BIOD102/ BIOD 102 Essential Biology II Module 3 V2 (Portage) | Latest Updated Q&A 2026/ 2027 | Verified Answers | Grade A+

BIOD102/ BIOD 102 Essential Biology II Module 3 V2 (Portage) | Latest Updated Q&A 2026/ 2027 | Verified Answers | Grade A+ Q: Nearly all animals rely on three main classes of molecules as sources of energy and building blocks for growth and development. These classes are: Answer proteins, fats, and carbohydrates. Q: An essential amino acid is defined as one that: Answer cannot be synthesized by an organism's cellular biochemical pathways. Q: The process of digestion begins in the: Answer mouth Q: Salivary amylase starts the chemical digestion of: Answer carbohydrates in the mouth. Q: Peristalsis is: Answer the waves of muscular contractions that move food through the digestive system. Q: In the digestive system, most of the water and inorganic ions are absorbed by the: Answer large intestine. Q: Which of the structures greatly increase the surface area for nutrient absorption in the small intestines? Answer villi and microvilli Q: Most animals rely on _____, in which food is isolated and broken down in a body compartment rather than inside individual cells. Answer extracellular digestion Q: Most nutrient absorption takes place in the Answer small intestine. Q: When animals excrete nitrogenous waste, what form does it take? Answer uric acid, urea, ammonia Q: Which process is responsible for creating most of an animal's nitrogenous waste? Answer protein breakdown during metabolism Q: The outer layer of the mammalian kidney is the _____, and the inner layer is the _____. Answer cortex; medulla Q: Which of the structures is responsible for holding urine until it is excreted from the body? Answer bladder Q: The membranous sac enclosing the glomerulus of a mammalian kidney is called: Answer Bowman's capsule. Q: Osmoregulators _____ internal solute concentrations compared to their external environment. Answer have different Q: Which of these processes occur within Bowman's capsule? Answer filtration Q: The basic unit of the kidney, the nephron, contains: Answer the glomerulus, the collecting duct, renal tubules. Q: Osmosis describes: Answer the movement of water from an area of lower solute concentration to an area of higher solute concentration across a selectively permeable membrane. Q: In which of the structures are oocytes produced? Answer ovaries Q: The fluid-filled ball of cells produced at the end of cleavage is called the: Answer blastula Q: A fertilized egg is called a(n): Answer zygote Q: Male gametes (sperm) develop inside the: Answer seminiferous tubules Q: Which hormone(s) do ovaries secrete? Answer estrogen and progesterone Q: In humans, fertilization usually occurs in the: Answer fallopian tubes. Q: A ____ is a haploid reproductive cell capable of developing into a new individual without fusion Answer Spore Q: _____ is the division of the nucleus and DNA that results in 4 genetically different haploid cells Answer Meiosis Q: ______ sporophyte produces haploid spores via meiosis. Answer Diploid Q: Define alternation of generations Answer A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae. Sporophyte and gametophyte are both present is the life cycle of plants. Q: Which generation is dominant in mosses(bryophytes)? Answer gametophyte Kingdom Plantae are included in Supergroup _______ . Answer Archaeplastida Which groups are derived from an endosymbiotic relationship between a heterotrophic protist and a cyanobacterium? Answer Archaeplastida (Red algae, green algae, and terrestrial plants) What key characteristic determines the depth at which each phylum of seaweed can be found? Answer different pigment. Different pigments absorb different wavelengths of light. Different wavelengths can extend to different depths. Name 3 characteristics shared by red algae, green algae, and plants. Answer Wavelength reflect, photosynthesis happens, and they all have chlorophyll.Chloroplasts, photosynthetic, plastids, cell walls, multicellular, common ancestor, chlorophyll a Chlorophyta and Charophyta are non-_______ and therefore cannot live out of the water. Answer non- vascular ______ are cells that must fuse while _______ are cells that do not fuse. Both are haploid cells that develop into multi celled individuals. Answer Gamete, spore Diploid _____ produces haploid _____ via meiosis. Answer sporophyte, spores Plants reproduce via a system known as ______ __ _______ . Answer alteration