HOW WAS BIOLOGY 42??

[NIXORCollege]

Estrogen/Progesterone Contraceptive pill

1 (oestrogen / progesterone affect) hypothalamus / anterior pituitary ;
2 inhibit secretion of, FSH / LH / GnRH ;
3 follicles do not develop ;
4 no ovulation ; R ref to eggs
5 ref. negative feedback ;
6 alters cervical mucus to stop sperm ;
7 prevents implantation / effect on endometrium ; R endometrium thickens

[4 max]

 

[NIXORCollege]

kindly come to the questions like that zona pllucida and the proteins etc

I don't remember the question clearly.. wasn't that one straight forward? Zona pellucida- A glycoprotein- receptor where the acrosome binds- "block" (wow CIE) ZP3 gene expression- no zona pellucida produced by the granulosa cells- Sperm cannot "find" the secondary oocyte to fuse with- hence no fertilization- therefore,a contraceptive

thats what I wrote =/

 

[bionology]

yeah i wrote that too.

What about the CO2 question? why wasn't it affecting the rate of CO2 collected?

 

[NIXORCollege]

yeah i wrote that too.

What about the CO2 question? why wasn't it affecting the rate of CO2 collected?

i wrote this: Hot dry climate- high stress condition for plant, more transpiration, ABA, stomatal closure, less C02 uptake as CO2 enters only through the stomata.
What did you write?

 

[NIXORCollege]

1 mesophyll cells tightly packed/AW ;
2 so O2 cannot reach bundle sheath cells ;
3 light independent stage/Calvin cycle or RuBP, in bundle sheath cells ;
4 ref. malate shunt ;
5 maintains high CO2 concentration (in bundle sheath cells) ;
6 PEP carboxylase, has high optimum temperature/has higher affinity for CO2 /doesn’t
accept O2 ;
7 (PEP carboxylase) not denatured ;
8 photorespiration is avoided ;

 

[LittleMonster]

@NixorCollege: that's pretty much what I wrote too.

 

[bionology]

yeah i wrote that too.

What about the CO2 question? why wasn't it affecting the rate of CO2 collected?

i wrote this: Hot dry climate- high stress condition for plant, more transpiration, ABA, stomatal closure, less C02 uptake as CO2 enters only through the stomata.
What did you write?

The points u mentioned are for why photorespiration occurs at high temp, right?

well it had to say that some other factor was limiting, i wrote this when he asked for 1 reason why it was not affecting the CO2 collection
for 2nd question i wrote (didn't know about that) it was getting smaller due to stoma being closed (at night)

 

[LittleMonster]

The paper was very easy. I just messed up with Theca Cells.

 

[desolator619]

MA paper was so effing easy! i dont think anyone mustve done badly

 

[angelgurl]

ya it was easy

 

[Aloo007]

can anyone explain the last two questions in the question about the maize relating to the graph i think one was something to do with same rate at low and high concentration of co2 and the other about the differnce in rate of photosynthesis at 0700 and 1900 hours?

 

[imissknow2]

ABA stomatal closure essay

1 ref. ABA absence ;
2 H+ transported out of guard cells, actively / using ATP ;
3 low H+ conc / negative charge, inside cell ;
4 K+ channels open / K+ diffuses into cell ;
5 water potential of cell falls ; A decrease in solute potential
6 water moves into cell by osmosis ;
7 volume of guard cells increase / turgor increases ;
guard cells:
8 have hoops of cellulose microfibrils which ensure increase in length rather than
diameter ;
9 have ends that are joined together ;
10 have, thicker inner walls / thinner outer walls ;
11 curve apart / bend, (to open stoma) ;
[8 max]

excuse me, wasn't the question on closing of the stomata with ABA
it has to be added that ABA can bind to the receptors of proton pump so H+ does not transports out, and bla bla

Yup, tat is why you shud actually answer the question the other way round .. but explaining in the form of ABA Absence will also be accepted as long as the candidate qualify that in the presence of ABA the opposite process occurs

 

[imissknow2]

can anyone explain the last two questions in the question about the maize relating to the graph i think one was something to do with same rate at low and high concentration of co2 and the other about the differnce in rate of photosynthesis at 0700 and 1900 hours?

there is no clear diff in photosyn rate at low and high co2 condition because other factors such as light intensity, concentration of RuBP, number of stomata are now becoming the limiting factors

difference in rate of photosyn fr 0700 and 1900 is probably due to weather condition eg. cloud cover, rain, or sunset at around 1800h etc

Hope this clear up yur doubts

 

[Aloo007]

Thanks i think ill lose one mark in the first one but in the second one i wrote about sunlight so probs get 2 there thanks
I think my paper was good but my only worry is that although i wrote Question 10 while answering the Q in section B i forgot to mark which question i did on the front page :s

 

[skyfox]

what did you write on question no 10 ?

 

[Aloo007]

umm.. while answering i wrote Q10 a) and then Q10 b) but didnt circle Q 10 on the front page do u think ill lose marks ?

 

[Aloo007]

oh wait do you mean how i answered it? for the frst part i said how chlorphyl is found in the thylakoid lamella of the chloroplasts and how the accesory pigmants pass on energy to the chlorophyl A then I just explained cyclic phosphryltion how it only invovles photosystem one. for the second part i just explained photolysys and photosystem two and all that is used to reduce Nadp and how NadpH is used to convert GP to TP which is then used to make hexose sugar or regenerate RUBP
hopefully its correct

 

[bionology]

Yup, tat is why you shud actually answer the question the other way round .. but explaining in the form of ABA Absence will also be accepted as long as the candidate qualify that in the presence of ABA the opposite process occurs

i think the question was worth 8 marks. You had to mention first how the stomata opens, and after that you had to mention about ABA closing the stomata

okay what about the question why the proteins should only be present at zona pellucida and not elsewhere?
I just wrote that some other diseases might result in e.g. Cystic fibrosis or mutation may occur

 

[Aloo007]

@bionology I think the question was y is it beneficial for us that only zona pellucida have the gene for that protein well i wrote it would avoid any unwanted consuquences as it wont effect other cells also it would be easy to do this kind of genetherapy as you know the target cells

 

[bionology]

@bionology I think the question was y is it beneficial for us that only zona pellucida have the gene for that protein well i wrote it would avoid any unwanted consuquences as it wont effect other cells also it would be easy to do this kind of genetherapy as you know the target cells

mutation is the same thing -.-
I just gave the other side arguments that if this is not done, this may happen....