9_2DRQ_ANS_ Q1_Q2_Q3 by shiva sharma https://padlet.com/nee_shiva/9_2DRQ_ANS Made with a creative frenzy en-us 2020-04-07 01:21:01 UTC 2025-11-25 13:22:12 UTC hello@padlet.com nicole_chung https://padlet.com/nee_shiva/9_2DRQ_ANS/wish/490234329 1.
ai) Plant increase sugar concentration of phloem sap to high levels by active transport. From a lower sugar concentration to a higher sugar concentration using ATP.
aii) High sugar concentrations means a lower water potential. Therefore, water molecules will move into the phloem via osmosis, the movement of water molecules from a region of high water potential to a region of lower water potential down a concentration gradient. Due to the incompressible nature of water, the movement of water created high hydrostatic pressure in the phloem.
bi) When dietary sucrose concentration is below 0.24mol the percentage of oligosaccharides is  zero. As the sucrose concentration of phloem sap increases after 0.25 and the percentage of oligosaccharides increases at a decreasing rate until it reaches a plateau at 0.50mols.
bii) Aphids secrete enzymes to reduce the solute concentration of the fluid in the gut in order to maintain the concentration gradient between cells in the gut and the surrounding cells. If there is higher water potential in the cells of the gut than in the surrounding cells, then water would leave the gut via osmosis, and the cells would be crenated.
ci) Phloem sap is not the ideal source of amino acids for aphids as as seen in Fig 11, the percentage of essential amino acids in the phloem sap is between 0% to 3% with one exception of one essential amino acid being present at 9% in phloem sap. Non essential amino acids are more widely present in the phloem sap however they are not essential and does not help the aphids in their survival.
cii) Differences in amino acids content in phloem sap and in aphid protein may be due to the higher percentage of non essential amino acids which are not utilised by the aphids in protein formation.
di) Antibiotics can be used to obtain evidence of the role of Buchnera in aphids as on a growth medium without amino acids aphids can grow and reproduce but if an anti biotic is used to kill the bacteria added, the aphids fail to grow. Hence, Buchnera is needed for supplying the amino acids. 
dii) Reasons for few animals using phloem sap as a main part of their diet is due to the majority of it comprising of non-essential amino acids. all 8 essential amino acids are found less than 10% in the phloem sap, with two being found at 0%. If phloem sap was their main diet they would lack protein due to the absence of essential amino acids. ]]> 2020-04-03 03:33:12 UTC https://padlet.com/nee_shiva/9_2DRQ_ANS/wish/490234329 https://padlet.com/nee_shiva/9_2DRQ_ANS/wish/495937432 1. (i) Leaves 1 and 6 
1. (ii) The sink leaves, leaves 1 and 6 are the young leaves and comparatively to the other older leaves, they have a smaller surface area to volume ratio and thus carry out less photosynthesis to produce glucose. Therefore, the source leaves are the ones above and close to the sink leaves. 
1. (iii) The hypothesis is rejected. As seen from Figures 14A and B, the sink leaves are the newly emerged leaves rather than those in between the source leaves. For instance, in 14A,  leaves 1 and 6 are below all the other larger leaves and in 14B, even after pruning, leaves 1,2, and 3 are too, lower than the older leaves. Therefore, it shows that there are pruning does not lead to a rerouting of the translocation pathways. ]]> 2020-04-07 01:47:14 UTC https://padlet.com/nee_shiva/9_2DRQ_ANS/wish/495937432 https://padlet.com/nee_shiva/9_2DRQ_ANS/wish/499856968 i) Leaves 1, 6
ii) In Figure 14A, the sink leaves are closest to the source leaf, whereby source leaves such as leaves 1 and 6 are angled towards the source leaf 14 at the top of the figure. Sink leaves are below the source leaf, closer to the middle. 
iii) The hypothesis is somewhat accepted. Figure 14A shows that with leaf 14 as the source leaf, leaf 6 is directly below the source leaf and receives the most photosynthate as seen by its high shading intensity. However, leaf 9 and is also directly below the source leaf, but receives the same amount of photosynthate, similar to leaves furthest away from the source leaf. The hypothesis is somewhat accepted. Figure 14A shows that with leaf 14 as the source leaf, leaf 6 is directly below the source leaf and receives the most photosynthate as seen by its high shading intensity. However, leaf 9 and is also directly below the source leaf, but receives the same amount of photosynthate, similar to leaves furthest away from the source leaf. In Figure 14B, leaf 10 is the source leaf, and rerouting of translocation pathways to include lateral leaves is seen in the increase in shading intensity of leaf 2. However, the rerouting is not demonstrated in leaf 5 and 7 where the intensity remained the same. 
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