ANIMAL SYSTEMS QUESTION 1979:			L. PETERSON/ECHS
	Describe the structure and function of the stomach, pancreas, and small intestine
	as digestive and endocrine organs in the human. (For each organ, include the 
	relevant cell types and their functions.)

STANDARDS:
	[1 point for each statement unless otherwise indicated]

Stomach (max. 7 points)
STRUCTURE:
Regions = cardiac, fundic, pyloric / pyloric sphincter (1 pt. for 2 of 3)
Layers of muscle; thick walls
Presence of RUGAE (cellular composition = histology)

DIGESTIVE FUNCTION:
Mention chief cells and parietal cells
OR
Name and function of chief cells - secrete renin, lipase, pepsinogen
Name and function of parietal cells - secrete HCl
Presence of mucous coat protects the stomach
Function of HCl = aids protein digestion OR converts pepsinogen to pepsin
Pepsin - produced in inactive form to protect OR its function in protein digestion
Churning aids mechanical digestion
Absorption of alcohol, etc. in stomach

ENDOCRINE FUNCTION:
Name and function of gastrin = stimulates production of digestive juice
Presence of Food = stimulus for gastrin release
Factors such as stress effects gastrin/stomach function

Small Intestine (max. 7 points)
STRUCTURE:
Increased surface area by folds or villi or microvilli
Structure of villi = blood vessels, lymph
Regions = duodenum, jejeunum, ileum

DIGESTIVE FUNCTION:
Name 3 enzymes from intestinal glands 
	(peptidases, sucrases, enterokinase, lipase, amylase, nuclease)
Function of each enzyme (max. 2)
Bile released in small amounts plus:
	a) produced in the liver or b) stored in gall bladder or c) emulsifier
Site of most absorption
Mechanical absorption of long fatty acids
Peristalsis
Change in pH

ENDOCRINE FUNCTION:
Secretin /function = stimulates release of alkaline secretions by pancreas
Enterogasterone /function = inhibits stomach
Cholecystokinin /function = stimulates gall bladder to release bile
Pancreozymin /function = stimulates pancrease to secrete digestive enzymes
Enterokinin /function = stimulates intestinal glands to secrete enzymes

Pancreas (max. 7 points)

STRUCTURE:
Connects to small intestine by pancreatic duct
Comprised of exocrine and endocrine cells

DIGESTIVE FUNCTION:
Secretion of pancreatic juice and digestive function of enzyme mixture
OR
Name 3 enzymes in pancreatic juice:
		 amylase, trypsinogen, chymotrypsin, carboxypeptidase, lipase
Function of each pancreatic enzyme (max. 2)
Secretion of bicarbonate ions to neutralize

ENDOCRINE FUNCTION:
Mention of Islets of Langerhans - function in glucose metabolism
Alpha cells secrete glucagon
Glucagon stimulates liver to convert glycogen to glucose
Beta cells secrete insulin
Insulin stimulates uptake of glucose by cells

ANIMAL SYSTEMS QUESTION 1982			L. PETERSON/ECHS
	Describe the following mechanisms of response to foreign materials in the human body.
		a.  The antigen-antibody response to a skin graft from another person.
		b.  The reactions of the body leading to inflammation of a wound infected 
		     by bacteria.

STANDARDS:
[1 point for each statement]
					* = additional points occasionally encountered

ANTIGENS- REJECTION
Recognition as foreign antigens
Rejection by Immune System
Antigens on surface of graft cells		*Surface glycoproteins as Antigens
Antigens stimulate Antibody production or T-cells

ANTIBODIES
Lymphocytes - B Lymphocytes
B Lymphocytes (Antigen Exposure) -> Plasma Cells
Plasma cells synthesize Antibodies
						*Antibodies are Globulins (Immunoglobulins)
						      	Types = IgG, A, M, D, E
							Antibodies are proteins
							Antibodies remain in circulatory system
							Antibody structure
Antibodies circulate to sites needed
Antibodies precipitate Antigens or complex w/Antigens
Antibodies make Antigens susceptible to phagocytosis by WBCs
Antibody variability due to genes / Clonal Selection Theory
Antibody specificity - broad/narrow
Antibodies important in both graft rejection and in fighting bacteria, etc.

