Chance & Selection Lab

Model 1 · Probability

The Coin-Toss Probability Lab

An offspring inherits an allele by chance — like a coin toss. Heads = dominant allele, Tails = recessive allele. Flip a few times, then a lot. Watch what happens to the pattern.

Heads · Dominant

Tails · Recessive

Heads

Tails

Total flips: 0 · Ratio — : —

Start by flipping 1× a few times — can you predict the result? Then flip 1000× and watch the ratio settle.

Reflect ▸You can't predict one coin toss, but you can predict the pattern of 1000 tosses. In your own words, what does this tell us about how probability works?

Section 4 · Regents-Style Practice

Trait Frequency & Probability

A population of mice lives on dark volcanic rock. The dark-fur allele (D) is dominant; light-fur (d) is recessive. Hawks hunt by sight, so dark mice are better camouflaged. Use the data to answer.

Table 1. Percentage of dark-fur and light-fur mice over five generations.
Generation	1	2	3	4	5
% Dark-Fur	30%	45%	62%	80%	91%
% Light-Fur	70%	55%	38%	20%	9%

Q4 ▸Use the terms variation, selective pressure, and natural selection to explain why the dark-fur trait increased over the five generations.

Q6 ▸Suppose a volcanic eruption covered the ground in light-colored ash for many generations. Predict what happens to the dark-fur and light-fur frequencies, and explain using natural selection and trait frequency.

The Coin-Toss Probability Lab

Vocabulary Match-Up

Trait Frequency & Probability

Finish & Turn In

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