Final Flashcards
● Distinguishing characteristics of fungi (yeasts and molds).
Eukaryotes, enclosed by cell walls composed of chitin (a nitrogen-containing sugar), heterotrophic, secrete digestive enzymes and then absorb the predigested food, decomposers or parasites, grow in syrups, more closely related to animals than plants.
● Distinguish between specific and nonspecific defense mechanisms
Non-specific defense mechanisms include mechanical and chemical barriers. The skin is the first defense (sweat and sebum are antibacterial); tears contain lysozyme; stomach acids destroy pathogens; nose hairs and mucous trap pathogens. Other chemicals involved in BOTH non-specific and specific immune responses include cytokines (regulatory proteins), interferons (protein produced when cells are virally infected to interfere with viral replication), and interleukins (secreted by macrophages and lymphocytes to do such things as cause fever). [We’ll cover complement in objective 5, it is a chemical involved in defense]. In addition, inflammation (pain, heat, swelling, redness) is a nonspecific mechanism as is the phagocytosis brought on by inflammation. Specific defense mechanisms include antibody-mediated immunity and cell-mediated immunity. These are brought on over several days but are long lasting and are very specific as to what they attack. They include antibody-mediated immunity involving B-cells and cell-mediated immunity involving T-cells.
● Pathway of water from soil through the various root tissues
Root hair to epidermis to cortex (via apoplast and symplast) to endodermis to pericycle to root xylem.
● Summarize mechanisms of antibody-mediated immunity, including the effects of antigen-antibody complexes on pathogens
and a discussion of the complement system
Once the B cells are selected and activated to produce the specific antibody, they produce antibodies that can bind to form Ag-Ab complexes that inactivate the antigen (whether it is a pathogen or a toxin). The complex may stimulate phagocytosis or work with complement to destroy the pathogen. Complement is a set of plasma proteins that stimulates other defense mechanisms. The selection and activation process involves macrophages that present the antigen to the B cell and helper T cells. These macrophages secrete interleukins to activate the helper T cells. The B cell then binds to the complimentary antigen presented, receives the foreign antigen-MHC complex from the macrophage and gets selected and then grows, divides and forms a clone where some of the cells mature into plasma cells to produce antibody specific to the antigen presented. Some of the B cells become memory cells which can be reactivated if the body is exposed to that antigen again.
Justifications for scientific names and organism classifications
Allows communication between scientists internationally. Allows logical ordering of organisms to permit study.
● List the functions of the lymphatic system and describe how it operates to maintain fluid balance
The lymphatic system returns interstitial fluid to the circulatory system, it also functions in immunity and adsorption of lipids from the gastrointestinal tract. Because the veins flow more serum into the tissues than the tissues can remove back into the veins, the lymphatic system drains the tissues of the excess interstitial fluid. The lymph tissues are made of connective tissues containing considerable lymphocytes (WBCs). Throughout the system are lymph nodes that filter the lymph. The spleen, tonsils, and thymus are larger organs of the lymphatic system. Lymph capillaries are one-way vessels that ultimately empty into the subclavian veins via the larger thoracic duct and the right lymphatic duct. The homeostatic role that this system plays is to keep the interstitial fluid in balance within the tissues.
Immunology Chap. 45
Describe the structure of a virus
Viruses consist of either an RNA or DNA core surrounded by a protein capsid. Some viruses are further surrounded by an envelope which is derived from the membrane of the cell that the virus was infecting. Their shapes can be bizarre ranging from bacteriophages that look like little lunar landers to helical rods to polyhedral shapes. Viruses are not classified in any Kingdom as they are not technically alive.
Characteristics of lichens
Symbiotic relationship between a phototroph (algae or cyanobacterium) and a fungus (basidiomycete or an ascomycete). The phototroph can survive and grow without the fungus. Distinguish between crustose, foliose, and fruticose lichens. A pioneer species that moves into bare areas; they are sensitive to pollution. Reproduce asexually by fragmentation into soredia that contain both fungi and algae.
