One of the Reasons That Free Oxygen in Our Atmosphere

question 67

Multiple Choice

One of the reasons that free oxygen in our atmosphere is important to the development and maintenance of life on Earth is because oxygen:

• A)combines with iron in volcanic rocks.
• B)can form ozone and block some UV radiation.
• C)is necessary for photosynthesis to occur.
• D)reduces atmospheric temperature.
• E)was very abundant in Earth's early atmosphere.

---

Definitions:

Expected Frequencies

Quantitative descriptions of the number of occurrences of events expected to happen in a scientific experiment based on probability distributions.

Fisher's Exact Test

A statistical significance test used to examine the association between two categorical variables in a contingency table, especially useful for small sample sizes.

Yates' Correction

A statistical adjustment made to the chi-squared test for small sample sizes, to better approximate the chi-squared distribution.

Expected Frequencies

The predicted counts of occurrences across different categories or intervals that one would expect by chance.