Final Flashcards

Question

Compare life cycles of homosporous and heterosporous plants

Answer 1

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.

Answer 2

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.

Answer 3

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.

Answer 4

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.

Answer 5

In woody plants (dicots) roots undergo secondary growth due to meristematic activity in the vascular cambium.

Answer 6

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.

Answer 7

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.

Answer 8

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.

Answer 9

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).

Answer 10

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.

Answer 11

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.

Answer 12

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.

Answer 13

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.

Answer 14

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.

Answer 15

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.

Answer 16

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.

Answer 17

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.

Answer 18

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.

Answer 19

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.

Answer 20

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.

Answer 21

1) seeds contain a food supply for the developing embryo 2) seeds are protected by a resistant coating 3) seeds already contain a multicellular well-developed embryonic young plant with root, stem, and leaf already formed whereas spores are like single cells.

Answer 22

In a lytic infection (or cycle), the virus goes through attachment, penetration, replication, assembly, and then destroys the cell to release the next "generation" of a 100 or so new viruses. In a lysogenic (or temperate) infection, the same steps of attachment and penetration occur but then the genome (the entire set of nucleic acid making up the genes of the virus) inserts itself into the host cell's DNA without killing it. Some bacteria receive antibiotic resistance genes or ability to produce toxins from this viral mechanism of sharing genes between bacteria. This is also the process by which the human immunodeficiency virus (HIV) infects but remains dormant for years before the disease progresses from HIV+ to Aids Related Complex (ARC).

Answer 23

C? Asexual- may be advantageous if environment is stable Sexual- About diversity

Answer 24

Prop roots support the plant; pneumatophores involved in gas exchange; epiphytes have aerial roots to anchor the plant to the host; Corms or bulbs are not roots but underground stems or leaves adapted for asexual reproduction. They get pulled down by contractile roots. The onion you eat is leaves!

Answer 25

Invertebrates without a circulatory system have a gastrovascular cavity that functions in circulation or rely on diffusion of the body for gas exchange or use fluids in a pseudocoelom that circulate by body movements. Those invertebrates with an open circulatory system (arthropods) contain hemolymph (blood and interstitial fluid mixed) where the heart has two atria and one ventricle. The hemolymph is pumped from the gills to the atria and to the ventricle to the tissues back to the sinuses called a hemocoel, then back to the gills. Earthworms have a closed circulatory system but no heart and is entirely dependent on movement of the worm where the dorsal blood vessels carry blood anteriorly and the ventral vessels carry blood posteriorly. Cephalopods (octopuses) also have a closed system with "extra" hearts at the bases of the gills. The closed system of vertebrates has a ventral muscular heart that pumps blood through a system of closed vessels and has specific functions of nutrient transport, respiratory gases, wastes and hormones, maintenance of fluid balance, internal defense (chap 43) and thermoregulation.

Answer 26

Bronchial constriction is a normal reaction against inhaling particles to exclude particles from the bronchioles and alveoli which have no mucous or cilia to remove them. Chronic obstructive pulmonary disease includes bronchitis and emphysema that causes bronchial constrictions and is due to breathing polluted air and/or smoking.

Answer 27

Primary growth involves an increase in the LENGTH of a plant. Secondary growth involves the increase in the DIAMETER diameter of a plant. Typically, only gymnosperms and woody plants (and a few herbaceous dicots) exhibit secondary growth; all plants show primary growth but monocots show only primary growth and no secondary growth. In roots, an apical meristem occurs just behind the root cap. In buds, a dome of meristematic cells forms the apical meristem. Secondary growth takes place at the lateral meristem. It increases girth around a stem. The lateral meristem goes the entire length of stems and roots; it is composed of vascular cambium and cork cambium.

Answer 28

Gills are adapted for respiration in water and require lots of energy to extract oxygen from the water; trachea and lungs are adapted for terrestrial respiration but gas exchange must take place across a moist surface to prevent water loss in terrestrial organisms. Respiratory structures must be highly vascularized and have thin walls to allow for gases to exchange between the blood and the atmosphere. Body surfaces may be adapted for gas exchange where the surface to volume ratio is high (e.g. annelids, shell-mollusks like nudibranchs, and amphibians. Tracheal tubes of arthropods deliver air directly to the cells where the branching is extensive throughout the body. Gills are evaginations (outfoldings) of the body surface; dermal gills occur in echinoderms, mollusk gills are highly folded and ciliated for filter feeding; chordate gills (e.g. fish) are internal and covered with a bony operculum. Fish gills are efficient because of the countercurrent flow of blood and water. Lungs are invaginations from the body surfaces that exchange gases. Many amphibians rely on both cutaneous respiration and lungs; reptilian lungs are simple with some inner folds; birds have air sacs which increase respiratory efficiency with a countercurrent flow between the air and the blood and they have no diaphraghm; mammal lungs are complex and have a great surface area.

Answer 29

This is a single layer in herbaceous plants and thicker with periderm in woody plants. The epidermis in plants is composed of parenchyma cells with guard cells and outgrowths called trichomes. Epidermal cells are nonphotosynthetic and relatively transparent allowing light to penetrate; they also have a waxy cuticle to retard water loss along with stomata surrounded with guard cells to allow diffusion of gases. Trichomes are hairlike projections which function to increase the effective surface area of the root or salt excretion in halophytes if on leaves. Epidermis is replaced by periderm in woody plants and is composed of cork cells; these cells are dead at maturity and function in waterproofing and storage.

Answer 30

C? Think about these "just-so" stories and spin a naturalistic tale. Just don't get too attached to your particular story so much that you think it's the only right one! And be sure you can test the idea (at lest in principle).

Answer 31

Three domains are Eubacteria, Archaea, and Eukarya. Plantae, Animalia, Fungi, Protista, Eubacteria and Archaebacteria are the six kingdoms. This is the Woese idea which superimposes a three domain organization over the six kingdoms. See figures 23-2, 23-3 and Table 23-2.

Answer 32

Parenchyma is a tissue composed of cells with thin primary walls whose function is storage (starch, oil, water and salts), photosynthesis, and secretion; the cells remain alive at maturity. Think of this tissue as analogous to muscle tissue. Collenchyma is a tissue composed of cells with unevenly thickened primary walls whose function is to provide support in soft plant organs; the cells remain alive at maturity. Think of this tissue as analogous to tendons and cartilage. Sclerenchyma is a tissue composed of cells with both primary walls and thick secondary walls rich in lignin whose function is support; the cells are often dead at maturity. Think of this as analogous to the skeleton.

Answer 33

Seeds must absorb water by imbibition to be hydrated enough for germination; they must have plenty of oxygen to respire for enough ATP (energy) to germinate; temperature must be optimum (some require an exposure to cold before they can germinate); light sometimes enhances germination especially for seeds that are close to the surface. Both kinds of seeds send out the root from the seed first. Then, dicots form a hook that pulls the cotyledons and stem tip through the soil so the shoot is protected. Monocots produce a sheath of leaves called the coleoptile to protect the emerging stem tip.

Answer 34

Eggs are formed in the ovule from the megasporocyte which forms an egg and two polar nuclei. Pollen grains are formed in the anthers (see figure 37-3). Pollination is just the transfer of pollen from anther to stigma. Fertilization involves meiosis to form gametes: sperm and eggs. Each pollen grain, when it lands on the stigma of the female carpels is composed of two cells. One cell forms two non-flagellated male gametes (sperm) and the other produces a pollen tube through which the sperm travel to reach the ovule. One of the sperm fuses with the two polar nuclei to form the endosperm that becomes the nutritive tissue that surrounds the embryonic plant in a seed. The other sperm fertilizes the egg to form a zygote that develops into an embryonic plant contained in a seed (37-7 and 37-8). The ovary and floral tube surrounding the seed develops into a fruit.

Answer 35

The same characteristics can be shared derived OR ancestral depending on which taxa you are examining. For example, the three bones in the ear in mammals is a shared derived characteristic (synapomorphic - different from the immediate ancestral condition) when you are considering all the mammals and how they are different from reptiles (Class) which do not have these bones in their ears but instead have a tympanic ossicle and a segmented jaw from which the 3 ear bones in mammalian ears (the ossicles) were derived. The three bones in the mammal ear is a shared ancestral characteristic (pleisiomorphic -unchanged from the distant ancestor) when you are considering how the mammals within their Class (Orders) are different since the three bones have slight differences depending on whether you are a Carnivore, a Primate, a Chiropteran, or any of their other 14 or so orders.

Answer 36

Plasma is the fluid portion of the blood (serum is the fluid without clotting factors). Cellular components of the blood include: red blood cells that are flexible biconcave discs filled with hemoglobin to transport oxygen; white blood cells, leu-kocytes, to defend against disease; and platelets involved in clotting. Leukocytes are further divided into the granular leuko-cytes (neutrophils with phagocytic activities, eosinophils involved in allergic reactions, basophils that produce histamine and heparin) and agranular leukocytes that include the T and B lymphocytes that produce and control antibody production (chap 43) and the monocytes which turn into macrophages that phagocytize foreign materials. During clotting, the platelets form a temporary clot at the site of the cut followed by a process involving a series of reactions that forms a thrombin and fibrin permanent clot. Arteries carry blood away from the heart (mostly carry oxygenated blood) and undergo extensive branching to form arterioles then capillaries (one cell thin) where exchange of serum and interstitial fluid can occur as can exchange of gases, dissolved nutrients and wastes. The capillaries then merge into venules then veins which carry blood back to the heart (mostly carry de-oxygenated blood). The walls of arteries and veins are thick and do not allow materials to pass through; they have three layers: tunica intima (the inner layer composed of endothelium), tunica media (middle layer com-posed of connective tissue and smooth muscle), and tunica adventitia (outer layer composed of elastic and collagen fibers).

