Can you put a brieft explanation of why its the correct answer. Thanks 16. You’v

Question

Can you put a brieft explanation of why its the correct answer. Thanks

16. You’ve made a hot drink by dissolving a teaspoon of instant coffee coffee and a teaspoon of sugar in a cup of hot water. Which of the following statements is true?

22. Why are lipids Hydrophobic

A. Because they are polar

B. Because they are not polymers

C. Because they are non-polar

37. Insulin is a protein that is produced by pancreatic cells and secreted into bloodstream. which of the following options correctly lists the order of the structures through which insulin passes from its production to its exit from the cell?

A. Rough ER, transport vesicles, Golgi Apparatus transport vesicles, cell membrane

B. Rough ER, lysosomes, tranport vesicles, cell membrane

C. Rough ER, Golgi Apparatus smooth ER, cell membrane

Explanation / Answer

16. Ans. You've just prepared an aqueous solution

Explanation: Solution is a mixture of solute and solvent. In this example Instant coffee powder (which is prepared from roasted coffee, ground and brewed coffee beans-(obtained from Coffea arabica and Coffee robusta of family Rubiaceae) inorder to render it more water soluble. It should be remembered that Caffeine- a xanthine derivative is not completely water soluble and solube only in hot water). Along with coffee powder sugar (sucrose) was added in hot water.

So, it is obviously an aqueous solution consisting of two different solutes i.e., coffee powder and sugar in the solvent of water. Hence, the answer

Second option is wrong since water is solvent but not the solute

Third option is also wrong as we can see from the above discussion that coffee and sugar are solutes but not solvents

Fourth option states that instant coffee and sugar dissolve because they have no charged regions to repel the partial charges on the water molecules which is also not true because caffeine and sugar dissolve by hydrophobic hydration in which the molecules stack face to face with triad of protons rather than by hydrogen bonding or repelling of partial charges

Fifth option is partially true since caffeine is not soluble in cold water, but sugar is soluble in water irrespective of the temperature making this option also a wrong choice

22. Why are lipids Hydrophobic?

C. Because they are non polar

As water is polar in nature and do not share electrons, lipids are not soluble in water making them hydrophobic. Lipids have long hydrocarbon backbones, with less oxygen and do not possess charge. All these properties render them hydrophobic

Option A states that lipids are polar which is not true. Option B states that Because they are not polymers which is also not true because polymers refers to the large molecules which are formed by reaction of large number of monomers by chemical reaction. The properties of polymers depend upon the monomers added. Since lipids are long chain of carbon surrounded by hydrogen, but not a polymer, this option is also wrong

37. Ans. Option A. Rough ER, transport vesicles, Golgi Apparatus, transport vesicles, cell membrane

DNA responsible for Insulin production is unzipped and transcripted to mRNA. With the mRNA insulin proteins are translated and insulin thus formed moves to the Endoplasmic reticulum, and then transported to Golgi apparatus with the help of transport vesicles. The insulin is then modified into active form (PreproInsulin---> Proinsulin----> Insulin) and whenever there is increased glucose level (Hyperglycemia), Insulin is released into the blood stream with the help of transport vesicles thus explaining the above order of transport

Remaining option B and C are not true as they do not follow the above said order. Lysosomes mentioned in second option cannot be true, because Insulin being a polypeptide will be cleaved by the enzymes in lysosomes if it pass through it.

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