Application of inheritance concepts (2023)

Apply concepts of inheritance

level of education

6 - 8


In this lesson, students complete monohybrid and dihybrid Punnett squares to prepare for the challenge of growing cotton plants that naturally produce blue cotton.Klassen 6-8

Estimated time

Two or three 45 minute sessions

Necessary materials

For the teacher:

  • Applying Inheritance ConceptsPowerPointslideshow

For each student:

  • Vocabulary review worksheet
  • A worksheet from the Blue Genes Challenge
  • Basic information on the cotton worksheet.
  • Punnett squares worksheet
essential files
  • Answer Key - Plane of Punnett Squares
  • Application of inheritance concepts in PowerPoint
  • Basic information on the cotton worksheet.
  • Punnett squares worksheet
  • A worksheet from the Blue Genes Challenge
  • Vocabulary review worksheet

Alleles:a variant of a gene

Character:a trait that is inherited, such as B. flower color, hair color and size

Chromosome:a thread-like structure of nucleic acids and proteins found at the nucleus of most living cells that carries genetic information in the form of genes

codominance:the offspring of two true parents resemble both parents and neither trait is completely dominant as a blue flower crossed with a yellow flower would produce offspring with blue and yellow striped flowers

Deoxyribonucleic Acid (DNA):deoxyribonucleic acid; a self-replicating material present in almost all living organisms as the main component of chromosomes; Carrier of genetic information

Main feature:the trait or allele that is expressed despite the fact that an individual has inherited only one copy of that allele

Gen:a unit of heredity passed from a parent to its offspring and maintained to determine a trait in the offspring

Genotype:the genetic makeup of an organism

Estate:the transmission of traits from a parent to its offspring

Heterocigot:have two different alleles for a trait

homocigot:having two identical alleles for a trait

incomplete dominance:The offspring of two true parents do not resemble either parent but are an intermediate product of both parents, as if a red flower were crossed with a white flower, the offspring would have pink flowers

phenotype:the set of observable traits of an organism resulting from the interaction of its genotype with the environment

recessive treatment:is only expressed when an individual has inherited one copy of the recessive allele from both parents

Special feature:observable physical property obtained through genetic inheritance

Background Agricultural connections

This lesson is part ofFrom genes to jeans IISeries written to encourage students to enhance basic genetic concepts and skills through a defined vocabulary and provide explanations while applying the terms to agricultural concepts used in industry. Other related lessons and activities include:

  • Apply concepts of inheritance
  • Use of biotechnology in the selection of suitable plants
  • Research project and lecture to improve our world

Students should have some prior knowledge of Gregor Mendel and inheritance, but it will be helpful to review basic vocabulary at the beginning of the lesson.

Punnett squares are a tool used by scientists, farmers, and ranchers to predict the outcome of possible crosses between two parents. It is important for students to understand that genetics is very complex and that Punnett squares are simplified in this activity to teach the basic concepts of heredity.

Cotton is used as an example in this lesson. Cotton is grown in many US states, including California.

Cotton is the country's fifth most important crop. Most of the cotton harvest is used for clothing and home textiles. Cottonseed and cottonseed are by-products of cotton production that are used as livestock and poultry feed. Cottonseed oil is used in salad dressings, margarine, and other oils. US fiat money is 75% cotton.

Cotton grows wild in some parts of the world and has been cultivated for centuries. Fragments of cotton fabric have been found that are at least seven thousand years old. Wild cotton can be found in shades of green and brown, as well as white. Most commercial cotton is white due to years of selective breeding by farmers. White cotton is dyed with fabric dyes when making clothing.

cotton production

  • The soil is prepared by loosening, removing weeds and adding fertilizer.
  • When the ground reaches about 65 degrees, cotton seeds are planted.
  • Depending on the part of the country and the climate, the plants can be watered by natural rainfall or, in drier areas, the irrigation water must be given to the cotton plants.
  • A combination of methods are used to kill weeds, including mechanical cultivators, hand weeders, and herbicides to keep the weeds from growing out of the cotton in water, sunlight, and nutrients.
  • Nutrient requirements are monitored and fertilizers can be added as needed.
  • Integrated pest management using a combination of insecticides and beneficial insects can be used to control pests that would otherwise destroy the cotton crop.
  • Harvesting aids are applied when the cotton bolls are opened to speed up plant maturation. The leaves then dry up and fall off, making it easier to harvest the cotton bolls, which must be picked before the weather damages the cotton. Mechanical cotton pickers harvest the cotton. The cotton is then packed into modules and transported to the gin where the cotton fibers are separated from the seed.
  • The clean, raw cotton fiber is called lint and is packed into large rectangles, each weighing 500 pounds, for shipment to textile mills where it is made into fabric.

In the 1980s, a scientist named Sally Fox was involved in research for a cotton grower in Davis, California, trying to identify plants with natural resistance to pests. During her research, Sally found plants with brown instead of white cotton fibers.

Although these plants exhibited some pest-resistant traits, their color and short fibers made them unsuitable for fabric. Despite this, Sally continued to collect and plant seeds from the brown cotton plants. He selected seeds from the plants that produced brown cotton with the longest fibers. Over time, Sally grew a variety of brown cotton plants whose fibers were long enough to be woven into cloth. She founded FoxFibre®and began selling various shades of natural green and brown cotton for large garments.