Answer 37

Yeasts are unicellular (although at cool temperatures, they can be filamentous since they are dimorphic). Molds are filamentous. Each filament is a hyphae and many hyphae make up a mycelium. The hyphae may have septa to separate cells or they may lack septa entirely (coenocytic). Cytoplasm streams between hyphae via pores in septate hyphae.

Answer 38

Lymphocytes and macrophages are involved in the immune system. The three types of lymphocytes include B, T, and natural killer (NK) cells. T cells are responsible for cellular immunity originating from stem cells in the bone marrow but becoming immunocompetent in the thymus; they attack tumor cells and cells infected by pathogens. Cytotoxic T cells (or killer T cells) and suppressor T cells have a receptor site called CD8 on them; they destroy cells with foreign antibodies (virally-infected, tumor cells, foreign tissue) by releasing cytokines and various enzymes. Suppressor T cells release cytokines that inhibit the B cells (and some T cells) from acting. Helper T cells have a CD4 marker site; they enhance the action of cell-mediated responses as well as antibody production by B cells. B cells are produced in the bone marrow and mature to become immunocompetent there. [In birds, this site of maturation is thought to be the bursa of the gut and some have thought that the Peyer’s patches in our gut serves the same function – we’ll stick to the bone story for now]. T cells also have their origin in the bone marrow but differentiate further in the thymus. B cells have specific antigenic receptors but when it binds to an antigen, it is selected by that antigen to divide rapidly and form a clone of cells with the specificity to produce an antibody for that antigen once they mature into plasma cells. Natural killer cells attack cancer cells; they are related to T cells but can attack without prior exposure to antigens to produce cytokines and enzymes that destroy the foreign cell. Macrophages are involved in both specific and nonspecific defense; they digest foreign particle (e.g. bacteria) but retain some of the antigens and present them to activate helper T cells.

Answer 39

Leaves are designed to maximise photosynthesis and reduce water loss. The epidermis is relatively transparent to let light reach the photosynthetic mesophyll cells; stomata allow exchange of gases. Xylem brings water to the leaf; phloem carries sugars to other parts of the plant. Leaves of each plant help it to survive in the environment to which it was adapted.

Answer 40

Most water is lost through the stomata; light, wind, and low humidity increase water loss. Transpiration causes the upward movement of water through the xylem; it results in evaporative cooling and the uptake of minerals from the soil. Temporary wilting occurs when a plant loses more water than it can take in. Plants that exude water as a liquid at the edges of the leaf do so when the plant takes up more water than it needs and thus gives the appearance of dew of leaves (guttation).

Answer 41

B) oxygen-hemoglobin dissociation curve. Oxygen is actually transported not as a gas dissolved in the blood but as a compound bound to hemoglobin (Hb) to form oxyhemoglobin (HbO2). As oxygen concentrations rise, the concentration of HbO2 increases. It dissociates more readily in the slightly acidic environment of the capillaries due to CO2 or in active muscles due to lactic acid; this is called the Bohr effect.

Answer 42

C?Coevolution occurs when two species rely on each other so much that they affect the evolution of certain features (either physical or behavioral) in each other to the point where neither can survive without the other. The example of the orchids (Ophrys sp.) and the wasps is an odd case of “coevolution” (perhaps we should call it behavioral parasitism) where the reproductive success of the orchid is dependent on the wasp but it does not help the wasp!

Answer 43

(B) as bicarbonate ions (7% dissolved in blood and 20% carried by Hb). CO2 combines with water in the blood to form carbonic acid which dissociates to form bicarbonate ions in the blood.

Answer 44

Inspiration is caused by contraction of the diaphragm (pulling down of the muscle when the stomach goes out) and the rib muscles pull the ribs apart to expand the chest. Expiration occurs when the diaphragm and the rib muscles relax to decrease the volume of the thoracic cavity. Respiratory centers in the brain regulate breathing. The medulla controls the basic rhythm of breathing while the pons controls the transition for inspiration to expiration. Chemoreceptors in the medulla, aorta and carotid arteries sense the carbon dioxide concentration as bicarbonate and a change in pH (lower when there is too much CO2 in the blood). The signal to breathe is a result of too much carbon dioxide not a lack of oxygen! Vital capacity is the maximum exhalation following a maximal inhalation; tidal volume is the amount of air moved in or out in a normal inspiration or expiration

