The Cell Cycle & Mitosis — Practice · Grade 7 Science

Chapter: Genes, Cell Division & Heredity

What this practice covers

By the end of The Cell Cycle & Mitosis you should be able to:

8 questions, written answer, multiple choice and numeric, each with a worked explanation.

Vocabulary used: cell cycle, replication, sister chromatids, mitosis, daughter cell.

Problem 1

Why is copying needed before the modeled division?
Answer and explanation

It provides corresponding genetic information for the daughter nuclei rather than merely splitting the original information into incomplete portions.

Problem 2

Does DNA replication mean each daughter must have eight chromosomes in a four-chromosome model?
Answer and explanation

No. Proper separation gives each daughter the original four-chromosome set; copying DNA is not permanent doubling of each daughter’s set.

Problem 3

Why is mitosis not automatically gamete formation?
Answer and explanation

Mitosis normally preserves the studied chromosome set; meiosis reduces the set in the sexual reproduction model.

Problem 4

Can a stable cell count coexist with division?
Answer and explanation

Yes. Division can replace cells that are lost, giving no net change in total count.

Problem 5

Illustrative cell starts with six chromosomes. DNA is copied, corresponding copies separate normally, and the cell forms two daughters. State each daughter’s chromosome count and distinguish DNA copying from permanent doubling of the chromosome set.
Answer and explanation

Each daughter receives six chromosomes in the stipulated normal model. Replication supplied DNA copies so both receive the set; it does not leave each daughter with twelve chromosomes. The result depends on normal distribution and does not describe every real division error or specialized cell.

Begin with the six-chromosome set.

Represent each as copied before separation.

Distribute one corresponding copy to each daughter.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 6

A tissue gains four cells by division and loses four in the same interval. What is its net change, and did division occur?
Answer and explanation

Net change is zero, but division occurred. Equal gains and losses can keep the total count stable.

Response criteria

  • Explain the relevant biological process accurately.
  • Use the supplied evidence and show calculation steps with units where needed.
  • Connect a labeled model or mechanism with the claim.
  • State an assumption, evidence limitation, or useful next observation.

Problem 7

What is the modeled chromosome set after normal mitosis?
  1. Half in every daughter
  2. The corresponding starting set in each daughter
  3. No DNA
  4. Double forever
Answer and explanation

The corresponding starting set in each daughter

Normal mitosis distributes corresponding sets after replication.

Problem 8

Five cells each divide once into two; none are lost. How many daughter cells result?
Answer and explanation

10 cells

5×2=10 daughter cells under the stipulated model.

Browse all courses