AP Biology MCQ Questions and Answers

Glycogen is the correct answer because it is a storage carbohydrate found in animal tissues, particularly in skeletal muscle and liver cells. It serves as a readily available source of glucose for energy during periods of high demand or low blood sugar levels. Glycogen is synthesized and stored in the liver and muscles, and can be broken down into glucose when needed through the process of glycogenolysis.

The iris is the part of the eye that determines eye color. It is a thin, circular structure that surrounds the pupil and contains pigments that give the eye its color. The iris controls the size of the pupil and regulates the amount of light that enters the eye. It also helps protect the eye from harmful UV radiation. The other options listed (pupil, retina, and fovea) are all important parts of the eye, but they do not directly determine eye color.

Motor nerves are responsible for carrying impulses from the central nervous system (CNS) to the muscles and glands, allowing for voluntary and involuntary movements and the secretion of hormones. The term "efferent" refers to the flow of information away from the CNS, which aligns with the function of motor nerves. Therefore, the correct answer is "Efferent."

Negative feedback is the correct answer because it refers to a regulatory mechanism in which the output of a system counteracts the original stimulus, resulting in a reduction or shutting off of the effect. This feedback loop helps maintain stability and balance in biological systems, such as maintaining body temperature or blood sugar levels. Positive feedback, on the other hand, amplifies the original stimulus, leading to an increase or continuation of the effect. Homeostasis is the overall process of maintaining internal stability, while a variable refers to any factor that can change or vary in a system.

Enzymes are proteins that act as catalysts in the body, speeding up the chemical reactions that occur within cells. They play a crucial role in metabolism by facilitating the breakdown of molecules and the synthesis of new molecules. Without enzymes, metabolic processes would occur too slowly to sustain life. Therefore, enzymes are the proteins that speed up metabolism or the chemical reactions of the body.

Antagonists are muscles that oppose or reverse a particular movement. They work in opposition to the prime mover, which is responsible for initiating a specific movement. Synergistic muscles work together with the prime mover to enhance the movement, while fixator muscles stabilize the origin of the prime mover to allow for more efficient movement. In this context, the correct answer is "Antagonists" as they directly oppose or reverse the movement initiated by the prime mover.

Homeostasis refers to the ability of an organism to maintain relatively stable internal conditions, regardless of external changes. It involves various physiological processes that help regulate body temperature, blood pH, and other vital parameters within a narrow range. Osmosis is the movement of water across a semipermeable membrane, which is not directly related to maintaining stable conditions. Positive feedback amplifies a response, while the endocrine system is responsible for hormone production and regulation. Therefore, the correct answer is Homeostasis.

Medial refers to a position or direction that is closer to the midline of the body. In anatomical terms, the midline is an imaginary line that divides the body into left and right halves. Therefore, when something is described as medial, it means it is located or moving towards the midline of the body. In this case, the correct answer is "Medial" because it describes a position or direction that is closer to the midline of the body.

Mitochondria are complex organelles that generate most of the chemical energy needed to power cells. They are often referred to as the "powerhouses" of the cell because they produce adenosine triphosphate (ATP), which is the main source of energy for cellular processes. Mitochondria have their own DNA and are able to self-replicate, indicating that they likely evolved from independent bacteria that were engulfed by ancestral eukaryotic cells.

Osmosis is the correct answer because it refers to the diffusion of water through a selectively permeable membrane. In osmosis, water molecules move from an area of lower solute concentration to an area of higher solute concentration, in order to equalize the concentration on both sides of the membrane. This process is crucial for maintaining the balance of water and solutes in cells and is responsible for processes such as hydration and the movement of water in plants.

The Sella Turcica is a bony depression located in the skull, specifically in the sphenoid bone. It is shaped like a saddle and its main function is to provide a secure seat for the pituitary gland. The pituitary gland is a small, pea-sized gland that is considered the "master gland" of the body as it produces and releases various hormones that control many different bodily functions. The Sella Turcica acts as a protective enclosure for the pituitary gland, ensuring its stability and proper functioning.

Fissures are deep grooves on the brain surface. They are the deepest and most prominent grooves that divide the brain into different lobes and hemispheres. Fissures play a crucial role in separating and organizing different regions of the brain, allowing for efficient communication and specialization of functions. Sulci are shallow grooves, gyri are raised folds, and commissures are bundles of nerve fibers that connect the two hemispheres of the brain. However, none of these options specifically refer to deeper grooves like fissures do.

