Exam 3 Flashcards
Describe the evidence that supports the theory that mitochondria and plastids evolved by primary (and sometimes secondary) endosymbiosis.
The mitochondria and plastids(basically the mitochondria of plants) both have two plasma layers; their own DNA; they have their own proteins that carry out process that sustains life; use O2 to make ATP; use fission to create new mitochondria
Describe the evidence that suggests that mitochondria were acquired before plastids in eukaryotic evolution.
All eukaryotes have mitochondria but only a few have plastids.
Define secondary endosymbiosis and explain its role in the evolution of photosynthetic protists.
Secondary endosymbiosis is when a larger eukaryote engulfs another eukaryote that has undergone primary endosymbiosis( the eukaryote engulfed a prokaryote to use it(prokaryote) to its(eukaryote) advantage.
List examples of symbiosis in animals.
- Sea anemones (Cnidaria) that contain zoxanthellae (dinoflagellate protists)
- nudibranch mollusks that have photosynthetic algae on their backs.
- spotted salamander eggs that contain green algae.
- the origins of mitochondria and chloroplasts way back in the early history of eukaryotes.
Describe the formation of tissue layers in embryos.
Tissue layers a formed through a process called gastrulation. In this process, a hollow cluster of cells forms into a blastula. The blastula then can reorganize into two primary layers: the endoderm (inner layer of tissue around the digestive tract) and the ectoderm( very outer layer of the blastopore). This blastula can form two types of organisms: Diploblastic( just endo and ectoderm) or Trophoblastic(endoderm, mesoderm, and ectoderm)
Identify some examples of body parts/organ systems that arise from endoderm. (Likewise for ectoderm and mesoderm.)
Endoderm: Lining of the gastrointestinal and respiratory tract; the Liver; Epithelial lining of the urinary bladder and urethra
Mesoderm: Connective tissues, Cartilage, and Bones; the Kidneys; the Gonads(ovaries and testes)
Ectoderm: Cental Nervous System(brain and spinal cord); Epidermis(skin) and its appendages(hair and nails)
Explain the adaptive significance and function of different symmetry patterns.
Radial: Usually used by stationary or slow moving organisms (such as the Cnidarians) so that they can sense what happening around them in a 360-degree motion. This type of symmetry doesn’t have a left or right side and if the organism is cut in half, the parts would look the same.
Bilateral: This type of symmetry has a left and right side and allows the organisms to sense in all directions (up, down, left, right, etc). This is advantageous to organisms that move constantly so that they can hunt prey and/or escape predators.
Explain the significance of cephalization.
Cephalization is the concentration of the nervous system into one place, the head. This concentration allows for a more complex brain which leads to a more complex and intelligent organism.
Describe how segmentation can be important in the evolution of body shape/structure/function.
Allows organism to duplicate organs and identical body structures, such as arms and legs. Segmentation also separates different body functions into different body systems (such as digestive, respiratory, cardiovascular, etc.)
Discuss the advantages of a complete digestive tract.
- allow for continuous intake of food
2. more efficient at absorbing nutrients than an incomplect digestive tract
Identify the functions of skeletons and give examples.
- To provide support: spinal column allows humans to stand upright
- To provide protection: the rib cage and skull protects sensitive organs from external forces
- To provide movement: bones along with muscle allows organisms to move
List the characteristics (synapomorphies) of animals.
- extracellular matrix containing collagen and elastin
- multicellularity with division of labor
- heterotrophic methods of food acquisition
Describe the anatomy of sponges.
The anatomy of a sponge consists of…
- Pores: allows water into the sponges central cavity
- Osculum: large hole at the top of sponge where water exits
- Choanocytes: specialized cells that filter food from water
- Spicules: skeletal structures made of calcium carbonate (CaCO3), silicon dioxide, and proteins (they look like tiny spikes)
- Archaeocytes: specialized cells that make spicules, digest and moves food, and carry sperm cells to eggs
Describe the classes of Cnidaria and their body forms.
There are three classes of the Phylum Cnidaria.
