November 30, 2007 at 9:20 am #8684NavinParticipant
I managed to get my hand on my exam booklet – and here are several qns that stumped me. I’ll post the qns first, then followed by my reasoned answers.
1. What process in bacteria ALWAYS allow both chromosomal and non-chromosomal DNA to be transferred?
A binary fission
2.What describes common features of the telomere and the centromere?
A both have protein associated with them
B both are made up of DNA with a high incidence of A and T
C both DNA are conserved throughout the life of the organism
D During interphae, replication takes plae simultaneously in both regions
3. Which statements are true?
1 Continuous variation is always influenced by the environment
2 Continuous variation is always caused by many genes
3 Discontinuous variation is always caused by one gene
4 Discontinuous variation is sometimes influenced by the environment
A 1&4, B 2&3, C 2&4, D 3&4
4. Which process cld produce a large number of genetically identical plants?
A anther culture
B embryo culture
C pollen cultue
D protoplast culture
For 1,i chose D – but now I’m unsure if A cld be the answer. Is the plasmid also transferred during binary fission?
For 2, i chose A as there are kinetochore proteins and the enzyme telomerase. But the rest seem plausible too.
For 3, i chose C, i know 4 is definitely true(i know some examples) and 3 definitely false – but what about 1 and 2?
For 4, i chose D, although i completely have no clue how to tackle this qn.
Any help would greatly be appreciated. Thanks 🙂
November 30, 2007 at 3:18 pm #78755mithParticipant
1. Transformation can be only plasmid transfer
November 30, 2007 at 3:32 pm #78756NavinParticipant
Not really – besides plasmid transformation, there is also the uptake of naked DNA when bacteria in natural populations are in a state of natural competence. Fragments of chromosomal DNA from lysed bacteria can enter into neigbouring bacteria (then followed by homologous recombination).
There is a famous experiment showing this: avirulent Streptococcus pneumoniae became virulent by being exposed to heat-killed virulent cells.
But I see your point; the question stresses ALWAYS, so i guess transformation then is not the answer, as both are not always transferred.
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