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Summarize the main stages of animal development. What family of control genes plays a major role?

What animal characteristics would be needed by an imaginary plant that could chase, capture, and digest its prey鈥攜et could also extract nutrients from soil and conduct photosynthesis?

One of the characteristics unique to animals is

(A) gastrulation.

(B) multicellularity.

(C) sexual reproduction.

(D) flagellated sperm.

Put the following milestones in animal evolution in order from oldest to most recent: (a) origin of mammals, (b) earliest evidence of terrestrial arthropods, (c) Ediacaran fauna, (d) extinction of large, nonflying dinosaurs.

First, practice reading the data table. For the eighth observation (i = 8), what are x_i and y_i? For which phylum are these data?

Explain what is represented by the red-colored portion of the branch leading to animals. (See Figure 26.5, 鈥淰isualizing Phylogenetic Relationships,鈥� to review phylogenetic tree diagrams.)

Next, we鈥檒l calculate the mean and standard deviation for each variable. (a) The mean( $\stackrel{炉}{x}鈥�$ ) is the sum of the data values divided by n, the number of observations:. Calculate the mean number of miRNAs ($\stackrel{炉}{x}鈥�$ ) and the mean number of cell types ( $\stackrel{-}{x}$) and enter them in the data table (for $\stackrel{炉}{y}$, replace each x in the formula with a y). (b) Next, calculate ( $x_i鈥�-鈥�\stackrel{炉}{x}$) and ( $y_i鈥�-鈥�\stackrel{炉}{y}$) for each observation, recording your results in the appropriate column. Square each of those results in the appropriate column. Square each of those results to complete the $(x_i鈥�-鈥�\stackrel{炉}{x)}{鈥�}^2$and $(y_i鈥�-鈥�\stackrel{炉}{y)}{鈥�}^2$ columns; sum the results for those columns. (c) The standard deviation, s, which describes the variation found in the data, is calculated using the following formula:

$s_x鈥�=\sqrt{\frac{1}{n-1}}鈭�(x_i-鈥�\stackrel{炉}{x}{)}^2$

Calculate s_x and s_y by substituting the results in (b) into the formula for the standard deviation.

Evaluate whether the origin of cell-to-cell attachment proteins in animals illustrates descent with modification. (See Concept 22.2.)

Next, calculate the correlation coefficient r for the variables x and y. (a) First, use the results in 3 (b) to complete the($x_i鈥�-鈥�\stackrel{炉}{x}$)($y_i鈥�-鈥�\stackrel{炉}{y}$) column; sum the results in that column. (b) Now use the values ofs_x and s_yfrom 3(c) along with the results from 4(a) in the formula for r.

Do these data indicate that miRNA diversity and animal complexity are negatively correlated, positively correlated, or uncorrelated? Explain