Cell Cycle Timing in an Onion Root Tip

Begin with the color code sheets and the lifestyle sheet, then use the case studies and mystery cells for application. Close with the mitosis group of sheets.

Turn a count of onion root tip cells into percents and hours for each stage, then draw a bar graph. The share of cells seen in a stage shows the share of the cycle spent in that stage. If 50 of 200 cells were in a stage, that is 25 percent of the cells, or 6 hours of a 24 hour cycle. The directions on the page read: Use the sample count and the two formulas to fill in the percent of cells and the time for each stage. Add each column. An answer key is included.

Yes, both. We made it for 7th grade living things, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.

The nucleus holds DNA, mitochondria release energy, chloroplasts capture light, lysosomes hold digestive enzymes and the endoplasmic reticulum makes proteins.

In fresh water a plant cell becomes turgid as the vacuole swells and presses against the wall. The potato strip data shows how mass changes in salt solutions.

Interphase, prophase, metaphase, anaphase, telophase and cytokinesis. Each new cell gets a full copy of the DNA.

It is a phospholipid bilayer that lets small uncharged molecules pass, needs channels for ions and blocks large molecules.