Coffee's genetic make-up is no trivial concern; 10 million tonnes of the crop…
CUET English 2024 · English · 6 questions
Coffee's genetic make-up is no trivial concern; 10 million tonnes of the crop were grown and sold in 2022-23. The coffee that we drink comes from two species: Coffea Canephora, which is also known as Robusta and Coffea Arabica, known as Arabica. In many cases, beans from the two species are blended to make a brew. But the beans of single species are also roasted and sold. Overall, Arabica beans represent around 56% of all coffee sold.
Most genetic variation in living organisms comes from hybridization with other species. However, this is a relatively rare event for Coffea Arabica because it has more than two copies of each chromosome, a phenomenon called polyploidy. Coffea Canephora has two copies of each chromosome, but Coffea Arabica contains multiple copies. This makes it much more difficult for Arabica to interbreed with other species. As a result, Coffea Arabica's main source of single nucleotide variation is mutation, which occurs at a steady rate over time. However, the species is also relatively young, having formed as a hybrid of Robusta and Coffea Eugenioides, another coffee species that is not widely cultivated, within the past 50,000 years. From that single plant, which has basically no variation, you create the whole species, and then the variation is only the novel mutations that have occurred since that event.
Despite this, there is substantial variation in the physical characteristics of the Arabica coffee plant, including different flavour profiles in the beans and variations in disease resistance, says emeritus geneticist Juan Medrano at the UC Davis Coffee Center at the University of California, Davis. "We're always talking about low variability at the DNA level, but there is variability at the structural level, at the chromosomal level, at the level of deletions and insertions," Medrano says.
Question 1
Which of the following varieties of coffee is the most sold in the world?
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