Answer 45

``` Domain Kingdom Phylum Class Order Family Group Species (Dear King Philip Came Over For Great Sex) ```

Answer 46

Multicellular eukaryotes; cells specialized into tissues and organs; heterotrophs that ingest their food followed by digesting it inside the body; can move (at least for part of their life cycle); sense organs and nervous system; sexual reproduction with non-motile egg and flagellated sperm.

Answer 47

AIDS is an immune disorder brought on by a retrovirus known as HIV. It destroys T cells (CD8) so that B cells have no control. Risk factors include unprotected promiscuous sex regardless of whether it is homosexual, heterosexual, or bisexual and IV drug use. A vaccine is nearly impossible since the virus encloses its genome into the body's own cells and is difficult for the immune system to detect it .

Answer 48

This chapter covers the animals with a triplobastic features. Some are acoelomate or pseudocoelomate, others have a true coelom (body cavity lined completely by mesoderm that lies between the digestive organs and the outer body wall) and in which the mouth develops from the blastopore (the first opening that forms in the embryonic gut). A coelom permits a clear separation between the muscles of the body and the wall of the digestive tract to allow food to move along it independently of body movements. The coelom can serve as a hydrostatic skeleton, provide a medium for transporting materials, and provide a space for organs to develop.

Answer 49

See figure 44-9 and know the parts. The atrioventricular (AV) valves are located between the atria and the ventricles. The right AV is the tricuspid valve while the left AV is the bicuspid or mitral valve. These are closed during ventricular contraction. The semilunar valves are between the ventricle and the great blood vessels: the pulmonary semilunar valve is located between the pulmonary artery and the right ventricle while the aortic valve is located between the aorta and the left ventricle. Cardiac muscle cells are joined by dense bands called intercalated discs that are gap junctions where the two cells are connected through pores and thus it offers very little resistance to the passage of an action potential so the entire atrial (or ventricular) muscle mass contracts as one giant cell. The contraction is controlled by the sinoatrial node ( a pacemaker) located in the right atrium. When the SA node fibers fire, an action potential is spread across both atria simultaneously. The atria then contract (systole). The atrioventricular node (in the right atrium) receives the signal next and acts as a delay and relay node. After the slight delay, transmission of the electrical signal continues to the Purkinje fibers which make up the AV bundle which splits to send branches upward over both ventricles to cause ventricular contraction (systole). The cardiac cycle lasts about 0.8 sec and consists of the atrial systole (contraction) and the ventricular systole followed by the atrial relaxation (diastole) and ventricular diastole. The "lub-dup" heart sounds mark the beginning of the ventricular systole followed by the ventricular diastole.

Answer 50

There is no circulation of fluids in plants. Water and dissolved minerals are transported from roots to other parts of the plant through xylem; dissolved sugar is translocated in phloem to other parts of the plant. All this is driven by physical processes rather than through a "pumping organ," like a heart, as in many animals.

Answer 51

Root system is below ground and shoot system is above (stem, leaves, flowers, and fruits). Just like an animal body, plants are composed of cells and tissues; roots, stems, leaves, flowers, fruits are the organs.

Answer 52

Respiratory structures must be highly vascularized and have thin walls to allow for gases to exchange between the blood and the atmosphere. Body surfaces may be adapted for gas exchange where the surface to volume ratio is high (e.g. annelids, shell-mollusks like nudibranchs, and amphibians. Tracheal tubes of arthropods deliver air directly to the cells where the branching is extensive throughout the body. Gills are evaginations (outfoldings) of the body surface; dermal gills occur in echinoderms, mollusk gills are highly folded and ciliated for filter feeding; chordate gills (e.g. fish) are internal and covered with a bony operculum. Fish gills are efficient because of the countercurrent flow of blood and water. Lungs are invaginations from the body surfaces that exchange gases. Many amphibians rely on both cutaneous respiration and lungs; reptilian lungs are simple with some inner folds; birds have air sacs which increase respiratory efficiency with a countercurrent flow between the air and the blood and they have no diaphraghm; mammal lungs are complex and have a great surface area.

Answer 53

Animals in this chapter are marine animals or animals that exist in close association with moisture (e.g. worms). The insects in this chapter and many of the animals in chapter 30 have adapted to the hazards of life on land. Air-breathing animals first appear as fossils during the Silurian period 438 million years ago (mya): the invertebrates, Arthropoda. The first terrestrial vertebrates (amphibians) do not appear until the Devonian period 408 mya. A major adaptation is to overcome is desiccation. Since water is scarce on land and breathing loses considerable moisture, respiration needs to be deep within the animal. Another adaptation is to gravity; an endoskeleton or exoskeleton is needed to support the body. Internal fertilization helps prevent desiccation of the embryo.

Answer 54

See figure 37-1. Flowers are composed of sepals, petals, stamens, and carpels arranged in whorls. The sepals are collectively called the calyx. The collective term for petals is corolla. Just inside the petals are the stamens the collective term for the filaments and the anthers where pollen grains form. Each pollen grain produces two cells; one cell forms two non-flagellated male gametes and the other produces a pollen tube for the sperm to travel through to reach the ovary. The term carpel is a collective term for the all of the pistils consisting of the stigma, style, and ovary the female reproductive organs. The pistil includes the ovules which may produce seeds if fertilized. The stigma provides a site for the pollen to land; the style provides a structure through which the pollen tube grows; the ovary contains one or more ovules which contain one female gamete and two polar nuclei which participate directly in fertilization.

Answer 55

B) filter, warm, and moisten the inhaled air; mucous traps particles in inspired air and cilia moves it back towards the throat where the mucous is swallowed. The nasal and oral cavities connect to the pharynx which leads to the larynx that is designed for sound production. The epiglottis covers the entrance to the larynx during swallowing (only occurs in adult humans). Air passes from the larynx to the trachea which is supported by cartilaginous rings. The trachea branch into two bronchi which are lined with ciliated mucous membranes. The air then passes into the two lungs which are divided into lobes and covered by pleural membranes which provide pleural fluid for lubrication during breathing. The lungs are formed by bronchi which branch to form millions of bronchioles which lead to highly vascularized alveoli composed of a single layer of epithelial cells.

Answer 56

Risk factors for developing atherosclerosis (hardening of the arteries) are elevated cholesterol levels (>200), hypertension (e.g. 140/95 or higher), tobacco use (smokeless or cigarettes), diabetes mellitus, family history. It can lead to stokes, heart attacks or chest pains. The key development in this disease is the deposition of lipids on the smooth muscle cells of the arterial wall that thickens up the lining and eventually stops blood flow. The key lipid that deposits is cholesterol from LDLs that also attracts calcium to form a hardened plaque to cause the artery to become blocked.

Answer 57

Flowering is a photoperiodic response. Some plants are short-day plants; they flower when the length of uninterrupted darkness exceeds a critical period (usually flowers in late summer or fall as the nights grow long). Other plants are long-day plants; they flower when the length of darkness is less than some critical period (usually flowers in spring and early summer as nights grow short). Day neutral plants do not respond to light or dark (they typically grow in the tropics where the day length does not vary much during the year). Control of photoperiodism is due to a pigment called phytochrome which actually detects various periods of light. Phytochrome is in all cells of vascular plants and exists in two forms: Pfr and Pr. When Pfr absorbs far-red light (e.g. heat during the night), it converts to Pr. When Pr absorbs red light (e.g. sunlight during the day), it converts to Pfr. During the day, Pr converts to Pfr; during the night, Pfr converts back to Pr. In short-day plants, Pfr inhibits flowering; thus only when the night gets long and the Pfr turns into more Pr, does the plant flower. In long-day plants, Pfr induces flowering; thus only when the night is short and more Pfr remains, does the plant flower.

Answer 58

Insect-pollinated plants have blue or yellow petals because insects see well in the violet, blue, and yellow range of visible light; they also have a strong scent that can be either pleasant or foul to attract the insects. Bird-pollinated plants are usually red, orange, or yellow because these are the colors that most birds see well; they do not have a strong scent since most birds lack a strong sense of smell. Bat-pollinated flowers are usually white and night blooming; they also have a strong fermented fruit smell. Wind-pollinated flowers produce large quantities of pollen; the flower is small and inconspicuous without scent or nectar.

Answer 59

Gametophytes (haploid) have sexual structures (antheridia and archegonia) which produce gametes, which unite to form the zygote (the first stage of the sporophyte generation). The zygote develops within the archegonium into the embryo and then the sporophyte generation(diploid). The sporophyte produces haploid spores by meiosis, which ultimately form the new gametophyte generation which forms by mitosis. The sporophyte is the portion of the plant cycle which, in primitive plants, is dependent on the gametophyte for nutrition. The gametophyte generation is dominant in mosses, liverworts, and hornworts whereas the sporophyte generation is dominant in all other plants including ferns.

Answer 60

Through the phloem, sucrose is translocated slowly from an excess supply (leaf) to a sink or storage site such as roots, apical meristems, fruits and seeds.

Answer 61

It is not always easy to determine which shared characteristics are a result of homologous (similarities in different species resulting from a common ancestor; e.g. wings of several birds) or homoplastic structures (similarities due to convergent evolution but not as a result of common descent; e.g. fins on fish compared to fins on dolphins) within a taxon. This makes it difficult to construct the monophyletic taxonomic criteria desired. Instead, many times we have to be satisfied with a polyphyletic scheme.

Answer 62

A stimulus occurs and is received by either autonomic or somatic sense organs; the stimulus is transmitted by afferent (sensory) neurons to the central nervous system to be integrated, interpreted, and a response initiated; efferent (motor) neurons transmit the impulse to the effectors to cause response.

Answer 63

See figures 36-3 and 36-8. Roots have epidermis or periderm, cortex (storage), and vascular tissues. The epidermis covers the root but it does not have a cuticle to prevent the inflow of water. The cortex (the bulk of the root) is made up of parenchyma cells and its primary function is storage. The spaces between the cells in the cortex provide a way for water to enter and also for aeration. At the center of the root is the stele, a centrally located vascular tissue composed of xylem and phloem and other tissues. At the inner layer of the cortex (or outer layer of the stele) is the tissue known as the endodermis which controls what actually enters the xylem at the root's interior. Surrounding each endodermis cell is a strip of waterproof material composed of suberin called the Casparian strip that prevents water and minerals from coming into the stele (center portion of the root). The only way they can enter is by active transport through carrier proteins that require ATP expenditure. The pericycle is just inside the endodermis and is composed of meristematic parenchyma cells; it forms the vascular cambium which gives rise to lateral meristems involved in the growth of woody plants; vascular cambium is located between the phloem and xylum in dicots. In herbaceous dicot roots, the xylem and phloem are not organized into bundles around a core of pith as they are in monocots; instead, they are arranged as an inner core composed of xylem and phloem. In monocots, xylem and phloem are located as bundles circling around a central core of pith; there is no vascular cambium.

Answer 64

Herbaceous dicot stems (Figure 35-1) -- Vascular bundles in a circle around a central core of pith. Monocot stems (Figure 35-2) -- Vascular bundles scattered throughout the stem and embedded in ground tissue. No distinct areas of cortex and pith as in above. No vascular cambium or cork cambium. Epidermis provides protection and reduction of water loss. Cortex is involved in photosynthesis, storage, and support; it is composed of parenchyma (thin walled), collenchyma (varible thickness of wall/support), sclerenchyma (thick walled-strength and support). Phloem fiber cap provides fibers for support. Phloem moves sugars from leaves to other parts of plant. Vascular cambium provides a lateral meristem for secondary growth. Xylem provides transport of water and minerals from root to leaf. Pith is composed of large thin-walled parenchyma cells for storage.

Answer 65

Formation of offspring without the fusion of gametes (similar to cloning). rhizomes (grasses), tubers (potatoes), bulbs (onions), corms (irises), stolons (strawberries) are specialized stems for asexual reproduction. Some leaves produce plantlets because they have meristematic tissue along the leaf margin. Roots may develop adventitious buds that turn into suckers which give rise to new plants (aspens). Apomixis is the production of seeds and fruits without sexual reproduction (e.g. oranges).

Answer 66

``` The next four phyla have simple brains and a symmetrical body. The first two are acoelomate (without a body cavity) and the last two are pseudocoelomate (with a false body cavity). The pseudocoelomates, have a body plan that acts as a type of hydrostatic skeleton allowing for greater movement; they lack a circulatory system and are dioecious. Platyhelminthes are the flatworms and are in four classes. They are beginnings of cephalization (forming a brain). They have organs, a simple nervous system, excretory structures called protonephridia and a digestive cavity with one opening. Class Turbellaria include the planarians that take in food through the mouth to the gastrovascular cavity. Class Trematoda and Monogenea include the flukes that inflect the liver. Class Cestoda includes the tapeworms that are segmented into proglottids and lack a mouth or digestive system absorbing nutrients directly into the body. Nemertea includes the proboscis worms that have a proboscis that can be shot out of the mouth to grab prey. This is the first group to have a complete digestive tract from mouth to anus; it also has separate digestive and circulatory systems but no heart. Nematoda include the roundworms (Ascaris), hookworms, trichina worms and pinworms. Rotifera are known as wheel animals because of their corona of cilia on the anterior end; they exist in freshwater. Mollusca (50,000 species) Soft body with a dorsal shell; broad flat muscular foot ventrally; visceral body mass located above the foot with a mantle that covers visceral mass and secretes a shell; it also has a radula or belt of teeth in the mouth region (except for the bivalves like clams); the coelom is reduced to small compartments around certain organs including the heart and nephridia; the main body cavity is a hemocoel; sexes are separate and fertilization is external; trochophore larvae are the first stage followed by the veliger larvae unique to molluscs. Class Polyplacophora including Chitons. Segmented shells of eight separate transverse plates. Head reduced and eyes absent; has a broad foot for locomotion. Class Gastropoda including snails, slugs, and nudibranchs. Body and shell coiled with well-developed head with tentacles and eyes; use their mantles as lungs; some gastropods have uncoiled shells (limpets) others have no shells (nudibranchs). ClassBivalvia including clams, oysters and mussels. Laterally compressed body with a two-part shell hinged dorsally with strong muscles to hold the shells together; hatchet shaped foot; they feed by bringing water in via the incurrent siphon and trap food particles in the mucous on the gills. Class Cephalopoda including squids and octopods. Foot divided into tentacles usually bearing suckers; well-developed eyes. Active predators with 8 tentacles in octopods, 10 in squid, and 90 in the nautilus; squids and octopods have tentacles with suckers, a radula and a beak for killing and biting prey. Annelida (15,000 species) External and internal segmented bodies (metamerism); well-developed coelom, closed circulatory system and a complete digestive tract extending from mouth to anus; respiration takes place through the skin or by gills; excretion occurs through structures called nephridia within each segment; nervous system of an anterior brain and set of nerves. Class Polychaeta including sandworms and tubeworms. Segmented worms with each segment bearing a pair of parapodia (appendages from each segment) with many setae (bristle-like structures). Well-developed head. Christmas-tree worms. Class Oligochaeta including earthworms. Lack parapodia. Lubricus terrestris is the common earthworm. Food (soil) moves its way through the pharynx, esophagus, crop and gizzard, intestine and exits the anus. Gas exchange occurs through the skin; circulatory system closed. Oligochetes are all hermaphroditic and simultaneously exchange sperm with the clitellum of the other worm which is shed bearing fertilized eggs and serves as a cocoon in which the worms develop. Class Hirudinea including leeches. Muscular suckers at both anterior and posterior ends. Secrete anticoagulants into their host and thus are used to remove coagulated blood from a wound. Arthropoda Paired jointed appendages for locomotion, feeding, reproduction; exoskeleton; segmented body fused to form a head, thorax, and abdomen; aquatic arthropods have gills, terrestrial ones have book lungs or trachea; nervous system composed of brain and ladder-like nerve cords; circulatory system open and coelom reduced Subphylum Chelicerata (Trilobites may have been their ancestors?) Class Merostomata: only one species left in this class, the Horseshoe crab Limulus polyphemus Class Arachnida 65,000 species including spiders, scorpions, ticks, mites. Have chelicerae and pedipalps and four pairs of walking legs; breathe by trachea or book lungs. Subphylum Crustacea Class Malacostraca 32,000 species including lobsters, crabs, shrimp, barnacles. Mandibles, biramous appendages, two pairs of antennae. Order Decapoda: lobsters, crayfish, crabs, and shrimp with specialization in their appendages and segments. Subphylum Hexapoda Class Insecta 800,000 species. Six jointed legs, trachea for respiration; simple and compound eyes; Malpighian tubes for excretion; dioecious with internal fertilization; most advanced insects undergo several stages of metamorphosis. Highly successful due to ability to fly and small size; metamorphosis prevents competition of adults with larvae; variety in coloration and behavior. Subphylum Myriapoda Class Chilopoda 3,000 species including the centipedes. One pair of legs per body segment; carnivorous. Class Diplopoda 7,500 species including the millipedes. Two pairs of legs per segment; herbivores or scavengers. ```

