bio mcq's ..may / june 2006 help

[kanz123]

??

 

[kanz123]

??

 

[sweetiepie]

A mitochondrion in a mammalian muscle cell measured 1.2 micrometer .On an electron micrograph the length of this organelle was 36mm
what is the magnification of the electron micrograph ?
A.3000 times
B.12 000 times
C.15 000 times
D.30 000 times

plzz sumone help me wid this one???

 

[sweetiepie]

30 is C

x=0.12 -0.05 = 0.07s

i hope itx clear...

 

[RiseAgainst]

??

The answer's B.
20% of the bases are cytosine, so there will be the same amount of guanine bases (also 20%).
Altogether then we've accounted for 40% of the bases - there's 60% left which must be adenine and thymine.
You just divide by 2 because they're both present in the same amounts (due to complementary base pairing).
The answer is 60/2 = 30.

 

[kanz123]

ohh dat wz easyy mann ...thnkxxx !!

 

[RiseAgainst]

A mitochondrion in a mammalian muscle cell measured 1.2 micrometer .On an electron micrograph the length of this organelle was 36mm
what is the magnification of the electron micrograph ?
A.3000 times
B.12 000 times
C.15 000 times
D.30 000 times

plzz sumone help me wid this one???

It's D?
Magnification = size of image / actual size of image.
First of all you gotta get them both in the same units.
36mm = 36000 um.
Magnification = 36000 / 1.2 = 30000.

 

[kanz123]

i guess its D ..

umm on the electron micrograph it measures 36 mm ryt ?...dat means this the image length..change 36 mm to micrometres i.e 36000 micrometres...

and its also given dat the real legnth is 1.2 micrometres..so apply the formula noe..image / real...36000/1.2=30000

 

[RiseAgainst]

ohh dat wz easyy mann ...thnkxxx !!

Lol, they usually are easy, but they're just worded weirdly and get people confused.
Just read the question super carefully!
And you're welcome.

 

[sweetiepie]

thank u ....

 

[kanz123]

umm all bacteria have ribosomes isnt it..den how can the answer be D for dis ??...n also dey have cellsurface membranes...help plzzz :S

 

[suwaylem]

the answer is D cos HIV is a virus look at the V part and viruses don respire or do things that living organisms do =@

 

[Talha]

22 Which enzyme rejoins sections of DNA in genetic engineering?

A DNA ligase
B DNA polymerase
C restriction enzyme
D reverse transcriptase

Plz explain dis..

 

[kanz123]

is it C ??

 

[workinghard]

da ans is A... ligase joins sugar-phospahate backbone of da DNA molecule
polymerase makes a DNA mol from a DNA mol as a template
restriction enxyme cuts da DNA molecule at specific base sequences
reverse transcritase is enxyme found in viruses which make DNA 4m RNA

 

[kanz123]

oh ahan..bt neway restriction enzyme is used in genetic engineering ryt ...never heard of ligase..

 

[Xthegreat]

umm all bacteria have ribosomes isnt it..den how can the answer be D for dis ??...n also dey have cellsurface membranes...help plzzz :S

oh yes, all BACTERIA have ribosomes and cell surface membrane
BUT HIV is a virus, not a bacteria
hence HIV does not have ribosomes, no cell surface membrane and does not respire