There are vastly different systems of sex determination among animal life on earth. In this TED Ed presentation biologist, Aaron Reedy, shows us the incredible differences between species when it comes to determination of gender. [5:46]

This site focuses on the first 16 weeks of embryo development when the sex of the child is determined.

Find out about the chromosomal basis of sex determination, X and Y chromosomes, and X-linkage.

Meet the freshwater Tetrahymena, a single-celled creature that has seven possible sexes. This article presents information from recent research that helps explain how the creature reproduces and how its sex is determined.

This animation explains how Nettie Stevens research on meal worms unlocked the chromosomal basis of gender.

[Free Registration/Login may be required to access all resource tools.] What determines if a baby is a male or female? Recall that you have 23 pairs of chromosomes-and one of those pairs is the sex chromosomes. Everyone has two sex...

A library of information on chromosomes and their role in heredity. Articles found on the website study chromosome structure, chromosome composition, chromosome abnormalities, roles that chromosome plays in sex determination, and changes...

This resource presents a detailed discussion and explanation of the Y-chromosome and how it determines the male sex.

Our genes are inherited from our parents, and the different combinations of these genes make us unique. Genetic inheritance controls the characteristics of all living things. This lesson focuses on the inheritance of biological sex in...

Thomas Hunt Morgan will explain the research he did to determine that some traits are linked to the sex of an individual.

This site is a must see for any lesson or unit on biotechnology! It is a companion to the PBS video "Bloodlines: Technology Hits Home," although it can certainly be used without the video. It's a fantastic site that will challenge...

Excellent site where students are challenged to read several case studies and make choices about what they would do in the situation. After they choose they are presented with some of the consequences that their decision may produce in...

Using chromosome and gene models, students play the roles of two parents in this genetics simulation. The object is to create four offspring and determine their genotypes and phenotypes, and determine the probability of having offspring...

The basic principles of genetics are in this effective site. Gender determination, recessive traits, and the Punnet Square are the topics examined. There is also a Punnet Square practice exercise to assess your comprehension of the...

Monoecious refers to organisms having both male and female characteristics in a single individual, i.e., a hermaphrodite, while dioecious organisms have separated genders. The two terms are compared for their similarities an differences...

Animated activity offers a simple look at meiosis and the production of gametes for reproduction. The stages are well animated and then students can put the gametes together to make baby dragons to illustrate how different they can be....

Learners explore fruits and vegetables. The activity includes a questionnaire that asks an individual's age, sex, and level of physical activity to determine the fruits and vegetables needed in an individual's diet. The resource consists...

In this lab experiment site, you will observe the external and internal anatomy of a perch, determine the sex of a perch using internal anatomy, and collect statistical data on perch length.

Students will explore Gregor Mendel's laws of genetics in this lesson plan. Students will be paired in male and female groups. If girls and boys can't be evenly divided, same sex students can be paired to represent research scientists....

In this lab experiment site, you will "Observe the external and internal anatomy of a crayfish, determine the sex of a crayfish using external anatomy, and collect statistical data on crayfish length and cheliped length."

In this lab experiment, you will observe the external anatomy of a grasshopper, determine the sex of a grasshopper using external anatomy, and collect statistical data on grasshopper length. You will also be asked to describe the...