2009 Biology Unit 3 Exam Suggested Solutions

[polky]

Mitochondria are apparently the 2nd largest organelle in animal cells, after the nucleus.

Google-fu ftw!

[simpak]

it states largest sediment form at low speed
the first tube is at the lowest speed - thus must contain largest sediment aka nucleus

you just have to understand, that the larger the organelle is, the slower speed test tube it was

thus it had to be C or D
however mitochondria anre invariably larger than ribosomes so it must be C

Ohhhhhhhhhh!  Thankyou.
I understand where I stuffed this up now.
Speed, as in, the speed in the table of values they gave you.
Not speed as in, the time taken.

I have a warped perception sometimes.
Oh well.  One out of 25 wrong isn't bad.

[simpak]

It's out of 150 because your score is doubled if marked only once or added together if marked twice

25 marks means 12.5 really so the cut off was 62.5/75

it gets marked twice O_O y soo?
so u don't get a linient examiner and a hard marking examiner ><
OH NO! i wish for 2 lininetn exmainersss D: T___T

It gets marked if you apply for a Statement of Marks to find out your exam score (hence why I had a half mark in the score I gave above). Otherwise, it'll be just doubled.

Actually, all Biology exams are getting marked twice this year

[rasangi]

for the question abt why would it be an advantage to produce jasmonic acid when leaves are being eaten by caterpillars, would it be correct to say that because jasmonic acid aatracts wasps which act as pollen vectors transferring the pollen of tomato plants to other areas?

[TrueLight]

isn't jasmonic acid a plant hormone that activates defense genes? sorta like what ethylene does as well...
maybe the chitinase gene? ... but maybe it does attract the insects like mosquitos? so it can lay eggs in like caterpillar eggs........ haha just guessing anyway.... someone else can answer this...

[Greggler]

the real thing that jasmonic acid does is attract the wasps which in turn kill the caterpillars

i said on the exam that "perhaps the acid deters the caterpillars from eating the tomato plant"
i dunno if i'll get the mark probs not - but the question was pretty broad

"explain why it may be an advantage to the plant to produce jasmonic acid when its leaves are being eaten by caterpillers"

[studyhound]

yeah i said the wasps would eat the caterpillars phewww

[hard]

for the experiment

i go that

you have two groups of caterpillars with one being the beet type and the other being a different specied that are both placed in same conditions with same tomatoe plant. Wasps are placed in the area and if the wasps are attracted to the jasmonic acid produced when beet aacterpillars eat the tomatoe than the hypothesis is supported etc but dont know if thats how i said it. would that be alright?

[Greggler]

wtf???

i said two groups of the same identical tomato plant
one group exposed to caterpillars, the other not, measure jasmonic acid levels after few days
then expose to wasps, observe behaviour

group which is exposed to caterpillars shold have higher jasmonic acid levels - also that gruop the wasps should visibly be more attracted; something along those lines

[hard]

yer  i think i kinda stuffed that on up, hopefully at least 2/3 or 1/3 for that one. so i guess thas 7 makrs gone. ehh thas an A+ hopefully.

[TrueLight]

greggler your answer sounds logical to me...

[Greggler]

o god thanks

hard: you probs get a mark or two for saying results or stating a control/varible - never know may get all marks?

and btw last years exam you could drop like 12 marks and still get an a+ - this years exam was slightly a bit harder i think in the multi so i reckon a+ cutoff will be a bit lower this year

at least i hope so, so that a 69 becomes a midrange/high a+

[Shanilka]

TSH is the only protein based hormone that can pass through the lipid bilayer, i think

[shinny]

TSH is the only protein based hormone that can pass through the lipid bilayer, i think

Nope, a wiki search reveals that it's on the surface of cells. General rule is that protein hormones have surface receptors, and amino-acid derived and lipid-based/steroidal hormones are inside the cell.

[simpak]

wtf???

i said two groups of the same identical tomato plant
one group exposed to caterpillars, the other not, measure jasmonic acid levels after few days
then expose to wasps, observe behaviour

group which is exposed to caterpillars shold have higher jasmonic acid levels - also that gruop the wasps should visibly be more attracted; something along those lines

(y)