1. When studying animal behavior, the distribution of organisms within a choice chamber can be studied to identify animal preferences. 20 Isopods are

placed in a 2-choice choice chamber. A cotton ball dampened with distilled

water is placed in Chamber A; A dry cotton ball is placed in Chamber B.

After 15 minutes 2 Isopods are located in Chamber B, and 18 isopods are found

in Chamber A. Perform the chi-squared test to determine if the distribution

of isopods is significant or due to random chance. (3 points)

The distribution  of isopods is statistically significant.

Explanation:

H₀= Individuals will be equally distributed

H₁ = Individuals will not be equally distributed.  

∑ is the sum of the terms

O are the Observed individuals: 2 in chamber B, and 18 in chamber A.  

E are the Expected individuals: 10 in each chamber

X² = ∑ ((O-E)²/E) = ((2 - 10)²/10) + ((18 - 10)²/10) = 6.4 + 6.4 = 12.8

X² = 12.8

(K = Independent variables = dry cotton and wet cotton)

12.8 > 3.84 meaning that the difference between the observed individuals and what the expected individuals in each chamber is statistically significant. Not probably to occur by random chances.

There is enough evidence to reject the null hypothesis.  

c. live where it’s cold and icy

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.