Unit 2 Core studies

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What is a mutation?
Change in quantity or structure of DNA.
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What is conjugation?
Recombines DNA of 2 individuals.
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What is the process of conjugation?
Conjugation tubes joins another cell; Donor cell replicated plasmids; Plasmid broken into linear pieces; contact is brief so only a small portion of DNA transferred; Recipient cell gains new characteristics
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How do antibiotics work?
prevents bacteria form forming cell walls by inhibiting synthesis and important important polypeptide linkages in cell walls = osmotic lysis
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How does antibiotic resistance take place?
vertical gene transmission and horizontal gene transmission of resistant allele; antibiotics kill normal variety of bacteria causing mutant bacteria to gain an advantage
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What is biodiversity?
number of different species and individuals in one community
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what is ecosystem diversity?
range of different habitats in an area
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What are the different groups of classification in order?
Kingdom; Phylum; Class; Order; Family; Genus; Species
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What is Phylogeny?
evolutionary relationships between species; reflects evolutionary branch; represented by phylogenetic tree
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What is the process of DNA hybridisation?
DNA extracted; DNA labelled; Heated to separate strands; cooled and strands recombine; Hybridisation of combined strands occurs; Hybrid DNA heated again and temperature recorded at each stage
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What does it mean when Hybrid DNA separates at a higher temperature?
More closely related species due to more complimentary bas pairs = more hydrogen bonds = more heat energy needed to separate the strands
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Why is courtship behaviour necessary?
Recognise members of own species; Identified a mate that is capable of breeding; form a pair bond; synchronise mating
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How is courtship initiated?
By a stimulus that leads to a stimulus-response chain
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What are examples of exchange between an organism and its environment?
Nutrients; respiratory gasses; excretory products; heat
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How do insects exchange gas?
Oxygen diffuses through spiracle to the trachea; which split into tracheoles and oxygen is transported directly to the respiring tissue
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How do fish exchange gas?
water taken in via mouth and rushed over gill filaments; lamellae are present to increase surface area; countercurrent flow increases diffusion of oxygen
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What is the structure of arteries, arterioles and veins?
Tough outer layer to resist pressure changes; muscle layer to contract; elastic layer to maintain blood pressure; thin endothelium to prevent friction; lumen where blood flows
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What is the structure of a capillary and its function?
walls consist of thin lining for a short diffusion pathway; numerous and highly branched for large surface area; narrow diameter permeate tissue; lumen is narrow so red blood cell squeezed against capillary; spacing between endothelial cell for WBC
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What is the apoplectic pathway?
water drawn in and more water pulled behind it due to cohesion; creates tension that draws water along cells walls of root cortex; no resistance due to water filled spaces on cells
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What is the symplastic pathway?
osmosis of water into plasmodesmata of cortex cells; increases water potential in cell; higher water potential than next cell; water moves along to next cell via water potential gradient; lowers water potential of first cell and cycle continuous
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How does water pass into xylem?
apoplectic water forced into cell membrane by casperian *****; active transport of salts into xylem to decrease water potential; water then moves into xylem via osmosis;
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What is root pressure?
Force that helps water move up plants
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What evidence is there for root pressure?
metabolic inhibitors; decrease in oxygen availability; pressure increase with a rise in temperature
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How does cohesion tension theory work?
water forms pathway across mesophyll to xylem; water evaporates from stomata in leaf as it is pulled up the stem to the leaf; more water pulled up as it is cohesive; called transpiration pull
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What is the evidence for cohesion tension theory?
change in diameter across tree trunk; xylem vessel broken so tree no longer draws up water and water does not leak out
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What is the role of transpiration?
mineral ions, sugars, hormones moved around while dissolved in water; water carried up; loss of water
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What are the factors affecting transpiration?
Light; Temperature; humidity; air movement (Moving air = higher transpiration rate)
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How do xerophytic plants limit water loss?
thick cuticle so less water can escape via transpiration; Rolling up leaves/hairy leaves/Stoma in pits leads to trapped ration of air saturated with water = no water potential gradient; Reduced surface area:volume = slower rate of diffusion
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Card 2


What is conjugation?


Recombines DNA of 2 individuals.

Card 3


What is the process of conjugation?


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Card 4


How do antibiotics work?


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Card 5


How does antibiotic resistance take place?


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