Answer 67

The stomata opens when the guard cells become filled with water (turgidity); as they fill, the inner walls bend outward to produce a pore. The stomata open and close depending on light levels and carbon dioxide concentration within the leaf; also affecting it are dehydration, hormones, and a biological clock. Potassium ions are triggered to flow into guard cells by light; water then passes into the guard cells by osmosis and the cell swells to open the pore of the stomata.

Answer 68

Figure 28-13. Dominant sporophyte generation with only a few cells serving as the gametophyte. Ovules contain a megasporocyte which undergoes meiosis to produce 4 haploid megaspores. Only one develops and divides mitotically to form the gametophyte (or embryo sac). This female gametophyte consists of 8 cells but only 3 will participate in fertilization. Meanwhile, the anther contains microsporocytes that undergo meiosis to produce 4 haploid microspores. Each one develops into the male gametophyte (pollen grain) consisting of 2 cells – a tube cell and the germ cell. Pollination involves transfer of the pollen grain to the style of the flower. Once there, the tube cell grows a pollen tube down through the stigma to the ovaries. Just like the gymnosperms above in objective #3, the germ cell within the pollen grain divides to form two non-flagellated sperm. BUT, here, both sperm remain alive and both participate in double fertilization. One sperm fertilizes the egg to result in the diploid zygote. The other sperm and two haploid polar nuclei fuse together to form a triploid (3n) cell that develops into the endosperm. This is the part that serves as the nutritive material for the developing plant embryo. The other five cells may either disintegrate or perhaps become part of the seed coat. As the seed develops, the ovary wall (from the sporocyte part of the plant that has existed all along) thickens and becomes the flesh of the fruit that protects and facilitates dispersal of the seeds within it.

Answer 69

The two lateral meristems are tissues called the vascular cambium and cork cambium. These tissues are in the stems of woody plants but not in monocots. See Table 33-1 to understand which secondary tissues arise from these lateral meristems: Vascular cambium Secondary xylem (produced inward) Secondary phloem (produced outward) Cork Cells Cork parenchyma Cork Cambium periderm (replaces the epidermis in woody plants) Describe what's happening in Figure 35-3.

Answer 70

Monocots have parallel leaf venation, floral parts in multiples of three, fibrous root systems, one cotyledon in the seed with persistent endosperm (e.g. herbaceous plants like lilies, grasses, corn, palms, orchids). Dicots have netted leaf venation, floral parts in multiples of 4 or 5, a tap root system, two cotyledons in the seed which absorb the endosperm (e.g. herbaceous or woody plants like roses, oaks, potatoes, daises).

Answer 71

Upper and lower epidermis are composed of non-photosynthetic parenchyma cells with a waxy cuticle. Some leaves have trichomes to retard water loss or prevent insects from grazing, or reflect sunlight to prevent overheating, or to excrete excess salt. Stomata surrounded by guard cells allow for water and carbon dioxide exchange. The mesophyll lies between the epidermal layers and is made of parenchyma specialized for photosynthesis. The upper cells form the palisade layer with the lower part of the leaf loosely arranged in the spongy layer. Vascular bundles composed of xylem on the upper side of the bundle (to allow water and mineral transport) and phloem on the lower side of the bundle (to allow sugars transport). The bundles are surrounded by sheath cells of either parenchyma or sclerenchyma cells. They provide support to the leaf.

Answer 72

In autoimmune diseases, the body attacks itself and are basically hypersensitivities to oneself. Diseases like these include rheumatoid arthritis, multiple sclerosis, lupus, insulin-dependent diabetes. They may be triggered by viral or bacterial infections. Allergic reactions are due to sensitization to a common allergen where the macrophage that degrades the allergen and displays it to the T cells activate the T cells and stimulate the B cells to produce IgE. Mast cells are activated by the allergen binding to the IgE on them to release histamine that causes inflammation which further damages the tissue unneedlessly. Systemic anaphylaxis occurs after the development of an allergy – widespread vasodilation.

Answer 73

Xylem is composed of conducting cells called tracheids and vessel elements which conduct water and dissolved materials from the root to the shoot system; it also has fiber and parenchyma cells that provide structural support; the tracheids and vessel elements are dead at maturity and are hollow tubes. Phloem is composed of seive tube members which conduct dissolved sugars throughout the plant; it is also composed of fibers and parenchyma cells for support. Seive tube members are alive at maturity but most organelles have degenerated. Therefore, companion cells are adjacent to seive tube members and often direct their activities via cytoplasmic connections through the plasmodesmata (cytoplasmic projections). Think of the xylem and phloem as the circulatory system of plants.

Answer 74

A primary response occurs the first time the body is exposed to the antigen within 3-14 days with IgM being first to appear and declining once the infection is suppressed; IgG then gets produced. Upon secondary exposure, a secondary response occurs that is more rapid and effective due to the presence of memory B cells. Active immunity occurs following exposure to antigen either artificially (vaccination) or naturally (sickness). Passive immunity is the receipt of antibodies rather than the body actually making them; it may be either natural (baby receiving colostrum from nursing) or artificial (injection of antitoxin).

Answer 75

After fertilization, the ovule develops into the seed, the endosperm provides the nutritive tissue, while the ovary and floral tube develops into the fruit. [Think of this as analogous to the ovaries and uterus.] Within the seed is a complete plant embryo that is nurtured by the plant as the seed develops. Cell divisions of the fertilized egg proceed to form the embryonic plant (figure 37-8). The bottom cell develops into the suspensor which anchors the embryo into the endosperm and allows uptake of nutrients from it. [Think of the suspensor as analogous to the umbilical cord and the endosperm as analogous to the placenta.] The top cell actually develops into the embryo by dividing into a short chain of cells called the proembryo, then into the globular embryo where it begins to differentiate into the various tissues like the two cotyledons (if a dicot); this stage is called the heart stage since the two lobes of the developing cotyledons look like a heart. During the torpedo stage, the embryo continues growing and the cotyledons elongate. The parts of a seed include the seed coat, the radicle (embryonic root), the cotyledons, the hypocotyl, and the plumule. After fertilization, the ovule develops into the seed, the endosperm provides the nutritive tissue, while the ovary and floral tube develops into the fruit. [Think of this as analogous to the ovaries and uterus.] Within the seed is a complete plant embryo that is nurtured by the plant as the seed develops. Cell divisions of the fertilized egg proceed to form the embryonic plant (figure 37-8). The bottom cell develops into the suspensor which anchors the embryo into the endosperm and allows uptake of nutrients from it. [Think of the suspensor as analogous to the umbilical cord and the endosperm as analogous to the placenta.] The top cell actually develops into the embryo by dividing into a short chain of cells called the proembryo, then into the globular embryo where it begins to differentiate into the various tissues like the two cotyledons (if a dicot); this stage is called the heart stage since the two lobes of the developing cotyledons look like a heart. During the torpedo stage, the embryo continues growing and the cotyledons elongate. The parts of a seed include the seed coat, the radicle (embryonic root), the cotyledons, the hypocotyl, and the plumule.

Answer 76

1. Inorganic minerals 2. Organic matter 3. Soil organisms 4. Soil air 5. Soil water. All interact and cycle from the soil to the organisms of the soil.

Answer 77

See figure 37-1. Flowers are composed of sepals, petals, stamens, and carpels arranged in whorls. The sepals are collectively called the calyx. The collective term for petals is corolla. Just inside the petals are the stamens the collective term for the filaments and the anthers where pollen grains form. Each pollen grain produces two cells; one cell forms two non-flagellated male gametes and the other produces a pollen tube for the sperm to travel through to reach the ovary. The term carpel is a collective term for the all of the pistils consisting of the stigma, style, and ovary the female reproductive organs. The pistil includes the ovules which may produce seeds if fertilized. The stigma provides a site for the pollen to land; the style provides a structure through which the pollen tube grows; the ovary contains one or more ovules which contain one female gamete and two polar nuclei which participate directly in fertilization.

