Login

Welcome, Guest. Please login or register.

March 29, 2024, 10:46:54 am

Author Topic: % of DNA?! How do i solve these MC questions?  (Read 3607 times)  Share 

0 Members and 1 Guest are viewing this topic.

kaiz0r

  • Victorian
  • Adventurer
  • *
  • Posts: 6
  • Respect: 0
% of DNA?! How do i solve these MC questions?
« on: June 05, 2009, 04:21:50 pm »
0
I have no idea how to go abotu doing this question? can someone give me full working out please? It's from the IARTV Unit 3 Paper.

If the percentage of bases on the strand of DNA being copied is 35% thymine, 20% guanine and 15% cytosine, the percentage of bases in the RNA that is produced in this copying process will be
A.   15% thymine
B.   35% guanine
C.   15% adenine
D.   30% uracil

The answer is supposed to be A.

There was also a similar question:
The Percentage of the base adenine in human DNA is 31.2%... this means that:
A. 18.8% of Cytosine.

What happened here?

Thanks in advance!

n.f

  • Victorian
  • Trendsetter
  • **
  • Posts: 147
  • Respect: +1
Re: % of DNA?! How do i solve these MC questions?
« Reply #1 on: June 05, 2009, 04:44:15 pm »
0
The first one isn't clicking for me atm but the second one is:
The Percentage of the base adenine in human DNA is 31.2%... this means that:
A. 18.8% of Cytosine.
31.2% X 2 = 62.4 A=31.2 so T = 31.2
100 - 62.4 = 37.6% remaining for C + G
37.6/2 = 18.8

kaiz0r

  • Victorian
  • Adventurer
  • *
  • Posts: 6
  • Respect: 0
Re: % of DNA?! How do i solve these MC questions?
« Reply #2 on: June 05, 2009, 04:47:11 pm »
0
okay! thanks! :) That helps heaps!

hard

  • Guest
Re: % of DNA?! How do i solve these MC questions?
« Reply #3 on: June 05, 2009, 05:34:40 pm »
0
there shouldn't be maths in bio!

NE2000

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1221
  • living an alternate reality
  • Respect: +4
Re: % of DNA?! How do i solve these MC questions?
« Reply #4 on: June 05, 2009, 05:39:41 pm »
0
there shouldn't be maths in bio!

Just simple stuff normally, in Unit 4 there is generally one simple ratios question in all of the exams (both VCAA and trial) although this expected question was missing from last year's Unit 4...
2009: English, Specialist Math, Mathematical Methods, Chemistry, Physics

kaiz0r

  • Victorian
  • Adventurer
  • *
  • Posts: 6
  • Respect: 0
Re: % of DNA?! How do i solve these MC questions?
« Reply #5 on: June 05, 2009, 06:47:11 pm »
0
there shouldn't be maths in bio!

Hahhahaha agreed! This is as hard as it gets i guess

Mao

  • CH41RMN
  • Honorary Moderator
  • Great Wonder of ATAR Notes
  • *******
  • Posts: 9181
  • Respect: +390
  • School: Kambrya College
  • School Grad Year: 2008
Re: % of DNA?! How do i solve these MC questions?
« Reply #6 on: June 05, 2009, 06:57:46 pm »
0
If the percentage of bases on the strand of DNA being copied is 35% thymine, 20% guanine and 15% cytosine, the percentage of bases in the RNA that is produced in this copying process will be
A.   15% thymine
B.   35% guanine
C.   15% adenine
D.   30% uracil

I don't do biology, but remembering stuff from chemistry last year, shouldn't it be D?

There are 35% T, 20% G, 15% C hence 30% A in DNA, copied onto RNA of same length will give its complementary, 30% U
Editor for ATARNotes Chemistry study guides.

VCE 2008 | Monash BSc (Chem., Appl. Math.) 2009-2011 | UoM BScHon (Chem.) 2012 | UoM PhD (Chem.) 2013-2015

n.f

  • Victorian
  • Trendsetter
  • **
  • Posts: 147
  • Respect: +1
Re: % of DNA?! How do i solve these MC questions?
« Reply #7 on: June 05, 2009, 07:22:20 pm »
0
Quote
percentage of bases on the strand of DNA
Just clicked after seeing Mao's reasoning. It's talking about a single strand of DNA so there's 30% remainder of adenine. This means it must be D 30% Uracil.

lacoste

  • Victorian
  • Forum Leader
  • ****
  • Posts: 973
  • Respect: +2
Re: % of DNA?! How do i solve these MC questions?
« Reply #8 on: June 05, 2009, 08:00:40 pm »
0
there shouldn't be maths in bio!

theres more in unit 4

kaiz0r

  • Victorian
  • Adventurer
  • *
  • Posts: 6
  • Respect: 0
Re: % of DNA?! How do i solve these MC questions?
« Reply #9 on: June 05, 2009, 08:04:37 pm »
0
Mao's right! It must've been a typo from IARTV then, or whoever sourced the paper to me. Thanks for clearing that up. :)

Studyinghard

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1313
  • Respect: +4
Re: % of DNA?! How do i solve these MC questions?
« Reply #10 on: June 07, 2009, 07:47:11 pm »
0
There was another question on the same paper that got me.

