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Knowledge Check: Unit 7 — Chapters 33–43

Knowledge Check: Unit 7 — Chapters 33–43

Test yourself on Unit 7: Animal Structure and Function (Chapters 33–43). Every question below was written from the chapters’ own text — their summaries, key terms, explanations, and tables — and none repeats a question from the section pages. There are no hints: treat it like a test. Questions are grouped by the section they come from, so a miss tells you exactly which section to review.

Chapter 33: The Animal Body: Basic Form and Function

33.1 Animal Form and Function

Approximately what is the basal metabolic rate (BMR) of a human male?

An animal with no pattern or symmetry to its body, such as a sponge, is described as ________.

Why does a larger spherical cell have less effective diffusion than a smaller one, in terms of its surface-to-volume ratio?

Show model answer
As the cell gets bigger, its surface-to-volume ratio decreases, making diffusion less efficient. The larger the size of the sphere, or animal, the less surface area for diffusion it possesses.

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33.2 Animal Primary Tissues

The type of tissue that either lines or covers organs or other tissues in the body is called ________.

Besides storing fat for energy metabolism, what other roles does adipose tissue serve?

What components make up loose (areolar) connective tissue, and where in the body is it found?

Show model answer
Loose connective tissue, also called areolar connective tissue, has a sampling of all of the components of a connective tissue, including fibroblasts and macrophages. Loose connective tissue is found around every blood vessel and helps to keep the vessel in place, and it is also found around and between most body organs.

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33.3 Homeostasis

The hormone released when blood calcium levels decrease, increasing calcium absorption through the intestines and kidneys, is called ________.

Which mechanism helps an endotherm conserve heat by reducing blood flow in peripheral blood vessels and forcing blood toward the body’s core?

When a change occurs in an animal’s environment, what is the pathway of events from detection to response?

Show model answer
The receptor senses the change in the environment, then sends a signal to the control center, which in turn generates a response that is signaled to an effector. The effector is a muscle that contracts or relaxes, or a gland that secretes.

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Chapter 34: Animal Nutrition and the Digestive System

34.1 Digestive Systems

In earthworms, the digestive system consisting of one tube with a mouth at one end and an anus at the other is called the ________.

A ring-like muscle that forms valves controlling the movement of materials through the digestive tract is called a ________.

How does the stomach protect its own lining from being digested by the enzyme pepsin?

Show model answer
The stomach protects its lining in two ways. First, pepsin is synthesized in an inactive form called pepsinogen, which protects the chief cells because pepsinogen does not have the same enzyme functionality as pepsin. Second, the stomach has a thick mucus lining that protects the underlying tissue from the action of the digestive juices.

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34.2 Nutrition and Energy Production

The enzyme humans lack that would let them derive glucose from the polysaccharide cellulose is called ________.

Sort each amino acid according to whether the human body must consume it in the diet or can anabolize (build) it for itself.

Must be consumed

    Anabolized by the body

      What happens in the liver when the amount of ATP available exceeds the body’s requirements, and what happens to that stored form when blood sugar drops?

      Show model answer
      When the amount of ATP is available in excess of the body’s requirements, the liver uses the excess ATP and excess glucose to produce molecules called glycogen, a polymeric form of glucose stored in the liver and skeletal muscle cells. When blood sugar drops, the liver releases glucose from stores of glycogen.

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      34.3 Digestive System Processes

      Which of the following peptide-digesting enzymes both reduces peptides to free amino acids and is produced by the pancreas?

      The elimination of food by forceful expulsion through the mouth, regulated by the medulla, is called ________.

      Why does emulsification by bile salts increase the efficiency of lipid digestion by pancreatic lipases?

      Show model answer
      If the lipid in the chyme aggregates into large globules, very little surface area of the lipids is available for the lipases to act on, leaving lipid digestion incomplete. By forming an emulsion, bile salts increase the available surface area of the lipids manyfold, so the pancreatic lipases can then act on the lipids more efficiently and digest them.

