DAT Biology ?

[Beagle]

Which of the following is not a feature of the unit membrane model of the cell membrane?
A. Continuous lipid bilayer present
B. Globular poteins floating in lipids
C. Hydrophobic ends of lipids in contact with water
D. Continuous protein bilayers outside lipid layer
E. Poorly defined pores for movement of large and/or non-lipid molecules

The answer is B.....
However, I was wondering---isn't C the correct answer as well? Is my book wrong? And choice B--aren't there globular proteins in the lipids???

2. All are parts of the kidney except for
A. Glomerulus
B. Loop of Henle
C. Bowman's Capsule
D. Malpighian tubules
E. Collecting Ducts

Answer : E. Can someone explain what the collecting ducts are considered to be in ???? I always thought they were part of the kidneys and diagrams so the such.

3. The greatest resistance to blood flow is in the
A. capillaries
B. Veins
C. Arteries
D. Arterioles
E. Aorta

Answer: D, however I thought it was in the capillaries? Are the capillaries the smallest, or am I wrong?

Thank you~

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[DesiDentist]

Originally posted by Beagle
Which of the following is not a feature of the unit membrane model of the cell membrane?
A. Continuous lipid bilayer present
B. Globular poteins floating in lipids
C. Hydrophobic ends of lipids in contact with water
D. Continuous protein bilayers outside lipid layer
E. Poorly defined pores for movement of large and/or non-lipid molecules

The answer is B.....
However, I was wondering---isn't C the correct answer as well? Is my book wrong? And choice B--aren't there globular proteins in the lipids???

I agree with you.. Hydrophobic means water hating and they are in the inner positon of the phospholipid membrane "sandwich." The answer should be C.


2. All are parts of the kidney except for
A. Glomerulus
B. Loop of Henle
C. Bowman's Capsule
D. Malpighian tubules
E. Collecting Ducts

Answer : E. Can someone explain what the collecting ducts are considered to be in ???? I always thought they were part of the kidneys and diagrams so the such.

Malphighian tubules is the correct answer for question two. Only Arthopods have malpighian tubules not humans. We are dealing with the "ENTIRE" kidney thats why collecting duct and glomerulus count. If it was a nephron I believe you could eliminate glomerulus, depending upon the other choices given. But in this case malpighian tubules is wrong and is the correct choice.



3. The greatest resistance to blood flow is in the
A. capillaries
B. Veins
C. Arteries
D. Arterioles
E. Aorta

Answer: D, however I thought it was in the capillaries? Are the capillaries the smallest, or am I wrong?

I believe capillaries do have the greatest resistance, since when width decreases; resistance increases. I would go with capillaries if I had to guess.


Thank you~

Where did you get these questions. These are very erroraneous and I would be skeptical of every question if I was using this book.

DesiDentist

 

[ItsGavinC]

****DISCLAIMER**** I don't remember 25% of the stuff I used to!

#1. I don't know about because I'm not familiar with the unit membrane model of the cell. Is this different from the fluid mosaic model, or the same?

#2. should be (D). The Malphigian tubules are where salts and uric acid accumulate in arthropods. Human kidneys don't have Mal. tubules.

The collecting duct is most certainly part of kidney structure (its located in the medulla region). Your book is incorrect on this question.

#3. For the purposes of the DAT all you really need to know about are arteries, veins, and capillaries. Of these capillaries would have the greatest resistance to blood flow due to decreased diameter.

Still, from the question given, (D) would be correct. Remember that the arterioles, which are the major site of the peripheral resistance, are within the individual organs, so they can sense what is happening in that organ and alter the flow to that organ alone. For example, when there is a shortage of oxygen in an organ, the arterioles detect this and reduce the resistance to flow in that organ, so that the blood flow increases, bringing more oxygen to the organ. The arterioles have smooth muscle in their walls and the contraction of it will narrow the vessel, increasing the resistance. When the muscle relaxes the pressure inside the vessel will make it dilate; the dilatation will reduce the resistance, increasing the blood flow to the organ.

 

[ItsGavinC]

If it was a nephron I believe you could eliminate glomerulus

The glomerulus is one of the components of the nephron.

And I completely agree with Desi: those questions are relatively useless.

