Kids LOVE this activity! This karyotyping activity clearly shows that gametes have half the number of chromosomes as the parent, and they combine to make a complete zygote. Students are excited to find out if their baby koala is a male (called a buck) or a female (called a doe)! This is a fun – and minimally awkward – way to teach sexual reproduction!
This activity reinforces:
- Sexual reproduction requires two parents.
- Gametes have half the number of chromosomes as the parents.
- Gametes combine to make a zygote in the process of fertilization.
- Chromosomes have homologous pairing and differ based on size and banding pattern.
- A karyotype is an organized map of chromosomes.
- Different organisms have different numbers of chromosomes.
- XX makes a female koala offspring and XY makes a male koala offspring.
In this activity, students will:
- Read background information about sexual reproduction, including the terms gametes, zygote, fertilization, sperm, egg, and homologous chromosomes.
- Obtain a koala egg and a koala sperm. (We do this activity in pairs, so one student gets the male gamete and the other gets a female gamete.)
- Cut out the chromosomes and match the homologous pairs using a provided key. (Koalas have 16 total chromosomes, so the cutting is minimized compared to a human karyotype.)
- Paste the homologous chromosome pairs onto their karyotype page and identify whether it is male or female.
- Answer follow-up questions on a worksheet.
- Introductory reading passage with koala chromosome key
- Koala egg and koala sperm (2 versions to make male and female babies)
- Blank koala karyotype
- Follow-up questions worksheet
- Helpful teacher notes
- Science & Engineering Practice: Developing and using models
- You may also find our Asexual & Sexual Reproduction Test helpful.
- Please note: This resource is NOT editable.
- Answer key included.
- Check out more resources in the asexual and sexual reproduction section of our shop!
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