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      34.4 Digestive System Regulation

      Which of the following is one of the three factors that stimulate the gastric phase?

      During the gastric phase, G cells in the stomach secrete the hormone gastrin in response to the presence of which of the following?

      Besides controlling the rate of gastric emptying, what does the intestinal phase coordinate once chyme enters the small intestine?

      Show model answer
      When chyme enters the small intestine, in addition to controlling the rate of gastric emptying, it triggers other hormonal and neural events that coordinate the activities of the intestinal tract, pancreas, liver, and gallbladder.

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      Chapter 35: The Nervous System

      35.1 Neurons and Glial Cells

      Which structure on a neuron’s cell body integrates signals from multiple synapses and serves as the junction between the cell body and the axon?

      The glial cells that line the brain’s fluid-filled ventricles and the spinal cord’s central canal, producing the cerebrospinal fluid that cushions the brain, are called ________.

      What is neurogenesis, and what factors are known to promote or inhibit it in the hippocampus?

      Show model answer
      Neurogenesis is the birth of new neurons, and it continues into adulthood, with about 1,000 new neurons developing in the hippocampus each day. Exercise and some antidepressant medications promote neurogenesis in the hippocampus, while stress has the opposite effect.

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      35.2 How Neurons Communicate

      Once all of a neuron’s Na⁺ channels open during an action potential, to what membrane potential does the neuron completely depolarize?

      The postsynaptic glutamate receptor normally blocked by magnesium ions until the membrane depolarizes, at which point calcium ions can pass into the postsynaptic cell through it, is called the ________ receptor.

      After a neurotransmitter has bound receptors on the postsynaptic membrane, in what three ways can it be removed from the synaptic cleft?

      Show model answer
      The neurotransmitter can diffuse away from the synaptic cleft, it can be degraded by enzymes in the synaptic cleft, or it can be recycled, sometimes called reuptake, by the presynaptic neuron.

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      35.3 The Central Nervous System

      Which brain structure sits at the base of the brain atop the brainstem and controls balance while helping coordinate movement and learning new motor tasks?

      The temporal-lobe structure within the limbic system that is important for the sensation of fear and for recognizing fearful faces is called the ________.

      Besides movement control, what other function do the basal ganglia serve, and what did a case of bilateral basal ganglia damage from a wasp sting reveal about it?

      Show model answer
      The basal ganglia also regulate motivation. When a wasp sting led to bilateral basal ganglia damage in a 25-year-old businessman, he began to spend all his days in bed and showed no interest in anything or anybody, but when he was externally stimulated, as when someone asked to play a card game with him, he was able to function normally, and he did not report feeling bored or frustrated by his state.

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      35.4 The Peripheral Nervous System

      The division of the peripheral nervous system that controls bodily functions without conscious control is called the ________.

      Besides being released by postganglionic sympathetic neurons directly onto target organs, what other source releases norepinephrine into the bloodstream, amplifying the sympathetic response?

      Cranial nerves can carry only sensory information, only motor information, or a mix of both. Name one example nerve of each type and what it does.

      Show model answer
      The olfactory nerve transmits only sensory information, carrying information about smells from the nose to the brainstem. The oculomotor nerve transmits almost solely motor information, controlling the opening and closing of the eyelid and some eye movements. The glossopharyngeal nerve carries a mix of sensory and motor fibers, playing a role in both taste and swallowing.

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      35.5 Nervous System Disorders

      A nervous system disorder characterized by the progressive loss of neurological functioning, usually caused by neuron death, is called a ________.

      Research on the cause of ADHD points to a delay and dysfunction in the development of which brain region, along with disturbances in neurotransmission?

      How do antipsychotic medications treat schizophrenia, and what side effect can this treatment cause?

      Show model answer
      Antipsychotic medications work by blocking dopamine receptors and decreasing dopamine neurotransmission in the brain. This decrease in dopamine can cause Parkinson’s disease-like symptoms in some patients.

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      Chapter 36: Sensory Systems

      36.1 Sensory Processes

      Which special sense’s signals travel to the cerebral cortex without first passing through the thalamus?

