Test: Cell division - Grade 10 MCQ

Guard cells in plants are specialised to open and close to let carbon dioxide into the leaf for photosynthesis. The two guard cells form the boundary of a stoma.

Plant stem cells occur in meristems. Meristems are found just below the growing tip of the shoot and root.

If 16 out of 100 cells are undergoing mitosis, and the cell cycle is 400 hours, then mitosis lasts for 64 hours. The calculation is 16/100 x 400.

The stage before mitosis involves a period of growth, during which time DNA is checked for errors. The daughter cells must be perfect copies of the parent cell.

Humans have 23 pairs of chromosomes in each body cell. These consist of 22 pairs of autosomes, and a pair of sex chromosomes.

Meristematic cells are grown in sterile culture media to avoid the growth of microorganisms. Certain microorganisms will infect the meristematic cells in culture and may cause them to decay.

An ethical consideration about embryonic stem cell use is that embryos are being produced just so that stem cells can be extracted for research. Some people question whether it is right to do this.

Embryonic stem cells can differentiate into different cell types. Adult stem cells can differentiate into cells of a similar type only.

Two daughter cells are produced when a cell divides by mitosis. Each has the same number of chromosomes as the parent cells. Cells produced by mitosis must be identical to the parent cells.

A gene is a short section of DNA that codes for a protein. It is estimated that there are around 20 000 to 25 000 genes that code for proteins.