T - CELLS
T -cells involved in cell mediated immunity
Lymphocytes -> T -cells
						*T -cells:  thymus involvement
							     as "helper" cells
COMPATIBILITY
Tissues / Graft must be compatible / Tissue matching
Blood groups as examples of compatibility
Genetic basis of compatibility
						*Tolerance / Immunosuppression
MEMORY
Memory cells
Secondary Response
						*Complement = serum
						       proteins acts by Antibody-Antigen Complex
						       complement inactivates or kills bacteria





WBCS
WBCs invade inflection site - destroy bacteria or wall-off
Phagocytosis
						*WBCs
						       types: neutrophils, basophils, eosinophils,
							    monocytes;
						       lysosomes in phagocytic WBCs
						       macrophages
						       WBCs from marrow
						       bacterial presence -> WBC production
PUS/FLUIDS
Pus = WBCs, Dead Cells, etc,
Fluids, plasma -> swelling
Inflammed area = hot (kills bacteria)
Lymphatic System Filters
CLOT
Clot walls-off inflammed area
Clotting Mechanism - some detail
DILATION
Dilation of Blood Vessels increases circulation; WBCs
						*Histamines -> Dilation
						  Histamines from mast cells
CHEMOTAXIS
WBCs accumulate /"message" calls WBCs to inflammed site
						*Kinin - chemotactic or increases dilation































ANIMAL SYSTEMS QUESTION 1983			L. PETERSON/ECHS

	Describe the structure of a mammalian respiratory system. Include in your
	discussion the mechanisms of inspiration and expiration.

STANDARDS:
	21 points possible - max. = 15 
	[must include description &/or function to get point]

DESCRIPTION - STRUCTURE
1 - Nasal Chambers - hard/soft palate, cilia, mucous membranes
       Sinuses - air spaces, sensory receptors
1 - Pharynx - eustachian tube, tonsils
1 - Larynx - vocal cords, epiglottis
1 - Trachea - cartilaginous rings
1 - Bronchial tree - bronchioles
1 - Lungs - pleural membranes
1 - Alveoli - site of gas exchange, thin-walled
1 or 2:
2 - Sequential Listing of 5 or more portions of system
1 - Incorrect sequence or less than 5 organs

MECHANISMS - INSPIRATION
1 - Diaphragm - contraction, goes down
1 - Intercostal muscles
1 - Thoracic cage - outward and upward
1 - Negative pressure (Concept)

MECHANISMS - EXPIRATION
1 - Passive recoil (Concept)
1 - Thoracic and abdominal muscles
1 - Thoracic cage - downward and inward
1 - Diaphragm - goes upward

NEURAL CONTROL
1 - Medulla
1 - Inspiratory center
1 - Expiratory neuron, inhibition
1 - pH














ANIMAL SYSTEMS QUESTION 1984			L. PETERSON/ECHS
	Discuss the sources and actions of each of the following pairs of hormones in humans
	and describe the feedback mechanisms that control their release.
		a.  Insulin..glucagon
		b.  Parathyroid hormone..calcitonin
		c.  Thyrotropin (TSH)..thyroxine (T4)

STANDARDS:
	Maximum of any 6 points on each of three sections.
	Must answer all three sections of exam to score 15.
	Discretionary point on adequate discussion of feedback loop and/or homeostasis.

INSULIN/GLUCAGON SECTION
INSULIN:
 SOURCE
	2 - Beta cells of pancreas
	1 - Pancreas or Islets of Langerhans
 ACTION
	1 - Lowers blood sugar
	1 - Promotes glucose oxidation in cells
	1 - Glycogen synthesis (liver and muscle)
RELEASE
	1 - Chemical - blood glucose level
	1 - Hormonal - secretin, gastrin, etc.
	1 - Neural - Acetylcholine (parasympathetic) stimulates
GLUCAGON:
SOURCE
	2 - Alpha cells of pancreas
	1 - Pancreas or Islets of Langerhans
ACTION
	1 - Increases blood glucose
	1 - Stimulates glycogen -> glucose (liver)
	1 - Synthesis of glucose from amino acids and fatty acids
RELEASE
	1 - Level of blood glucose, i.e. low glucose / increases glucagon
	1 - Neural - Autonomic system




