● Functions of roots; correlation of structure and function
Roots have three functions: 1) anchoring the plant, 2) absorbing water and dissolved minerals from the soil for transport throughout the plant via the xylem, and 3) storage of surplus sugars as
starch or sucrose until needed by the plant [this is why raw carrots are slightly sweet!]. Some roots are taproots and arise from the embryonic root in the seed. An example are the roots such as those in dicots and gymnosperms; they typically reach down into the ground to find water. Others are fibrous and adventitious (arising from the stem). An example are the roots such as those in monocots; they typically spread out to capture rainwater from a larger area as it drains into the soil.
● Compare the types of internal defense mechanisms in invertebrates and vertebrates
Non-specific defense mechanisms exist in invertebrates including phagocytes; chemical defense mechanisms are in sponges. Vertebrates, have both non-specific and specific immune responses due to the specialized lymphatic system that can make antibodies due to lymphocytes.
● Distinguish among simple, aggregate, multiple, and accessory fruits; give examples and cite different methods of seed and fruit dispersal
C? Refer to figure 37-10. Simple fruits develop from flowers with a single pistil: berries have many seeds within a fleshy ovary – tomato and grape; drupes have a hard stony pit within a fleshy ovary – peach and cherry; follicles have a dry ovary that splits along one side to release seeds – milkweed and columbine; legumes split along both sides to release their seeds – bean and pea; capsules split along many sides or pores to release their seeds – cotton, poppy; grains have a dry ovary that does not open and the seed is fully fused to the fruit wall (the ovary) – wheat and corn; achenes are also dry and do not open but the seed is attached to the ovary wall only at the base – sunflower seeds; nuts have a hard thick fruit wall – acorn and chestnut. Aggregate fruits develop from a flower with many separate ovaries – raspberry, blackberry. Multiple fruits develop from many flowers borne together on one stalk fusing their ovaries (pineapple). Accessory fruits develop from the floral tube enlarging to become the fruit (apple, strawberry).
● Describe how the body destroys cancer; summarize immunological basis of graft rejection & how it can be minimized
NK cells and cytotoxic cells produce interferons, interleukins, and TNF to ward off cancer. Graft rejection is a result of the tissues and organs of the donor having different MHC antigens than the donee. This is minimized by close matching of the MHC (major histocompatibility) antigen. In humans, the MHC is the HLA (human leucocyte antigen) group.
● Structure and function of various tissues: epithelial, connective, muscle, nervous
The need for exposure to cold before germination (vernalization) allows the plant to survive winter by not germinating until it is over. The requirement for light allows the seed to not germinate until it is closer to the surface of the soil where it has enough energy to reach the surface. Genetic controls may prevent germination despite all environmental conditions being favorable: immature embryos present in the seeds will not germinate until they are more mature. The presence of abscissic acid in the seed prevents germination until enough water washes it all away (typical of desert plant seeds).
● Define cardiac output how it is regulated and the factors affecting it. Identify factors that determine and regulate blood
pressure and compare blood pressure in different types of blood vessels
Cardiac output is the amount of blood pumped by one ventricle in one beat (the stroke volume) multiplied by the number of ventricular contractions per minute (about 5 l/min); cardiac centers in the medulla communicate with the heart via autonomic fibers; hormones from the adrenal glands speed the heart rate. Blood pressure is a function of blood flow and resistance to blood flow. Blood pressure is measured as ventricular systole and diastole
(ventricles contracting and relaxing). The systolic pressure is listed on top and the diastolic pressure on the bottom (e.g. 130/70). If the diastolic is above 95 then hypertension needs to be treated. Blood pressure is highest in arteries because of the ventricular systole that pumps blood into the artery and because they are smaller in diameter than the veins to which the blood is flowing. Since the veins have lower pressure in them, the large veins have valves to prevent backflow.
● Draw a typical neuron and label its parts
See fig 39-2. Glial cells support and protect neurons (insulation, phagocytic, anchoring neurons). A neuron consists of a cell body, dendrites, and an axon. The cell body has the cytoplasm, nucleus, and other organelles. Dendrites are short, highly branched extensions which receive stimuli and transmit them to the cell body. Axons conduct impulses from the cell body to a neighboring neuron or muscle or glandular cell. Axons end in branchings with synaptic terminals (boutons) that can release neurotransmitters to the next neuron, cell, or muscle. A synaptic terminal would synapse with what structure of the next neuron? Axons may be uncovered or covered. If they are covered, Schwann cells (a type of glial cell) surround the axon to form a neurilemma and the inner myelin sheath is formed by the Schwann cell wrapping around itself several times. Each cell will form a wrapping of insulation creating gaps between them called nodes of Ranvier.
