IB Biology SL 3.2.18 COVID-19 pandemic data evaluation Question Bank

Practise IB Biology SL 3.2.18 by calculating percentages and comparing quorum-sensing data from bacterial strains.

[Maximum number: 4]

Vibrio cholerae live in aquatic environments and cause cholera. Some V. cholerae form aggregates that show characteristics not seen in individual bacteria. The bacteria in these aggregates monitor the population densities by quorum sensing. They produce quorum sensing proteins ( $\mathrm{QS}^{+}$ ). Some V. cholerae strains do not produce quorum sensing proteins (QS ${ }^{-}$ ) and some only produce quorum sensing proteins in low amounts (QS ${ }^{\mathrm{c}}$ ).
V. cholerae strains isolated in China were examined. The pie charts show the percentage of different quorum-sensing systems in strains that contain cholera toxin genes and in strains that do not contain cholera toxin genes.

Cholera producing strains

Non-cholera producing strains

(a)

State the percentage of cholera producing strains that do not produce quorum sensing proteins ( $\mathrm{QS}^{-}$ ). \%

[ 1 ]

(b)

Determine the approximate percentage of non-cholera producing strains that produce quorum sensing proteins in low amounts ( $\mathrm{QS}^{\mathrm{c}}$ ).

[ 1 ]

(c)

Compare the percentage of strains that do not produce quorum sensing proteins (QS ${ }^{-}$ ) in strains with and without the cholera toxin genes.

[ 2 ]

a. there are less $\mathrm{QS}^{-}$ strains that produce cholera than those that do not produce cholera;
b. approximately 50 % in cholera producing and approximately 70 % in noncholera producing;
c. greatest percentage in $\mathrm{QS}^{-}$ in both so most are not quorum sensing;

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C3.2.18—COVID-19 pandemic data evaluation question 1

Question (a)

Question (b)

Question (c)