PARATHYROID HORMONE/CALCITONIN SECTION
PARATHYROID HORMONE:
SOURCE
	1 - Parathyroid gland on posterior surface of thyroid
ACTION
	1 - Control of Ca (inc.) and P (dec.) level
	1 - Acts on bones, kidneys, and intestine
	1 - Increases activity of osteoclasts (Ca and P bone -> blood)
	1 - Kidney Ca reabsorbed, P excreted
RELEASE
	1 - Blood Ca low, PTH high  (vice-versa)
CALCITONIN:
SOURCE
	1 - Cells in thyroid gland
ACTION
	1 - Decreases osteoclast activity
	1 - Inhibits release of Ca and P from bone
	1 - Lowers blood Ca and P
RELEASE
	1 - Increased blood Ca causes increase in Calcitonin
THYROTROPIN/THYROXINE SECTION
THYROTROPIN
SOURCE
	1 - Anterior Pituitary
ACTION
	1 - Stimulates thyroid hormone synthesis and secretion
	1 - Increases iodide binding, T3, T4 synthesis
	1 - T3, T4 release
RELEASE
	1 - Thyroid Hormone level decreases, TSH increases (vice-versa)
THYROID HORMONE
SOURCE
	1 - Follicles of thyroid gland or thyroid gland
ACTION
	1 - Maintains metabolic level
 	1 - Increases O2 consumption
	1 - Maintains normal development and function
RELEASE
	1 - Neural via hypothalamus (low thyroid hormone, increases TSH)
	1 - TSH feedback (thyroid and anterior pituitary
























ANIMAL SYSTEMS QUESTION 1985			L. PETERSON/ECHS
	Describe the anatomical and functional similarities and differences within each 
	of the following pairs of structures.
	a.  Artery..vein
	b.  Small intestine..colon
	c.  Skeletal muscle..cardiac muscle
	d.  Anterior pituitary..posterior pituitary

STANDARDS:
 	15 point maximum - must answer all four parts for 15

A.  ARTERY-VEIN 				(7 points possible - 4 points maximum)
1 - Wall thickness or lumen - relate to blood pressure
1 - 3 layers identify or elaborate
1 - Valves in veins - function
1 - Direction of flow
1 - O2/CO2 concentration - mention of pulmonary circulation
1 - Capillary relationship - hydrostatic or osmotic pressure
1 - Pulsating/elasticity - explanation of pressure

B.  SMALL INTESTINE-COLON		(8 points possible - 4 points maximum)
1 - Villi - function - increase in absorption
1 - Length - diameter - size comparison or elaboration
1 - Glands of intestine - Digestive vs. mucous
1 - Regions - elaboration
1 - Smooth muscle - peristalsis
1 - Three tissue layers - elaboration
1 - Absorption - food materials, water, salts, mention of surface area
1 - Flora - comparison/explanation 

C.  SKELETAL-CARDIAC MUSCLE		(7 points possible - 4 points maximum)
1 - Location - explanation
1 - Nervous control - voluntary/involuntary
2 - Appearance - Similarities  ex. striations / actin-myosin, etc.
		   Differences   ex. discs / branching, etc.
3 - Physiology (Comparisons)  ex. contraction / refraction / ions / specific nerves / nodes, etc.

D.  ANTERIOR-POSTERIOR PITUITARY 	(8 points possible - 4 points maximum)
1 - Origin - mouth - brain	
1 - Location - hypothalamus - connection to brain
1 - Control - anterior/hormonal; posterior/nervous
2 - Hormones (list and explain 2 or more) 
	 6 anterior: FSH, LH, ACTH, TSH, somatotropin, prolactin
	 2 posterior: ADH, oxytocin
1 - Anterior production / Posterior storage
1- Endocrine - elaboration or definition
1 - Feedback mechanism 















ANIMAL SYSTEMS QUESTION 1986:			L. PETERSON/ECHS
	Describe the processes of fat and protein digestion and product absorption 
	as they occur in the human stomach and small intestine.
	Include a discussion of the enzymatic reactions involved.
STANDARDS:

STOMACH:
GENERAL POINTS
1 - no absorption in the stomach
1 - mechanical breakdown occurs in the stomach
1 - protection of the stomach
1 - chyme (definition)
1 - chyme is in stomach for several hours (implied)
1 - mention of the stomach being acidic due to HCl
1 - parietal cells produce HCl / chief cells produce pepsinogen
1 - gastrin (hormone)
1 - hydrolysis (definition)
PROTEIN POINTS
1 - HCl - pepsinogen -> pepsin
1 - pepsin--protein -> polypeptide
FAT POINTS
1 - very little digestion of fat in the stomach

