Reproduction—the process of having children or offspring—is a highly important step in the life cycle of all living things. Without it, entire species would disappear as their individual members died off. Living things reproduce using one of two basic methods. Each one has advantages (its good points) and disadvantages (its bad points). In this lesson you’ll learn about these two methods: sexual and asexual reproduction.

Goals
Here are the big ideas you will learn about in this lesson:

• Reproduction is essential to the survival of a species
• All living things reproduce using either sexual or asexual methods of reproduction
• Each method of reproduction has its advantages and disadvantages

Strategies
You will be using many reading and writing strategies to complete this lesson. The key strategies that you will focus on are:

• Comparing and contrasting ideas
• Making inferences
• Determining important information

• clone
• genes
• natural selection

Have you ever wished you could make a copy of yourself? In asexual reproduction, a single parent does just that. Because the offspring are copies of the parent, they share the same traits as the parent. That is, the parent and the offspring almost always look and behave exactly alike.

What are some reasons why a living thing might want exact copies of itself? Write your answer here.

An amoeba (uh-MEE-buh) is a kind of living thing made of just one cell. It uses asexual reproduction to create more amoebas. First, an amoeba makes a copy of its full set of genes. (Genes are like instructions that exist inside every cell of every living thing. They influence how every organism looks and acts.)

Next, the amoeba divides in two. Each of the two amoebas now contains its own set of genes. These two amoebas can then pass along these genes to their own offspring.

Not all asexual reproducers have just one cell like amoebas. And not all asexual reproducers divide in two to create their offspring. Watch this video segment to learn about an unusual species of lizard.

Click "View" on the left to watch the video.

Most animal, insect, and plant species reproduce in pairs, or twos. In sexual reproduction, two individuals of the same species each contribute a half-set of their genes. Thus, in their whole set of genes, offspring inherit, or receive from their parents, a mixture of traits.

Write down some traits that parents pass on to their offspring. In what ways do these traits help a species survive? Use the box below for your ideas.

You will now learn about two different species of fish that live in the same environment. One reproduces asexually, the other sexually. This video explains how sexual reproduction provides an important advantage against the spread of disease. Click "View" on the left to watch the video.

Then show what you've learned by answering these three questions. Be sure to save all your answers before you go to the next screen.

While most living things are born as a result of sexual reproduction, others result from asexual reproduction. In this passage, you will read more about the advantages and disadvantages of each method of reproduction.

Click "View" on the left to read the passage.

After you have finished reading the passage, describe in your own words what natural selection means in the box below. Give one example of how an animal's environment can influence the method it uses to reproduce.

Think of what you've learned so far about asexual and sexual reproduction. In this activity, you will compare some basic ideas about these two reproductive methods. You may want to watch the videos again or review the passage before doing the activity (see below).

Click "View" on the left to begin the activity. Your teacher will review the answers with you.

Asexual Reproducers

Video
Length: 2m 05s

View

Why Sexual Reproduction?

Video
Length: 3m 12s

View

Reproduction—The Pros and Cons of Each Method

Document

View

You will now check your understanding of the vocabulary words for this lesson by placing them in sentences. Click "View" on the left to begin the activity.

Before moving to the next screen, choose two words from the vocabulary list and write a new sentence for each word.

Vocabulary words: reproduction, offspring, traits, clone, genes, natural selection

In this lesson, you have learned about the two forms of reproduction and how they relate to natural selection, the process that drives evolution. You will now write an essay that shares what you have learned and what you think about it.

Begin by reviewing your notes. Click "review my work" above and view print out the screen that pops up.

Final Assignment Instructions

• Click Reproduction: One Goal, Two Methods—Final Assignment (PDF).
• Choose one of the topics in the PDF and write an essay.
• Organize your response so that it includes at least three supporting details that you have learned from the reading passage, video(s), and other materials in this lesson.
• Use at least three vocabulary words (or form of the words) as part of your supporting details.