      Receptive fields differ among the senses. For which sense must a stimulus come into contact with the body?

      What are the two broad types of cellular systems that perform sensory transduction, and what serves as the sensory receptor in each?

      Show model answer
      In one type, a neuron works with a sensory receptor, a cell or cell process that is specialized to engage with and detect a specific stimulus, and stimulation of the sensory receptor activates the associated afferent neuron, which carries information about the stimulus to the central nervous system. In the second type, a sensory nerve ending responds to a stimulus in the internal or external environment, and this neuron constitutes the sensory receptor.

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      36.2 Somatosensation

      A tension receptor related to muscle spindles that detects the force of muscle contraction is called a ________.

      Thermoreceptor pathways from the skin into the brain run from the spinal cord through the thalamus to which structure?

      Why do peppers taste ‘hot’ even though capsaicin is a harmless stimulus rather than a true source of tissue injury?

      Show model answer
      Pain also can be caused by harmless stimuli that mimic the action of damaging stimuli, such as contact with capsaicins, the compounds that cause peppers to taste hot. Peppers taste hot because the protein receptors that bind capsaicin open the same calcium channels that are activated by warm receptors.

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      36.3 Taste and Smell

      Which fundamental taste was identified in 1908 by Japanese scientist Kikunae Ikeda while he worked with seaweed broth?

      A cluster of gustatory receptors located within the papillae on the tongue is called a ________.

      Trace the path taste signals take from the taste cells to the primary gustatory cortex, naming the two brain structures they pass through in order.

      Show model answer
      Taste neurons project from taste cells in the tongue, esophagus, and palate to the medulla, in the brainstem. From the medulla, taste signals travel to the thalamus and then to the primary gustatory cortex.

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      36.4 Hearing and Vestibular Sensation

      Which of the following animals can detect the highest sound frequency, up to about 180,000 Hz?

      A bony, hollow structure that is the most interior portion of the ear and that contains the structures of the inner ear is called the ________.

      Besides the pons and thalamus, vestibular hair-cell signals from the utricle, saccule, and semicircular canals also project to the cerebellum. Trace that pathway and explain why the cerebellar connection matters.

      Show model answer
      Hair cells from the utricle, saccule, and semicircular canals communicate through bipolar neurons to the cochlear nucleus in the medulla, which sends ascending projections to the pons, thalamus, and cerebellum. Connections to the cerebellum are important for coordinated movements.

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      36.5 Vision

      A light wave’s wavelength, which varies inversely with frequency, manifests itself to the visual system as ________.

      The region in the center back of the eye that has a high density of cones and is responsible for acute vision is called the ________.

      Describe how the information carried by the magnocellular and parvocellular pathways differs, from the optic nerve through the thalamus.

      Show model answer
      The magnocellular (big cell) pathway carries information about form, movement, depth, and differences in brightness, while the parvocellular (small cell) pathway carries information on color and fine detail. In the thalamus, the magnocellular and parvocellular distinctions remain intact, with different layers of the thalamus dedicated to each.

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      Chapter 37: The Endocrine System

      37.1 Types of Hormones

      Steroid hormones are insoluble in water and are transported by transport proteins in the blood. What effect does this have on them compared with peptide hormones?

      The pineal gland in the brain makes and secretes ________, which regulates sleep cycles.

      Why can’t amino acid-derived and peptide hormones enter target cells directly, and where are their receptors located instead?

      Show model answer
      Amino acid-derived and polypeptide hormones are water-soluble and insoluble in lipids. These hormones cannot pass through plasma membranes of cells; therefore, their receptors are found on the surface of the target cells.

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      37.2 How Hormones Work

      Vitamin D and thyroxine are lipid-soluble hormones that are not steroid hormones. Where are their receptors located?

      The hormone that binds to a plasma membrane receptor is called a first messenger, and the cellular component it activates is called a ________.

      How does the plasma membrane hormone receptor pathway amplify the effect of a single hormone molecule binding its receptor?