SMALL INTESTINE:
GENERAL POINTS
1 - pH becomes more basic
1 - secretin (hormone)
ABSORPTION
1 - occurs in small intestine
1 - microvilli
1 - villi
1 - increase surface area
1 - amino acids -> capillary or amino acid absorption products
1 - amino acids
1 - fatty acids -> lacteals or lymphatic
1 - glycerol -> capillaries
1 - fatty acids by diffusion
PROTEIN POINTS
1 - trypsinogen/trypsin
1 - chymotrypsinogen/chymotrypsin
1 - peptidase/di/tripeptidase
1 - endopeptidase (within molecule)
1 - exopeptidase (terminal end of molecule)
1 - protease
1 - pancreas / intestinal gland
1 - protein/polypeptide -> amino acid
FAT POINTS
1 - bile (liver - gall bladder)
1 - cholecystokinin (hormone)
1 - emulsify (definition)
1 - lipase/pancreas
1 - lipase function: lipids -> fatty acids and glycerol
1 - Na bicarbonate
 
ANIMAL SYSTEMS QUESTION 1986:			L. PETERSON/ECHS
	Beginning at the presynaptic membrane of the neuromuscular junction, describe
	the physical and biochemical events involved in the contraction of a skeletal
	muscle fiber. Include the structure of the fiber in your discussion.

STANDARDS:

Presynaptic (must be a motor neuron)
1 - Nature of impulse  +++
		            ---      	 
1 - Increase of permeability of Ca 2+
1 - Movement of vesicles
1 - Fusion of vesicles with membrane
1 - Transmitter release
1 - Acetylcholine
1 - Diffusion of transmitter (20 nm)
1 - Cholinesterase
1 - Motor end plate or terminal bouton

Postsynaptic (muscle be a muscle fiber)

A. Transmitter Effects
1 - Specific receptor sites
1 - Causes depolarization/action potential
1 - Action potential sweeps fiber membrane/T. tubules
1 - Release of Ca 2+ from Sarcoplasmic reticulum (T. cisternae)

B. Calcium Effects
1 - Calcium floods sarcomere
1 - Calcium binds to troponin
1 - Bound troponin displaces tropomyosin
1 - Calcium returned by active transport (Ca2+ pump)

C. Actinomyosin Complex
1 - Binding sites actin exposed by tropomyosin displacement
1 - Myosin cross bridges bind actin
1 - ATP used
1 - Power stroke, recovery flip
1 - ATP needed to separate actin-myosin
1 - Rigor Mortis

D. Other
1 - Sliding Filament Theory
1 - Diagram/explanation contracted muscle
1 - Muscle twitch, tetany, fatigue
1 - Lactic acid, O2 debt
1 - Creatine phosphate--ATP




Muscle Fiber Structure

1 - Definition
1 - Characteristics
2 - Striations, banding multi-nucleated, many mitochondria
1 - Myofibrils (as sub-units)
1 - Sarcomere (as unit of myofibril)
1 - Sarcoplasmic reticulum (cell membrane, etc.) (terminal cisternae)
1 - T. tubules (cell membrane connection, etc.)
1 - Banding Pattern (explain or diagram)
1 - Actin/myosin (protein or thin, thick, etc.)
1 - Actin a globular protein
1 - Myosin a linear protein w/cross bridges
1 - Troponin/tropomyosin associated with actin
 














































ANIMAL SYSTEMS QUESTION 1987:			L. PETERSON/ECHS
	Discuss the exchange of oxygen and carbon dioxide that occur at the alveoli and 
	muscle cells of mammals. Include in your answer a description of the transport of 
	these gases in the blood.

STANDARDS:

EXCHANGE (8 points max.)
1 - O2/CO2 diffusion or correct direction of O2/CO2 gas movement
1 - concentration gradient or explanation
1 - Alveoli/membrane characteristics
(large surface area, or thin-walled, or "grape clusters", or sacs, or surrounded by capillaries)
1 - moist surface necessary for exchange
1 - interstitial fluid role in transport
1 - P O2/CO2 description
1 - Illustrated curve on graph or explanation
				        100 mm Hg lungs
				           40 mm Hg muscles (rest)
				           20 mm Hg muscles (exercise)
1 - temperature effects
1 - further explanation as:
	(tissues) higher temperatures -> less affinity
	    OR
	(lungs) lower temperatures -> more affinity
	    OR
	graph
1 - CO2 in plasma lowers pH of blood
1 - Bohr effect - acidity affects affinity of Hb for O2
1-  example 	lower  pH -> less affinity
	             higher pH -> more affinity
		OR graph
1 - myoglobin in muscle stores O2
       (greater affinity for O2)
1 -  air is approximately 20% oxygen
1 - other hemoglobin adaptations, such as: (maternal-fetal or low altitude-high altitude)

