Question | Answer |
Hallmarks of Multicellularity | Specialization of cells and the cooperation of these cells to maintain life |
Closest living ancestor to animals | Choanoflagellates |
What is required to achieve cooperation of cells | Cell adhesion and cell communication |
Cell adhesion | Cells must adhere to one another, requires genes for cell adhesion proteins |
Why do choanoflagellates have genes needed for multicellularity? | These genes are probably used to stick to surfaces and capture prey but then were repurposed by evolution to perform the functions of cell adhesion and communication in multicelluar animals |
Cell Communication | Required in order for cells to cooperate, requires genes for signaling proteins and protein receptors |
Evolution of multicellularity | Multicellularity has evolved many times independently (convergent evolution) |
Sponges | Multicellular, no tissues, no organs, no organ system; cells is the highest unit in proifera- "pore bearers" |
Spongocoel | The central, open cavity in a sponge through which water flows |
Osculum | A large opening in a sponge through which water flows out of the sponge. Sponges may have more than one oscula. |
Choanocyte | Line the inner cavity of the sponge; have a sticky, funnel-shaped collar that collects food particles and a flagellum to pump water through the sponge. The sponge obtains its nutrients and oxygen by processing flowing water |
Porocyte | Cells with pores that allow water into the sponge; they are located all over the sponge's body |
Mesohyl | The gelatinous layer between the outer body of the sponge and the spongocoel |
Spicule | Sharp spikes (made of calcium carbonate) located in the mesohyl; form the "skeleton" of many sponges |
Amoebocyte | Digests food particles and distributes them |
Symmetry | Asymmetry; asconoids and syconoid sponges have radial symmetry |
Sponges are sessile | Immobile |
Basic tasks of staying alive | Get nutrients (glucose, amino acids, fatty acids) to cells, get rid of indigestible material= ingestion, digestion, absorption elimination. Circulation, gas exchange, excretion, nerve and muscle, and reproduction |
Leucenoids | Most surface area= more choanocytes so can grow bigger in size from nutrients |
Asconoids | Cannot increase in size, because theres a smaller surface area and therefore less choanocytes |
Sponges need to get rid of... | Ammonia |
Sponges are vulnerable to | Attacks by predators, being crowded by other organisms competing for space on reefs, being overgrown which affects water flow, infection by pathogenic microorganisms |
Sponge's Defense | Spicules and chemical toxins |
Porifera Reproduction | Individual sponge produces egg and sperm. Sperm are released and enter another sponge where it fertilizes an egg. A larva develops and is carried out by the water current; it settles down on a surface and develops into an adult sponge |
Sponges are dependent on ____ for staying alive | Water flow |
Gas exchange and excretion between cells and environment | Each cell is on a surface (single layer) so they're all touching seawater; gases and wastes can diffuse across cell membranes |
Parazoa | Only living animals in this clade are sponges |
Focus using 4x objective and 10x objective | Coarse focus knob |
As objective moves up, working distance _____ | Decreases |
Focus using 40x objective | Fine focus knob |
Preferable way to adjust light | Diaphragm |
What are tardigrades? | Eukaryotic, multicellular, heterotroph that ingests food... animal! |
Microvilli | Capture small particles |
Working Distance | The distance between the objective that is in place and the slide |
The ocular lenses have a magnifying power of | 10x |
Total magnification of micrscope = | Ocular power (10x) times Objective power (4x, 10x, or 40x) |
Depth of Field | The range of depth that a specimen is in acceptable focus; as magnification increases, depth of field decreases |