MediumBiologyHigh School (9–10)GeneralHeredity and Evolution › Heredity and InheritanceConceptualBoard Exam
A team checks turtle nests on a beach. Nests in hot sand give mostly females, and nests in cool…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A team checks turtle nests on a beach. Nests in hot sand give mostly females, and nests in cool sand give mostly males. What decides the sex in these turtles? Name another kind of animal in which sex is not fixed by genes at birth.
Need a reminder? The key ideaShow
In some reptiles the temperature of the eggs decides the sex, and some snails change sex. Human women are XX and men are XY. Every egg carries X; half the sperm carry X and half Y. An X sperm gives a girl, a Y sperm a boy, with an equal chance each time.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The cause. The temperature at which the eggs develop decides the sex.
Step 2. Not genes. So in these turtles, sex is decided by the environment.
Step 3. Another case. Some snails can change their sex.
Answer: the temperature of the nest decides the sex; some snails can change sex.
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