Root and Root modifications- Practice Test 6

Answer: Option C

Explanation

The cells present in meristematic region are active and repeatedly undergo mitotic divisions to produce daughter cells.

Answer: Option D

Explanation

When permanent change occurs in the structure of a root to perform new functions suitable for the environment, it is called root modification.

Answer: Option C

Explanation

According to the question,

In 1 day

work completed by (A+B)= $\frac{1}{72}$

work completed by (B+C)= $\frac{1}{120}$

work completed by (A+C)= $\frac{1}{90}$

2(A+B+C)'s  1day's work $=\frac{1}{72}+\frac{1}{120}+\frac{1}{90}$

∴ (A+B+C)'s 1 day's work $=\frac{5+3+4}{360}\times \frac{1}{2}=\frac{12}{360\times 2}=\frac{1}{60}$

∴ No. of days in which A alone will complete the work= (A+B+C)'s 1day work - (B+C)'s 1 day work

$=\frac{1}{60}-\frac{1}{120}=\frac{2-1}{120}=\frac{1}{120}$

∴ A alone can finish the work in 120 days

Hence option C is the correct.

Answer: Option D

Explanation

According to the question,

Let us assume

time taken by B = x

then time taken by A = 2x

and time taken by C =3x

$=\frac{1}{x}+\frac{1}{2x}+\frac{1}{3x}=\frac{1}{12}$

⇒ $1+\frac{1}{2}+\frac{1}{3}=\frac{x}{12}$

$$\begin{gathered} \Rightarrow \frac{6+3+2}{6}=\frac{x}{12} \\ \Rightarrow 11=\frac{x}{2} \end{gathered}$$

∴   x=22

∴ Required no. of days= 2x= 2×22= 44 days

Hence option D is the correct .