What may have occurred to prevent species that are of the same grade from also belonging to the same clade?

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#Question id: 32937

#XL - S Microbiology

A bacterial culture initially contains 1,000,000 (10⁶) CFU. After 6 minutes of heat treatment at 80°C, the bacterial count decreases to 1,000 (10³) CFU. Calculate the decimal reduction time (D-value) at 80°C.

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#Question id: 20250

#XL - P Chemistry

What is the work done against the atmosphere when 25 grams of water vaporizes at 373 K against a constant external pressure of 1 atm ? Assume that steam obeys perfect gas laws. Given that the molar enthalpy of vaporization is 9.72 kcal/mole, what is the change of internal energy in the above process ?

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#Question id: 15254

#XL - S Microbiology

For growth, most bacteria require water activity levels above

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#Question id: 4932

#XL - S Microbiology

Which of the following is the best hypothesis regarding origins of nucleic acids?

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#Question id: 4615

#XL - S Microbiology

Currently, two of the living elephant species (X and Y) are placed in the genus Loxodonta, and a third surviving species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?