A fixator is a muscle or group of muscles that immobilizes a bone or muscle origin, providing a stable base for the prime mover to act on. In other words, when synergistic muscles contract to assist the prime mover in its action, the fixator muscles stabilize the origin of the prime mover, allowing it to work more effectively. Therefore, the fixator is the correct answer in this context.

The term "proximal" refers to a location that is closer to the trunk or the point of origin of a structure. In this question, the term "proximal" is the correct answer because it describes a position that is closer to the trunk. "Distal" would refer to a location that is farther away from the trunk, "posterior" refers to the back side of the body, and "inferior" refers to a position that is below another structure.

ATP (adenosine triphosphate) is a molecule that transfers energy within cells. It provides a form of energy that is readily available and can be used immediately for various cellular processes. Unlike other molecules listed, such as calcium or adrenaline, ATP specifically functions as a universal energy currency in cells. Enzymes, on the other hand, are proteins that facilitate biochemical reactions but do not directly provide energy. Therefore, ATP is the correct answer as it fits the description of transferring energy molecules in cells and providing immediate energy.

Lysosomes are responsible for the digestion of particles and performing metabolic functions within cells. They contain enzymes that break down waste materials, cellular debris, and foreign substances. This process, known as autophagy, helps maintain cellular homeostasis by recycling nutrients and eliminating harmful substances. Lysosomes also play a crucial role in cell death, as they release their enzymes to break down cellular components during apoptosis. Therefore, lysosomes are the correct answer for the given question.

Endocrine glands are ductless glands that secrete hormones directly into the bloodstream. These hormones then travel to target organs or tissues in the body, where they regulate various physiological processes. Unlike exocrine glands, which secrete their products through ducts into body cavities or onto body surfaces, endocrine glands release their secretions directly into the blood. Therefore, the correct answer is endocrine.

Extension refers to the movement that increases the angle of a joint. It is the opposite of flexion, which decreases the angle of a joint. Hyperextension, on the other hand, refers to an excessive extension beyond the normal range of motion. Gliding, also known as sliding, is a type of movement that occurs between joint surfaces. Therefore, the correct answer is extension as it accurately describes the movement that increases the angle of a joint.

Commissures are neural pathways that connect the right and left hemispheres of the brain. They allow for communication and coordination between the two hemispheres, enabling them to work together and share information. Gyri, sulci, and fissures are all structural features of the brain, but they do not specifically connect the two hemispheres. Therefore, the correct answer is "Commissures."

The parasympathetic nervous system controls homeostasis and the body at rest, as well as being responsible for the "rest and digest" function. It works in opposition to the sympathetic nervous system, which is responsible for the "fight or flight" response. The parasympathetic nervous system helps to regulate heart rate, digestion, and other bodily functions during periods of rest and relaxation.

The sympathetic nervous system controls the body's responses to a perceived threat and is responsible for the fight or flight response. This system prepares the body for action by increasing heart rate, dilating blood vessels, and releasing stress hormones. It activates when the body senses danger or stress, allowing for quick reactions and heightened physical abilities.

The muscle that has the major responsibility for producing a specific movement is known as the prime mover. In the context of speech production, the prime mover muscle would be the muscle primarily responsible for generating the movements required for speech, such as the muscles of the tongue, lips, and vocal cords. These muscles work together as the prime movers to produce the precise articulation and phonation needed for speech.

The term "synergistic" refers to something that works together with another element to enhance or amplify its effect. In the context of the question, it suggests that adding a little extra effort or reducing unnecessary movements can work in harmony with the prime movers, resulting in more efficient and effective movement. It implies that by coordinating and cooperating with the prime movers, the synergistic element can contribute positively to the overall movement.

The ventral cavity consists of the thoracic and abdominopelvic cavities. The thoracic cavity is located in the chest and contains organs such as the heart and lungs. The abdominopelvic cavity is located in the abdomen and pelvis and contains organs such as the stomach, liver, intestines, and reproductive organs. The brain and spinal cord are part of the dorsal cavity, not the ventral cavity. The diaphragm is a muscle that separates the thoracic and abdominopelvic cavities.

