AS biology!

[libra94]

Assalamo Alaikum
can someone plz hepl me in this question?
question 30 http://www.xtremepapers.net/CIE/Interna ... 6_qp_1.pdf

thanks!

 

[libra94]

this one too
Q 39 and 40 http://www.xtremepapers.net/CIE/Interna ... 7_qp_1.pdf

 

[hassam]

cardiac cycle: av valves will be closed when pressure in ventricle is greater than the pressure in atrium....SL valve will be closed when the pressure in aorta is greater than pressure in ventricle.....at 1 ventricle pressure increases than atrial pressure and hence av valve closes.....and sl valve is already closes since pressure has not increased than that in aorta and will remain close until 2...u read-off time at 2 and at 1 subtract the two....u get ur anser

 

[hassam]

39.after volcano no. of animals and plants gonna decrease ryt.....???.....so means dead animals increased i.e moor food for decomposers.....when more ammonium ions formed from decomposition nitrifying bacteria will also increase
40.its simple .....75/1.75 i.e (NP passed to herbivores)/NP
HOPE that helps

 

[rz123]

can anyone plz explain me the role of endodermis in plants and tell me whats casparian strip, anticodon, secretory vesicles, and the function of mRNA and tRNA.

 

[hassam]

endodermis is a layer of cells with suberised cell walls thus around the vascular bundle in roots thus blocking out the appoplast pathway so that water must pass through cell membrane b4 passing to xylem so that membrane can select for which minerals to pass through.....

 

[rz123]

tnx a lot man. and the rest..:|

 

[libra94]

@hassam bro thnks

@rviboy
Casparan strip...its a strip of suberin formed on the cells of endodermis, this suberin strip is waterproof and doesn't allow water to pass, therefore there are some passage cells which allow the water to pass.

Anticodon....these are the bases present on the tRNA which forms complementary pairs with the mRNA strand during translation of protiein sysnthesis

Secretory vesicles....after the modification of protein by the Golgi body, the protein goes out of the cell by exocytosis. the secretory vesicles are the vesicles which encloses the protein inside them and fuses with the cell membrane and excretes the protein.

Function of mRNA and tRNA...they are used in protein sysnthesis
mRNA is a single strand, while tRna is also a single stran but in a clove shape.
tRNA molecule has 3 bases attached to it (anticodons) and is attached to a specific amino acid molecule.
during translation, mRNA forms comlementary base pairs with tRNA molecule on the surface of ribosome.
the nxt tRNA with a specific amino acid comes and forms complementary base pairs with mRNA and a peptide bond is formed b/w two amino acids...this is how mRNA and tRNA helps in protein sysnthesis.

 

[rz123]

oh man thanks a lot. i appreciate this.. this helped to make concepts clear

 

[libra94]

oh man thanks a lot. i appreciate this.. this helped to make concepts clear

i'm a woman anyways, ur welcome

 

[rz123]

oops second time in these forums i have identified the gender of a person wrongly. now i am not gonna use this word ''man'' while thanking

 

[hassam]

.Describe how bacteria are taken up by phagocytes...need.esp the wording for that pesuedopdia part...

 

[hassam]

hmm....this is a good diagram explaining opsoninsation....but tell me abt psuedopodia