1) least descriptive of lipids
a)non polar
b)hydrophillic (ans)
c)carbon containing
d)amphipathic
On first glance, I thought it was "c" because everything is made up of carbons (carbs, pros, nuc, lipid) that's seemed pretty indescriptive. But its "b" because remember lipids are insoluble in water. I think you made the assumption that a phospholipid (cell membrane) is actually stand-alone lipid. It's not - its a lipid attached to a polar head. And we know that phopholipids have a hydrophilic tail so that's was what threw you off. All the other answers are true. Nonpolar so that do not mix with water/they are long carbon chains/ and they can be amphipathic if they are attached to a polar molecule.
2)least polar of the following
a)ethanol
b)cholesterol(ans)
c)palmitic acid
d)glycocholic acid
Ok, it's not ethanol because it has an -OH group to it. -OH is polar. It can't be either acid because recall, that acids are negatively charged molecules. Think of amino acids ASP and Glutamic they have negative charges. Cholesterol, a steroid precursor (very nonpolar, that's how they can cross cell membranes and go directly into the nucleus, to change DNA), I guess is the only viable answer.
3)which of the following is most likely to form a micelle
a)serine
b)glycerol
c)phospholipid(ans)
d)triglycerol
Yep, an micelle is basically a ball of phospholips. A phosphlipid is a hydrophillic head with a hydrophobic tails. So if you threw an bunch of p-lipids into water, they would immediately form into a ball shape. With the hydrophillic heads in contact with H20 and the tails in the inside protected away from the H20.
4)what is the% of adenine if guanine is 22%
a)22%
b)28%(ans)
c)44%
d)56%
e)78%
Adenine & Guanine are purines while Cysteine &Thymine are pyrimidines. Now remember purines only pair with pyrimidines. (Exp: A cannot pair with G, kinda of like incest). A pairs with T and G pairs with C. So if 22% if G, that means there must be 22% of C too. Because these two must pair with each other. So we now know that 44% of the DNA is C & G. How much is A & T? 100-44 = 56%. We know the amount of A has to be the same amount as T, so all we need to do is divide 56% in half. That gives you the answer 28%
5)peices of dog parotid gland is transplanted under the skin og=f the donor animal ..and after circulation is re established,on ingestion of food,secretion will result from which of the following?
a)parotid
b)pancreas (ans)
c)both pancreas and parotid
d)neither
Uh... I had a difficult time understanding what this ques was asking. But if you take away the stupid dog story it simple asking, "what organ secretes digestive enzymes?" Enzymes such as Trypsin, Trypsinogen, Chymotrypsin etc... are all secreted by the pancreas. So i guess the answer would be (b) The parotid gland is mainly a serous salivary gland. So i'm guessing it plays a minor role in carb breakdown.
i think this is '98 .it would help if you could explain them..thanks for the help
I would strongly recommend you read (I mean really read)
Marieb - Physiology. I just started board prepping and if you are struggling with these questions- then you could be in serious trouble. Marieb will fill any holes in your foundation.