Describe the subphyla of the Phylum Chordata;
Subphylum Urochordata includes tunicates, sea squirts, and salps. Subphylum Cephalochordata includes lancelets that are fish-like. Subphylum Vertebrata has a vertebral column with a cranium at the anterior end. Endoskeleton grows within the animal; has two pairs of appendages. Closed circulatory system, paired kidneys, and a complete digestive tract; complex behaviors. Contains about 7 living classes. Class Agnatha Lampreys without jaws; ectoparasites. Class Acanthodii and Class Placodermi First jawed fish; now extinct; Late Silurian period Class Chondrichthyes includes sharks, rays, and skates with a cartilaginous skeleton; Devonian period. Class Actinopterygii includes bony fish; the most species of the vertebrate classes are found here. Class Amphibia includes frogs and toads (Order Anura), and salamanders (Order Urodela) all from the labrinthodonts during the Carboniferous period; rely heavily on cutaneous respiration; 3 chambered heart Class Reptilia includes turtles (Order Chelonia), lizards and snakes (Squamata), and crocodiles (Crocodilia). From the progenitors of this class, mammals are thought to have arisen, as well as modern reptiles, birds, and the dinosaurs all during the Mesozoic era. At the end of the Mesozoic (about 65 mya), the dinosaurs and half of all living animal species became extinct. Adaptations include development of an amniotic egg, scales to prevent cutaneous respiration, and excretion of uric acid as waste Class Aves characteristic feathers, complex behaviors, highly developed nervous system. Thought to have developed from saurischian dinosaurs. 27 different orders found in nearly every exploitable habitat. Class Mammalia have hair and mammary glands; specialized with dentition, diaphragm to aid in respiration, endothermy, 4-chambered heart; advanced nervous system; internal fertilization, viviparous. Three subclasses: placental (subclass Eutheria which undergo embryogenesis in a uterus), marsupial (subclass Metatheria; about 6 orders and are pouched), or monotreme (subclass Holotheria; only one order and two genera which lay eggs) had evolved by the end of the Cretacious period (65 mya), underwent a mass extinction and, during the Cenozoic era, began radiating into the many species we see today. See table 30-4 for 13 of the orders of the Eutheria (there are actually 17 orders in all). The chordates have a notachord (dorsal tubular nerve chord) and pharyngeal gill slits during some time of life cycle; coelomates with bilateral symmetry, endoskeleton, postanal tail.
● Rise of water and dissolved minerals in xylem is explained by the tension cohesion (or transpiration cohesion)model
Water is pulled up through the xylem as it enters from areas of low solutes (less negative water potential and more free energy) to areas of high solutes (more negative water potential and less free energy):
Roots
Moist soil Direction of the Water Flow
More solutes = more negative water potential Less free energy: water molecules can’t move about because they are ordered around the polar molecules of the solutes.
Less solutes = less negative water potential More free energy: water molecules can move about freely because they are not ordered.
Water is pulled up through the plant because of water potential – as water is transpired from the leaves, a continuous column of water moves up due to water’s cohesiveness (hydrogen bonding between water molecules). Root pressure may also contribute to the upward movement of water – the influx of water from the soil into the root causes an accumulation within the root that produces pressure to push the water up through the xylem. Root pressure is a less important mechanism to explain water movement; it may explain water movement in small plants, however.
● Describe functions and structure of spinal cord; know parts and function of human brain – medulla, pons, midbrain,
thalamus, hypothalamus, cerebellum, cerebrum. Know the functional areas of the cerebrum
B?
Fungal diseases of plants and humans
Humans: Ringworm, Athlete’s foot, Candidiasis (vaginal yeast infection)
Plants: Dutch Elm disease, powdery mildew, chestnut blight caused by actinomycetes and basidiomycetes.
● Name the four phyla of gymnosperms and their characteristics.
Gnetophores (Gnetophyta): Very closely related to the angiosperms since have vessel elements and cone clusters that resemble flower clusters.
Conifers (Coniferophyta): Monoecious with male and female cones on same tree. Needles for leaves that are typically evergreen (exception is Bald Cypress – look for these on ACU campus).