      Show model answer
      The binding of a hormone at a single receptor causes the activation of many G-proteins, which activates adenylyl cyclase. Each molecule of adenylyl cyclase then triggers the formation of many molecules of cAMP. Further amplification occurs as protein kinases, once activated by cAMP, can catalyze many reactions. In this way, a small amount of hormone can trigger the formation of a large amount of cellular product.

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      37.3 Regulation of Body Processes

      Within the thyroid follicle, TSH triggers the production of T₃ and T₄ from which substance?

      The hormone ________, produced by the parafollicular or C cells of the thyroid, has the opposite effect on blood calcium levels as does PTH.

      How does growth hormone act indirectly, through the liver, to promote tissue growth?

      Show model answer
      The indirect mechanism of GH action is mediated by insulin-like growth factors (IGFs), which are a family of growth-promoting proteins produced by the liver. IGFs stimulate the uptake of amino acids from the blood, allowing the formation of new proteins, particularly in skeletal muscle cells, cartilage cells, and other target cells.

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      37.4 Regulation of Hormone Production

      Which hormone released by the anterior pituitary stimulates the thyroid gland to produce the hormones T₃ and T₄?

      After a rise in blood glucose triggers insulin release, what signals the pancreas to stop producing insulin in the negative feedback loop?

      How does the nervous system trigger the release of epinephrine and norepinephrine during a stress response, and what is this mechanism called?

      Show model answer
      In some cases, the nervous system directly stimulates endocrine glands to release hormones, which is referred to as neural stimuli. Neuronal signaling from the sympathetic nervous system directly stimulates the adrenal medulla to release the hormones epinephrine and norepinephrine in response to stress.

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      37.5 Endocrine Glands

      Most people have how many parathyroid glands, though the number can vary?

      Each adrenal gland consists of an inner medulla and an outer ________, each of which secretes different hormones.

      Where is the thymus located, and what role do the hormones it produces play?

      Show model answer
      The thymus is found behind the sternum; it is most prominent in infants, becoming smaller in size through adulthood. The thymus produces hormones referred to as thymosins, which contribute to the development of the immune response.

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      Chapter 38: The Musculoskeletal System

      38.1 Types of Skeletal Systems

      The adult vertebral column comprises how many bones?

      What are the five main functions of the human endoskeleton?

      Show model answer
      The human endoskeleton has five main functions: providing support to the body, storing minerals and lipids, producing blood cells, protecting internal organs, and allowing for movement.

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      Any place at which two bones are joined is called a(n) ________.

      38.2 Bone

      Which type of bone is longer than it is wide and has a shaft and two ends?

      The process of deposition of mineral salts on the collagen fiber matrix that crystallizes and hardens bone tissue is called ________.

      What is appositional growth, and how do osteoblasts and osteoclasts work together to achieve it?

      Show model answer
      Appositional growth is the increase in the diameter of bones by the addition of bony tissue at the surface of bones. Osteoblasts at the bone surface secrete bone matrix, and osteoclasts on the inner surface break down bone. A balance between these two processes allows the bone to thicken without becoming too heavy.

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      38.3 Joints and Skeletal Movement

      Into how many categories are synovial joints classified, on the basis of the shape and structure of the joint?

      What are the four categories used to classify joints structurally, and what determines which category a joint belongs to?

      Show model answer
      The structural classification divides joints into bony, fibrous, cartilaginous, and synovial joints, depending on the material composing the joint and the presence or absence of a cavity in the joint.

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      Rheumatoid arthritis primarily affects the synovial joints of which body regions?

      38.4 Muscle Contraction and Locomotion

      The area of the sarcolemma on a muscle fiber that interacts with the neuron is called the ________.

      What is the approximate maximum length of a skeletal muscle fiber?

      When a sarcomere shortens during muscle contraction, which of its bands or zones shrink and which stay the same length?

