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JAMB Biology 2021 Paper

Question : 25

Total: 40

If a DNA strand has a base sequence TCA, its complementary strand must be?

Solution:

Concept:

DNA base pairing is specific: adenine (

\mathrm{A}

) pairs with thymine (

\mathrm{T}

), and cytosine (

\mathrm{C}

) pairs with guanine (

\mathrm{G}

Explanation:

The given DNA strand is

\mathrm{TCA}

Find the complement of each base in order.

\mathrm{T}

pairs with

\mathrm{A}

\mathrm{C}

pairs with

\mathrm{G}

\mathrm{A}

pairs with

\mathrm{T}

So the complementary strand becomes

\mathrm{AGT}

Among the options, this matches option D.

Answer:

\mathrm{AGT}

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