A2 Biology | Post your doubts here

[user]

Assalamoalaikum wr wb!

Explain how all organisms can potentially overproduce;
what are we supposed to write for this ....syllabus statement ..for selection and evolution..

 

[ousamah112]

Assalamoalaikum wr wb!

Explain how all organisms can potentially overproduce;
what are we supposed to write for this ....syllabus statement ..for selection and evolution..

some organisms have small incubation period.. and also depends upon their metabolism rate..or some animals reach reproduction age early... that wht i thnk is the answer..

 

[angelgirl:)]

Q4dii....can any1 explain that how do we come to know from this information in the table that which 1 is homo and which 1 is hetrozygous?

 

[omair tahir]

Q4dii....can any1 explain that how do we come to know from this information in the table that which 1 is homo and which 1 is hetrozygous?

Hybrid is heterozygous
HYbrid : an offspring resulting frm cross breeding

 

[angelgirl:)]

angelgirl said: ↑

Q4dii....can any1 explain that how do we come to know from this information in the table that which 1 is homo and which 1 is hetrozygous?

http://www.xtremepapers.com/community/attachments/9700_s09_qp_4-pdf.9774/​

Hybrid is heterozygous
HYbrid : an offspring resulting frm cross breeding

i no but in this Quesion they didnt give any clue about homo or heterozygocity...
then wat makes us write that this species is homo and this species in hetero..just from the numbers in the table...
​

 

[omair tahir]

angelgirl said: ↑

Q4dii....can any1 explain that how do we come to know from this information in the table that which 1 is homo and which 1 is hetrozygous?

http://www.xtremepapers.com/community/attachments/9700_s09_qp_4-pdf.9774/​

Hybrid is heterozygous
HYbrid : an offspring resulting frm cross breeding

i no but in this Quesion they didnt give any clue about homo or heterozygocity...
then wat makes us write that this species is homo and this species in hetero..just from the numbers in the table...
​

Yea i wasted time thinking about it
But wht i first wrote was :
Resistant group have maximum mutated gene .. Hybrid have less mutated gene thn resistan and susceptible have no mutated gene

 

[angelgirl:)]

angelgirl said: ↑

angelgirl said: ↑

Q4dii....can any1 explain that how do we come to know from this information in the table that which 1 is homo and which 1 is hetrozygous?

http://www.xtremepapers.com/community/attachments/9700_s09_qp_4-pdf.9774/​

Hybrid is heterozygous
HYbrid : an offspring resulting frm cross breeding

i no but in this Quesion they didnt give any clue about homo or heterozygocity...
then wat makes us write that this species is homo and this species in hetero..just from the numbers in the table...​

Yea i wasted time thinking about it
But wht i first wrote was :
Resistant group have maximum mutated gene .. Hybrid have less mutated gene thn resistan and susceptible have no mutated gene
ok look at the ms...
-resistance and susceptable r homozygous
-hybrid is heterozygous
-hybrid insects show co-dominance
how to arrive at this answer from the table?
​

 

[omair tahir]

I read it angelgirl and confirmed it from my teacher tht there is no way to show homo or heterozygocity by simply looking at this table
Only the thing tht u can tell by looking at the table is hybrid : heterozygous
U dont have details for otherx to explain

 

[angelgirl:)]

I read it angelgirl and confirmed it from my teacher tht there is no way to show homo or heterozygocity by simply looking at this table
Only the thing tht u can tell by looking at the table is hybrid : heterozygous
U dont have details for otherx to explain

ok thanks anyways ...

 

[omar hazem]

please can anyone tell me examples of the effect of the environment on the phenotype??

 

[doc.ahmed]

please can anyone tell me examples of the effect of the environment on the phenotype??

ome rthis thing was already discussed on few back pages i guess on page 5 or 6 go search for it

 

[hassam]

Assalamoalaikum wr wb!

Explain how all organisms can potentially overproduce;
what are we supposed to write for this ....syllabus statement ..for selection and evolution..

well......u knw the example quoted in mary jones book abt a rabbit population......so idea is that if the habitat is suited for population....like there is plentiful of food.....no natural predators.....good breeding spots available......no disease ........in short no selection pressures.....so population will become very large exponentially....however normally there are cheks and balances like disease, predators,interspecific competition

 

[user]

well......u knw the example quoted in mary jones book abt a rabbit population......so idea is that if the habitat is suited for population....like there is plentiful of food.....no natural predators.....good breeding spots available......no disease ........in short no selection pressures.....so population will become very large exponentially....however normally there are cheks and balances like disease, predators,interspecific competition

whats intraspecific competition...

people..tell me what and how to revise... i don't feel like studying at all...dunno what to do

 

[smartangel]

in the loop of henle..Na and Cl ions diffuse out of the ascending limb into the space between the two limbs. water moves via osmosis frm descending limb into the tissue fluid. Na and Cl ions due to their higher conc move into the descending limb. so how is the tissue fluid more concentrated as we move down towards the bottom of the loop? please help!!

 

[hassam]

yea good questionn........u got mee cnfused too.......bt its because.....the water that is moving out is reabsorbed by the peritubular capillaries or vasa recta their......so it does not dilutes the mmedullary interstitial fluid...

 

[hassam]

whats intraspecific competition...

people..tell me what and how to revise... i don't feel like studying at all...dunno what to do

interspecific comeptition.....competition for food from the members of same population

 

[hassam]

well http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w08_qp_4.pdf
q1http://www.xtremepapers.com/papers/...and AS Level/Biology (9700)/9700_w08_ms_4.pdf
ms says that eukaryotic DNA is in chromosome .....bt not that of prokaryotes....bt io guuess thats not true cos the circular dna (nucleoid)is chromosome........not all their dna is in plasmid form

 

[smartangel]

yea good questionn........u got mee cnfused too.......bt its because.....the water that is moving out is reabsorbed by the peritubular capillaries or vasa recta their......so it does not dilutes the mmedullary interstitial fluid...

ohh right. thanks a lot! peritubular capillaries provide the blood supply to loop of henle. what abt vasa recta?

 

[smartangel]

are we expected to know details of any other receptor other than pacinian corpuscle?

 

[aliya_zad]

are we expected to know details of any other receptor other than pacinian corpuscle?

They are just examples u'll need to quote when explaining reflex actions..
So yeah remember the 5 sense organs and their receptors
eye - rods and cones
ears- Hair cells
Nose - Olfactory cells
Tongue- Taste buds
Skin - Pacinian corpuscles for pressure and Meissner's corpuscles for touch..