      Show model answer
      When a sarcomere shortens, some regions shorten whereas others stay the same length. The H zone, the central region of the A band that contains only thick filaments, is shortened during contraction. The I band, which contains only thin filaments, also shortens. The A band does not shorten and remains the same length, although A bands of different sarcomeres move closer together during contraction. Thin filaments are pulled by the thick filaments toward the center of the sarcomere.

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      Chapter 39: The Respiratory System

      39.1 Systems of Gas Exchange

      Which respiratory structure do earthworms and amphibians use to exchange gases with the outside environment?

      The domed skeletal muscle located under the lungs that marks the end of the thoracic cavity is called the ________.

      How do cilia in the bronchi and bronchioles help protect the lungs, and how does cigarette smoke interfere with that protection?

      Show model answer
      The bronchi and bronchioles contain cilia, small hair-like projections that line the walls of the bronchi and bronchioles. These cilia beat in unison and move mucus and particles out of the bronchi and bronchioles back up to the throat where it is swallowed and eliminated via the esophagus. Tar and other substances in cigarette smoke destroy or paralyze the cilia, making the removal of particles more difficult, and smoking causes the lungs to produce more mucus, which the damaged cilia are not able to move.

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      39.2 Gas Exchange across Respiratory Surfaces

      About what percentage of atmospheric gas is oxygen?

      The maximum amount of air that can be inhaled or exhaled during a single respiratory cycle, equal to the sum of the expiratory reserve volume, tidal volume, and inspiratory reserve volume, is called the ________.

      Why does oxygen diffuse out of the alveoli and into the blood of the surrounding capillaries?

      Show model answer
      Alveolar oxygen partial pressure is higher in the alveoli than blood oxygen partial pressure in the capillaries. Because this pressure gradient exists, oxygen diffuses down its pressure gradient, moving out of the alveoli and entering the blood of the capillaries where oxygen binds to hemoglobin.

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      39.3 Breathing

      Why did birds evolve a respiratory system suited to high oxygen demand, and from which ancient organisms did birds evolve?

      Show model answer
      Flying is a high-energy process and requires a lot of oxygen, and many birds fly in high altitudes where the concentration of oxygen is low. Birds evolved from theropods, meat-eating dinosaurs; fossil evidence shows that meat-eating dinosaurs that lived more than 100 million years ago had a similar flow-through respiratory system with lungs and air sacs.

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      Emphysema, in which the walls of the alveoli are destroyed, has which effect on the lungs?

      A region of the lung that lacks proper ventilation or perfusion because of a functional impairment, such as infection or edema, rather than an anatomical block, is called ________.

      39.4 Transport of Gases in Human Bodily Fluids

      The protein molecule in red blood cells that can bind oxygen, carbon dioxide, and carbon monoxide is called ________.

      Which of the following conditions is caused by a defect in either the alpha or the beta subunit of hemoglobin, producing red blood cells with lower-than-normal levels of hemoglobin?

      Why is carbon monoxide poisoning particularly dangerous and hard to detect, and what symptoms can it cause?

      Show model answer
      Carbon monoxide is a colorless, odorless gas and is therefore difficult to detect. It is produced by gas-powered vehicles and tools. Carbon monoxide can cause headaches, confusion, and nausea; long-term exposure can cause brain damage or death.

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      Chapter 40: The Circulatory System

      40.1 Overview of the Circulatory System

      Blood flow in a single circuit, such as occurs in fish where the blood flows through the gills, then past the organs and the rest of the body, before returning to the heart, is called ________.

      Which animals are the most primitive to exhibit a four-chambered heart?

      Why do biologists describe the four-chambered hearts of birds and mammals as an example of convergent evolution?

      Show model answer
      The four-chambered heart of birds and mammals evolved independently from a three-chambered heart. This independent evolution of the same or a similar biological trait is referred to as convergent evolution.

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      40.2 Components of the Blood

      Which respiratory pigment uses copper instead of iron to bind oxygen, and is found in mollusks, crustaceans, and some arthropods?

      The most abundant protein in human blood plasma, which transports hormones and fatty acids, buffers pH, and maintains osmotic pressure, is called ________.