One of the many challenges of growing cotton is controlling the number of pests that eat cotton, the cost of purchasing and applying pesticides, and the resistance of pests to some pesticides. The soil bacterium Bacillus thuringiensis can be easily propagated by fermentation and is produced worldwide as an approved insecticide for organic farming. This insecticide has been used as a spray or soil application for over 40 years. However, this type of application does not protect the plant from pests for long, since it can be washed away by water or degraded by the sun.

In search of solutions to the problem of cotton pests, scientists have developed a strain of genetically modified cotton by plantingGeneof soil bacteriathuringiensis-Bazillusin cotton genes. Genes from soil bacteria produce a protein in plant tissue that protects the plant from being eaten by pests such as cotton bollworm and European corn borer. This type of cotton is commonly known as Bt cotton.

Before Bt cotton could be grown for commercial production, it had to pass many regulatory tests for toxicity and allergens to humans and other organisms. These tests were conducted by the United States Environmental Protection Agency (EPA). Bt is only toxic to certain insects that have receptor sites for Bt proteins to bind to in their gut. Humans, dogs, mice, fish, frogs, guinea pigs, salamanders, birds, bees, ladybugs and most beneficial insects do not have these receptors and are not affected by Bt.

The benefit of Bt cotton is that fewer crops are lost to insect damage and fewer pesticides need to be used. Bt cotton first became available in 1996, and as of 2013, approximately 75% of the cotton grown in the United States is Bt cotton. This Los Angeles Times article provides an interesting perspective on Bt cotton.1

  1. Ask your students what they know about cotton. Ask students to use their prior knowledge to gather facts about cotton. In your discussion, help students recognize that most of their clothing is made of cotton. Do you know where the cotton comes from?
  2. heart of americais a PBS show that features different agricultural crops in each episode. Choose aepisode about cottonthroughprovides a comprehensive description of the cultivation, harvesting and processing of cotton.
explore and explain
  1. Prepare students for this lesson by reviewing the vocabulary. One way to do this would be to give the students the list of words without the definitions. Post the definitions on poster paper around the room. Students should understand the definitions by drawing an explanation of each definition on their handout. Brochures and extended definitions are in theessential filessection of this lesson
  2. Ask the students to read themBasic information about cottonspreadsheet.
  3. Show the first part (slides 1-12) of theApplication of inheritance concepts in PowerPoint slidesto the class. Take time for a break and have the groups of students solve the monohybrid and dihybrid problems on the slides and then discuss them together in class. After completing a few examples, distribute thePunnett squares worksheetand ask students to work in pairs to solve the problems.
  4. Tell the class that for the second part of the activity they will use their genetic knowledge by taking on the role of the cotton farmer. You can use the photos on PowerPoint slides 13-21 to show in detail how cotton is grown.
  5. Pass outBlue Genes Challenge Worksheet.and work with the questions. Then have small groups solve the problems and discuss as a class.
  6. For the third part, use PowerPoint slides 22-26 to discuss the following with your students.
    • The co-dominant blue and white striped cotton has become a sensation and clothing companies around the world want to buy it because the specially dyed cotton doesn't need an acid wash or additional processing to give it that aged denim look. This saves apparel companies a lot of time, labor and money. Your farm tries to produce enough cotton to meet demand.
    • There's a problem with the pests though... they seem to be devouring all of your blue and white striped cotton. You've heard of a cotton variation called Bt cotton and are wondering if this could be a solution to your problem.
  7. See the information on Bt cotton in theBasic information on the cotton worksheet.🇧🇷 Have a class discussion about the opportunity to work with geneticiststhuringiensis-BazillusGenes inserted into their blue and white striped cotton genes to provide protection from hungry insects. Ask students to write a paragraph explaining how Bt genes could improve their blue and white striped cotton crop and why they would or would not use this approach to solve their problem.
Work out
  • Have students create Punnett squares for imaginary plants or animals and provide illustrations of possible variations on their creatures.

  • Complete a class research paper on genetically modified cotton. Divide the class into small groups to explore different aspects of the process including research, testing, outreach, do's and don'ts. Instruct the class to look for information from reliable sources such as the USDA and universities.


After completing these activities, summarize and review the following key concepts:

  • Farmers grow cotton.
  • Cotton is a natural fiber used to make fabrics. Most of our clothing is made of cotton.
  • Farmers use a basic knowledge of genetics and origins to help them produce the best cotton for consumer needs.

The development of this curriculum was funded by the Monsanto Fund in 2014 to provide teachers with science and biotechnology education that meets Common Science and Next Generation standards.

Managing Director: Judy Culbertson
Layout and design: Nina Danner

Recommended Supplemental Resources
  • Improve our search activities around the world
  • Selective Sheep Breeding: Punnet Square Practice
  • Journal of Agricultural Research
  • cotton reader
  • Sour/sweet cucumber taste test
  • Cotton boll kit
  • The Heart of America: Cotton Episodes
  • How to edit DNA with CRISPR
  • How it's made: Cotton thread
  • How Mendel's peas helped us understand genetics
  • Planet money makes a t-shirt.
  • Crop Modification Techniques
  • 23 and me
  • a world of cotton
  • Cotton Counts Educational Resources
  • Learning Center for Genetic Sciences
  • journey of a gene

Mandy Garner


California Foundation for Agriculture in the classroom

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