PAPER 3 2023 -

OH H 1/1

starch contains the molecule amylose and amylopectin, amylopectin contains 1,4 and 1,6 glycosidic bonds so is a branched coiled molecules whereas cellulose contains only 1,4 bonds and is a long straight molecule. starch is a polymer made up of alpha glucose monomers where as cellulose is a polymer made up of beta glucose monomers. cellulose is made up of lots of fibres and microfibres that are held together by hydrogen bonds, where as starch does not contain hydrogen bonds. starch’s use is for energy, where as cellulose has a structural role especially in plant cell walls 3/3

starch is made up of amylose and amylopectin, amylopectin has 1,4 and 1,6 glycosidic bonds making it a branched molecule, this means that the branches can be broken down quickly in hydrolysis reactions to be used quickly as an energy source. also both amylose and amylopectin molecules have a coiled structure, this means that they can be packaged tightly in a small area, so large amounts can be stored for when they are needed for energy 2/2

line drawn across the lower abdomen of the locus from the spiracle located under the front leg 0/1

the dissected locust would be covered with water to prevent the exposed tissues from drying out which could alter there internal structures and make them difficult to observe, for example if trying to observe tracheoles, but they have dried they may collapse 1/1

A = trachea 1/1

B = spiracle 1/1

tracheoles 1/1

measure the image size of the of structure a and x

then divide by 0.9 and times the diameter of structure x by that number 1/1

restriction endonucleases 0/1 DNA ligase

the A. tumefaciens bacteria 1/1

the plants can divide through mitosis to form genetically identical cells 1/2

if weeds are present in the soil around the growing soya beans they will take up water, nutrients, ions and space from the soil, this means there is competition for survival for the soya bean plants. if the soya beans are genetically modified and are resistant to herbicides, herbicides can be used to kill the weeds, but the genetically modified soya bean plants will be left unaffected. therefore more plants can grow, and plants will grow larger as the competition between the organisms will have been reduced resulting in a larger crop yield 2/3

to dilute this stock solution i would start by adding 1dm³ (10cm³) of solvent to a beaker. 1g dm³ is equal to 1000 microgram dm³, i divide this value by 1000, and then times this by 300, this would give me an amount of 0.3g dm³ = 300 micrograms/dm³, i would then measure out this amount using a very accurate and sensitive set of scales and add that amount (0.3 g) to the 1dm³ of solvent 0/2

the embryo of a plant does not produce amylase so its not needed for the experiment and the gibberellin will have no effect 0/1

sodium hypochlorite is an alkaline substance so by soaking the grains in the sodium hypochlorite they will have a higher PH which is similar conditions to if they were growing in the ground, this is done to ensure that PH doesnt affect the production of amylase, and is resultedly controlled 0/1

abiotic = i would control the conditions the agar plates are kept in, by making sure the temperature and humidity of the room are the same through the duration of the experiment for all samples by using an incubator 1/1

biotic = i would control the type of grain being used by ensuring they all come from the same species of plant thats been grown in a very similar area and conditions 1/1

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prokaryotic cells have 70s ribosomes whereas eukaryotic cells have 80s ribosomes

prokaryotic cells have membrane bound DNA enclosed in a nucleus and no plasmids whereas prokaryotic cells DNA is not membrane bound and may be in the form or plasmids and not enclosed in a nucleus 2/2

the bacteria collected from the infected person is gram positive this means that it has a thick layer of peptidoglycan in its cell wall causing the red stain to get trapped resulting in it maintaining a red colour from the stain after washing, this is helpful when deciding how to treat the person as antibiotic which works by inhibiting the formation of the bacteria’s cell wall can be selected as these will be the most effective 0/3

prepare a nutrient broth agar plate, take an inoculating loop, Bunsen burner and sample of bacteria, ensure gloves and goggles are worn to stop accidental contamination or infection. take the inoculating loop and place it into the Bunsen burner until it glows red, open the agar dish to forty five degrees and place the loop on the end of the plate to cool it, place the rim of the container holding the sample in the flame and then place the loop into the sample without touching the side, swipe the loop across one corner of the plate before turning the dish 90 degrees and repeating across all four of the dishes corners. close the lid and store upside down in an incubator at the optimum temperature for bacteria growth, for atleast 24 hours leave to grow before repreparing a loop and picking up a cells from an isolated growth on the plate, swipe this across a new plate in the same way, before storing upside down in an incubator 3/4

a solution thats only toxic to the unwanted pathogenic bacteria only could be added to the agar nutrient broth to stop them from being able to survive and grow on the surface, without the wanted bacteria being affected. only open the lid to a fourty five degree angle to stop contamination of unwanted bacteria from the air. 1/3

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