C4 plants like corn and sugar can are found in desert and grassland ecosystems in warm or hot climates. They are well adapted to these hot, dry conditions as they
A.   carry out the first step of carbon fixation more rapidly
B.   complete the steps of the Calvin cycle of the light-independent reaction in cells surrounding vascular bundles deep in the leaf tissue
C.   pick up and use more carbon dioxide more efficiently and therefore have a higher rate of photosynthesis
D.   partly close their stomata for long periods during the day

I would have thought to be C? Answer - D
"Your life is like a river, no matter what you just got to keep on going"

cns1511

  • Guest
Re: % of DNA?! How do i solve these MC questions?
« Reply #11 on: June 07, 2009, 07:51:47 pm »
0
There was another question on the same paper that got me.

C4 plants like corn and sugar can are found in desert and grassland ecosystems in warm or hot climates. They are well adapted to these hot, dry conditions as they
A.   carry out the first step of carbon fixation more rapidly
B.   complete the steps of the Calvin cycle of the light-independent reaction in cells surrounding vascular bundles deep in the leaf tissue
C.   pick up and use more carbon dioxide more efficiently and therefore have a higher rate of photosynthesis
D.   partly close their stomata for long periods during the day

I would have thought to be C? Answer - D
No, it is D. Because the plants are in the desert they have very high temperatures and therefore close their stromata partially during the day (can't remember why) but this helps with the plant photosynthesising. Someone will have a better explanation I'm sure :P

hard

  • Guest
Re: % of DNA?! How do i solve these MC questions?
« Reply #12 on: June 07, 2009, 07:57:21 pm »
0
There was another question on the same paper that got me.

C4 plants like corn and sugar can are found in desert and grassland ecosystems in warm or hot climates. They are well adapted to these hot, dry conditions as they
A.   carry out the first step of carbon fixation more rapidly
B.   complete the steps of the Calvin cycle of the light-independent reaction in cells surrounding vascular bundles deep in the leaf tissue
C.   pick up and use more carbon dioxide more efficiently and therefore have a higher rate of photosynthesis
D.   partly close their stomata for long periods during the day

I would have thought to be C? Answer - D
No, it is D. Because the plants are in the desert they have very high temperatures and therefore close their stromata partially during the day (can't remember why) but this helps with the plant photosynthesising. Someone will have a better explanation I'm sure :P
well they wouldn't photosynthesis more in hot conditions as there is less water to react with i'd assume.

Studyinghard

  • Victorian
  • Part of the furniture
  • *****
  • Posts: 1313
  • Respect: +4
Re: % of DNA?! How do i solve these MC questions?
« Reply #13 on: June 07, 2009, 08:06:37 pm »
0
There was another question on the same paper that got me.

C4 plants like corn and sugar can are found in desert and grassland ecosystems in warm or hot climates. They are well adapted to these hot, dry conditions as they
A.   carry out the first step of carbon fixation more rapidly
B.   complete the steps of the Calvin cycle of the light-independent reaction in cells surrounding vascular bundles deep in the leaf tissue
C.   pick up and use more carbon dioxide more efficiently and therefore have a higher rate of photosynthesis
D.   partly close their stomata for long periods during the day

I would have thought to be C? Answer - D
No, it is D. Because the plants are in the desert they have very high temperatures and therefore close their stromata partially during the day (can't remember why) but this helps with the plant photosynthesising. Someone will have a better explanation I'm sure :P
well they wouldn't photosynthesis more in hot conditions as there is less water to react with i'd assume.

Hm i guess C is partially correct in that they do capture CO2 but also D is so they dont loose water for photosynthesis. Still dodgy imo.
"Your life is like a river, no matter what you just got to keep on going"

polky

  • 2008 VN Dux
  • Victorian
  • Forum Obsessive
  • ***
  • Posts: 434
  • Respect: +25
Re: % of DNA?! How do i solve these MC questions?
« Reply #14 on: June 07, 2009, 08:49:03 pm »
0
There was another question on the same paper that got me.

C4 plants like corn and sugar can are found in desert and grassland ecosystems in warm or hot climates. They are well adapted to these hot, dry conditions as they
A.   carry out the first step of carbon fixation more rapidly
B.   complete the steps of the Calvin cycle of the light-independent reaction in cells surrounding vascular bundles deep in the leaf tissue
C.   pick up and use more carbon dioxide more efficiently and therefore have a higher rate of photosynthesis
D.   partly close their stomata for long periods during the day

I would have thought to be C? Answer - D
No, it is D. Because the plants are in the desert they have very high temperatures and therefore close their stromata partially during the day (can't remember why) but this helps with the plant photosynthesising. Someone will have a better explanation I'm sure :P

If I'm not wrong (plant bio was 2 year ago for me), D is so that they don't lose water vapour through transpiration to prevent dehydration.
ENTER 99.95
2008 50 English   49 Chemistry   43 Specialist   45 History:Revs
2007 46 Biology   42 Methods
2006 45 Chinese SL