Explain how infection by a pathogen can be detected by an ELISA test for antigens.
Outline how a defective gene can be replaced using viral vectors.
State a use of species of Aspergillus and Saccharomyces in food production.
Compare chemoautotrophs with photoheterotrophs.
Discuss the biological issues and ethical issues concerning biological pest control.
Describe one example of the use of transgenic techniques in animals.
The leaves of rice (Oryza sativa) may contain some vitamin A or its precursor beta-carotene, but in the edible rice grain this nutrient is not produced due to the absence of four enzymes required in the pathway. Using Agrobacterium tumefaciens as a vector, scientists successfully inserted genes into the beta-carotene pathway (two genes from daffodil and one gene from a bacterium) which allowed the rice grains to produce beta-carotene. They called this genetically modified plant Golden rice.
Identify the protein for which Gene 1 from daffodil codes.
Outline how the scientists would determine whether Gene 2 from daffodil had been taken up successfully by rice DNA.
Explain how Agrobacterium tumefaciens is used to produce genetically modified crop plants.
A study was carried out in Brazil on the transfer of pollen (cross-pollination) from transgenic strains to non-transgenic strains of soybean (Glycine max). The transgenic crop was resistant to the herbicide glyphosate. The graph below shows the percentage of cross-pollination between transgenic and non-transgenic crops in fields separated by different distances.
Suggest one undesirable consequence of cross-pollination involving glyphosate resistant crop plants with other plants.
Using the data, suggest one recommendation to farmers who plant transgenic soybeans.
Agrobacterium tumefaciens stains pink or red with the Gram stain. Deduce from this result what type of bacterium A. tumefaciens is.
Outline how A. tumefaciens is used to introduce genes into soybeans.
Over a thousand bacterial species occupy the human gut. The gut bacteria show much larger genetic diversity than the host cells. Gut bacteria are vital to proper food digestion and vitamin synthesis. Fecal samples were collected from people in various locations so the genomes of their gut bacteria could be analysed. Bacteria with the same unique DNA sequences were identified as species. The graph shows the number of bacterial species in the digestive tract of people in three different parts of the world. Key:
Identify the age and ethnic group of the individual with the highest diversity of gut bacterial species.
Outline the trends in the number of bacterial species in the digestive tracts of Amerindians.
Distinguish between the trends seen in the three populations.
Suggest two reasons for how the different environments of the three human populations affect the number of bacterial species in their digestive tracts after the age of four.
A century ago, it was discovered that each person belonged to one of four blood types. Now some researchers are reporting that human gut ecosystems fall into three distinct types, each involving a great number of similar bacterial species. Suggest one medical application based on the knowledge that humans could be typed according to their gut ecosystem.
Starch from different sources contains differing proportions of amylose and amylopectin. Potatoes (Solanum tuberosum) have been genetically modified to produce high-amylopectin starch (Amflora potatoes). Heat induces starch to form a gel in excess water. The graph shows gel formation temperature at different amylose concentrations.
Discuss the hypothesis that the temperature at which starches form a gel depends on the degree of cross-linking of amylopectin.
State one advantage of potatoes with a high amylopectin content.
The Amflora potato was approved for industrial applications in the European Union (EU) in 2010 and was withdrawn in January 2012 due to opposition. Discuss reasons for people supporting or opposing the introduction of the Amflora potato in the EU.
Researchers often use short pieces of DNA called Alu sequences to study relationships within populations and between species. The function of these sequences is not known. However, they have the ability to copy themselves at random and insert into other parts of the genome, increasing the DNA fragment size. Alu sequences have inserted into the genome of primates throughout their evolution. One particular group of sequences (Ye) began inserting into the genome relatively early in the evolution of Hominidae and continues to insert itself at low rates. The gel electrophoresis samples below were used to determine the phylogenetic origin of individual Ye5 sequences in primates. The larger DNA fragment in each case contains the Ye5 insert and the smaller fragments are the same region of DNA but without the insert. The green monkey and the owl monkey diverged from the Hominidae approximately 25 million years ago.
State which Alu insert is found in all of the Hominidae species but not in the other species.
Calculate the size of the Ye5AH140 insert.
Identify, giving a reason, which insert has the most recent origin.
Analyse the data to determine whether bonobos are most closely related to chimpanzees or orangutans.
Explain the use of two named bacteria in response to pollution incidents.
Which statement correctly describes genome and proteome?