatures
Why is frozen water less dense than liquid
Frozen water expands and a lot of hydrogen bonds form between these molecules these bonds hold water molecules further apart than in liquid water making water less dense
What are sieve plates
They are at the end of sieve tubes and they have holes in them
What are phloem sieve tubes
They are mostly made of lumen and they remain alive
What is translocation
The transport of organic molecules within in the phloem which requires photosynthesis
What are companion cells and what’s there role
They are along side the sieve tubes and they perform the metabolic functions that maintain the sieve tube and they contain mitochondria ribosomes and RER
What are phloem parenchyma cells
They aid in transporting sugars amino acids and other organic substances
Into the sieve tubes
How are parenchyma transfer cells adapted for their functions
They have lots of plasmodesmsts that link their cytoplasm with adjacent cells
They have increased surface area
They have lots of mitochondria that provides energy to load solutes into sieve tube
What is the method of transport in phloem sieve tubes
Mass transport
Describe stages of transport in phloem sieve tubes
Phloem parenchyma transfer cells load solutes into the phloem,this means by osmosis water to be drawn out into sieve tube from xylem cells
The hydrostatic pressure increase inside the lumen of sieve tube at the loading end
At sinks the solutes are unloaded and in the sieve tube the solute concentration is lowered
The hydrostatic pressure is lowered due to water being moved back into xylem by osmosis
Mass flow occurs as a result of the pressure difference at the loading and unloading sites that
What are sinks in a plant
Parts of the plant where sugar is used not produced
What features of plant fibres enable it to be used for things such as clothing
Strong
Flexible
Long thin
Describe ways in which plant fibres can be extracted
It can be done mechanically which involves pulling them out called retting
What chemical defences do plants produce which prevents attacks
They produce chemicals that may be toxic or distasteful
Have a bitter taste when eaten which may kill the predator
State the way bacteria grow
By binary fission which is an asexual process in which the circular DNA will replicate and new cell content is synthesised before a cell wall forms and divides the cell into equal parts
State the ideal conditions affecting the rate of growth in bacteria
Optimum temperature and ph
No bulid up of toxic products.
Sufficient oxygen
On a graph state each stage in bacteria growth and what occurs in each stage
Lag phase-when cells are adjusting to their conditions
Exponential growth-in their current conditions the cells are starting to divide exponentially at the fastest rate possible
Stationary phase-growth is limited e due to change in conditions
Death phase-the amount of cell firing is greater than amount of cells being formed
State the 5 stages of drug testing
Pre clinical
Clinical
Licensing trials
What happens in pre clinical trials
Thousands of chemicals are used in animal and human tissue cells
They are used to asses safety and to see if the compound is effective against the target disease
(Of
What happens in each of the clinical trials
Clinical trial phase 1- the drug is given to a number of volunteers and they are given different doses the volunteers are are healthy it’s done to see if the compound is absorbed,distributed,metabolised by the body properly
Clinical trials phase 2-a group of between 100-300 people with the disease are treated with the drug to see its effectiveness
Clinical trial phase 3 a large group of volunteers 1000-3000 are selected and divided into 2 groups one group is given the actually drug while the other is given a placebo it’s double blind
The compound being investigated is effective if it shows higher improvement in results than the placebo
What is a placebo
An inactive form of the drug/dummy
What is meant by drug trials being double blind
That neither patient nor doctor is aware of who has the actually drug or placebo
What is speciation
The formation of new species from a group of previously interbreeding organisms that had been geographically isolated
Describe the stages in speciation
A geographical feature like a river/mountain separated a group of individuals from the rest of the population meaning they can’t breed
As a result of different selection pressure and random mutation( which cause change in allele frequency the population become less like on another
If the differences are big enough natural selection occurs in which the two populations will not be able to interbreed
As a result of not being able to interbreed with one another they are considered two different species( they can’t produce fertile offspring)
This leads to speciation
What is biodiversity
The variety of species that belong to different groups of organisms and that’s there’s is genetic diversity in their species
What is the binomial system
The system of coming up with Latin names from groups of organisms
What is the genus
The first part of the name given to species
What is meant by gene pool
It consists of all the alleles present within a population
What is genetic diversity
Measuring of natural variation within the genetic code of a species or population
What is the hardy Weinberg equation used
Measuring allele frequency
Give the hardy Weinberg equation and state what each letter represents
P2+2PQ+Q2
P2- frequency of homozygous dominant individuals
2PQ- frequency of heterozygous individuals
Q2-frequency of homozygous recessive individuals
What is taxonomy
The placing of organisms into groups based on the features they share
What are the 3 domains
