ZO sex-determination system

High school (ages 12+)
Human Body

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/zo-sex-determination-system

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the genotypic sex determination?Males are ZZ (homogametic), females are ZO (heterogametic)
2. What is the evolutionary origin?Considered an ancestral sex-determination system for the ancestors of Trichoptera and Lepidoptera
3. How do insects decide if a baby is a boy or a girl with the ZO system?The male gives a Z chromosome, and the female gives either a Z or no second chromosome. If the baby gets two Zs it is a male; if it gets only one Z it is a female.
4. Why do some insects use the ZO system instead of other systems?The ZO system is an ancient way that helps keep a balanced number of male and female bugs, which is important for healthy populations and the food webs they support.

Heterogametic Sex: The sex that produces two different types of gametes (e.g., Z and O).
Homogametic Sex: The sex that produces only one type of gamete regarding sex chromosomes (e.g., Z).
Phylogenetic: Relating to the evolutionary development and history of a species or group.