Describe the mechanisms that lead to multiple births. What will be an ideal response?
Concepts to Consider: Monozygotic (identical) twins form when the cells of the two-celled embryo
separate and develop into complete organisms. They may also form when the inner cell mass divides
and forms two groups of cells, which both develop independently. If the two inner cell masses do not
separate completely, conjoined twins form. Dizygotic (fraternal) twins develop when two eggs are
ovulated and fertilized by different sperm.
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Moistening and lubrication of food occurs in the
human a. mouth. b. esophagus. c. stomach. d. duodenum. e. jejunum.
"Heartburn" is caused by
a. HCl sloshing back into the esophagus. b. pepsin sloshing back into the esophagus. c. pepsinogen sloshing back into the esophagus. d. chymotrypsin sloshing back into the esophagus. e. intrinsic factor sloshing back into the esophagus.
Effector B cells are called ____
a. memory cells b. macrophages c. plasma cells d. blood cells e. antigen producing cells
Phosphorylation of the Golgi matrix proteins by Cdk1 during mitosis
a. mediates breakdown of the Golgi apparatus into vesicles. b. activates proteins to degrade the Golgi proteins. c. inhibits association of the Golgi with microtubules. d. causes microtubules to pull the Golgi into two parts.