Ginkoes (Ginkgophyta): Dioecious with separate male and female trees. They still have flagellated sperm as a vestige of evolution from primitive plants. They have remained unchanged from their first appearance 200 million years ago with only one species left, Ginkgo biloba.
Cycads (Cycadophyta): Dioecious. Seed structure today still like some of the earliest seeds found in the fossil record. First appearance was 248 million years ago . Still have flagellated sperm as a vestige of being closely related to the non-vascular plants.
Living on land, sea, and fresh water.
Ecologically, animals are consumers. The sea is isotonic where the same salt concentration exists outside the organism as it does inside; the only negative is that currents are damaging. Consequently, the greatest diversity of life occurs in the oceans. Unlike the sea, fresh water is variable (oxygen, temperature, turbidity, food) and organisms must always be removing excess water from their bodies. Land presents the threat of dehydration, and need a support structure (like an endoskeleton or exoskeleton) to cope with gravity.
Describe “growth” in plants contrasting it with growth in animals
Plants grow only at meristems (tips of stems and roots) and includes growth due to mitosis, cell elongation and cell differentiation; they continue to grow as they age. Animals grow at various sites within a body not at tips of extremities; they have a finite stature that they can reach.
● Characteristics of Chytridiomycota, Zygomycetes, Ascomycetes, Basidiomycetes, and imperfect fungi (Deuteromycetes).
Main classification feature of fungi: sexual spores and their fruiting bodies. There are four phyla. There is one “form phylum” which is a polyphyletic phylum used for convenience to place any fungus where a sexual stage has yet to be observed. If (or when) a sexual stage is seen in any of the fungi in the group, then it is moved into one of the other three monophyletic fungal phyla.
Chytridiomycetes: produce a diploid thallus (e.g. Allomyces) from the fusion of two flagellated gametes which arise from a haploid thallus; only fungus that has flagellated cells; can be parasites or decomposers.
Zygomycetes: produce zygospores (e.g. Rhizopus); have coenocytic hyphae; heterothallic. The hyphae are haploid, whereas the zygote is diploid which undergoes meiosis right before it germinates to form haploid spores.
Ascomycetes: produce ascospores (e.g. mildew, morels, truffles); have septate, but perforate, hyphae with cytoplasm continuous; heterothallic or homothallic. The hyphae are haploid; they fuse when mating to produce a dikaryotic cell. When this forms an ascus, the nuclei fuse to form the diploid zygote. After meiosis and mitosis, 8 haploid nuclei develop into ascospores. Yeasts are in this group: reproduce by asexual budding.
Basidiomycetes: produce basidiospores (e.g. mushrooms, puff balls, bracket fungi); septate hyphae; heterothallic. The hyphae are haploid (and monokaryotic); they fuse to produce a dikaryotic cell from which the mycelium develops to form buttons and fruiting bodies (basidiocarps) we eat (mushrooms). The nuclei fuse, and after meiosis, form four basidiospores (spores in a club-like structure).
Symmetry, body cavity, and pattern of development in classification.
Radial symmetry allows the body to be divided into equal halves in more than one plane. Bilateral symmetry allows only one plane to divide the body into equal halves (right and left); this allows for a head with a brain.
Classification is further based on body plan and factors in the body cavity arrangement. The body cavity can be formed from two layers (diploblastic) or three embryonic layers (triploblastic). If triploblastic, it has an ectoderm (outer covering and nervous system), endoderm (inner layer and lining of GI tract), and mesoderm (middle layer and internal organs). This triploblastic layering allows for three body plans depending on the space resulting between the body wall and the digestive tube.
In the “solid worms” like flatworms and in the proboscis worm, there is no body cavity; they are acoelomates. In the nematodes and rotifers there is a false body cavity between the mesoderm and endoderm; they are pseudocoelomates. If there is a true coelom (a body cavity) which is completely lined with mesoderm, they are coelomates. The coelom develops between the ectoderm and the gut cavity.
Protostomes include mollusks, annelids, arthropods and others; they exhibit spiral cleavage during embryogenesis that is depending on the pattern of early embryo development. If the blastopore develops into the mouth first, it is a protostome; if it develops into the anus first with a second opening later developing into a mouth, then it is a deuterostome.
determinate; coelom formation is schizocoelous (mesoderm is split). Deuterostomes include echinoderms and chordates (the phylum we belong to); they exhibit radial cleavage during embryogenesis (with cell divisions parallel or at right angles to the axis) that is indeterminate so twinning is possible; coelom formation is enterocoelous (the mesoderm forms by outpocketings of the gut).
