Sexual Reproduction

Contributor: Hannah Brooks. Lesson ID: 12557

Do all butterflies, flowers, kittens, and people look alike? Although flies and hippopotami all seem alike, they are different, too. Sexual reproduction is the reason for diversity within species!


Life Science

learning style
personality style
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

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It has been said that "Variety is the spice of life." If all people looked alike, and there were only one variety of rose and dog and fish and potato, life would not be so spicy. Learn why biodiversity is so important and how it's done!

Many organisms use asexual reproduction strategies because they are very efficient, producing many offspring quickly.

While asexual reproduction does have some benefit, it also results in offspring that are genetically identical to the parent. Sexual reproduction strategies allow for a blending of genetic material that increases genetic diversity within a species. Genetic diversity helps species respond to changes in the environment. The great potato famine is a great example of what can happen when a species has low genetic diversity. Potatoes in Ireland were very similar in genetic makeup, so when a fungus attacked, it killed almost all the potato plants.

Before you continue, if you missed or would like to review the previous lesson in the Reproduction series, find it under Related Lessons in the right-hand sidebar.


Sexual reproduction helps promote more diversity, which protects species and promotes variety in living organisms. Sexual reproduction relies on gametes, or sex cells. The gamete for females is the egg, or ovum. The ovum is the round object in the photo below:


The male gamete is the sperm, shown below:


The ovum is much larger than the sperm, but males produce far more sperm than females produce eggs.

sperm and ovum

These gametes, or sex cells, are formed during a special cell division process, where the genetic material of the cell gets divided in half. This process of gamete formation is called "Meiosis."

Watch the video (below) on Meiosis. As you watch, answer the following quiz questions:

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Watch Meiosis: The Great Divide, from the Amoeba Sisters, to find the answers!

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Meiosis results in gametes that contain different genetic material. In order to have a complete offspring, the egg and sperm have to join together! That process is called "fertilization." Fertilization occurs when the male gamete — the sperm — meets the female gamete, the egg. Many organisms carry out fertilization processes differently during the reproductive cycle. Corals actually release the egg and sperm into water and fertilization takes place in the sea water. Pollen is the male gamete and must be carried by wind or pollinators to find the female egg in flowers or cones.

Once the egg and sperm meet, they combine and produce a genetically-diverse offspring. The offspring has half the genetic material of the father and half from the mother. This process increases the genetic diversity for the entire species!

Sexual reproduction happens in a variety of ways for different organisms, but always results in genetically-different daughter cells. The process increases genetic diversity for species, which has many benefits.

Benefits of sexual reproduction include increasing available genes for offspring, and stability in a species to respond to changes in the environment.

Discuss what you have learned about the basics of sexual reproduction with a parent or teacher.

In the Got It? section, you will learn more about the benefits of sexual reproduction for species.

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