Sex Determination & Chromosomes ^🔗

• Males carry one X and one Y chromosome (XY)
• Females carry two X chromosomes (XX)
• Since males can give either an X or a Y chromosomes, the chromosome in the male gamete (sperm) determines the biological sex of the offspring.

Fertalisation & Punnett Squares ^🔗

• In humans we need to fuse a sperm and an egg into a fertalised zygote.
• Therefore, we can visualise sex determination with a Punnett square.
• Complete this Punnett square and describe the genotypic and phenotypic ratios.
• Pātai: Does the probability of a particular sex change with each fertalisation? Why / why not?

Answers / Whakatika ^🔗

• The genotypic ratio is 1XX:1XY or 50% XX and 50% XY.
• The phenotypic ratio is 1male:1 female or 50% male and 50% female.
• The probability does not change with each fertalisation because each fertalisation is an independent event (one not affected by prior events).

Task / Ngohe ^🔗

1. Open https://scipadonline.co.nz/lesson/193-lessons
   • Join the class with code QWPR5 if first time.
2. Complete the lesson on variation.

Fast Finishers: Work on the Inheritance task on Education Perfect.

Finish: Blooket ^🔗