Unit 3: Genetics


7.14B compare the results of uniform or diverse offspring from sexual reproduction or asexual reproduction.

7.14C recognize that inherited traits of individuals are governed in the genetic material found in the genes within chromosomes in the nucleus.


Today, you will complete 3 missions that will help you better understand asexual and sexual reproduction and heredity. The activities will also introduce you to a new tool, Punnett squares, commonly used by scientists to predict an offspring's genotype and phenotype. Finally, you will investigate the controversy and debate surrounding genetic engineering. If you need to review vocabulary, please visit the genetics mind map.

You will need your composition book today to record your notes.

Mission 1: Asexual vs. Sexual Reproduction

  • Part 1: Methods of Asexual Reproduction

    • Introduction: Organisms can reproduce either sexually or asexually. As we discovered during the fruit fly investigation, sexual reproduction mixes the genetic information (DNA) of two parents, while asexual reproduction makes offspring using only the DNA from a single parent. Interestingly, asexual reproduction can occur many different ways (5 are listed below) and some organisms switch between asexual and sexual reproduction during their life. The video below shows yeast, a type of fungus, reproducing asexually by budding.

    • Methods of Asexual Reproduction
      1. Asexual Budding: the offspring begins as a small growth on the parent organism and grows into a new organism.
      2. Asexual Fragmentation: a piece or part of the parent organism breaks off and both parts grow into a full organism.
      3. Asexual Parthenogenesis: an egg in a female grows and develops without a male sperm cell.
      4. Asexual Vegetative: a part of a plant, like a root, stem, or clipping, grows into a new organism.
      5. Asexual Gynogensis: a sperm cell from a male causes an egg in a female to develop and grow; however, the sperm does not give its DNA to the egg cell.

    • Directions
      1. Choose 2 methods of asexual reproduction you find most interesting and copy the word and definition for both.
      2. Draw one example for the 2 methods of asexual reproduction you chose.

  • Part 2: Asexual vs. Sexual Reproduction

    • Directions:
      1. Watch the video to the right -->
      2. Answer the questions below in your composition book.

    • Questions:
      1. What difference did the scientists observe between the asexual and sexual reproducing fish populations?
      2. What hypothesis or explenation do the scientists propose to explain the difference between the asexual and sexual population?

  • Optional Review and Practice: Only complete if done with all other missions

    • Directions:
      1. Read the article, Sex and the Single Snail (you may listen to the article by clicking the play button near the top)
        • Vocabulary
          • Deleterious = harmful
          • Mutation = change in the DNA of an organism
      2. Answer the questions below in your composition book.

    • Questions:
      1. What type of investigation did the scientists conduct with the two snail populations: descriptive, comparative, or experimental? Explain your answer.
      2. What are 2 benefits or advantages of reproducing asexually?
      3. What advantage did the scientists discover among the sexually reproducing population of snails?

Mission 2:Punnet Squares

  • Part 1: Introduction to Punnett Squares

    • Introduction: During the fruit fly investigation, you generated 4 different offspring by randomly combining the chromosomes from a male and female fruit fly. In our investigation, each chromosome carried 4 alleles (versions) of 4 different genes. Sometimes, it is useful to predict the genotypes and phenotype of the offspring similar to how we predicted the genotypes and phenotypes of the fruit fly's offspring. To make these predictions, scientists use Punnett squares. Punnett squares were developed by the geneticist, Reginald Crundall Punnett, in 1905.

    • Directions:


      1. View the interactive animation, Mendel's Experiments and copy the first two Punnett square examples from animation onto the handout.

  • Part 2: Punnet Square Practice Problems

    • Directions:
      1. (Grade-Level only) Complete only the first 2 problems at Punnett Square Practice Problems
      2. (Pre-AP Only) Complete only the first 4 problems at Punnett Square Practice Problems
      3. Use the punnett square handout to help you solve the problems
      4. Check your answers and record the number of questions correct on the handout.

Mission 3: The Ethics of Genetics

  • Part 1

    • Directions:
      1. Watch the video to the right -->
      2. Answer the questions below in your composition book.
      3. Answer the 4 survey questions below the video

    • Questions:
      1. Why would parents not be able to choose any eye color for their child? (Why are their choices limited?)
      2. View the results of each survey; are you surprised by the results? In your composition book, explain why or why not the results of the survey questions surprise you.

  • Part 2: Genetically Modified Crops

    • Introduction: Sometimes, humans are not happy with what they have. And, if they cannot find what they want, then they just make it. Scientists are now creating new foods by taking genes from one organism and placing them in the DNA of other organisms. They do this because they are not satisfied by the traits of the natural organism, and therefor change it to something more desirable. For example, farmers were unhappy that their tomato crops were dying due to freezing temperatures. Now, most tomatoes have a gene from an Arctic fish that protects the tomato from freezing temperatures. Yes, the tomatoes you eat are a hybrid (mixture) of fish and tomato DNA. If you wish to more about this story, click here.

    • Directions:
      1. Watch the video to the right -->
      2. Answer the questions below in your composition book.
      3. Answer the 2 survey questions below the video.

    • Questions:
      1. Why do farmers want to genetically modify the banana?
      2. Where are the genes coming from that are being inserted into the banana's DNA?
      3. Why don't the farmers grow and sell the genetically modified banana plants?
      4. Based on the evidence in the video, is the genetically modified banana protected from the disease?