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Example Questions
Example Question #231 : General Biology
Growth in long bones must occur at the __________.
epiphysis
suture
epiphyseal plate
diaphysis
epiphyseal plate
Growth in long bones occurs at the epiphyseal plate, a region of hyaline cartilage at the metaphysis of the bone. In adolescents and children, cartilage cells are ossified by osteoblasts to increase bone length. Once adulthood is reached, the epiphyseal plate becomes the epiphyseal line at the junction of the epiphysis and the diaphysis (the center of the bone). The diaphysis and epiphysis themselves are composed of mature ossified bone and do not proliferate (they are simply added to by transformation of cells in the epiphyseal plate). A suture is a fibrous joint of the cranium and does not contribute to the development of long bones.
Example Question #231 : General Biology
The length of long bones is increased via the hypertrophy and eventual apoptosis of chondrocytes which leave cavities that are then colonized by osteoprogenitor cells. This process is referred to as __________.
endochondral mineralization
osteoblast mineralization
endochondral ossification
apoptotic ossification
endochondral ossification
Long bones are lengthened during childhood and adolescence via a process referred to as endochondral ossification. In this process, chondrocytes of the growth plate hypertrophy and eventual die, leaving cavities that are then colonized by osteoprogenitor cells. These osteoprogenitor cells then differentiate into osteoblasts, which mineralize the newly forming bone. None of the other answers are actual processes in bone formation or physiology.
Example Question #12 : Bone Physiology
Which of the following is not a common site of hematopoietic bone marrow in an adult?
Sternum
Skull
Tibia and fibula
Pelvis
Tibia and fibula
In adults, hematopoietic bone marrow is generally confined to the flat bones, including the sternum, the skull, the ribs, and the pelvis. Hematopoietic bone marrow also exists in the proximal end of the femur in most adults, but is not generally found in the tibia or fibula.
Example Question #232 : General Biology
Muscle is attached to the periosteum of bone via which of the following?
Ligaments
Articular cartilage
Sutures
Tendons
Tendons
Muscle attaches to bone via tendons, fibrous extensions of the sheath of the muscle body that are primarily composed of tightly packed collagen fibers. In comparison, ligaments attach bones to other bones without involvement with a muscle, such as the ligaments between the metacarpals of the wrist. Sutures are fibrous joints of the cranium, and hyaline cartilage is at the point of articulation of many bones but it is neither incorporated into muscle structure, nor does it attach to the bone with which it articulates. Rather, articular cartilage primarily serves to allow bones to glide more easily over each other during movement.
Example Question #1 : Muscle Physiology
The individual unit of muscle contraction in a muscle fibril is referred to as the __________.
sliding filament
sarcolemma
sarcoplasmic reticulum
sarcomere
sarcomere
The individual contractile unit of a muscle fibril is referred to as the sarcomere. These units are made of actin and myosin filaments and joined by Z-lines. The sliding filament theory refers to the idea that muscle contraction is the result of myosin strands within the fibril pulling themselves along actin strands similar to pulling on a rope, which shortens the whole sarcomere. The sarcolemma is the specialized cell membrane around the muscle fibril, and the sarcoplasmic reticulum is the smooth endoplasmic reticulum found within the muscle cell.
Example Question #2 : Muscle Physiology
Which of the following is the correct order of structures in a skeletal muscle, from largest to smallest?
Fiber - fibril - fascicle
Fascicle - fiber - fibril
Fascicle - fibril - fiber
Fibril - fascicle - fiber
Fiber - fascicle - fibril
Fascicle - fiber - fibril
The largest unit of muscle tissue is the fascicle. Each fascicle is made up of a bundle of muscle fibers, and every muscle fiber is made up of many fibrils (called myofibrils).
Example Question #233 : General Biology
The muscle body is encased in which of the following?
The epimysium
The endomysium
The perimysium
None of these
The epimysium
The muscle body is encased in a fibrous elastic sheath called the epimysium (epi meaning on or above and mys meaning muscle). It is composed of dense irregular connective tissue and is continuous with tendon fibers. The perimysium surrounds muscle fascicles, while the endomysium surrounds muscle fibers.
Example Question #1 : Muscle Physiology
Which of the following correctly describes an isometric muscle contraction?
There is a rapid burst of mechanical energy for a short powerful movement
The length of the muscle shortens and the angle of the joint changes during the contraction
This form of contraction can either be eccentric or concentric
The amount of muscle tension increases without any change in the length of the muscle or the angle of the joint
The amount of muscle tension increases without any change in the length of the muscle or the angle of the joint
Isometric muscle contraction are those in which the tension in the muscle increases, but the muscle does not change length, nor does the angle of the joint change. An example would be attempting to push or lift an object that is too heavy to move. This is in contrast to isotonic contraction, in which muscle tension remains constant, but the muscle length and joint angle both change.
Example Question #5 : Muscle Physiology
During contraction, the A band of the sarcomere does which of the following?
It lengthens
It shortens
It does not change
It thickens
It does not change
The A band in the sarcomere is created by the bipolar myosin filaments, joined at the M band. During contraction, the heads of the myosin filaments bind with the actin filament and pull it toward the M band at the center of the sarcomere. The myosin filaments do not themselves change length, and because of that the width of the A band does not change during contraction.
Example Question #234 : General Biology
In the sliding filament theory of muscle contraction, all but which of the following are functions of ATP?
ATP does all of these things during muscle contraction
It moves tropomyosin off of actin binding sites
It allows the myosin head to detach from the actin filament
It moves the myosin head into a high energy "cocked" position
It moves tropomyosin off of actin binding sites
According to the sliding filament theory of muscle contraction, ATP binds to the myosin head and is hydrolyzed to ADP and inorganic phosphate. The energy released during this change draws the myosin head back into a high energy state, from which it is able to bind with actin and execute its "power stroke," leading to muscle contraction. ADP and inorganic phosphate then are released from the myosin head and replaced by a new molecule of ATP, which allows the myosin head to detach from the actin binding site.
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