A: An area of ‘extensive commercial grain farming’ – The Prairies, USA.
B: A terminal station of ‘Trans-Siberian Railway’ – Vladivostok, Russia.
C: An area of ‘nomadic herding’ – Sahara Desert, Africa.
D: An area of ‘commercial livestock rearing’ – Pampas, Argentina.
E: A major sea port of Asia – Shanghai, China.
F: A major international airport of Europe – Heathrow, London.
G: A major shipping canal – Suez Canal, Egypt.

Draw a rough sketch for the curve $y = 2 + |x + 1|$. Using integration, find the area of the region bounded by the curve $y = 2 + |x + 1|$, $x = -4$, $x = 3$, and $y = 0$.
Study the given molecular structure of double-stranded polynucleotide chain of DNA and answer the questions that follow. 
(a) How many phosphodiester bonds are present in the given double-stranded polynucleotide chain?
(b) How many base pairs are there in each helical turn of double helix structure of DNA? Also write the distance between a base pair in a helix.
(c) In addition to H-bonds, what confers additional stability to the helical structure of DNA?
