2.6 & 2.7 IB Biology

Where are amino acids joined together to make polypeptides?

• Nucleus

• Nucleolus

• Golgi apparatus

• Ribosomes

Some yeast genes can be replaced by human genes that then continue to produce the same human proteins in the yeast cells. Which statement helps to explain this evidence?

• The DNA of yeast and humans is identical.

• Yeast and humans have the same number of chromosomes.

• The genetic code is universal.

• Yeast and humans are both eukaryotes.

Meselson and Stahl investigated DNA replication by first feeding bacteria with bases containing 15N (heavy), and then with bases containing 14N (light). The results are shown in the photographs.

From this information, what would be the composition of the DNA in generation 3?

• There will be a single 14N band.

• There will be a single 15N band and a single 14N band.

• There will be a darker 14N band and a lighter hybrid band.

• There will be a single 15N band, a single hybrid band and a single 14N band.

A short sequence of nucleotides reads GGACAGAGCGCAGACGA. In which type of molecule could this sequence be found?

• DNA molecule only

• RNA molecule only

• Both in a DNA and an RNA molecule

• In double-stranded DNA only

For which discovery about DNA do Watson and Crick receive credit?

• DNA is the molecule that genes are made of.

• The amount of adenine equals the amount of thymine in an organism.

• Phosphate–pentose bonding along the nucleotide backbone is covalent.

• The shape of DNA is a double helix.

Which type of bond is identified by the arrow?

• Phosphate

• Hydrogen

• Covalent

• Peptide

What is required to replicate DNA?

• Temperature of 37 °C

• Free nucleotides carrying A, C, G and T bases

• Plasmids

• Endonuclease

The base sequence of a fragment of DNA is:

ACC GTG CAG GAT

What is the base sequence on the messenger RNA (mRNA) molecule transcribed from it?

• TGG CAC GTC CTA

• TGG CUC GTC CTU

• UGG CTC GUC CUT

• UGG CAC GUC CUA

Which points to the 3′ end of a strand of DNA?

• I

• II

• III

• IV

What is formed during transcription?

• RNA strand complementary to DNA strand, formed by RNA polymerase

• DNA strand complementary to DNA strand, formed by DNA polymerase

• RNA strand complementary to RNA strand, formed by DNA polymerase

• DNA strand complementary to RNA strand, formed by RNA polymerase