Answer 78

Adaptation to land requires a CUTICLE to prevent desiccation, STOMATA to allow diffusion of gases into plant tissues, GAMETANGIA with cells to help protect the gametes (archegonium producing eggs and antheridium producing sperm) as well as the zygote/embryo, LINGIN to strengthen the plant. Algae are dependent on water for distribution of motile sperm and spores; primitive mosses and ferns have nonmotile spores but motile sperm and the advanced plants have both nonmotile sperm and spores.

Answer 79

C? When leaves have functions other than photosynthesis, they may be modified into spines for defense against herbivores, tendrils for attachment, bud scales to protect meristems, bulbs to store sugars, succulent leaves to store water. Insectivorous plants grow in low nitrogen soils and so trap insects to supply nitrogen. The trapping devices are typically modified leaves.

Answer 80

GENOME SEQUENCING Use of the actual genome of many organisms and its sequencing is likely to yield a much more accurate catalog of a species' characteristics rather than rely on the expression of those genes phenotypically. Use of restriction enzyme digests of highly conserved genes coupled with electrophoresis and PCR can yield molecular time clocks that better measure how much an organism has diverged from other organisms .

Answer 81

The vertebrate heart has one or two atria and a single or divided ventricle. In fish, the blood flows in a single circuit from heart to gills to capillaries to tissues in a low-pressure system that permits a slow metabolic rate; the sinus venosus flows into a single atrium followed by one ventricle from which blood flows out the conus arteriosus. Amphibians have a pulmonary circuit that flows to the lungs and skin and the systemic circulation that flows to the rest of the body. The atria are separate and the ventricle is undivided but oxygenated and unoxygenated blood do not mix because of the fold in the conus arteriosus which keeps blood apart. Reptiles have a partially divided ventricle that prevent mixing entirely; of the reptiles, only crocodiles have a heart that is four chambered. In birds and mammals the heart is four chambered where the conus arteriosus has divided to form the base of the aorta and the pulmonary artery. The sinus venosus is no longer a separate chamber but is present as a vestige in the wall of the right atrium as the sinoatrial node. The systemic circuit is a higher pressure circuit to deliver blood more efficiently allowing endothermy and high metabolic rates.

Answer 82

Roots have a root cap and root hairs; stems do not. The root cap is a protective layer of cells at the root tip that protects the root apical meristem. The parenchyma cells of the cap are sloughed off and replaced by new cells formed by the root apical meristem. The root cap also orients the root so that it grows downward apparently by detecting the direction of gravity. Stems have no structure that resembles this root cap. Root hairs are extensions of a single epidermal cell located behind the growing root tip. They increase the surface area to allow more water absorption. Roots lack nodes and internodes and do not produce leaves or buds.

