Which are the most primitive types of organisms?

What is the typical duration of the cell cycle in a yeast cell?

$A$ string fixed at one end and free at the other is vibrating in its second overtone. The length of the string is $10 \ cm$ and the maximum amplitude of vibration of particles of the string is $2 \ mm$. The amplitude of the particle at $9 \ cm$ from the fixed end is

Two resistors of resistance $R_1$ and $R_2$ having $R_1 > R_2$ are connected in parallel. For equivalent resistance $R$,the correct statement is

Which of the following is a characteristic feature of viruses?

$1+\frac{2}{4}+\frac{2 \cdot 5}{4 \cdot 8}+\frac{2 \cdot 5 \cdot 8}{4 \cdot 8 \cdot 12}+\frac{2 \cdot 5 \cdot 8 \cdot 11}{4 \cdot 8 \cdot 12 \cdot 16}+\ldots \ldots$ is equal to :