      What roles do T cells play in the immune response, and how do they specifically act against viruses?

      Show model answer
      T cells attack viruses, fungi, some bacteria, transplanted cells, and cancer cells. T cells attack viruses by releasing toxins that kill the viruses.

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      40.3 Mammalian Heart and Blood Vessels

      The complete blockage of the coronary arteries resulting in the death of cardiac muscle tissue is called ________.

      Which event produces the heart’s monosyllabic ’lup’ sound?

      How do vasoconstriction and vasodilation regulate the movement of materials at a capillary?

      Show model answer
      The movement of materials at the site of capillaries is regulated by vasoconstriction, narrowing of the blood vessels, and vasodilation, widening of the blood vessels; this is important in the overall regulation of blood pressure.

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      40.4 Blood Flow and Blood Pressure Regulation

      What percentage of the body’s capillary beds have blood actually flowing through them at any given moment?

      The pressure of the blood flow in the body is produced by the ________ of the fluid (blood) against the walls of the blood vessels.

      What are two ways cardiac output can be increased?

      Show model answer
      Cardiac output can be increased by increasing heart rate, as when exercising. Cardiac output can also be increased by increasing stroke volume, such as if the heart contracts with greater strength. Stroke volume can also be increased by speeding blood circulation through the body so that more blood enters the heart between contractions.

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      Chapter 41: Osmotic Regulation and Excretion

      41.1 Osmoregulation and Osmotic Balance

      Organisms such as goldfish that can tolerate only a relatively narrow range of salinity are referred to as ________.

      Sharks are cartilaginous fish with which organ to secrete salt and assist in osmoregulation?

      Why can a damaged or absent mechanism for regulating osmotic pressure have dire consequences for an organism?

      Show model answer
      Without a mechanism to regulate osmotic pressure, or when a disease damages this mechanism, there is a tendency to accumulate toxic waste and water, which can have dire consequences.

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      41.2 The Kidneys and Osmoregulatory Organs

      Which artery branches directly from the renal artery upon entering the kidney, before splitting further into interlobar arteries?

      The upper limit on the amount of solute that can be transported out of the renal tubules during reabsorption is called the ________.

      How do the macula densa and juxtaglomerular cells work together, and what do they ultimately help regulate?

      Show model answer
      The macula densa are cells in the ascending limb of the loop of Henle in the distal convoluted tubule, and juxtaglomerular cells are cells in the afferent arterioles that lie in contact with them. Together, the macula densa and juxtaglomerular cells form the juxtaglomerular complex, an endocrine structure that secretes the enzyme renin and the hormone erythropoietin. When hormones trigger the macula densa cells due to variations in blood volume, blood pressure, or electrolyte balance, these cells communicate the problem to the capillaries in the afferent and efferent arterioles, which constrict or relax to change the glomerular filtration rate of the kidneys.

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      41.3 Excretion Systems

      How are contractile vacuoles different from ordinary vacuoles in a unicellular organism, and how do they expel wastes from the cell?

      Show model answer
      Contractile vacuoles should not be confused with vacuoles, which store food or water. In unicellular eukaryotic organisms such as the amoeba, cellular wastes and excess water are excreted by exocytosis, when the contractile vacuoles merge with the cell membrane and expel wastes into the environment.

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      In the planarian’s excretory system, what happens to valuable metabolites drawn into the flame-cell tubules along with waste?

      In the exchange pumps that line the Malpighian tubules, which ion is actively transported into the cell while potassium and sodium ions are transported out?

      41.4 Nitrogenous Wastes

      An agent that prevents cell destruction by reactive oxygen species is called a(n) ________.

      Which enzyme catalyzes a key step of the urea cycle whose deficiency can lead to a toxic buildup of ammonia in the body?

      How does the way aquatic animals excrete ammonia differ from what terrestrial organisms must do with it?

      Show model answer
      Animals that live in aquatic environments tend to release ammonia into the water. Terrestrial organisms have evolved other mechanisms to excrete nitrogenous wastes: they must detoxify ammonia by converting it into a relatively nontoxic form such as urea or uric acid.