- Hydrozoa: Obelia (kinda looks like a polyp)
- Scyphozoa: Jellyfish
- Anthozoa: Coral and Sea Anemonies
Identify the synapomorphies that define the classes of Platyhelminthes.
Platyhelminthes are flatworms consists of three classes:
1. Cestoda (tapeworms): Synapomorphies- body form 3 tape like regions. Has suckers and hooks. Lacks mouth and digestive system
- Trematoda(flukeworms): Synapomorphies- possess oral and ventral suckers (no hooks). Characterized by being parasitic complete life cycle
- Turbellaria (Planarians): Synapomorphies- highly cephalized with eye spots (ocelli), incomplete gut, and flame cells called osmoregulate (meaning that if you touch it, it will feel as though your hand it on fire
Describe each of these basal phyla in terms of tissue layers and body cavities.
- Porifera (Sponges)
Tissue Layers: None
Body Cavity: None (They are Acoelomates) - Cnidarians (Jellyfish, Coral, and Sea Anemonies)
Tissue Layers: 2 (endo and ectoderm)
Body Cavity: None (They are Acoelomates as well)
Contrast the early embryology of protostomes and deuterostomes. Describe the fate of the blastopore and the origin of the mesoderm and coelom.
Protostomes: cells undergo spiral cleavage (2 cells wedge and twist themselves into the top of 4 other cells)
Fate- Protostomes have a determinate development, meaning that each cell already has a specialised job and if one were to split off, it would halt development( the organism dies). Blastopore becomes mouth. Mesoderm forms around the pocket of the gut.
Deuterostomes: cells undergo radial cleavage (the cells become uniform)
Fate- Deuterostomes have an indeterminate development, meaning that the cells haven’t specialised and if they were to separate, then they would just make another organism (twins!). Blastopore becomes anus. Mesoderm forms on top of the gut.
Identify which animal phyla are protostomes, which are deuterostomes, and which are in other groups.
Protostomes: Lophotrochozoa and Ecdysozoa
Deuterostomes: Chordates and Echinoderms
Others: Porifera and Cnidarians
Describe the characteristics (synapomorphies) of each class of mollusks.
Polyplacophora (Chitons): 7-8 shell plates; mantel fused with shell
Gastropoda (Slugs and Snails): a “head”; coiled shell; shell undergoes torsion
Bivalvia (Muscles, Clams, etc.): gills modified for filter feeding; shell in two halfs; loss of radula
Cephalopoda (Octopus and Squid): closed circular system (blood pumped by heart through blood vessels); beak mouth; siphuncle; seperate shell; tentacles and siphon; cranium; ink sac
Describe the characteristics (synapomorphies) of mollusks.
Spicules/shell, mantle, muscular foot, rabula
Describe the characteristics (synapomorphies) of annelids.
setae and segmentation
Describe the characteristics (synapomorphies) of each class of annelids.
Polychaeta (Marine Worms): Head with sensory appendage; parapodia
Oligochaeta (Earthworms): clitellum (specialized segment of body used for reproduction); hermaphroditic(has both male and female reproductive organs); loss of trochophore
Hirudinea (leeches): same synapomorphies as the earthworms; also have posterior sucker and superficial annuli
Describe the characteristics of arthropods.
- they have a chitinous exoskeleton that they shed during growth
- paired body parts are jointed
- segmented body parts separated into regions (head, cephalothorax, thorax, abdomen)
Describe the characteristics of each subphylum of arthropods.
Hexapoda
3 segment abdomen
Crustacea
- stalked eyes - nauplius larva - 2 pairs antennae
Myriapoda
-lose of compound eyes
chilopods (centipedes)
-fangs, venom
diplopods (millipedes)
-diplosegments
Chelicerata
- chellicerae
- reduced # of walking legs
- body in two segments: cephalothorax, abdomen
Pycnogonida -water spiders
Merostomes
-long telson
-book gills
Arachnida
-4 paired legs
-Arachnid lungs and or book lungs
Scorpions
-stinger
-pincers
Mites & ticks
Spiders
-spinnerets