Answer 83

(A) Objective 2 and 4: Identify each of the structures of the human digestive system on a diagram or model; know their functions. Summarize the functions of the accessory digestive glands of humans and other terrestrial vertebrates. See figure 47-4 and know it. The mouth begins the food processing with incisors for biting, canines for tearing and premolars and molars for grinding; saliva is produced by three pairs of salivary glands to moisten and begin enzymatic digestion of starches. The pharynx and esophagus conduct food to the stomach; when a bolus is swallowed, the epiglottis covers the opening to the airway and peristalsis moves the bolus to the stomach. Food is mechanically and enzymatically digested in the stomach where parietal cells secrete HCl and "intrinsic factor" to absorb vitamin B; chief cells produce pepsinogen which gets changed to pepsin in the presence of the acid and is responsible for initiation of protein digestion. After partial digestion in the stomach the contents are called chyme which moves through the pyloric sphincter to the small intestine where most enzymatic digestion takes place. In the duodenum of the small intestine, bile from the liver and enzymes from the pancreas empty via ducts. The villi and microvilli of the small intestine absorb the digested food. The liver secretes bile where it is stored in the gall bladder and then used to emulsify fats; the liver also converts glucose to glycogen for storage, converts amino acids to fatty acids and urea, stores iron and fat-soluble vitamins, detoxifies alcohol and drugs. The pancreas secretes digestive enzymes: trypsin and chymotrypsin (proteases); lipases to degrade fats; amylase to degrade carbohydrates; ribonucleases and deoxyribonucleases to split RNA and DNA to free nucleotides. The chyme is digested mainly in the duodenum of the small intestine and then moves on to the jejunum where villi and microvilli absorb nutrients; then on to the ileum. From there, it enters the cecum of the large intestine where the appendix is located (on the right) on to the ascending transverse and descending colon to the sigmoid colon, rectum and anus. The large intestine functions mainly to remove water from the chyme. (A) Objective 3: Trace the pathway of an ingested meal in the human digestive system including the step-by-step digestion of carbohydrate, protein, and lipid. See above for details of the pathway: mouth to pharynx to esophagus to stomach to small intestine to large intestine to anus. Enzymatic digestion of carbohydrates to monosaccharides begins with addition of amylase from saliva. Proteins are digested to amino acids by trypsin, chymotrypsin, pepsin, carboxypeptidase and dipeptidases from the pancreas. Fats are degraded to fatty acids and monoacylglycerols by pancreatic lipases after the fat is emulsified by the bile from the gall bladder. (B) figure 47-10(b) and know the parts. Villi and microvilli increase surface area greatly to absorb better. Each villus is composed of a single layer of columnar epithelial cells through which the digested nutrients diffuse or are actively transported; then, they are picked up by capillary or lymph vessels. Amino acids and glucose are transported to the liver first via the hepatic portal vein. Lipids combine with bile to form micelles in the intestine which are then absorbed by the epithelial cells lining the microvilli. The micelle releases the fat which gets processed by the smooth endoplasmic reticulum of the epithelial cells to form chylomicrons (little droplets of fat). These diffuse into the lacteal (a lymph vessel of the villus). The lymph vessels enter the blood stream directly. (C) Objective 6: Trace the fate of glucose, lipids, and amino acids after their absorption, and discuss their roles in the body. Excess monosaccharides are converted to glucose and then into glycogen by the liver; too much carbohydrate leads to glucose conversion into lipids. Lipids in the diet usually occur as triacylglycerols which get digested in the liver via β-oxidation into acetyl coenzyme A (a part of the Krebs cycle or citric acid cycle). These are then transported to cells as ketones. Proteins are degraded to amino acids which are then used for human nutrition by rearranging the amino acids into enzymes needed for metabolism. Excess amino acids are deaminated by liver cells producing ammonia and urea as a by-product and energy. (B) Vitamins are organic compounds essential for normal metabolism; they are usually needed in small amounts as coenzymes to make metabolic processes work more efficiently. Water-soluble vitamins include the B and C vitamins. Fat-soluble vitamins include A, D, E, and K. Be familiar with Table 45-4. Minerals are inorganic nutrients required by cells. Na, Cl, K, Ca, P, Mg and S are needed in amounts of 100 mg/d. Fe, Cu, I, F, and Se are trace elements required in lower amounts. (C) Objective 8: Contrast basal metabolic rate (BMR) with total metabolic rate; write the basic energy equation for maintaining body weight, and describe the consequences of altering it in either direction. Metabolism is balanced when energy input equals output. The BMR is the rate of energy required during resting and post-digestive conditions. Thus the total metabolic rate equals the BMR plus the energy needed for other activities. Allow more energy input than is needed for total metabolic rate and one gains weight. Allow less energy input than is needed for total metabolic rate and one loses weight. Objective 5: Draw and label a diagram of an intestinal villus; explain how its structure is adapted to its function. See Objective 7: Discuss the roles of vitamins and minerals, and distinguish between water-soluble and fat-soluble vitamins. Objective 9: In general terms, describe the problem of world food supply relative to world population, and describe the (B) effects of malnutrition. Malnutrition results primarily from a lack of adequate essential amino acids to result in kwashiorkor. The problem is not the lack of food but the unequal distribution of food. While 250 million Americans are spending millions of dollars each year to lose their inebriation of fat from overindulgence in food, billions of Africans and South Americans and Asians die from malnutrition. If we would each fast one day a week and give the money we saved (about $5) to a relief agency like Red Cross or any number of church sponsored relief agencies, the problem would be solved. (C) Objective 10: Summarize the challenges encountered in obtaining adequate amounts of amino acids in a vegetarian diet and how a nutritionally balanced vegetarian diet could be planned. Most grains and vegetables do not supply all the amino acids essential for growth and metabolism. The solution is to mix grains and legumes (e.g. rice and beans) not just to eat them at different times. In addition, one must provide plenty of leafy vegetables and fruits for vitamins and minerals. Finally, if one is ovolacto (with eggs or dairy products) then it is much easier to be a vegetarian. The advantage of a vegetarian diet is that it is less costly economically and ecologically than eating meat to get all of ones amino acids. (A) Objective 1: Relate the principal functions of excretory systems to specific osmoregulatory challenges posed by various environments. Excretory systems help maintain homeostasis. Body fluids (e.g. serum) are collected by excretory systems; selective excretion of wastes (e.g. urea) from metabolism is accomplished without getting rid of critical non-waste materials within the body fluid. In marine environments that are stable, simple organisms simply pass wastes by diffusion and lack specialized structures. In estuaries and freshwater environments, the organisms must get rid of wastes and excess water. Terrestrial organisms must conserve water. (B) Objective 2: Contrast the advantages and disadvantages of excreting ammonia, uric acid, or urea. The principal metabolic wastes are water, carbon dioxide, and nitrogenous wastes such as ammonia, uric acid, and urea. Ammonia is the result of de-amination of amino acids as an organism gets energy from protein. It is very toxic and must be excreted rapidly unless it can be converted to uric acid or urea. Uric acid forms crystals, is relatively non-toxic and is excreted in a relatively dehydrated form. For egg-laying animals, this is important since development within an egg allows for no excretion. Urea is excreted by amphibians and mammals and is made in the liver; it is highly soluble and requires a high amount of water for storage and excretion. (B) Objective 3: Compare nephridial organs and Malpighian tubules as osmoregulatory organs. Nephridial organs (protonephridia and metanephridia) are specialized for regulation and excretion. Flatworms, rotifers, lancelets and nemerteans have protonephridia with closed ciliated flame cells that bring fluid in from the body cavity and then passes through a system of tubules and excretory ducts to leave the body through excretory pores. Annelids and mollusks have metanephridia which are open at both ends and have cilia; metanephridia are highly vascularized (lots of capillaries surrounding the tubule) in order to reabsorb water, and glucose; they process coelomic fluid and produce a concentrated waste product. Malpighian tubules are found in insects and spiders and are blind tubes which process hemolymph and dump uric acid into the intestine which reabsorbs water and salts. (B) Objective 4: Relate the function of the vertebrate kidney to the success of vertebrates in a wide variety of habitats. Most vertebrates live in environments where osmoregulation is critical. Many organisms living in the ocean not only must get rid of wastes but they need to excrete excess salt and sequester water if they ingest seawater or prey with high salt content. Organisms living in freshwater need to excrete excess water and bring salts in. Land animals must conserve water while getting rid of the wastes of metabolism. The kidneys (which all these vertebrates have) have allowed a wide adaptation to a variety of habitats. In an odd sort of way, it’s the kidneys that have allowed vertebrates to adapt to so many niches. (A) Objective 5: Compare the adaptations that freshwater fishes have evolved to solve their challenges of osmoregulation with those of marine bony fishes, sharks and marine mammals. Freshwater fishes must get rid of excess water. Since their body fluids are more concentrated than their surroundings (they are hypertonic), they must bring in salts from the surrounding water. They do this with gills that transport salt in and they excrete very dilute (watery) urine. Freshwater amphibians have cells in the skin that transport in salts. Marine bony fishes are hypotonic compared to their surroundings. They have cells in their gills which excrete salts and they have very few glomeruli in their kidneys so that they excrete a very concentrated urine thus conserving water within their bodies. Sharks, however, deal with the ocean differently; they concentrate urea in their bodies and are thus hypertonic to the ocean; they have well developed kidneys to secrete a dilute urine since water actually flows into the shark; they also secrete salt through a specialized rectal gland. Marine mammals must produce a very concentrated urine to get rid of all the salt they ingest from the seawater they swallow as they eat their food; the high protein diet of these animals (whales, seals, etc) demands that they get rid of urea as well. (A) Objective 6: Label on a diagram the organs of the mammalian urinary system, and give the functions of each. Know figure 48-7 and 48-8. The kidney, urinary bladder and their ducts (ureters leading from kidney to bladder and urethra leading from bladder to exit) and the adrenal glands are all part of the urinary system. TOsmoregulation, Wastes Chap. 48 he kidney is composed of an outer cortex and an inner medulla. The medulla is composed of 8-10 "pyramids" of renal papilla where the collecting ducts empty. These then go into the ureters which goes into the bladder. (B) Objective 7: Identify on a diagram the principal parts of a nephron (including associated blood vessels), and give the functions of each structure. Know figure 48-9 and figure 48-10. The nephron is the functional unit of the kidney; a single kidney contains several million nephrons. Bowman's capsule collects fluid (serum) from the glomerulus (a conglomeration of afferent arterioles). The fluid collected from Bowman's capsule then goes through the renal tubule which consists of the proximal convoluted tubule, loop of Henle, and the distal convoluted tubule which then goes into the collecting duct of the kidney now as urine. All along this renal tubule, water is reabsorbed into the capillaries while the wastes remain within the tubule. The blood that went into the glomerulus (that was surrounded by Bowman's capsule) flows out into the efferent arterioles that branch into a second set of capillaries called the peritubular capillaries which surround the renal tubules and reabsorb non-waste materials to return them to the venous circulation ultimately merging in the renal vein. (B) Objective 8: Trace a drop of filtrate from Bowman's capsule to its release from the body as urine. Small molecules are forced out of the glomerular capillaries (which are fenestrated - have small pores) into the lumen of Bowman's capsule which also has cells that are permeable (called podocytes and are separated from each other with slit pores). The glomerular capillary walls and podocytes make up the filtration membrane which is impassable to cells in the blood and most proteins. Up to 4.5x the amount of fluid in the entire body is filtered and mostly reabsorbed. The reabsorption process is highly selective with 99% of the filtrate being reabsorbed from the renal tubules. The proximal convoluted tubule is the most important in reabsorption. The cortical nephrons have small glomeruli and short loops of Henle and produce a relatively dilute urine. Juxtamedullary nephrons have large glomeruli and long loops of Henle and produce a concentrated urine. The descending loop of Henle has walls which are permeable to water but impermeable to sodium and urea thus allowing water to come out of the renal tubule and be reabsorbed by the capillaries (called vasa recta). The ascending loop has walls that are just the opposite in permeability and allow salt to come out but not water. Thus the interstitial fluid in the medulla becomes quite salty and pulls even