Clams, snails, sea slugs, and octopuses belong to the phylum

A) Annelida.
B) Mollusca.
C) Porifera.
D) Platyhelminthes.
E) Arthropoda.

For each animal cell that begins oogenesis, the number of ova produced is four.

Ectothermic animals

A) depend on heat from the external environment to adjust their body temperatures.
B) may dilate blood vessels to increase blood flow and heat to the skin.
C) maintain a relatively constant body temperature despite external temperatures.
D) may have feathers to keep them insulated.
E) may have body fat to keep them insulated.

Some transcription factors, such as leucine zipper proteins, form homodimers or heterodimers. How does this increase the complexity of available strategies of gene regulation?

The hypothalamohypophysial portal system extends from the hypothalamus to the ________.

Cycads may be characterized as being:

A) dioecious and having motile sperm.
B) the most primitive flowering plants.
C) monoecious and having motile sperm.
D) dioecious and having nonmotile sperm.
E) monoecious and having nonmotile sperm.