of generations A _____ consists of a miniature embryonic plant and stored food for its early development after germination. Answer seed What are advantages gained when plants moved from an aquatic existence to a terrestrial life? Answer sunlight is abundant, more wavelengths available, more carbon dioxide ght is abundant more wavelengths available (water acts as a filter) carbon dioxide is more readily available in air than in water, because it diffuses faster in air no predators _______ are non-vascular dioicous plants that are found in damp environments and reproduce via spores rather than flowers or seeds. The gametophyte is dominant stage with the developing within the archegonia. They include mosses, hornworts, and liverworts. Bryophyta ______ are also dioicous, meaning they have haploid gametophytes with separate sexes. Liverworts/bryophytes The word ______ is from old English actually means root, herb, or plant. Wort The female _______ produces an egg while the male plants _____ produces sperm. Archegonia, antheridia The green leafy portion of this plant is the haploid ____ and the brown flower-like structure is the diploid ______ . Gametophyte, sporophyte Although lycophytes and ferns may look similar, lycophytes have leaves known as _______ while ferns have leaves known as ________ . microphylsl, megaphylls Veins within leaves are actually _______ bundles. vascular tissue Flowers are actually modified ______ . leaves What are key characteristics of pterophytes? vascular,found in damp environments, true roots, complex leaves, etc..reproduce via spores rather than flowers or seeds, sporophyte is dominant stage What is this structure? Does it produce gametes or spores? Is it haploid or diploid? Fern Gametophyte, gametes, Haploid Explain golden brown dots you may find on the undersides of some fern fronds. They are the reproductive spores of the fern.They are sori where diploid sporangia are located. What does the name gymnosperm mean? naked seed What we generally refer to as a pine cone is actually a ______ . female cone How large are the haploid gametophytes in gymnosperms and angiosperms? microscopic Name a gymnosperm that is a 'living dinosaur'. Ginko biloba What does the names 'angiosperm' mean? Seeds that are in a vessel Where are the microscopic male gametophytes found in angiosperms? Pollen Grains What are the 3 parts of the carpel? stigma, style, ovary What is the reproductive process that is unique to flowering plants? Double Fertilization ________ is the 3n cell in the ovary that develops as a food source for embryonic plants. The name means 'within the seed.' Endosperm Within the ovary of flowering plants, a single diploid sporophyte divides by mitosis 3 times giving rise to how many haploid nuclei? 8 Which haploid cell within the ovary will be fertilized by a haploid sperm to give rise to a diploid zygote? Egg cell Which cell within the ovary will be fertilized by a haploid sperm to give rise to endosperm? Central Cell What is the purpose of the pollen tube? To fertilize the egg. Helps carries the male gametes for double fertilization. How many haploid nuclei are in a pollen grain? 3 ( The tube nucleus and two sperm nuclei.) Neurons communicating cells of the nervous system Sensory neurons neurons that receive information from the external and internal environment and transmit the information to the brain Interneurons Connecting neurons that integrate information so a response can occur; usually part of a circuit; typically affect communication between neurons located in the same region of the nervous system Motor neurons neurons that send outgoing messages from the brain to muscle fibers to elicit a desired response. Cell body of neuron contains nucleus and organelles Dendrite branched extension extending out of a neuron. Axon hillock cone shaped area of cell body that meets the axon; where signals (action potentials) are generated. Axon Single extension that serves as the highway for the transport of action potentials; where the signal travels along Synaptic terminals Ends of axons that form one side of the synaptic cleft; forms junction with the next neuron/target cell; location where neurotransmitters are stored. What is responsible for collectively receiving signals from other cells? dendrites and cell body Where are signals (action potentials) generated? axon hillock Polarization the state of having a difference in the charge/voltage across the membrane; overall charge