1. in cladistic analysis, similar genes that appear in dissimilar organisms, indicate that they share a common

2. the air spaces in the layer of a leaf connect with air through stomata in the epidermis of the leaf.

3. one of the differences between cambrian animals was the appearance of such as antennae as cambrian animals evolved.

4. the body needs in only small amounts, but these organic molecules are an important part in perform cellular reactions.

word list:
a. ancestor
b. antigens
c. appendages
d. brain stem
e. cerebrum
f. classical
g. color
h. descendant
i. ears
j. higher
k. hormones
l. innate
m. lower
n. melanin
o. spongy mesophyll
p. vitamins
q. white blood cells

In number 1, the correct answer is ancestor. Cladistic analysis means organisms are organized dichotomously by cladograms determining whether or not the organisms are related or having shared a common ancestor. Dissimilar organisms that share same genetic components most likely will reveal that they have a common ancestor. 

In number 2, the correct answer is the spongy mesophyll. The mesophyll of plants has two layers; the upper palisade mesophyll which actions to absorb light efficiently and the spongy mesophyll which are filled with air spaces in order to perform gas exchange of carbon dioxide and oxygen efficiently. 

In number 3, the correct answer is appendages. Cambrian animal and animal-like life forms mostly live in water. The development of appendages is an evolutionary measure wherein they use the appendages to (1) propel the water for a more efficient locomotion and (2) propel the water to create currents so that they can efficiently catch a prey. 

In number 4, the correct answer is vitamins. Vitamins are derived from organic molecules and act as co-factors in most enzymatic reactions in the body (i.e. Vitamin C or ascorbic acid is needed for the reduction reaction of glutathione to be an effective anti-oxidant). Vitamins can be classified as fat-soluble (vitamins A, D, E, and K) and water soluble (vitamins A and B complex). Vitamins are only needed in small amounts but there are certain deficiencies and toxicities wherein vitamins are involved.