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Explain how restriction endonucleases are used to form recombinant DNA plasmids.

Endonucleases cut DNA at palindromic sites producing 'sticky ends'. The endonuclease cuts the plasmid DNA and the DNA to be inserted at the same palindromic site. The sticky ends of the plasmid DNA and the i...
TD
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Describe how the strong nuclear force between two nucleons varies with the separation of the nucleons, quoting suitable values for separation.

The strong nuclear force is repulsive for nucleon separations less than 0.5 femtometres but doesn't act at roughly 1 femtometre. It becomes attractive between 1 femtometre and 3-4 femtometres, afterwhich it ...
Answered by • Physics tutor
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A spacecraft called Deep Space 1, mass 486 kg, uses an “ion-drive” engine which expels 0.13 kg of xenon propellant each day at 30kms^-1. What is the initial increase in speed of the spacecraft

Use conservation of momentum (p=mv).Momentum of Xenon = 0.13 kg × 30000 m s^-1 = 3900 kg m s^-1Momentum of spacecraft = 486 kg × v v= 3900kgms^−1 /486kg=8.02ms^−1
Answered by • Physics tutor
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Why does butan-2-ol have no effect on plane polarised light?

Butan-2-ol can be produced as a result of reducing butanone with NaBH4. The hydride ion in NaBH4 is used as a nucleophile which can attack the C on the (C=O )either above or below the plane, depending on the...
SK
Answered by Sunzida K. • Chemistry tutor
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Solve the Simultaneous equations x^2 + y^2 =29, y-x=3.

y=x+3, Substitute into equation 1 : (x^2) + (x+3)^2 = 29Expand the Brackets : (x^2) + (x^2 + 6x + 9) = 29Collect like terms : 2x^2 + 6x - 20 = 0Take out a factor of two : x^2 +3x -10 = 0Factorise : (x-2)(x+5...
TM
Answered by Theo M. • Maths tutor
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