Final answer:
Pour plates can have both surface and subsurface colonies due to the bacteria being mixed with molten agar before solidification, whereas spread plates only support the growth of surface colonies since the bacteria are spread on top of the agar and do not penetrate the medium.
The correct option is b and d.
Step-by-step explanation:
The question pertains to the different characteristics of pour plates and spread plates in microbiology, specifically regarding where colonies grow on them. Pour plates can exhibit both surface and subsurface colonies due to the method of mixing the bacteria with molten agar before pouring it into a plate.
In contrast, spread plates involve spreading a bacterial sample on the surface of the agar, hence only surface colonies grow because the bacteria do not penetrate below the surface.
The correct answer to the statement 'Pour plates have surface and subsurface colonies; spread plates only have surface colonies.' is:
b. Pour plates lack surface colonies - Incorrect, as pour plates have both surface and subsurface colonies.
d. Pour plates lack subsurface colonies - Incorrect, as pour plates are characterized by having subsurface colonies.
Therefore, the statement intends to highlight that spread plates do not support the growth of subsurface colonies.
The correct option is b and d.