Positive feedback occurs when the initial response enhances the original stimulus. In this case, the correct answer is positive feedback because it aligns with the given explanation. Positive feedback is a process that amplifies or increases the effects of a stimulus, leading to a greater response. This is in contrast to negative feedback, which works to counteract or reduce the effects of a stimulus. The term "receptor" refers to a sensory organ or cell that detects stimuli, and "variable" refers to a factor that can change or vary.

Glycogen, a form of glucose storage, is stored in skeletal muscle and liver cells. These cells have the ability to convert excess glucose into glycogen and store it for later use. The liver acts as a central storage site for glycogen, releasing glucose into the bloodstream when needed to maintain blood sugar levels. Skeletal muscles store glycogen to provide a local source of energy during physical activity. The presence of glycogen in both skeletal muscle and liver cells allows for efficient energy storage and utilization in the body.

Peroxisomes are small organelles that resemble small lysosomes and are involved in detoxification processes within cells. They contain enzymes that break down toxic substances, such as hydrogen peroxide, into harmless molecules. This detoxification function is similar to that of lysosomes, which also contain enzymes involved in breaking down waste materials. Mitochondria, on the other hand, are responsible for energy production in cells, while periosteum is a connective tissue layer that covers bones.

Exocrine glands are responsible for secreting substances onto a surface or into a cavity through ducts. Unlike endocrine glands, which release hormones directly into the bloodstream, exocrine glands secrete their products to a specific site. Therefore, the correct answer is Exocrine.

Elastic cartilage is the correct answer because it is a type of connective tissue that contains elastic fibers, which give it the ability to stretch and recoil. This property allows elastic cartilage to maintain the shape of the ear, as it can withstand deformation from external forces and then return to its original shape.

Osteoclasts are specialized cells that are responsible for bone resorption, which is the breakdown of bone tissue. They play a crucial role in maintaining bone health by removing old or damaged bone tissue and allowing for the formation of new bone. Osteoclasts are derived from monocytes, a type of white blood cell, and they have the ability to fuse together to form large, multinucleated cells. This fusion allows them to create a larger surface area for resorption and efficiently break down bone. Therefore, osteoclasts are the correct answer in this context.

Sebaceous glands are responsible for producing a secretion called sebum. This sebum is released into hair follicles and acts as a natural lubricant for both the skin and hair. Sebaceous glands are found all over the body, except for the palms of the hands and soles of the feet. They play an important role in keeping the skin and hair moisturized and protected.

The hypothalamus is responsible for regulating various bodily functions such as electrolyte and fluid balance, blood pressure, body temperature, and weight. It acts as a control center by using a set-point to maintain homeostasis in the body. This means that it constantly monitors the internal environment and makes adjustments to keep the body's systems in balance. The hypothalamus receives signals from other parts of the body and initiates appropriate responses to maintain optimal functioning.

Beta blockers are medications that block the effects of adrenaline on the beta receptors in the body. By doing so, they decrease heart rate and contractility, leading to a decrease in cardiac output. This ultimately results in a decrease in blood pressure. Therefore, beta blockers are the correct answer to the given question.

Cones are responsible for color vision and high acuity. They are active at higher light levels, known as photopic vision. Unlike rods, which are more sensitive to low light levels and are responsible for scotopic vision, cones allow us to perceive colors and see fine details. The fovea, a small area in the center of the retina, contains a high concentration of cones, making it the region of highest visual acuity. Therefore, cones are the correct answer for this question.

Afferent nerves are responsible for transmitting impulses from the sensory receptors in the skin, muscles, and joints to the central nervous system (CNS). These nerves carry sensory information such as touch, pain, temperature, and proprioception from the periphery to the brain and spinal cord, allowing us to perceive and respond to our environment. Efferent nerves, on the other hand, transmit impulses from the CNS to the muscles and glands, enabling motor responses. Therefore, the correct answer is Afferent.

The absolute refractory period is a brief period of time after an action potential where the neuron cannot generate another action potential, regardless of the strength of the stimulus. This enforces one-way transmission of nerve impulses because it ensures that each action potential is all-or-nothing, meaning it either occurs fully or not at all. During this period, the voltage-gated sodium channels are inactivated and cannot be reopened, preventing the generation of another action potential.

Distal refers to a position farther away from the center of the body or a specific reference point. The back of the shoulder blades, also known as the scapulae, are located on the posterior side of the body, away from the central axis. Therefore, the answer "Distal" is correct as it accurately describes the position of the shoulder blades in relation to the body.