Compare life cycles of homosporous and heterosporous plants
Bryophtes, whisk ferns, horsetails, most ferns, and many club mosses are homosporous with the production of only one type of spore that develops into the gametophyte that form the archegonium and antheridium. In heterosporous plants (some club mosses and some ferns and all seed plants), megaspores and microspores form. This was a key development in the evolution of seed plants. During the sporophyte generation, both microsporangia and macrosporangia form, and undergo meiosis to form the gametophyte generation of microspores and megaspores. These develop into the male gametophyte or antheridium and the female gametophyte or archegonium to form sperm and egg.
● Contrast nerve nets, radial nervous systems and bilateral nervous systems; compare vertebrate with bilateral invertebrate
nervous systems.
Nerve nets (e.g. in Hydra) have neurons scattered throughout the body; no central control organ or definite pathways present. Bilaterally symmetric nervous systems (e.g. in chordates) have increased numbers of nerve cells, nerve cells that concentrate into ganglia, brains and nerve cords; specialization into peripheral afferent and efferent nerves; increased number of association neurons and other synaptic connections; cephalization (formation of a brain) at one head end. Bilateral invertebrates (e.g. flatworms, annelids, arthropods) have a ventrally located nerve cord; mollusks have 3 pairs of ganglia (cerebral, visceral, and pedal). Vertebrates have a hollow dorsal nerve cord and well-developed brain; nervous system divided into CNS (central nervous system including the brain and spinal cord) and PNS (peripheral nervous system including sensory receptors and nerves). Afferent nerves are sensory and lead to the CNS; efferent nerves supply the muscles or glands and lead away from the CNS. The PNS is divided into somatic (serves external body, muscles and sensory receptors on body surface) and autonomic (serves internal visceral functions of body regulating smooth and cardiac muscle) divisions; the autonomic division is split into two pathways – the sympathetic nerves which mobilize energy during stress and parasympathetic nerves which conserve energy during relaxation.
● Define antigen and antibody, how antigens stimulate the immune response and draw the basic structure of an antibody
An antigen is any foreign material (it can be protein, nucleic acid, silicone, pollen, etc) recognized as non-self. There are 5 classes of immunoglobulins: G, A, M, E, D. IgG makes up 75% of the immunoglobulins; it along with IgM defend against the major pathogens. IgA is a surface-associated immunoglobulin and is found in mucus, tears, saliva and breast milk and prevents pathogens from attaching to the surface. IgD is present in low concentrations and, with IgM, is involved in the functioning of B cells. IgE is involved in allergies and parasitic infections and participates in release of histamine. Antigens stimulate antibody production by reacting with and selecting specific sites on B and T cells that then stimulate the B cells to produce antibodies that react with the specific antigenic determinants; haptens are small molecules that help stimulate this immune response. The typical antibody is Y-shaped consisting of four polypeptide chains. The arms of the Ab act to bind to the antigen and is where the specificity is to an antigen. The tail of the Ab binds cells (e.g macrophages) and activates complement (obj. 5). The four polypeptide chains consist of two identical heavy chains and two identical short chains. Each chain has a constant segment (C region), a junctional or joining segment (J region) which is somewhat variable, and a variable segment (V region) that is unique to only the one Ab for that specific Ag and even for that epitopic site.
Explain leaf abscission, why it occurs, and the physiological/anatomical changes that precede it
All trees shed leaves. Even conifers lose leaves but do so continuously rather than during the Fall. Many angiosperms abscise in the fall in preparation for winter. Abscission is initiated by plant hormones. Chlorophylls break down and nutrients are transported from the leaves to the woody tissues. Abscission occurs at a specific zone near the base of the petiole. This zone is composed of thin-walled parenchyma cells where it is weak; the middle lamella is dissolved by enzymes and the leaf falls off.
● Structure of roots with secondary growth; how secondary tissues form
In woody plants (dicots) roots undergo secondary growth due to meristematic activity in the vascular cambium.