TRANSPORT (8 points max.)
	OXYGEN
1 - carried by hemoglobin or in red blood cell
1 - hemoglobin found in red blood cell
1 - hemoglobin characteristics such as:
          protein, or 4 subgroups, or Heme, or iron and porphyrin ring
1 - Hb cooperativity (allosteric) - one O2 increases affinity for others
          S-shaped curve
1 - CO can compete with O2 for Hb binding site
	CARBON DIOXIDE		         -
1 - majority carried as bicarbonate ions (HCO3)
1 - enzyme carbonic anhydrase speeds reactions








					         -
1 - CO2  +  H2O  <--> H2CO3  <--> H+  +  HCO3
1 -some CO2 carried aqueously (dissolved)
1- some CO2 carried by Hb (on a different site - does not compete with O2)
1 - Hb picks up H+ ions to buffer blood
	CIRCULATORY TRANSPORT PATHWAY
1 - from alveolus to muscle cell
      (pulmonary vein -> left atrium -> left ventricle -> artery -> capillary)
1 - from muscle cell to alveolus
      (capillary -> vein -> right atrium -> right ventricle -> pulmonary artery)
























 
	 









 
















ANIMAL SYSTEMS QUESTION 1989:			L. PETERSON/ECHS
	Describe negative and positive feedback loops, and discuss how feedback mechanisms
	regulate each of the following:
		a.   The menstrual cycle in a nonpregnant human female
		b.   Blood glucose levels in humans

STANDARDS:

Introduction: (describe -/+ feedback loops)
1 pt 		1.  Definition as an overview of the process: Control mechanism which is 		      regulated through the effect it brings about.
1 + 1 pts	2.  Negative feedback: Endproduct acts as an inhibitor of pathway (stimulatory-
		      inhibitory).
		      Seek terms such as inhibit/turn off. Examples: ACTH -> cortisol -> feedback;
		      Lac operon; thermostat metaphor; CO2 respiration, etc.
1 + 1 pts	3.  Positive feedback: change in variable amplifies the pathway (stimulatory-
		      stimulatory).
		      Seek terms such as turn on/stimulate/induce. Examples: Oxytocin/birth;
	   	      LH surge; trypsinogen/trypsin; neural membrane permeability; mating
		      process; sound amplification metaphor; etc.
	[one point for definition and one point for example] 
	Note: these points might be embedded in Parts A and B.	
Total of 3 points maximum for introduction out of 5 points possible.

Part A: Menstrual Cycle
1 pt		1.  Primary function of the cycle as an overall concept: production of gamete
		      and preparation of the uterus. A borad interpretation OK.
1 + 1 + 1 pts	2.  Hormones and interactions: look for information that suggests cause and
		      effect and a pathway. Items a-c are complete examples. To earn a point,
		      three targets, hormones, and sources must be given in a logical sequence.
		      Wrong information will void a string of three. The goal is to find physio-
	 	      logical relationships and not just terms.
	    a.  GnRH (hypothalamus) -> FSH (pituitary) -> estrogen (ovary) -> endometrium
	    b.  GnRH (hypothalamus) -> LH (pituitary) -> progesterone (corpus luteum) ->
	         endometrium
	    c.  estrogen -> LH surge -> ovulation
     Research on the regulation of the menstrual cycle is rapidly evolving and textbooks can
     reflect different philosophies or progress of research.
1 or 2 pts	3.  Negative feedback results on hypothalamus/pituitary.
		     Estrogen/progesterone inhibits FSH and LH production at the GnRH (hypo-
		     thalamus) and pituitary level. If no choriogonadotropic hormone -> estrogen/
		     progesterone levels drop and endometrium stimulus no longer supported - >
		     endometrium lost as cycle begins again and FSH and LH released from
		     inhibition. [2 points for completeness]
1 pt		4.  Positive feedback: estrogen -> LH surge. Note: estrogen can be both inhibitory
		     and stimulatory on the hypothalamus/pituitary.

Total of 5 points maximum for Part A out of 7 points possible.





