O-Level Biology

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Re: O-Level Biology

Postby zombie » Sun Jul 26, 2015 11:00 am

Can someone help with this question ?

Explain how it is possible that parents with different blood groups are able to produce only children with blood groups different from themselves.

Thank you !

zombie
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Re: O-Level Biology - tRNA's role in DNA replication

Postby zombie » Sun Jul 26, 2015 11:17 am

I need help on this question. I understand this topic, but I don't know how to present it.
Also, mine is a bit long winded. I do not want to write too long and I end up not having enough time for other questions.

Is my answer sufficient ?

"Describe the role of tRNA in DNA replication.
Protein synthesis, also called translation , begins when the two ribosomal subunits link onto the mRNA. Transfer molecules are comprised of nucleotides, which are small building blocks for both RNA and DNA. The role of tRNA is to read the message of nucleic acids (nucleotides) and translate it into proteins (amino acids). Transfer RNA (tRNA) is the key to deciphering the code words in mRNA. tRNA reads the mRNA in short, three-letter words called codons. RNA (tRNA) molecules transfer amino acids and carries them to the ribosomes. Ribosomes have a binding site for mRNA and binding sites for two transfer RNA (tRNA) molecules. Ribosomes facilitate complementary base pairing between tRNA anticodons and mRNA codons; one protein is an enzyme that joins amino acids together by means of a peptide bond. Each codon on the mRNA specifies a particular amino acid, which is recognized by the anticodon of the complementary tRNA. tRNAs have the same general cloverleaf shape with base-paired arms, but with one variable side arm and a different anti-codon sequence. tRNA is a single-stranded ribonucleic acid that doubles back on itself to create regions where complementary bases are hydrogen-bonded to one another. At one end tRNA binds to amino acid; at other end it has an anticodon that binds to mRNA codon; anticodon is group of nucleotides on a tRNA molecule complementary to codon on mRNA. The tRNA aligns with the codon and brings the appropriate amino acid to the translation machinery. Ribosome moves down mRNA molecule, new tRNAs arrive; amino acids join; polypeptide forms. Amino acids become sequenced in polypeptides according to information provided by gene; tRNAs accomplish translation, converting nucleic acid code into amino acid sequence. The amino acid it carries can be used to add to a growing polypeptide chain. The ribosome forms a peptide bond between the two amino acids that were brought in by the tRNAsFinally, during termination, the ribosome unbinds from the mRNA, and the amino acid chain goes on to be processed and folded to make the final, functional protein. The tRNA is reused and collects another specific amino acid. "

Do we have to mention Okazaki fragments ?

I'm not sure whether this topic is in the current syllabus. I've found it in a school exam paper, with no answer solution.

The answer is a long story line, I'm not sure how much info input I have to mention.
I have tried to summarise, but it seems that I can't do it as the key words have to be mentioned too.

Can someone please advise me ?

Thank you very much ! :salute:

zombie
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Re: O-Level Biology

Postby secschbioteacher » Sat Oct 03, 2015 8:16 pm

zombie wrote:Can someone help with this question ?

Explain how it is possible that parents with different blood groups are able to produce only children with blood groups different from themselves.

Thank you !


It is possible if a person with blood group O marries a person with blood group AB. Then their children can only inherit IO allele from the parent with blood group O and inherit IA or IB allele from parent with blood group AB, resulting in the genotype of either IAIO or IBIO. So the children from this pair of parents can only be blood group A or blood group B. :imcool:

secschbioteacher
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Re: O-Level Biology - tRNA's role in DNA replication

Postby secschbioteacher » Sat Oct 03, 2015 8:20 pm

zombie wrote:I need help on this question. I understand this topic, but I don't know how to present it.
Also, mine is a bit long winded. I do not want to write too long and I end up not having enough time for other questions.

Is my answer sufficient ?