inside the neuron (negative) is different from the outside of the neuron (positive) Potentials Changes in the membrane's voltage Resting membrane potentials Membrane voltage inside the neuron when the neuron is not actively firing (-70 mV), outside of neuron is positive charge Action potential a neural impulse; how information is transmitted along the neuron; a brief electrical charge that travels down an axon Gated ion channels ion channels that open or close in response to stimuli; typically closed to prevent flow of ions out of the cell. 2 types of gated ion channels Voltage-gated ion channels, Ligand-gated ion channels Changes in the membrane potential are necessary to initiate and propagate an action potential (t/f) True Are there more K+ (potassium) ions outside of the neuron or inside the neuron? Inside- if the potassium channels open, the K+ ions within the cell will flow out of the neuron and down the potassium's gradient as there are less K+ ions outside of the neuron than there are inside Hyperpolarization The movement of the membrane potential of a cell away from rest potential in a more negative direction (-90 mV) when positive potassium ions leave the cell or negative ions flow into the cell through voltage gated ion channels. Depolarization The movement of the membrane potential of a cell away from resting potential in a more positive direction when positive ions flow into the cell or negative ions flow out. If depolarization is large enough, it will initiate the generation of an action potential (t/f) True How does depolarization occur in a neuron? Voltage-gated sodium channels open and positively charged sodium ions flow into the cell, pushing the cell's membrane to +62 mV Graded potentials small changes in membrane potential that by themselves are insufficient to trigger an action potential; positive (depolarization) or negative (hyperpolrization) Graded potentials are proportional to the magnitude of the stimulus (t/f) True- the larger the stimulus the greater change in membrane potential Threshold of a neuron the level of stimulation required to cause opening of voltage-gated sodium channels to trigger a neural impulse (-55 mV) What are the 5 phases of an action potential? 1. Resting phase 2. Depolarization 3. Rising phase 4. Falling phase 5. Undershoot excitatory postsynaptic potential (EPSP) Depolarization of the post-synaptic membrane in a positive direction closer to threshold value; typically caused by sodium ions Inhibitory post-synaptic potential (IPSP) hyperpolarization of the post-synaptic membrane in the negative direction away from the threshold caused by an influx of negatively charged ions. Post-synaptic cells receive EPSP and IPSP messages from one pre-synaptic cell at a time (t/f) False. Post-synaptic cells receive EPSP and IPSP messages from DOZENS TO HUNDREDS of pre-synaptic cells at one time. Summation Combined effect coffee 2 or more EPSPs or IPSPs to cause a depolarization or hyperpolarization at the axon hillock of the post-synaptic cell. What are the two ways to clear neurotransmitters from synaptic cleft after the desired response has been generated in the post-synaptic cell? Inactivating enzymes and reuptake Inactivating enzymes Enzymes present in the SYNAPTIC CLEF that degrade the neurotransmitter so it can't act on post-synaptic neuron after the desired response. Reuptake The process by which neurotransmitter transport channels in the pre-synaptic cell recapture and endocytose the excess neurotransmitters from the synaptic cleft so they can't act on the post synaptic cell after the desired response. Acetylcholinesterase An enzyme that breaks down the neurotransmitter acetylcholine. 3 types of muscle cells skeletal, cardiac, smooth smooth muscle Involuntary muscle found within blood vessels and organs cardiac muscle Involuntary and striated muscle exclusive to the heart. skeletal muscle Voluntary and striated muscle that has the main role of contracting and relaxing to move bones. Each muscle is composed of a bundle of individual ____ Muscle fibers muscle fiber Muscle cell that contains numerous mitochondria, multiple nuclei, microtubules, endoplasmic reticulum, intermediate filaments, and microfilaments Myofibrils Longitudinal proteins that make up muscle fibers and consist of bundles of thin and thick filaments. What do thin filaments in myofibrils consist of? actin What do thick filaments in myofibrils consist of? Myosin Why do skeletal muscles appear