Exam 2 BIOL& 212

Describe the endosymbiosis theory of the formation of eukaryotic cells.

unicellular → colonial → eukaryotes * started out with prokaryotes * then colony of prokaryotes * colony of prokaryotes became multicellular organisms

Porifera may not be monophyletic; instead many scientists believe that this is a paraphyletic group. How would you represent this in a cladogram? What does it mean?

with some taxa of sponges being more closely related to the other animal phyla than to other porifera taxa.

What are the properties of an animal body plan. Discuss the different types of symmetry, body cavities (coelem), support, segmentation, cephalization and appendages.

Symmetry: radial, bilateral - allowed for observation and consumption of prey - allowed for development of organs Coelem: mouth, anus Support: Segmentation: - allowed for flexibility in movement. - each segement can be controlled - Specialization of each segment Cephalization: *Concentration of sense organs in anterior, allowing for head and brain can react quickly to environment and threats *Appendages: - allow for easier movement/quicker movement - can catch pray easier

Define the following terms: acoelomate, pseudocoelomate, and coelomate. Give an example of a worm (genus and phyla) that is acoelomate. Give an example of a worm (genus and phyla) that is pseudocoelomate. Give an example of a worm (genus and phyla) that is coelomate. What is the advantage of a coelom?

acoelomate - animal with no body cavities Pseudocoelomate - animals. EX: roundworm (nematoda) false cavities not as organized as a real cavity Coelomate - animal with body cavity. EX: annelida (segmented worms) Advantages of coelom: - independent movement of body wall and enclosed organs - more space for complex organs and organ systems - storage area for eggs and sperm. It also contains fluid that protects internal organs, and can provide oxygen and nutrients to cells, collect wastes, and function as a hydrostatic skeleton.

Briefly discuss three critical characteristics that are used by zoologists to classify animal phyla.

characteristics used to classify animal phyla symmetry segmentation body cavities germ layers

Briefly discuss three critical characteristics that are used by zoologists to classify animal phyla. #1

coelom, symmetry, body plan, presence of segmentation

Define the following developmental terms: diploblastic, triploblastic, endoderm, mesoderm, ectoderm, deuterostomes and protostomes.

diploblastic - two germ layers triploblastic - three germ layers endoderm - innermost germ layer mesoderm - middle germ layer ectoderm - outermost germ layer deuterostome - blastopore becomes anus protostome - blastopore becomes mouth

What is meant by life cycle? What are the possible stages for an animal life cycle? Contrast 'direct development' and 'metamorphosis'. Give examples.

life cycle - cycle of life the series of changes in the life of an organism possible stages of life cycle fetus embryo immature adult (toddler, adolescence) adult direct development - when offspring resembles the adult when offspring emerges from embryo or egg looking like a tiny adult looks like a tiny version of the adult ex: humans, bears, doggos metamorphosis - process in which an animal has to further develop after birth offspring emerges from embryo or egg looking different from adult offspring goes through drastic physical changes in development outside embryo / egg ex: butterflies, frogs

Are animals, metazoans, a monophyletic group? What does this mean?

metazoans are a monophyletic group, meaning they all descended from a common ancestor (choanoflagellates)

Define sessile and motile and give examples. Compare and contrast two methods of getting food, one that would be most likely used by a sessile animal and one that would most likely be used by a motile animal (or in a motile stage of the life cycle).

sessile organisms do not possess means of locomotion ex: coral, sea anemone motile organisms possess means of locomotion ex: humans, puppies, cats

Define Metazoa. What are the unifying characteristics of the animal kingdom (i.e. what characteristics are shared by all animals)? List and describe these.

*Metazoa is a group of multicellular eukaryotes *Protozoa is a group of single celled eukaryotes *unifying characteristics of animal kingdom - symmetry - body cavity (ex: dorsal cavity, pelvic cavity) -segmentation - embryonic tissue layer (germ layers)

Describe the choanoflagellates? What is the significance of these organisms to zoology? If you drew a cladogram with animals and choanoflagellates, what type of group would choanoflagellates represent in this diagram?

*choanoflagellates are protists and are the closest living relative to animals *on a cladogram with animals and choanoflagellates, the choanoflagellates would be first common ancestor

Define heterotrophs and distinguish this term from autotroph. How do animals obtain food? Describe different categories of feeding strategies and their importance.

*heterotrophs must consume other organisms for food autotrophs can make their own food *autotrophs ex: plants can get food from the sun (photosynthesis) *heterotrophs ex: humans, animals must consume other organisms for food (plants, other animals)

What is dispersal? Why is it important? How do sessile animals (like mussels) disperse?

dispersal - movement of organism from birth site to breeding site, and breeding site to breeding site dispersal is important because it allows a way for sessile animals to reproduce benefits new resources escaping unfavorable conditions sessile animals disperse through budding ex: dandelions + wind, cacti seeds + birds

Know the following branches of the current animal phylogenetic tree: parazoa, eumetazoa, radiata, bilateria, protostomia, deuterostromia, lophotrochozoa and ecdysozoa. Give a brief description of each term and an example of an animal in each group.

parazoa animals with no tissue ex: sponge (in Porifera) eumetazoa animals with tissue ex: puppies (in Chordata) radiata eumetazoa → radiata radial symmetry diploblastic (two germ layers) ex: jellyfish (in cnidaria) bilateria eumetazoa → bilateria bilateral symmetry triploblastic ex: cats (in Chordata) protostomia eumetazoa → bilateria → protostomia body cavity from cell masses blastopore becomes mouth ex: mussels (in Mollusca) deuterostomia eumetazoa → bilateria → deuterostomia body cavities from digestive tubes blastopore becomes anus ex: lizard (in Chordata) lophotrochozoa eumetazoa → bilateria → lophotrochozoa has lophophore (structure that rings the mouth and fxns in suspension feeding) trochophore (type of larva) ex) flatworms (in Platyhelminthes) ecdysozoa grow by molting (shedding external cover) ex) crabs (in Arthropoda)

Define parazoa and eumetazoa and give examples of each.

parazoa animals with no true tissues ex: sponges eumetazoa animals with tissues ex: puppies, cats