Archea
Eurkaryote
Bacteria
What is molecular phylogeny
Looks at DNA molecules and proteins to see how closely organisms are
similar molecules means they are closely related share same bases
How is scientific work like woeses varified
Conferences- in which scientists go and discus there theories to other
scientists
Peer review in which their work is examined and checked by other scientists for validity
Scientific journals in which they publish their work and any experiments they conducted
What are sources of genetic variation
Crossing over
Muatations
Independent assortment
What are the 3 ways of measuring biodiversity and state the difference
Using the biodiversity index
Species richness
Species eveness
Species richness is counting the number of species present in a given area
Species eveness- is a comparison of the size of populations of different species in a particular area
How is genetic diversity measured
Number of heterozygous/
Number of individual in a population
What are the aims of captive breeding programmes
Animals to be reintroduced into the wild
Exchange animals and gamates between zoos
For genetic diversity to be maintained in a captive population
Allowing unrealated mates to mate using stud books
Increasing the number of individuals of a species of numbers are low
What is genetic drift
This is the change in allele frequency some alleles aren’t passed onto offspring
How does inbreeding depression occur and why is it an issue
It results from inbreeding among closely related individuals meaning homozygous genotype rise they are passed into offspring who are less able to survive as a result
State the ways genetic diversity is maintained in zoos
Use of stud books
IVF/new gamates
Exchange animals,gamates between zoos
Allow untealated mates to mate
What does the millennium seed bank do
It aims to maintain and conserve seed samples from threaten plant species
State the ways seeds are stored
They are kept dry in cool conditions to stop them freezing
They are germinated on an agar plate to see if they survive in storage conditions
What happens if germination is below a certain point
The seeds will be grown to collect new seed samples that are placed back in storage
How did withering test the for the correct dosage for dropsy
He used trial and error in which he would gradually increase dosage until side effects showers then would reduce it to get more effective dose
What is a species
A group of organisms that Can interbreed to produce fertile offspring
What is a habitat
A place in which an organisms lived it has a certain set of conditions that enable an organism to thrive in that area
What is a population
A group of interbreeding individuals of the same species found in a area
What is a community
Various populations of organisms within a habitat
What is a niche
The way an organism exploits its environment
What are adaptations and give the 3 types of adapatations
They are features that enable an organism to survive
Behavioural
Anatomical
Physiological
What is meant by behavioural adaptations
Any action by an organisms that enables to survive and reproduce
Ie plants turn their leaves towards to the sun to maximise
What are physiological adaptations
Process inside an organisms body the increase its chance of survival
What are anatomical adaptations
Structural features in an organism and that increase its chance of survival
What is meant by co adaptation
When two organisms become dependent on each other as a result of becoming closely adapated
What is natural selection
The survival of the fittest and the organisms that are well adapted to their environments are more likely to survive and reproduce
What is evolution
A change in allele frequency over time in a population
State the stages of natural selection
As a result of a mutation alleles are created in their are some genetic variation
Change in selection pressures acting on the population occur due to change in environment (create struggle for survival)
An allele that had no previous advantages becomes favourable
Organisms that have that allele as a result are likely to survive and reproduce and pass it on organisms with out the allele die out
The offspring they produce are more likely to reproduce as these alleles become more common in the population
Why are secs stored in dry and cold conditions
This is done to prevent enzyme activity
To prevent germination of seeds as well as them decay
State how in terms of function xylem and sclerenchyma are similar and different
They both provide support for the plant with lignin
They are both waterproof as a result
Differences:
Xylem transports water and inorganic molecules through the plant under tension
While scelrencyma doesn’t
State how terms of function phloem and xylem are similar and how they differ
They both transport substances around the plant
Differences
Phloem transports in both directions
Xylem transports in one direction
State how in terms of structure xylem,phloem and scelrencyma differ
All contain cellouse
Xylem and phloem contain pits while scelrencyma don’t
Phloem and scelrencyma have end walls xylem don’t
Phloem doesn’t contain lignin while the others do
Phloem is alive the others are dead it has companion cells the others don’t
Give two reasons why plant fibres are useful to humans
The arrangements of cellulose microfibrils in the cell wall
Secondary thickening of cell walls
What does the hardy eirinberg equation predict
That allele frequency won’t change over time
What is secondary cell wall thickening and why is it benefitcal
It’s when xylem and scelrencyma produce a secondary cell wall between the normal cell wall and cell membrane
It’s thicker and contains more lignin and it makes plant fibres stronger