 

[gryffindor]

Question #3 was something that came up when I was reviewing for the boards. The answer given there is that arterioles demonstrate the most resistance b/c they can change their diameter due to the amount of muscle in the tunica media. I am pretty sure that arterioles is the correct answer to this question. I'll post the reference when I find it, I'm not near my books right now.

 

[ItsGavinC]

griffin,

(D) is absolutely the correct answer. As you said, the arterioles have smooth muscle in their walls and the contraction that smooth muscle will narrow the vessel, thereby increasing the resistance.

I still feel the question is a bit useless because the DAT will not test on arterioles.

 

[gryffindor]

ItsGavinC - So they won't ask it on the DATs, but now you've learned something that they may ask on the boards! The problem is remembering it between now and July 2005.

 

[Beagle]

Everyone
Thanks for the replies!!!! So the answer to the last question is indeed arterioles?? Not that we need to know!
I thought the malpighian tubules was a correct answer since the ? did not specifiy if they were referring to a human or insect?
Anyway, these questions came from that horrid williams and wilkins book....
It has many errors so I wanted to check up on it.
Thanks again!

 

[vixen]

I"m up studying the reproduction of plants. WHY do we have to know this? Ok, I can't change the DAT, so back to studying.

 

[DesiDentist]

Originally posted by vixen
I"m up studying the reproduction of plants. WHY do we have to know this? Ok, I can't change the DAT, so back to studying.

because not a lot of people end up studying for it and these points become weed out points. Seema, there are definately going to be questions on plants. Expect 10-15% of the questions to come from botany and photosynthesis.

DesiDentist

 

[ItsGavinC]

Like Desi said, the entire exam is pretty much a crapshoot. I studied the plant sections quite intensively because I felt it was the portion I understood the least (which means I cared about it the least). I would have done just fine on my DAT without studying for that, however.

I had one question about anthers, one question about palisade layers, and 0 questions about photosynthesis.

 

[dent-2002]

Arteriles is definitely correct. I learned that in physiology class. I took kaplan right after taking First yearbio and was jinxed by the number of physiology q's, so i decided to delay the DAT by a year and take physio. so glad I did. Arterioles have stretch sensors that constrict blood. They have msucle. capillaries are like tissue paper. if they provided too much resistance, they would collapse and blood from veins and arteries would be a problem!

 

[UBTom]

Whoa, that's a pretty old thread you replied to there Dent-2002..

Anyway, you definitely would want to remember that one yep-- It's a frequent National Board Part-I question.

 

[DesiDentist]

Wow, what a resurrection.

However, lets hope Beagle didn't miss this question on the DAT, since I believe her DAT was today. I hope she did good.

hey beagle, give us a holler will ya!!!

DesiDentist

 

[nvcwby]

Beagle,

I think that the reason they say that the arterioles have the greatest resistence is because they are the blood vessels that are the smallest most proximal to the heart, thus slowing the blood before it even reaches the capillaries causing the most resistance. This is what makes sense to me I don't know if it is the answer.

Good Luck

 

[UBTom]

Hi Nvcwby,

Beagle is right. The arterioles are the primary contributors to maintaining blood pressure due to the fact that they are the smallest musculated vessels.

When you take physiology in dental school, you will learn that the body has a very powerful hormonal system for controlling blood pressure-- The Renin-Angiotensin system. When renin triggers the release and activation of Angiotensin, it starts a cascade involving the conversion of Angiotensin-I to II in the lungs, which is an extremely powerful vasoconstrictor that causes arterioles' smooth muscles to constrict and make blood pressure skyrocket.

This is why ACE-inhibitors like Prinivil and Zestril are popular antihypertensive drugs-- ACE-inhibitors act on the Angiotensin Converting Enzyme (ACE) in the lungs to prevent the formation of Angiotensin-II, the absence of which causes arterioles to relax and lower blood pressure.

The downside of ACE-inhibitors: because the main site of action of ACE is in the lungs, taking ACE-inhibitors can irritate the respiratory tract and make one cough uncontrollably. Very annoying.

Want to learn more? Get into dental/med school!

And no, the above will not be on DATs. Might make an appearance on National Board Part-I's though.

 

[nvcwby]

UBTOM,

Thanks for the explanation and I definitly look forward to all this wonderful detail in dental school!!!!!!!

Phew atleast it won't be on the DAT!!!!!!!