12.7_6thSci_TR 3.6

Last updated almost 3 years ago

3 questions

Slides and Objective

TR Ch 3 Task: Reproduction in Darwin’s Bark Spiders
Objective:  KWBAT analyze and interpret data to write a scientific argument regarding spider offspring.

Part 1

Part 1: Do Now

Where did Offspring B get her F2 gene?

Why does Offspring B have a different gene version (F1F2) than her brother (F1F1)?

Why is Offspring D the only spider with High Silk Flexibility?

Part 2

Part 2: Reasoning About Darwin’s Bark Spider Traits

We began with three claims to explain why there was variation among the offspring for silk flexibility:
As you can see, we eliminated Claim 2 because we saw that each offspring gets an equal number of genes from each parent.  We’ll use the reasoning tool below to decide between Claim 1 and Claim 3.


Review the Family Tree diagram carefully, paying special attention to the spiders’ combinations of gene versions. Use the diagram to help you complete the reasoning tool below.

Based on what we just read, we can safely eliminate claim 1 (none of the spiders have a “new” gene version).  If the offspring were having mutations, we would expect to see new gene versions that neither parent had.  (Also, mutations *rarely* have an impact on traits).

To conclude our study of these spiders, we’ll write a summary of how we know Claim 3 is correct.

Part 3: Chapter Task Assignment is on Google Docs.

It is right next to where you found your TR 3.6 assignment!