Question

A cell’s division time is 1 minute.In 20 minutes a culture tube (culture medium) is $\dfrac{1}{8}th$ filled with cells. When will the tube be fully filled?
A. 21 minutes
B. 23 minutes
C. 60 minutes
D. 120 minutes

Answer 1

Hint:Cell division is the process by which a parent cell divides into two or more daughter cells. The generation time is 1 minute means after every minute, the cell gets doubled of its initial value.

Complete answer:
> There are two types of cell division: Meiosis and Mitosis. Most of the time when people refer to cell division,they mean mitosis, the process of making new body cells. Meiosis is the type of cell division that creates sperm and egg cells.
> Mitosis is a fundamental process for life. During mitosis, a cell duplicates all of its contents, including chromosomes, and splits into two identical daughter cells. The steps of mitosis are carefully controlled by a number of genes because this process is very critical.Health problems such as cancer can result,when mitosis is not regulated correctly.
> Meiosis is a two-step process that reduces the chromosome number by half—from 46 to 23—to form sperm and egg cells. When sperm cells and egg cells unite at conception, each contributes 23 chromosomes so the resulting embryo will have the usual 46.

> In 20 mins culture tube is $\dfrac{1}{8}th$ filled means after 1 min it will get doubled so in 21-minute culture tube will be,
$\dfrac{1}{8}\times 2=\dfrac{1}{4}$ quarterly filled. 
Again, after 1 min. It will be $\dfrac{1}{4}\times 2=\dfrac{1}{2}$ Half filled.
And, finally after 1 min, it will be $\dfrac{1}{2}\times 2=1$ Fully filled.

This means in 23 minutes the vessel will be completely filled.

So, the correct option is B. '23 minutes'.

Note: When embryos are developed in an external environment like in a lab it is known as in-vitro fertilization.
The advantages of this process are:
i) They can be sued for diagnosing fertilisation problems.
ii) They are more successful than IUI.
iii)They are safe.
iv) They help patients to conceive who could not otherwise.