A Decision to Branch Out

By Dongfang Wang

Abstract

In this flipped case study, students use the scientific method to investigate how changes in a few genes have shaped the evolution of maize plant architecture during domestication. To prepare for the case, students first watch a video developed by HHMI BioInteractive to learn the story behind maize domestication and make connections between traits and fitness. In a second video, students learn the vocabulary of scientific methodology, such as independent and dependent variables, correlation, requirement, and sufficiency. In class, students engage in data analysis and discussion focusing on the effects of mutation on gene expression, plant architecture, and the evolutionary fitness of individuals within a population. In addition to training students to use the method of science, the case also reinforces core concepts in evolution, information flow, and structure function. The case is suitable for sophomore-level introductory biology courses and bio-elective courses.

Download Case

Date Posted

06/27/2016

Overview

Objectives

Draw conclusions based on experimental data, which includes the ability to identify independent and dependent variables, as well as the difference between correlative, loss-of-function, and gain-of-function evidence.
Compare and contrast natural and artificial selection.

Keywords

scientific method; domestication; plant architecture; gene expression; evolution; corn; maize; branching; teosinte

Subject Headings

Evolutionary Biology

Genetics / Heredity

Molecular Biology

EDUCATIONAL LEVEL

Undergraduate lower division, Undergraduate upper division

FORMAT

PDF

TOPICAL AREAS

N/A

LANGUAGE

English

TYPE/METHODS

Analysis (Issues), Discussion, Flipped, Journal Article

Teaching Notes & Answer Key

Teaching Notes

Case teaching notes are protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, purchase a subscription here.

Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

Download Notes

Answer Key

Answer Keys are protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, purchase a subscription here.

Download Answer Key

Materials & Media

Supplemental Materials

Videos

Popped Secret: The Mysterious Origin of Corn
This video tells the story of the genetic changes involved in the transformation of a wild grass called teosinte into corn. Running time: 17:51 min. Produced by HHMI BioInteractive, 2015.
A Decision to Branch Out
This video explains the use of the scientific method to investigate the genetic changes behind maize domestication. Running time: 5:41 min. Created by Dongfang Wang for the National Center for Case Study Teaching in Science, 2015.