striated? Presence of sarcomeres Sarcomere Smallest contractile unit of skeletal muscles; oriented in repeating patterns Z lines (sarcomere) Overlapping ends of sarcomeres that serve as the physical border of sarcomeres and attachment points for thin filaments; appear as dark vertical lines and are perpendicular to thin and thick filaments. M lines (sarcomere) Attachment site for thick filaments; Positioned vertically in each sarcomere sliding filament model states that actin and myosin slide past each other and overlap during muscle contraction leaving their size unchanged. As the muscle begins to contract, the distance between each Z line gradually decreases as the actin filaments slide toward one another. At full contraction, the actin filament regions seem to have disappeared completely because they have slid past one another and overlapped. aerobic respiration Respiration in which oxygen is consumed and glucose is broken down entirely; used when greater amounts of energy are needed such as repetitive contractions or endurance; allows for about 1 hour of intense work. anaerobic respiration Respiration in the absence of oxygen; generates ATP and produces lactic acid as byproduct; provides about 1 minute of sustained muscle contraction The use of ATP during muscle contraction is metabolically exhausting (t/f) True- there is only enough ATP for a few contractions rigor mortis Muscle stiffness and rigidity that occurs after death and persists for 72 hours. Why does rigor mortis occur? After death, cells are more permeable to calcium ions, which causes a contraction with the myosin heads binding to the actin filaments and forming the cross-bridge linkage. But without respiration and O2, ATP is not available to break the cross-bridges that have formed. Muscles then stay partially contracted until muscle tissue begins to decompose. What molecules are important for muscle contractions? ATP, tropomyosin, troponin complex, calcium tropomyosin a regulatory protein involved in muscle contraction. Two of these molecules surround actin filaments and are responsible for shielding the myosin-binding sites along the actin filament. What happens when calcium binds is released into the cytosol during a muscle contraction? the calcium ions bind to the troponin complex, causing a change in the tropomyosin strands exposing the myosin-binding site. Now the cross-linkage between the myosin head and the actin filaments can take place. A muscle contraction is a voluntary process controlled by the somatic nervous system (t/f) true What kind of neuron delivers a stimulus to the muscle fiber? motor neuron Motor unit A single motor neuron and all of the muscle fibers it innervates/controls. Each motor neuron branches to form a connection with one muscle fiber (t/f) False. Each motor neuron branches to form a connection with MANY muscle fibers. Transverse (T) tubules Tunnels that extend across the sarcoplasm and allow electrical impulses to travel deep into the cell Sarcoplasmic reticulum modified endoplasmic reticulum that overlays each muscle fiber, and store calcium ions. What specialized structures ensure rapid propagation of an action potential? Transverse tubules, sarcoplasmic reticulum Role of acetylcholine during skeletal muscle contraction An action potential is transmitted down the axon, reaches the terminal, depolarization of the plasma membrane causes release of ACh into the synaptic cleft. ACh diffuses across cleft, binds to LIGAND-GATE ION CHANNELS of post-synaptic cell (muscle cell), which triggers depolarization of muscle cell/sarcomere to contract. ACh has an EXCITATORY EFFECT. ACh at the neuromuscular junction is considered inhibitory (t/f) False. ACH at the neuromuscular junction is considered excitatory. Once a muscle fiber has depolarized, what enzyme removes ACh from the synaptic cleft? Acetylcholinesterase Sarin a lethal substance used in chemical warfare that blocks the activity of acetylcholinesterase at the synapse leaving ACH to continue rapid firing of the skeletal muscle leading to a sustained contraction. This prohibits victim from using muscles of the chest to breathe leading to suffocation. The failure to remove excess acetylcholine is deadly (t/f) True Twitch single stimulus-contraction-relaxation sequence in a muscle fiber Recruitment tension of a muscle is progressively increased during a contraction as motor units are sequentially recruited to increase the force of contraction. Ex. piling books