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Griffith's R strain of pneumococcus is called rough because it:
ALacks a protective capsule
BCarries an extra capsule
CGrows only on rough agar
DDivides at an uneven rate
Answer & Solution
Correct answer: A. Lacks a protective capsule
1. The names describe how the colonies look under magnification.
2. The R strain is non-pathogenic and is called rough because its outer surface is a cell wall and lacks a capsule.
3. As a result the cell surface appears uneven under the microscope.
4. The S strain has that capsule, so it has a smooth appearance instead.
_Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 14 'DNA Structure and Function', sections 14.1-14.6_
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