● Compare continuous conduction with saltatory conduction
Continuous conduction occurs in unmyelinated axons. Saltatory conduction occurs in “jumps” from node of Ranvier to node of Ranvier in myelinated axons. This jumping from node to node greatly speeds the conduction of the impulse and requires less energy.
How does a virus infect an animal or plant cell?
The same steps of attachment and penetration occur except that penetration involves taking the entire virus into the cell rather than just the virus injecting DNA into the cell as with bacteriophage.
Once the virus enters the cell, it uncoats to reveal the DNA or RNA nucleic acid core which then directs the cell to replicate the component parts of the virus.
● Characteristics of sponges and diploblasts
The first phylum (Porifera) has an asymmetrical body and only
a single layer of cells; the last two (Cnidarians and Ctenophores) are radial and only two layers; they have no space between the body wall and digestive tube since they lack a digestive tube! The sponges have no nervous system whereas the Cnidarians and Ctenophores have nerve nets.
which create water currents that flow into the spongocoel to bring food into and wastes out of the sponge. The sponges do not have distinctive layers at all. Instead, they are one of the first examples of individual flagellated cells coming together in a colonial tissue. Based on this, the hypothesis is that animals evolved from colonial flagellates, a type of protist.
Porifera (sponges about 9,000 species) are asymmetric, brightly colored, composed of multicellular associations of choanocytes
The next two phyla are diplobastic: Cnidaria (about 10,000 species) have stinging cells called cnidocytes and consists of these classes: Hydrozoa (Hydra and
Ctenophora (comb jellies about 100 species) are fragile luminescent animals that are bi-radially symmetrical and lack stinging
Physalia the Portugese man-o-war), Scyphozoa (jellyfish), Anthozoa (hard and soft corals and anemones).
cells.
● Conditions for fungal growth
They grow in dark, damp habitats and form spores when the environment becomes dry or hostile. The spores are dispersed by animals or wind after being produced on fruiting bodies that project up into the air (e.g. Pilobolus). The spores may be asexually or sexually produced. If sexually produced, hyphae of two different mating types fuse and form a diploid zygote (e.g. Rhizopus). In ascomycetes and basidiomycetes, the hyphae fuse but the nuclei do not, initially. They, instead, remain in a dikaryotic condition (n + n) until the fruiting body (ascus or basidium) forms. When asci or the basidium form, the nuclei fuse and undergo meiosis (see Ascomycetes and Basidiomycetes figures).
● Describe the mechanisms of cell-mediated immunity, including development of memory cells.
C) Objective 6: Describe the mechanisms of cell-mediated immunity, including development of memory cells. Cell-mediated immunity involves T cells and macrophages that destroy cells attacked by pathogens or tumor cells. This activation gives rise to cytotoxic and memory T cells. The cytotoxic cells secrete enzymes that destroy the foreign material as well as lymphotoxins that destroy cancer cells. Suppressor T cells are also produced that inhibit T cells, B cells, and macrophages.
Evolution of vertebrates according to current theory.
:
Compare leaf anatomy in dicots and monocots
Monocots have leaves with parallel veins and without a petiole (the stem that attaches the leaf to the main stem).
The mesophyll of monocots does not have palisade and spongy layers like dicots do. The guard cells in certain monocots (grasses, reeds, and sedges) are dumbell shaped; in dicots and the other monocots, they are kidney bean shaped.
Contrast the two approaches of systematics: cladistics (phylogenetic systematics), and classical evolutionary taxonomy.
Phenetics compares similarities only and is rarely used in taxonomy and systematics today; no distinction made with regard to homologous or analogous structures. Results in polyphyletic taxa. Cladistics focuses on when a lineage divided or branched as based on homologous structures (shared derived characteristics) and the assumption of a common ancestor. Evolutionary Taxonomy focuses on both evolutionary branching like cladistics does AND the extent of divergence that has occurred since the branching happened for that taxa. It is based on shared ancestral characteristics.
Phylum Echinodermata. Describe five main classes of echinoderms.
Spiny-skinned marine animals; found in intertidal areas and benthic ecosystems in the abyss. Secondarily radial as adults; but their larvae are bilateral. They actually have an endoskeleton since the calcareous plates of their arms are covered with an epidermis; they have a water vascular system and tube feet, well developed coelom, no excretory organs, nerve net, dioecious with external fertilization.