"Describe the role of tRNA in DNA replication.
Protein synthesis, also called translation , begins when the two ribosomal subunits link onto the mRNA. Transfer molecules are comprised of nucleotides, which are small building blocks for both RNA and DNA. The role of tRNA is to read the message of nucleic acids (nucleotides) and translate it into proteins (amino acids). Transfer RNA (tRNA) is the key to deciphering the code words in mRNA. tRNA reads the mRNA in short, three-letter words called codons. RNA (tRNA) molecules transfer amino acids and carries them to the ribosomes. Ribosomes have a binding site for mRNA and binding sites for two transfer RNA (tRNA) molecules. Ribosomes facilitate complementary base pairing between tRNA anticodons and mRNA codons; one protein is an enzyme that joins amino acids together by means of a peptide bond. Each codon on the mRNA specifies a particular amino acid, which is recognized by the anticodon of the complementary tRNA. tRNAs have the same general cloverleaf shape with base-paired arms, but with one variable side arm and a different anti-codon sequence. tRNA is a single-stranded ribonucleic acid that doubles back on itself to create regions where complementary bases are hydrogen-bonded to one another. At one end tRNA binds to amino acid; at other end it has an anticodon that binds to mRNA codon; anticodon is group of nucleotides on a tRNA molecule complementary to codon on mRNA. The tRNA aligns with the codon and brings the appropriate amino acid to the translation machinery. Ribosome moves down mRNA molecule, new tRNAs arrive; amino acids join; polypeptide forms. Amino acids become sequenced in polypeptides according to information provided by gene; tRNAs accomplish translation, converting nucleic acid code into amino acid sequence. The amino acid it carries can be used to add to a growing polypeptide chain. The ribosome forms a peptide bond between the two amino acids that were brought in by the tRNAsFinally, during termination, the ribosome unbinds from the mRNA, and the amino acid chain goes on to be processed and folded to make the final, functional protein. The tRNA is reused and collects another specific amino acid. "

Do we have to mention Okazaki fragments ?

I'm not sure whether this topic is in the current syllabus. I've found it in a school exam paper, with no answer solution.

The answer is a long story line, I'm not sure how much info input I have to mention.
I have tried to summarise, but it seems that I can't do it as the key words have to be mentioned too.

Can someone please advise me ?

Thank you very much ! :salute:


GCE O Level syllabus (subject code 5107) does not require details of translation and transcription, hence knowledge of tRNA function is also not needed. :boogie:

secschbioteacher
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Re: O-Level Biology

Postby questionable_i » Sun Jan 31, 2016 1:15 pm

Can anyone help me?

Which statement is true of active transport in plants?

(a) It depends on the availability of energy.

(B) It eventually achieves equilibrium.

(C) It involves the random movement of molecules.

(D) It relies on the kinetic energy of molecules.

questionable_i
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Re: O-Level Biology

Postby secschbioteacher » Sun Jan 31, 2016 9:26 pm

questionable_i wrote:Can anyone help me?

Which statement is true of active transport in plants?

(a) It depends on the availability of energy.

(B) It eventually achieves equilibrium.

(C) It involves the random movement of molecules.

(D) It relies on the kinetic energy of molecules.


Answer is (A).

(B) It eventually achieves equilibrium. -> True only for diffusion and osmosis.
(C) It involves the random movement of molecules. -> True only for diffusion and osmosis.
(D) It relies on the kinetic energy of molecules.-> True only for diffusion and osmosis.

secschbioteacher
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Re: O-Level Biology

Postby SMC67 » Tue May 03, 2016 4:27 pm

Aspire2015 wrote:If you are looking for any O level Biology books-textbook, guides, TYS, prelim papers,please pm me. You can also look under Garage Sale, where I post pictures.

Other O Level books of other subjects are also available.

Hi
hiw can I get from you the o level bio prelim exam papers?
Kindly email me your contacts at:smc67pk@gmail.com.

SMC67
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Re: O-Level Biology

Postby SMC67 » Tue May 03, 2016 4:27 pm

Aspire2015 wrote:If you are looking for any O level Biology books-textbook, guides, TYS, prelim papers,please pm me. You can also look under Garage Sale, where I post pictures.

Other O Level books of other subjects are also available.

Hi
hiw can I get from you the o level bio prelim exam papers?
Kindly email me your contacts at:smc67pk@gmail.com.

SMC67
KiasuNewbie
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Re: O-Level Biology

Postby SMC67 » Tue May 03, 2016 4:29 pm

Aspire2015 wrote:If you are looking for any O level Biology books-textbook, guides, TYS, prelim papers,please pm me. You can also look under Garage Sale, where I post pictures.

Other O Level books of other subjects are also available.

Hi
hiw can I get from you the o level bio prelim exam papers?
Kindly email me your contacts at:smc67pk@gmail.com.

SMC67
KiasuNewbie
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Re: O-Level Biology

Postby Newtandcucumber » Fri May 06, 2016 2:17 pm

I would highly recommend the CGP KS3 books in Biology and the soon to be released GCSE Books in Biology.

The KS3 link is here. the green revision guides and the white work books are brilliant and cheap. I have seen the SG O level Biology paper, and my 12 year old son ( UK Y8, same as SG S1) can cover that content by virtue of the KS3 books used

https://www.cgpbooks.co.uk/Parent/books_ks3_science

Newtandcucumber
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