Lesson 3: Copies or Combinations? Asexual Reproduction

  1. Introduction
  2. Teach It
  3. Dig Deeper

Introduction

When organisms reproduce asexually, they produce clones with the same genetic material. Students will be able to identify the advantages and disadvantages to this type of reproduction.

Time: one class period

Objectives:

  • Students will use a model to depict the results of asexual reproduction.
  • Students will compare asexual and sexual reproduction.
  • Students will test their hypothesis about what will happen to the offspring of asexually-reproducing paramecium in a harmful environment.

Type of Activity:

  • Video and worksheet questions
  • Hands-on Simulation

Next Gen Science Standards:

  • Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation. MS-LS3-2

STEAM Habit of Mind:

  • Students will test a hypothesis, analyze the results and draw conclusions from them.
  • Students will model events and envision future results.
  • Students will communicate an idea using words and images.

Suggested Do Nows:

Word Wall:

  • Asexual reproduction
  • Sexual reproduction
  • Multicellular
  • Unicellular

Teach It

Materials Needed:

Activity:

Sometimes we get so busy that we wish we could make a copy of ourselves in order to get everything done. Although humans can’t clone themselves at will, unicellular organisms, such as bacteria, can. They don’t need a partner to mate with because they use asexual reproduction. Are there any advantages or disadvantages that you can think of to this type of reproduction? After soliciting answers from the students, explain that in class they will model the asexual reproduction of paramecia. However, first, they will watch the Asexual Reproduction video as a class. 

Discuss the video and then provide students with the Lab #1: Asexual Reproduction worksheet. Students can work in pairs to answer the questions in the Research section of the lab. 

In Step 2, students will write a hypothesis about what they think will happen to a population of paramecia in a harmful environment.

While students are working on the questions, hand out a bag of “paramecia” and a white sheet of paper to each pair of students. On the paper, students should draw a pond of water for their paramecia to live in. Since each color represents a paramecium that has specific genes, three circles of each color will start their lives in the pond. This is Generation 0, and its population should be recorded in the table.

Students can then work on the next part either on their own in groups or guided by the teacher. Using the Lab #1 – Asexual Reproduction Events Slide Show, students will create multiple generations of paramecia, some of which will die because of harmful events that affect their environment and some of which will reproduce asexually. As paramecia die or are born, students will move the colored circles in or out of the pond to model the effects of the events and the multiple generations. Students will then complete the steps of their experiment, analyzing the data and forming conclusions. 

At the end of the lesson, the class should be able to create an explanation that compares sexual and asexual reproduction using Sketchnotes (See Additional Resources). 

Dig Deeper (Extension)

Challenge students to answer this question: Unicellular organisms have the ability to mutate. How does this mutation in a unicellular organism affect the population compared to multicellular organisms? 

If one of your cells contain genes that mutates, this doesn’t make a big difference because you are a multicellular organism. Many mutations never even show up in our phenotype. However, for a unicellular organism, they have a fewer number of genes (because they are smaller) so the effect of a mutation is much greater. A single-celled organism can’t just get rid of a mutated cell and move on because that cell is the entire organism. So a mutation is more likely to affect the phenotype of a unicellular organism.

Go to Lesson 4: Creative Science – Dragon Eggs Found in the Arctic