Part B: Blood Sugar
1 pt		1.  Concept of homeostasis, equilibrium, and/or maintenance of glucose level.
1 pts		2.  Concept of antagonistic relationship of glucagon and insulin.
1 + 1 pts	3a. Low blood glucose -> glucagon release -> glycogen converted to glucose/
		      glucose mobilized from liver to blood or alpha cells in pancreas release
		      glucagon
1 + 1 pts	3b. High blood glucose -> insulin release - glucose mobilized into cells ->
		      lower blood levels/glucose mobilized into liver or muscle or beta cells
		      of pancreas release insulin
1 pt		4.  Alternate loops of blood glucose levels (only one point possible here):
		      a.  adrenalin, noradrenalin
		      b.  ACTH, cortisol
		      c.  somatostatin

Total of 5 points maximum for Part B out of 7 points possible.
    

			      





















 ANIMAL SYSTEMS QUESTION 1990:			L. PETERSON/ECHS
	A.  Describe the differences between the terms in each of the following pairs.
		(1)  Coelomate versus  acoelomate body plan
		(2)  Protostome versus  deuterostome development
		(3)  Radial versus  bilateral symmetry
	B.  Explain how each of these pairs of features was important in constructing the 
	      phylogenetic tree shown below. Use specific examples from the tree in your
	      discussion.
					Chordata

								Arthropoda
									Annelida

		Echinodermata						Mollusca


								   Nematoda

									Rotifera

								         Platyhelminthes

			Cnidaria


			     Porifera
STANDARDS:

A. (1)  COELOMATE VS. ACOELOMATE

1 -  Coelomate: internal body cavity lined with mesoderm
		(not sufficient to say: "true body cavity")
1 -  Acoelomate: lacking internal cavities altogether or having:
			a pseudocoelom (Nematoda and Rotifera)
			a spongocoel (Porifera)
			mesoglea (Cnidaria)
			a solid layer of mesoderm (Platyhelminthes)
[Max. = 2 / must define both for full credit]














    (2)  PROTOSTOME VS. DEUTEROSTOME DEVELOPMENT

1 - Protostome: mouth develops near/at the blastopore or anus forms secondarily (later),
       OR featuring:
			spiral cleavage (micromeres between macromeres);
			determinate/mosaic development (blastomere fate is established
			   at very early stages of development);
			mesoderm from cells that migrate into the blastocoel near blastopore
			schizocoelous coelomation (internal split in solid wedge of mesoderm
			   that is independent of gut);
			trochophore larva;
1 - Deuterostome: anus develops near/at the blastopore or the mouth forms secondarily (later),
       OR featuring:
			radial cleavage (micromeres directly above macromeres);
			indeterminate/regulative development (blastopore fate is variable
			   and not established until late in development);
			mesoderm arises from outpocketings of the gut;
			enterocoelous coelomation (outpocketings of gut);
			dipleurula larva
[Max. = 2 / must define both for full credit]

    (3) RADIAL VS. BILATERAL SYMMETRY
1 - Radial: several planes passing through the long or central axis can divide the organism
	     into similar parts.
1 - Bilateral: (only) one plane passing through the long axis divides the organism into
	     similar right and left sides -- exhibits cephalization.
1 - Echinoderms: bilaterally symmetrical larvae, but appear to have radially symmetrical
	     adult forms.
[Max. = 2]

B.  PHYLOGENETIC TREE
1 - for examples of contrasting pairs (phyla or organisms) using terms from above;
       answer here or in part A.
1 - for using above terms in explanation of why phyla are in separate groups (or separate
       branches) of the tree.

1/1 - Body symmetry (cephalization) permits separation of Porifera and Cnidaria
	(radially symmetrical) from other phyla (bilaterally symmetrical).
1/1 - Coelomation permits separation of Platyhelminthes, Nematoda, and Rotifera from
	other phyla above Cnidaria: flatworms are acoelomate, whereas those other than
	nematodes and rotifers are coelomate.
1/1 - Origin of the mouth and anus permit separation of Echinodermata and Chordata
	(deuterostomes) from Arthropoda, Annelida, and Mollusca (protostomes).

	[Some include Platyhelminthes, Nematodes, and Rotifers as protostomes.]
1 - Nematodes and rotifers are grouped separately because both are pseudocoelomate.
1 - Phylogenetic trees based taxonomic relationships on homologous structures,
         patterns of embryonic development, and common ancestry.
[Max. = 6]