IB Biology Topic 3.5

Which technique separates proteins according to size?

• Treatment with restriction endonucleases

• PCR

• Gel electrophoresis

• DNA profiling

Which technique is used to amplify very small samples of DNA?

• Cloning

• Gel electrophoresis

• PCR

• DNA Profiling

The image shows the results of Griffith’s experiment with S and R strains of Streptococcus pneumoniae in mice (Mus musculus).

What is an explanation for the results?

• Mice vary in their resistance to bacteria.

• The R strain and S strain mated.

• R strain bacteria are more heat-stable than S strain.

• DNA was transferred from heat-killed S cells to R cells.

Ampicillin (Amp) is an antibiotic. A plasmid carrying a gene for Amp resistance was used to transform bacteria in a tube of broth. A control tube without plasmid was also produced. The results were plated as shown. Which plate has only colonies of transformed bacteria?

• A

• B

• C

• D

For what purpose are restriction endonucleases used in the laboratory?

• To limit the length of DNA molecules in the nucleus

• To cut specific base sequences to open DNA molecules

• To prevent release of DNA from the nucleus

• To protect viral DNA from digestion by bacterial enzymes

HindIII is an endonuclease that recognizes the sequence A A G C T T, cutting between the two adenines.

Into how many DNA fragments would the strand shown be cut by HindIII?

• 2

• 3

• 4

• 5

What is produced by somatic-cell nuclear transfer?

• Adult sheep

• Cloned Embryos

• Rooted stem-cuttings

• Genetically modified food

Genetically modified maize, called Bt maize, is thought to be affecting the monarch butterfly (Danaus plexippus) in the USA. What is the reason for this?

• The monarch butterfly feeds on maize nectar, which contains Bt toxin.

• The monarch caterpillar feeds on maize leaves, which contain Bt toxin.

• Bt toxin kills the plants that the monarch caterpillar usually eats.

• Bt toxin is in maize pollen, which blows on to plants that the monarch caterpillar eats.

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