Facilitated diffusion is the correct answer because it refers to the movement of molecules down their concentration gradient with the help of membrane carrier proteins. Unlike simple diffusion where molecules pass directly through the lipid bilayer of the membrane, facilitated diffusion involves the use of specific carrier proteins to transport molecules across the membrane. This process is necessary for larger or charged molecules that cannot easily diffuse through the membrane on their own. Therefore, facilitated diffusion accurately describes the movement of substances attached to a membrane carrier.

The correct answer is "Osteogenic" because osteogenic cells are the stem cells that differentiate into osteoblasts or bone lining cells. Osteogenic cells are responsible for the formation of new bone tissue and play a crucial role in bone remodeling and repair. Osteocytes, on the other hand, are mature bone cells that are derived from osteoblasts and are involved in maintaining bone health. Osteoclasts, on the other hand, are responsible for bone resorption and breakdown. Therefore, the answer "Osteogenic" is the most appropriate choice in this context.

Osteoblasts are cells responsible for the production and secretion of the bone matrix called osteoid. This osteoid is made up of collagen and calcium, which are essential for bone building. Osteoblasts play a crucial role in bone formation and remodeling. They are responsible for the synthesis and deposition of new bone tissue.

Osteocytes are mature bone cells that are found in lacunae, which are small spaces within the bone matrix. These cells no longer divide but play a crucial role in bone remodeling. They communicate important information to osteoblasts and osteoclasts, which are responsible for the formation and resorption of bone tissue. Osteocytes help regulate bone density and maintain the overall health and structure of the bone.

Flexion refers to the movement that decreases the angle of a joint. It is the bending movement that brings two bones closer together, typically occurring in the sagittal plane. This movement is commonly observed in joints such as the elbow, knee, and spine. Flexion allows for increased mobility and range of motion in the joint, enabling various activities such as bending the arm, curling the spine, or bringing the leg closer to the body. Therefore, flexion is the correct answer as it accurately describes the action of decreasing the angle of a joint.

Adduction refers to the movement of a body part towards the midline of the body along the frontal axis. In this movement, the body part is brought closer to the midline, reducing the angle between the body part and the midline. For example, when you bring your arms down from a raised position to your sides, you are performing adduction at the shoulder joint. Therefore, adduction is the correct answer in this context.

The correct answer is "Longitudinal fissures." The longitudinal fissures are deep grooves that divide the cerebral hemispheres into left and right halves. They are the largest and most prominent fissures in the brain, running along the midline from the front to the back. The cerebral hemispheres are responsible for higher cognitive functions, and the longitudinal fissures play a crucial role in separating and organizing the different regions of the brain.

The subarachnoid space is located internal to the dura mater and is normally empty. It is a space filled with cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. It acts as a protective cushion, helping to absorb shocks and distribute nutrients to the central nervous system. The subarachnoid space is also important for the circulation of CSF, which helps to remove waste products and maintain a stable environment for the brain and spinal cord.

The medulla oblongata is responsible for controlling vital functions such as heart rate and breathing. It is located in the brainstem and serves as a relay center between the spinal cord and higher brain regions. The medulla oblongata contains various nuclei that regulate autonomic functions, including the cardiac and respiratory centers. These centers receive sensory information and send out motor signals to control heart rate, blood pressure, and breathing rate. Therefore, the medulla oblongata is the correct answer as it houses the vital centers for the control of visceral activities.

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The correct answer is "Blood vessels, pilomotor muscles, sweat glands, adrenal medulla." The sympathetic nervous system is responsible for the fight-or-flight response, which involves the release of adrenaline from the adrenal medulla. This response leads to increased blood flow to the muscles, dilation of blood vessels, activation of the sweat glands, and contraction of the pilomotor muscles (causing goosebumps). Therefore, these are the structures that are specifically affected by the sympathetic nervous system.

Preganglionic fibers synapse with several postganglionic fibers. This means that a single preganglionic neuron can activate multiple postganglionic neurons, leading to a widespread effect on the body. This allows for the sympathetic response to have a broad impact on various organs and tissues simultaneously.

The dorsal cavity holds the cranial and vertebral structures. The cranial cavity houses the brain, while the vertebral cavity contains the spinal cord. These structures are protected by the bones of the skull and vertebral column, respectively.