into your hands. Summation (muscle contraction) A phenomenon that results when a second action potential arrives before the muscle fiber has time to relax, summing the force of two twitches and giving a greater tension to the muscle contraction. Tetanus prolonged contraction with no rest between stimuli and involves the maximum tension that a muscle can exert. Stimuli are applied so rapidly that the motor neuron cannot relax at all. Combined effects of DOZENS of rapidly firing action potential. Ex. the bicep muscle fully contracted and engaged to hold heavy books. Fatigue (muscles) condition where a muscle fiber cannot be stimulated to contract. Influenced by conditions of aerobic and anaerobic metabolism. Reflexes Autonomic responses to stimuli that do not involve conscious thought and result in an involuntary movement of skeletal muscles. Sensory input of reflex does travel to the brain as it does with voluntary input. Instead, the sensory input of a reflex only travels to the spinal cord where a response is coordinatedterm-76 and sent back to the muscle group making a reflex much faster than a voluntary movement. What is the knee-jerk reflex? A rapid, protective response that occurs when pressure is applied to sensory neurons. How does the knee-jerk reflex work? -A stimulus is applied to the tendon in the knee that is connected to the quadricep stimulated to contract and prevent it from harm, and (2.) the sensory neuron communicates with an interneuron that inhibits the hamstring muscle to keep it relaxed. The interneuron is excitatory (t/f) False. The interneuron is inhibitory. Atria two upper chambers of the heart that collect blood returning from the lungs and body tissue Ventricles two lower chambers of the heart that forcefully contract to send blood to the lungs for oxygenation and oxygenated blood to the body tissue. Characteristics of cardiac muscle striated, multi-nucleated, involuntary/autorhythmic Intercalcated disks special junctions that fuse together adjacent cardiac muscle cells to ensure coordination of electrical information between adjacent cells. Allows for coordinated contraction of the entire heart muscle, even if a stimulus is only applied to one area. Contraction f cardiac muscle does not require voluntary thought nor nervous system input (t/f) True - cardiac muscle is autorhythmic. What regulates depolarization of cardiac muscle cells? pacemaker cells of the sinoatrial node. Sinoatrial node pacemaker of the heart; sends electrical impulses through walls of both atria for coordinated contraction without stimulation from neurons; located in R atria Atrioventricular node autorhymthic cells that serve as a delay point to suspend the impulses to ensure blood can empty completely from the atria before the larger ventricles are stimulated to contract; located between L & R atria Bundle branches Conduction fibers that send impulses through apex and ventricles that resulting in strong. coordinated contraction of ventricles. What is an electrocardiogram used for? to measure the electrical impulses as they travel through cardiac muscle Flow of impulses through the heart 1. pacemaker cells of SA node initiate action potentials that spread through atria. 2. Signals are temporarily delayed at AV node. 3. Once the delay ends, the signals are sent to the apex of the heart. 4. Bundle branches and Purkinge fibers transmit signals to the ventricles resulting in coordinated contraction of ventricles Cardiac cycle physiological process of the heart contracting to pump blood and then relaxing to allow blood to flow into the hollow chambers Systole contraction phase of cardiac cycle Diastole relaxation phase of cardiac cycle Cardiac output amount of blood the heart pumps in each MINUTE. Healthy cardiac output = 5 L/min. Cardiac output - heart rate x stroke volume Heart rate number of times the heart beats/contracts per minute (60-100 bpm) Stroke volume amount of blood the heart ejects with each BEAT.; healthy = 70 mL/heart beat Aorta carries blood from the heart to the body Pulmonary arteries carries blood from heart to lungs Role of cardiac valves ensure blood flows in the correct direction of the heart from chamber to chamber Atrioventricular valves located between each atrium and ventricle and snap CLOSED as ventricles contract to prevent blood from flowing back into the atria Semilunar valves located at where pulmonary arteries and aorta meet R & L ventricles (guard exits of heart); pushed