Class Crinoidea feather stars (motile) and sea lilies (sessile). Most ancient class with few existing species today. Class Asteroidea sea stars with 5 or more arms with tube feet, and gills for respiration; pedicellaria are pincher-like structures on the top skin that keep the body free of algal growth. Class Ophiuroidea basket stars and brittle stars with arms set off from the central disc and very flexible.
Class Echinoidea sea urchins (grazers) and sand dollars (detritus eaters); no arms; tube feet and pedicellaria.
Class Holothuroidea sea cucumbers; elongate fleshy animals with reduced skeletons and few tube feet. They eviscerate their internal organs when bothered.
● Describe the function of respiratory pigments
Hemoglobin in vertebrate blood greatly increases the amount of oxygen which can be transported by the blood. It does this because of an iron-porphyrin (heme) bound to a protein (globin). The iron portion has a high affinity for oxygen. Hemocyanins are copper-containing respiratory pigments in some mollusks and arthropods where the Cu acts to scavenge oxygen rather than Fe.
Discuss the relationship of the echinoderms and chordates. Why are they deuterostomes?
Both are deuterostomes, with bilateral symetry at some point during their lives (the “radial” starfish has a bilateral larva!); both have an epidermis and an endoskeleton.
● Trace the events that take place in synaptic transmission
We’ve just described how a single nerve transmit an electrical signal. But how does the neuron transmit a signal from one neuron to another or to a muscle cell to signal it to respond? Through a synapse! The neuron that ends just before the synapse is the synaptic terminal (or bouton) on the axon; the neuron that begins just after the synapse (dendrite end) is the postsynaptic neuron. There are electrical and chemical synapses. Electrical synapses involve close connections by protein channels and the passage of ions between the pre- and postsynaptic neurons. Far more common are chemical synapses between neurons. A synaptic cleft of at least 20 nm exists between the pre- and postsynaptic neuron. Presynaptic neurons constantly produce neurotransmitters within their cells using ATP for the energy to produce these chemical messengers which are then stored in synaptic vesicles. When the action potential reaches the synaptic knob of the presynaptic neuron, voltage-sensitive calcium channels open and calcium flows into the synaptic knob. This inflow of calcium causes the synaptic vesicles to fuse with its presynaptic nerve’s cell membrane and then release the chemical messengers into the synaptic cleft. The neurotransmitters then diffuse across the cleft, and bind to receptors on the postsynaptic cell. When this happens, the receptor controls ion channels which allow ions (i.e. Na+2, K+2) to pass through the membrane which sets off another action potential in that nerve.
● Describe the physiological effects of each of the following: hyperventilation; sudden decompression at 12,000 meters
altitude; surfacing too quickly from a deep-sea dive
Hyperventilation reduces the CO2 concentration in the body and thus the impulse to breathe. Sudden decompression from 12,000 feet or surfacing too quickly after a deep dive disrupts homeostasis. Oxygen deficiency (hypoxia) results in drowsiness, fatigue, or headache. Any rapid decreases in pressure can cause decompression sickness due to bubbles of nitrogen being released into the circulatory system and block capillaries to cause strokes or even heart attacks.
● Three functions of stems
1) To support leaves and reproductive structures to allow flowers access to insects, birds, and air currents; 2) to provide internal transport to conduct water and dissolved minerals from roots to leaves, and sugar from leaves to
roots; 3) to produce new living tissue.
● Pressure-flow hypothesis to explain sugar translocation
C? Dissolved sugar moves due to a difference in pressure that exists between the source where sugar is located and the sink where it is removed from the phloem. Sugar is moved by active transport using ATP into the companion cells of the phloem out of a source. Once there, it moves into the sieve tube members through many plasmodesmata. This causes water to flow into the seive tubes which pushes the sugar solution through the phloem. At the sink, active transport (ATP expenditure) removes the sugar and water moves out of the sieve tube member. Energy is spent at either end of the transport tube: loading and unloading the sugar.
● Describe how oxygen and carbon dioxide are exchanged in the lungs and in the tissues
O2 and CO2 move by diffusion from high to low concentrations. The exchange of gases is based on Dalton’s law of partial pressures which states that the pressure of a single gas is the same regardless of whether it is alone or in combination with other gases. Fick’s law describes the diffusion of oxygen or carbon dioxide based on partial pressure across a membrane.
