In 1973, a technique for genetic engineering was used for the first time. Recombinant DNA was made using a plasmid and this was successfully transferred into an organism. In 2012, a new technique for genetic engineering, called gene editing, was developed.

1. (a)Table 4.1 lists some statements about the two genetic engineering techniques. Complete Table 4.1 to compare the original genetic engineering technique using a plasmid vector with the newer technique of gene editing. For each row, place a tick (✔) in the correct column if the statement applies and leave a blank if the statement does not apply. Table 4.1 statement genetic engineering using a plasmid gene editing It may cause the organism to produce a different protein. It may cause a single base pair in a gene to be changed. The success of the technique can be evaluated using marker genes. It may use the CRISPR system. It uses DNA ligase.[5]
2. (b)Cassava plants, Manihot esculenta, produce roots that have a high starch content. These roots are an important food source in tropical regions. The growth of cassava plants is reduced by competition from weeds. Scientists used gene editing to develop two types of cassava plant with different mutations (changes to the DNA). The gene edited cassava plants showed resistance to the herbicide glyphosate. In susceptible plants, glyphosate prevents synthesis of three amino acids from a precursor molecule called shikimate. [Figure 4.1] shows the concentration of shikimate in the wild type (not gene edited) and the two types of gene edited cassava plant after they were exposed to three different concentrations of glyphosate.
3. (b)(i)Identify the letter in [Figure 4.1] that represents the wild type cassava plant.[1]
4. (b)(ii)Explain the social benefit of this example of gene editing.[3]