OPEN as the ventricles contract to send blood to the body, and then close so blood remaining in the aorta & pulmonary arteries don't flow back into ventricles after contraction. What is the "lub-dub" sound of the heart? Sound of heart as the four valves open and close Lub = blood hitting closed AV valves Dub = closure of aortic and pulmonary valves Acetylcholine at the synapse of cardiac cells ACh has an INHIBTORY effect. It binds to G-PROTEIN COUPLED RECEPTORS (instead of ligand-gated receptors of post-synaptic cells) signaling the transduction pathway. In this pathway, adenylyl cyclase is inhibited and potassium channels are opened, causing decrease in heart rate. Acetylcholine at the synapse of cardiac cells has an inhibitory effect (t/f) True. ACh at cardiac cells = inhibitory ACh at neuromuscular junctions = excitatory Arteries Arterioles small vessels that receive blood from the arteries and carry blood to capillary beds Capillary beds smallest vessels (diameter wide enough for single file line of RBCs) where gas exchange occurs, sending deoxygenated blood to venules Venules small vessels that gather deoxygenated blood from the capillaries and send blood into the veins. Veins carry deoxygenated blood to the heart so it can be pumped into the lungs for reoxygenation. Flow of blood circulation in vessels heart -- arteries -- arterioles -- capillary beds -- veinules -- veins --heart What blood vessels carry blood away from the heart? arteries and arterioles What blood vessels carry toward the heart? veinules and veins Where does gas exchange take placed? capillary beds What are the smallest blood capillary beds- wide enough to allow red blood cells to pass in single file line In what blood vessel does blood move the fastest? Aorta In what vessels is blood pressure the lowest? Venules Where is blood pressure the greatest? aorta and arteries What causes pressure throughout the blood vessels? forceful contraction of the ventricles. Recoiling mechanism responsible for maintaining adequate pressure and the propelling of blood through the network of vessels Where is blood pressure the weakest? veins and venules What is the pressure of ventricular contraction? Systolic pressure What is the pressure of artery walls recoiling back to their original size? Diastolic pressure. When does diastolic pressure decrease? when ventricles relax and vessels recoil Vasoconstriction contracting/narrowing of blood vessels, which increases blood pressure in vessels Vasodilation relaxing/widening blood vessels, which lowers blood pressure. Gravity has an impact of blood flow and adequate circulation throughout the body (t/f) True What activates the fainting mechanism? when the receptors of the brain and the large vessels of the neck detect a drop in the pressure greater than normal deviation What is the result of the fainting mechanism? Effectively, your head reaches the same level as your heart as you collapse to the ground in a lying position, and this small change in position quickly increases blood flow to your delicate brain tissue Resting phase the gated Na+ and K+ channels are both closed, and the membrane potential is around -70 mV. Depolarization A stimulus arrives at the dendrites and causes Na+ channels to open, which allows Na+ ions to flow into the cell down their gradient (from a high to low concentration). Note that K+ channels remain closed. A depolarization occurs causing the membrane potential to reach the threshold ( 55 mV) Rising phase Positive feedback causes the opening of more Na+ channels, and Na+ ions flow into the cell, causing a rapid shift in the membrane potential toward a more positive state. Notice that K+ channels are still closed. Falling phase Na+ channels become inactivated and close. Na+ is no longer flowing into the cell. K+ channels now open, and K+ flows out of the cell, making the cell more negative. Undershoot The Na+ channels remain closed, while the K+ channels remain open. This efflux of positive K+ ions brings the cell to a state that is more negative than the resting-state potential known as a hyperpolarized state Refractory period a period of inactivity after a neuron has fired due to inactivation of sodium channels and the hyperpolarized state of the neuron What do refractory periods prevent? Overstimulation of the neuron by ensuring an action potential cannot be generated. All-or-none response a neuron's reaction of either firing (with a full-strength response) or not firing.