more water out of the descending loop of Henle. The primary role of the loop of Henle, then, is to concentrate the urine even further. This process forms the urine (where the urea is concentrated) which goes to the collecting duct, etc as described in 7 above. (C) Objective 9: Describe the regulatory effects of ADH, aldosterone, and atrial natriuretic peptide (ANP). Urine volume is regulated by the hormone ADH (anti-diuretic hormone) which is produced by the posterior pituitary and targets the collecting ducts to make them more permeable to water resulting in concentrated urine. Secretion of ADH comes under the control of the hypothalamus which has receptors that are stimulated by osmotic changes in the blood; it also has a thirst receptor that causes increased fluid intake. Aldosterone controls sodium reabsorption. Aldosterone is produced by the adrenal cortex and stimulates the distal convoluted tubules and collecting ducts to increase sodium reabsorption. Endocrine Regulation Chap 49 (A) Objective 1: Define hormone and endocrine gland and identify sources of hormones other than endocrine glands. Hormones are chemical messengers responsible for the regulation of body processes. Endocrine glands produce hormones and secrete them into the surrounding tissue; there, they can get absorbed into the capillaries and transported by the blood to target tissues where the hormone has its effect. In addition, some hormones are produced by neuro-endocrine cells (part of the nervous system). There are four types of hormones: steroids synthesized from cholesterol (e.g. testos-terone, estradiol, and ecdysone); amino acid derivatives include amines (e.g. epinephrine and norepinephrine); protein (peptide)-type hormones are short chains (e.g. oxytocin, ADH, growth hormones, and TSH); and fatty acid derivatives likr prostaglandins. (C) Objective 2: Compare mechanisms of action of steroid and protein-type hormones; include the role of second messengers such as cyclic AMP. Some hormones bind to specific receptor proteins in target cells to affect the metabolism of the target cell (protein-type hormones). Some hormones enter the cell and activate genes (e.g. steroids) to produce specific enzymes; it is the enzymes, however, that actually cause the effect that the hormone stimulated. Cyclic AMP works as a second messenger. A primary hormone binds with receptors on the target cells to activate a membrane-bound enzyme such as adenylyl cyclase. The "G protein" is bound to GDP (guanosine diphosphate) when it is inactive. When the hormone binds to a stimulatory receptor it causes the G protein to release GDP and binds to GTP instead. When this happens, adenylyl cyclase is activated which then catalyzes the conversion of ATP to cAMP which activates protein kinase which catalyzes the phosphorylation of a specific protein which triggers a chain of reactions that causes the particular metabolic effect of the hormone. It’s a kind of Rube Goldberg device! (A) Objective 3: Summarize the roles of hormones in invertebrates. Invertebrate hormones regulate growth, development, metabolism, reproduction, molting, and pigmentation and are secreted by neurons (e.g. color changes in crustaceans). In some insects, temperature changes trigger neuroendocrine cells in the brain to release brain hormone (BH) which is transported down axons and stored in the corpora cardiaca; when released, BH stimulates the prothoracic glands to release molting hormone (MH). The MH triggers growth and molting. Endocrine glands also secrete juvenile hormone which suppresses metophorosis during larval growth to prevent the pupa from molting. When juvenile hormone is gone, the pupa can molt and progress on to an adult. (B) Objective 4: Identify the principal vertebrate endocrine glands, locate them in the body and list the hormones secreted by each. See figure 49-12 and table 49-1. (A) Objective 5: Summarize the regulation of endocrine glands by negative feedback mechanisms, and give specific examples. Vertebrate endocrine glands constantly secrete at least a small amount of hormone so that hormones are constantly circulating free or bound to plasma proteins and are constantly being removed from circulation by target tissues (e.g. liver and kidneys). Negative feedback regulates the secretion of most hormones (e.g. thyroid). A high concentration of hormone inhibits further secretion; the effect of a hormone is usually opposite the effects of the stimulus. (B) Objective 6: Justify the description of the hypothalamus as the link between nervous and endocrine systems, and describe the mechanisms by which the hypothalamus exerts its control. The hypothalamus integrates neural and endocrine regulation; it links the nervous and endocrine system. Neurons of the hypothalamus secrete neuro-hormones which target the release of hormones by the pituitary gland which then secretes at least 9 hormones that have a wide variety of target cells and effects on the body. The hypothalamus affects the pituitary gland. (C) Objective 7: Compare the functions of the posterior and anterior lobes of the pituitary; describe the actions of their hormones. The posterior lobe releases two hormones: oxytocin and ADH (peptide hormones). Oxytocin stimulates uterine contractions during labor; it also causes muscle cells in the breast to contract while nursing in order to result in the expulsion of milk (the "letting-down" reflex). The anterior lobes secrete tropic hormones (TSH, ACTH, FSH, and LH). TSH stimulates thyroid to produce thyroid hormones; ACTH stimulates the adrenal cortex to produce adrenal cortical hormones; FSH and LH stimulate gonad function. (C) Objective 8: Describe the actions of growth hormone on growth and metabolism, and contrast the consequences of hyposecretion and hypersecretion. Growth hormone (aka somatotropin) stimulates protein synthesis and thus growth as well as increasing fat and carbohydrate metabolism. Hyposecretion of GH causes dwarfism; hypersecretion causes gigantism or acromegaly. (B) Objective 9: Define the actions of the thyroid hormones, their regulation, and the thyroid disorder discussed in this chapter. Thyroid hormones increase metabolic rate. Thyroid is regulated by negative feedback. When thyroid drops, the pituitary produces TSH which stimulates the thyroid to produce thyroid hormones. Malfunction leads to goiter, sluggish metabolism, and even mental malfunction. Hypothyroidism leads to a condition known as cretinism (retarded physical growth) while hyperthyroidism leads to chronically feeling hungry or craving for something. (B) Objective 10: Contrast the actions of insulin and glucagon, and describe the disorders associated with the malfunction of the islets of the pancreas. Insulin lowers the concentration of glucose in the blood while glucagon raises the concentration of glucose in the blood. Malfunctions result in diabetes or hypoglycemia. (B) Objective 11: Describe the actions of the adrenal glands, including their role in helping the body adapt to stress. The adrenal glands are located above the kidney; they initiate an alarm reaction by secreting epinephrine and norepinephrine which control flight or fight reactions. is common among some animal groups and produces identical offspring from the parent with diversity coming only from mutations. Parthenogenesis can occur in some reptiles, insects, crustaceans and involves development from an unfertilized egg. Sexual reproduction is most common in most animals; it involves fusion of a sperm and an egg. External fertilization involves fusion of sperm and egg outside the body (aquatic organisms). Internal fertilization involves delivery of the sperm into the female body. Hermaphrodites can produce both sperm and egg within the same body. Reproduction Chap. 50 (not covered) (A) Objective 1: Compare asexual and sexual reproduction and compare external and internal fertilization. Asexual reproduction (A) Objective 2: Label the structures of the human male reproductive system on a diagram and describe their functions. See figures 50-3, 4, and 8 and read accompanying text. (B) Objective 3: Trace the passage of sperm cells through the human male reproductive system from their origin in the seminiferous tubules to their expulsion from the body in semen. Spermatogenesis occurs within the testis in the seminiferous tubules where spermatogonia (diploid) divide by mitosis to form more. These undergo meiosis to produce four haploid spermatids. The spermatids differentiate into a mature sperm by developing a flagellum, an enzyme cap (acrosome) and by decreasing their cytoplasm. Sperm leave the seminiferous tubules to go into the tubules of the epididymus where they mature and are stored. When they are ejaculated, they go from the epididymus into the vas deferens which leads to the ejaculatory duct that passes through the prostate gland to the urethra and out through the penis. Some of the accessory glands produce the fluid portion of the semen: seminal vescicles secrete a fluid rich in fructose (for energy) and prostaglandins (to neutralize the acids in the vagina). The bulbourethral glans produce a mucous secretion to lubricate the penis to facilitate penetration. (A) Objective 4: Describe the actions of testosterone and of the the gonadotropic hormones in the male. The hypothalamus secretes gonadotropin-releasing hormone which stimulates the anterior pituitary to secrete FSH and LH. FSH stimulates development of the seminiferous tubules; LH stimulates the interstitial cells to secrete testosterone. Inhibin (secreted by Sertoli cells) inhibits FSH production. Testosterone stimulates spermatogensis, growth, and development of the male primary and secondary sexual characteristics. (A) Objective 5: Label the structures of the human female reproductive system on a diagram and describe their functions. See figures 50-10, 11, 12 and 14 and read accompanying text. (B) Objective 6: Trace the development of an ovum and its passage through the female reproductive system until it is fertilized. Oogenesis occurs in the ovaries and begins with the development of the oogonia which become primary oocytes during prenatal development. Each primary oocyte and the cells surrounding it form a follicle. Each month, a primary oocyte completes its first meiotic development forming a first polar body and the secondary oocyte. The first polar body may go on to divide again to form two more polar bodies that ultimately disintegrate. Meanwhile, the secondary oocyte (which remains in meiosis stage II until fertilization) is ejected from the follicle during ovulation with the remaining follicular cells forming the corpus luteum. If a sperm cell penetrates the oocyte, the oocyte finishes meiosis to form one haploid ovum and a polar body prior to becoming diploid with the addition of the sperm cell’s chromosomes. The ovum, once fertilized, becomes a zygote that implants into the uterine wall to become an embryo. (B) Objective 7: Identify the important events of the menstrual cycle, such as ovulation and menstruation; explain the actions of each of the hormones involved; describe the hormonal regulation of the menstrual cycle. Gonadotropin-releasing hormone stimulates the anterior pituitary to release FSH and LH. FSH stimulates the development of a new follicle in the ovary. The follicle secretes estrogen that stimulates the development of the endometrium and stimulate production of LH. After ovulation, LH stimulates development of the corpus luteum which produces progesterone and some estrogens. If fertilization does not occur, the corpus luteum disentegrates and stops the production of hormones which brings on menstruation. If fertilization does occur and implantation happens, then human chorionic gonadotropin signals pregnancy. (A) Objective 8: Summarize the process of human fertilization. Fertilization is the result of the fusion of egg and sperm to produce a zygote. Fertilization can be the result of sexual response in which both males and females respond to sexual desire, excitement, orgasm, and resolution. Although orgasm is not necessary for a fertilization to take place for a woman it is required for a male since ejaculation usually accompanies a male's orgasm. (C) Objective 9: Compare the modes of action, effectiveness, advantages and disadvantages of birth control methods in table 48-3. See table 48-3! (C) Objective 10: Identify common sexually transmitted diseases, and describe their symptoms, effects, and treatments. See table 48-5! Development Chap 51 (not covered) (A) Objective 1: Summarize the roles of cell division, cell growth, morphogenesis, and cell differentiation in the development of an animal. The single-celled zygote undergoes division and then begins to divide over and again to produce an increase in cell numbers (division) and in cell size (growth). Morphogenesis is the process by which cells organize themselves by cell migrations to shape the animal into the intricate pattern of tissues and organs. But they must also become specialized by cell differentiation by biochemically and structurally becoming different to perform specific tasks for the development of the whole animal. (B) diploid number of chromosomes when the sperm and ovum come together. The first step in fertilization is contact and recognition where calcium release allows the acrosome to release proteolytic enzymes that digest a path through the jelly coat; bindin causes the acrosome of the sperm to adhere to the vitelline membrane of the egg in a species specific fashion. As the sperm enters the egg, an electrical change in the egg plasma membrane occurs to prevent additional sperm from entering; the slow block to polyspermy (cortical reaction) involves depolarization of the egg plasma membrane due to calcium release which also is involved in depolarization that causes a chemical change in the vitelline membrane to form a block (fast block to polyspermy). Then the egg and sperm nuclei fuse due to microtubules propelling the sperm nucleus toward the egg nucleus. Finally the egg is activated and development begins: protein synthesis is triggered and cytoplasm separates into specific areas for the further development of the embryo. (A) Objective 3: Trace the early development of the embryo from zygote through cleavage; formation of the morula, blastula, and gastrula; and early organ development. As the zygote divides, the ovum contributes the majority of the zygote cytoplasm despite both sperm and egg contributing the same number of chromosomes. Cleavage is a series of rapid mitotic divisions