Trouble with TRIALS? Post Here! Help here!

[kenhung123]

The answer says B because it has the oldest common ancestor but can someone explain my interpretation: I thought when they a species diverge to 2 species from 1 common ancestor it means they are more closely related than when 1 species diverge to a new branch species and the other diverge to a common ancestor which then diverges into 2 new species? I was expected the south african wild dog and east african wild dog to be more close due to this confusion.

[claire.anglim]

Hi guys, I'm having trouble understanding a question from the 2008 VCAA exam, question 3C


H substance is the substrate for the production of the antigens associated with the ABO blood group.
For example
H substance
in presence of IA allele
A antigen is produced
c. To which blood group would a person with the genotype hh IAIB be assigned after routine blood-group
testing?

The Answer said O blood group, but I thought it would be AB blood group,

probly sounds stupid, but could anyone explain this?

[cipherpol]

Their genotype is 'hh', so no H substance is produced. If there is no H substance, no antigen is produced by the blood cell, thus making them think it's blood type O.

[Harbourmastah]

The answer says B because it has the oldest common ancestor but can someone explain my interpretation: I thought when they a species diverge to 2 species from 1 common ancestor it means they are more closely related than when 1 species diverge to a new branch species and the other diverge to a common ancestor which then diverges into 2 new species? I was expected the south african wild dog and east african wild dog to be more close due to this confusion.

well my understanding is that the longer two species have spent apart the more time there is for mutations hence a more distant relationship. Maybe there were other descendants from the common ancestor of the two dogs but they may have become exinct not been discovered.

[minilunchbox]

Answer is C but I don't understand why it isn't A.

[kenhung123]

crossing over

[minilunchbox]

crossing over

Omg, it's so obvious. Hope I don't have a similar brainfart during the exam. Thanks.

[davyp3]

how to do?

Question 2
From the above information, one can conclude that
A.
during prophase I in meiosis, crossing over will occur between chromosomes 7 and 9.
B.
during mitosis, the alleles on these chromosomes will undergo independent assortment. (answer)
C.
at the end of meiosis there will only be two different kinds of gametes formed with these alleles.
D.
at the end of mitosis chromosomes 7 and 9 together with the relevant alleles will appear in different cells

*independent assortment occurs in mitosis?

and


Question 20
The genus Eucalyptus consists of around 700 different species of flowering plants and is thought to have evolved into so many different species because of Australia’s
A.
biogeography.
B.
geographic isolation. (answer)
C.
climatic conditions.
D.
lack of flowering plants.

need explanations

thanks

[cipherpol]

For q.20, geographical isolation helps speciation as it prevents gene flow.