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      41.5 Hormonal Control of Osmoregulatory Functions

      Besides promoting sodium reabsorption, aldosterone concurrently stimulates the renal tubules to do which of the following?

      Atrial natriuretic peptide is released by cells in the atrium of the heart in response to high blood pressure and in patients with which condition?

      How does atrial natriuretic peptide (ANP) lower blood pressure, and how do its actions relate to aldosterone, ADH, and renin?

      Show model answer
      Atrial natriuretic peptide lowers blood pressure by acting as a vasodilator. It also prevents sodium reabsorption by the renal tubules, decreasing water reabsorption and lowering blood pressure. Its actions suppress the actions of aldosterone, ADH, and renin.

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      Chapter 42: The Immune System

      42.1 Innate Immune Response

      A leukocyte that, like a neutrophil, releases chemicals to stimulate the inflammatory response is called a(n) ________.

      Toll-like receptors (TLRs) are described as one of the most ancient components of the immune system. Beyond the immune system, TLRs have also been identified in which body site?

      Why does a fever help the body fight certain bacterial pathogens?

      Show model answer
      Cytokines increase the core body temperature, causing a fever, which causes the liver to withhold iron from the blood. Without iron, certain pathogens, such as some bacteria, are unable to replicate; this is called nutritional immunity.

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      42.2 Adaptive Immune Response

      Approximately what percentage of circulating lymphocytes in human blood are T cells?

      The activation of B cells corresponding to one specific B cell receptor variant, and the dramatic proliferation of that variant, is called ________.

      Mycobacterium tuberculosis can evade a macrophage’s attempts to destroy it after being engulfed. How does a TH1 cell that forms in response to M. tuberculosis infection help the macrophage overcome this?

      Show model answer
      Macrophages can stimulate naïve T cells to become TH1 cells. These stimulated T cells secrete specific cytokines that send feedback to the macrophage to stimulate its digestive capabilities and allow it to destroy the colonizing M. tuberculosis.

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      42.3 Antibodies

      The basic principle of radioimmunoassay (RIA) is which of the following?

      An enzyme that randomly excises segments from the light chain gene and splices one V segment to one J segment is called ________.

      Antibodies protect the body against extracellular pathogens in three distinct ways after binding them. Describe neutralization, opsonization, and complement fixation.

      Show model answer
      Antibodies coat extracellular pathogens and neutralize them by blocking key sites on the pathogen that enhance their infectivity, preventing the pathogens from entering and infecting host cells. Antibodies also mark pathogens for destruction by phagocytic cells such as macrophages or neutrophils; this phagocytic enhancement by antibodies is called opsonization. In complement fixation, IgM and IgG in serum bind to antigens and provide docking sites onto which sequential complement proteins can bind, and the combination of antibodies and complement enhances opsonization even further.

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      42.4 Disruptions in the Immune System

      The failure, insufficiency, or delay in the response of the immune system, which may be acquired or inherited, is called ________.

      In the United States, 20 percent of the population exhibits symptoms of allergy or asthma. What percentage test positive against one or more allergens?

      How can infection with Streptococcus pyogenes lead to rheumatic fever through an autoimmune mechanism?

      Show model answer
      Infection with Streptococcus pyogenes may generate antibodies or T cells that react with heart muscle, because heart muscle has a similar structure to the surface of S. pyogenes. These antibodies can damage heart muscle with autoimmune attacks, leading to rheumatic fever.

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      Chapter 43: Animal Reproduction and Development

      43.1 Reproduction Methods

      Which of the following is given as an advantage of asexual reproduction for colonizing new habitats?

      What is hermaphroditism, and in what two ways can hermaphroditic animals reproduce?

      Show model answer
      Hermaphroditism occurs in animals where one individual has both male and female reproductive parts. Hermaphrodites may self-fertilize or may mate with another of their species, fertilizing each other and both producing offspring.

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      In some species that change sex during their lives, being female first and later becoming male is termed ________.