without cell growth until it reaches a 32 cell ball of cells called a morula. Divisions continue to form the hollow blastula with cavity called the blastocyst or blastocoel. Cells continue moving and migrating around by ameboid motion to form the gastrula from which the three germ layers are derived. (A) Objective 4 & 5: Contrast early development, including cleavage and gastrulation, in the sea star (or in amphioxus), the amphibian, and the bird. Summarize the fate of each of the germ layers. Isolethical eggs typically have a uniform yolk distribution and is typical of invertebrates and simple chordates; cleavage can be radial (deuterostomes) or spiral (protostomes). Telolethical eggs have their yolk concentrated at the vegetal pole (most vertebrates); in birds and some reptiles, the blastodisc splits into the epiblast and hypoblast separated by the blastocoel. The gastrula is a three-layered embryo including endoderm, mesoderm, and ectoderm each with a specific fate. The archenteron is endoderm that develops into the digestive tract and its accessory organs. The outer layer of the gastrula makes up the ectoderm which forms the epidermis, nervous system, and sense organs. The mesoderm develops between ectoderm and endoderm to give rise to skeletal, muscular, circulatory, excretory, and reproductive tissues. (B) development of the nervous system and is the first organ system to develop in vertebrates. The notochord grows and induces the overlying ectoderm to form a neural plate which folds in to form the neural groove and the surrounding neural folds which fuse to form a hollow neural tube where the anterior portion forms the brain and the rest forms the spinal cord. The neural crest forms on either side of the point of fusion and cells migrate to form the dorsal root ganglia, the postganglionic sympathetic neurons, many sense organs and all pigment forming cells. The trachea grows from the gut and the lungs develop from it. The pharyngeal pouches grow laterally from the pharynx. The branchial grooves meet the pharyngeal pouches and form the gill slits and gills in aquatic vertebrates. The heart/circulatory organs form from mesoderm. (B) membrane. Extraembryonic membranes protect and nourish the embryo. Terrestrial vertebrates have four extraembryonic membranes that develop from the germ layers but are not really part of the embryo since they are lost at birth. The chorion and amnion enclose the embryo where the amniotic cavity fills with fluid to cushion the embryo. The allantois is an outgrowth of the gut and stores or eliminates nitrogenous wastes in birds and reptiles. In humans, it contributes to the formaiton of the umbilical vessels. The yolk sac encloses the yolk in vertebrates and, in humans, helps in formation of red blood cells. (C) Objective 8: Describe the general course of human development from fertilization to birth. Gestation is 266 (38 weeks) days from conception. Development begins in the oviduct about 24 h after fertilization when the zygote divides to form a 2-celled embryo. As it enters the uterus after about 5 days it has just lost its zona pellucida and continues to float free for a few more days as a blastocyst. When it finally implants into the uterine wall, its trophoblast forms the chorion and amnion which later form the placenta and amniotic sac. The actual embryo begins to form on the 7th day of development from conception and only if it implants into the uterine wall. Organ development does not begin in the embryo until the 2nd or 3rd week when the nervous system begins to form and the heart begins to beat after 3.5 weeks. Only after 2 months of development does the embryo become a fetus when it is fully recognized as human and the sexes can be differentiated. During the 2nd and 3rd trimesters, the fetus moves freely and the heart can be heard with a stethoscope. If born at 24 weeks (168 days), the fetus has a 50% chance of survival. If born after 37 weeks it is premature; it has a good chance of surviving if born after 30 weeks. During initiation of parturition, the uterus becomes responsive to oxytocin and contracts; the cervix dilates and flattens and the amniotic sac ruptures. The second stage includes delivery of the fetus by a combination of contractions of uterine and abdominal muscles. The third stage includes expulsion of the placenta and fetal membranes. Objective 2: Summarize the functions of fertilization, and describe the four processes involved. Fertilization restores the Objective 6: Define organogenesis, and trace the early development of the nervous system. Organogenesis begins with the Objective 7: Trace the development of the extraembryonic membranes and placenta, giving the functions of each (C) Objective 9, 10, 11: Contrast postnatal with prenatal life, describing several adaptations that the neonate must make in order to live independently. List steps a pregnant woman can take to promote the well-being of her developing child. Identify the stages of the human life cycle; describe the anatomical and physiological changes that occur with aging, and discuss current hypotheses of aging. The neonate must adapt to its new environment, for example, by the initial breathing response due to the accumulation of carbon dioxide. Prenatal development is severely affected by anything circulating in the maternal blood (see table 49-3) demanding that a woman abstain from many drugs and foods for the health of the child. The human life cycle extends from fertilization to death with aging resulting in decreased functions of the organ systems: hormonal changes, autoimmune responses, accumulation of wastes in the cells, changes of molecular structure of critical macromolecules, even exposure to cosmic radiation and x-radiation have been hypothesized for the fact that despite all our advances in medicine, little significant changes in the average age of humans has been seen. Genetic predisposition for a long life is the best explanation: choose your parents wisely for a long life! Animal Behavior Chap. 52 "Do you know when the time is right for the mountain goats and deer to give birth? . . . Is it through your wisdom that the hawk flies? . . . Are you the one that commands the eagle to fly and build his nest so high?" God speaking to Job in Job 39. experience. Just because a behavior is innate, however, does not mean it is desirable in a social context. We are told to overcome our natural desires (Rom. 6:19; Rom 8:9-13 & Rom 13:14; Gal 5:16-19 & 24 Gal 6:8; Eph 2:3; Col 3:5; Jude 1:19) and be self-sacrificial in our Christian walk "considering others better than ourselves." (Phil. 2:3). Clearly, God asks us to reject our natural animal heritage of selfish behaviors to serve Him. No longer is the excuse "God made me this way" acceptable! Understanding animal behavior allows one to understand God's creative mind. (A) Objective 1: Explain why behavior is adaptive, homeostatic, and flexible. Behavioral capacity is inherited and is modified by the environment. Behaviors that permit adaptation to the environment and survival are passed on to their offspring; such behaviors also tend to be homeostatic for the individual as well. Behaviors, even some instinctual ones, can be modified by training and learning and therefore need to be considered flexible. Studies continue to support that much of even human behavior is genetically pre-determined or innate as well as much being learned by (A) Objective 2: Cite examples of biological rhythms and the mechanisms responsible for them. Biological rhythms occur oriented around environmental events such as tides, solar cycles and annual patterns. The animal behaviors actually anticipate these environmental changes (e.g. crabs returning to their burrows before high tide); they even occur in the absence of environmental cues that we might think could be training cues. How the crabs "know" that high tide is coming is encoded in the "wisdom" of the years of adaptation to that environment: DNA. This encoding causes the pineal gland and hypothalamus to secrete hormones that stimulate these behaviors in vertebrates. Other biological rhythms include circadian (daily) rhythms, diurnal, nocturnal, and crepuscular rhythms, and lunar. (B) Objective 3: Summarize the contributions of heredity, environment, and maturation to behavior. The capacity for certain behaviors is inherited but it also is modified by environmental factors depending on the nervous system and endocrine system development of the animal. The behaviors are also modified by learning: birds are born with the rudimentary genetic pattern of their specific mating songs but learn the details from their parents. Some behaviors are entirely innate (instinctual) just as some are entirely learned. One of the funniest innate behaviors (fixed action patterns) to watch is geese retrieving "eggs" that are placed outside of their nest (sign stimuli). One mother goose who had a nest on a golf course was frantic in trying to keep her "eggs" within the nest as the golfers tried making putts on the green where she had her brood. The golf balls resembled the eggs sufficiently to keep her frantically busy! (B) Objective 4: Classify a learned behavior as an example of classical conditioning, operant conditioning, habituation, or insight learning. Entirely learned behaviors are those influenced by experience alone. One way of learning is by classical conditioning where a reflex becomes associated with a new stimulus (Pavlov's dogs). In operant conditioning, spontaneous behavior is reinforced. Reinforcement may be positive (a behavior is rewarded with a stimulus if performed) or negative (a stimulus is removed if a behavior is performed). Habituation allows an animal to ignore irrelevant stimuli (animals not bothered by the presence of humans). Insight learning involves recalling past learning experiences to solve new problems (primates are particularly good at this). (B) Objective 5: Discuss adaptive significance of: imprinting, migration, optimal foraging behavior. Imprinting is learning that occurs during a critical period such as a chick recognizing its mother shortly after hatching so that the chick can survive. Migration is triggered by day length and may rely on celestial, magnetic, or olfactory clues. Migration allows for survival of harsh winters and cuts down on competition in a single area. Optimal foraging behavior is a set of hypotheses that describe how animals optimize time and reward in seeking food. (A) Objective 6: Give a description of an animal society and identify the adaptive advantages of cooperative behavior. Define kin selection (inclusive fitness) and its role in the maintenance of insect and other animal societies. Compare society of a social insect with human society. Social behavior involves interaction between members of the same species to enable the population to survive if its individuals cooperate with each other. Examples include bee and ant colonies, wolf packs, and others. Kin selection can promote altruistic behavior (selfless behavior). Siblings from the same set of parents each have the same set of genes (1/2 from each of the parents) equally shared by each brother or sister. Therefore, if one of the siblings has a child, he is just as related genetically to his own child (1/4 the genes of mom and dad) as he is to his nephew (also 1/4 the genes of mom and dad). One sees this behavior in wolf packs where only an alpha male and female are allowed to breed and the children help rear their parent's offspring since an "identical" set of genes are passed on by a related individual. The classic example of altruistic behavior is seen in bee colonies where the drones are haploid (they develop from unfertilized queen eggs). The female workers develop from the queen's eggs which are fertilized by a select drone and are diploid. Thus the workers are virtually identical to each other. If the female workers were to reproduce by mating with other drones, they would be less related to their own offspring than they are related to each other! Thus, the workers defer reproduction to care for the offspring of the queen. Humans often display altruistic behaviors for their comrades or friends that goes beyond kin selection because cultural elements can often overcome natural tendencies. This is especially well developed (or at least should be) in Christianity where Jesus gives us the ultimate example of how to be altruistic to our "brethren." (B) Objective 7: Summarize modes of communication that animals use. Communication is needed for social behavior and results in the modification of behavior by another organism. Communication between animals can be by sound, scent, electrical signals (in fish), pheromones (in insects mainly), dances (bees). (A) Objectives 8: Discuss adaptive significance of dominance hierarchy, territoriality, home range, courtship behavior, and pair bonds. Dominance hierarchies reduce aggressive behavior. Territoriality is a section of the home range that is defended and tends to reduce aggressive conflicts. Courtship behaviors allow for mate selection based on those behaviors rather than aggression. Pair bonds exist between mates to ensure reproductive success. Pair bonds are most common in bird species (90%) but very few other examples exist. Humans are the only primates that pair bond . . . or at least serially pair bond.

Answer 84

Unoxygenated blood is pumped to the lungs via the pulmonary trunk from the right ventricle. The respiratory gases diffuse into capillaries in the alveoli of the lungs. The pulmonary veins carry blood back to the left atria carrying oxygenated blood. The oxygenated blood from the left atrium goes to the left ventricle and then to the tissues via the aorta and other arteries (carotids supply the brain; subclavian supplies the upper appendages; mesenteric arteries supply the intestines; renal arteries supply the kidneys; the iliac arteries supply the lower appendages). After going through the tissues and being de-oxygenated, it returns via the veins to the right side of the heart (the jugular veins return blood from the brain; subclavian veins return blood from the arms; renal veins return blood from the kidneys; iliac veins return blood from the legs; hepatic veins return from the liver). The first two veins empty into the superior vena cava while the last three empty into the inferior vena cava. From the vena cava, the blood flows into the right atria to the right ventricle and the process starts over.

Final Flashcards

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