      43.2 Fertilization

      The process in which one or several females release their eggs and the male(s) release sperm in the same area, at the same time, is called ________.

      In annelids, sperm and eggs are produced from undifferentiated cells and stored in which cavity until they are released?

      How does the structure of the mammalian uterus differ between species that produce large numbers of offspring at a time and species, such as primates, that produce one offspring at a time?

      Show model answer
      The uterus has two chambers in species that produce large numbers of offspring at a time, while species that produce one offspring, such as primates, have a single uterus.

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      43.3 Human Reproductive Anatomy and Gametogenesis

      The muscular tube that allows menstrual flow to leave the body and serves as the receptacle for the penis during intercourse is called the ________.

      Which cells in the wall of the seminiferous tubules are described as ’nursemaid’ cells that protect the developing germ cells and promote their development?

      What is the acrosome, and how does it help a sperm fertilize an egg?

      Show model answer
      An acrosome is found at the top of the head of the sperm. This structure contains lysosomal enzymes that can digest the protective coverings that surround the egg to help the sperm penetrate and fertilize the egg.

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      43.4 Hormonal Control of Human Reproduction

      Which of the following is one of the secondary sexual characteristics that testosterone produces in males during adolescence?

      At the stage of prenatal development when a fertilized egg traveling through the fallopian tube contains 30 to 60 cells, it is called the ________.

      How can the loss of estrogen at menopause lead to osteoporosis?

      Show model answer
      Estrogen is involved in calcium metabolism and, without it, blood levels of calcium decrease. To replenish the blood, calcium is lost from bone which may decrease the bone density and lead to osteoporosis.

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      43.5 Human Pregnancy and Birth

      A condition in pregnant people during the first trimester that includes feelings of nausea is called ________.

      From eight weeks of gestation, when the body is essentially formed, which term applies to the developing human?

      How does an intrauterine device (IUD) work to prevent pregnancy?

      Show model answer
      IUDs are inserted into the uterus and establish an inflammatory condition that prevents fertilized eggs from implanting into the uterine wall.

      Did your answer mention:

      43.6 Fertilization and Early Embryonic Development

      What two mechanisms did Ernest Everett Just describe for preventing more than one sperm from fertilizing an egg?

      Show model answer
      The fast reaction is what Just called a “wave of negativity,” in which the membrane potential of the egg cell altered quickly. The slow block involved changing the membrane structure itself.

      Did your answer mention:

      Each cell within the blastula is called a ________.

      Which germ layer gives rise to the muscle cells and connective tissue in the body?

      43.7 Organogenesis and Vertebrate Axis Formation

      The nematode used to study organogenesis that has roughly 1,000 somatic cells with a mapped developmental fate for each individual cell is called ________.

      What would happen to the ectoderm during neural system formation if the signaling by growth factors at its edges were disrupted?

      Show model answer
      If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue.

      Did your answer mention:

      Even though animal bodies have externally visible symmetry, which organ lies on the right side of the body rather than the left?

      This knowledge check is written for Unit 7 (Chapters 33–43) of Biology 2e by Mary Ann Clark, Jung Choi, Matthew Douglas, and OpenStax, © OpenStax, licensed under CC BY-NC-SA 4.0. Access the original for free at openstax.org. Changes: every question is locally written from the pinned text of the chapters’ own modules — their section summaries, glossary definitions, body passages, and comparison tables — and none is transcribed from the book’s exercise sets, which the section pages already carry; no question carries a hint, and every self-check carries a rubric that decomposes a model answer made of the module’s own sentences; the 39.3 self-check prints “theropods” where module m66647 misspells the word (erratum 311), and no item is built on module m66664’s dendritic-cell definition, which places antigen presentation on the surface of other cells (erratum 312); the 38.4 self-check on sarcomere shortening prints “A band” where its source paragraph once says “A zone” (erratum 313), the module’s own term from its defining paragraph.

      Organogenesis and Vertebrate Axis FormationEcology and the Biosphere