What is the role of calcium in muscle contraction?
A. Calcium binds to tropomyosin to expose the myosin-binding sites on actin.
B. Calcium is released from the sarcoplasmic reticulum to initiate the sliding of actin and myosin filaments.
C. Calcium activates the motor neurons to stimulate muscle contraction.
D. Calcium is required for the relaxation of muscles after contraction.
For those aiming to excel in their ATI TEAS test and secure admission into their desired nursing program, ExamGates offers an invaluable resource. Our platform features practice questions meticulously crafted by tutors who have previously aced the exam themselves. With ExamGates, you can access content that is 100% relevant to the test, accompanied by vivid images and illustrations. Additionally, our platform provides comprehensive explanations for both correct and incorrect answers, empowering you to fully grasp the material and optimize your study efforts. Take the first step towards your nursing aspirations with ExamGates today.
Muscle contraction is a complex process that involves the interaction between actin and myosin filaments in the muscle fibers. The sliding of these filaments is initiated by the release of calcium ions from the sarcoplasmic reticulum, a specialized organelle in muscle cells. The calcium ions bind to the protein troponin, which causes a conformational change in the troponin-tropomyosin complex, exposing the myosin-binding sites on actin. This allows the myosin heads to bind to actin, forming cross-bridges that pull the actin filaments towards the center of the sarcomere, resulting in muscle contraction.
Option a) is incorrect because calcium does not bind to tropomyosin directly, but rather binds to the protein troponin, causing a conformational change in the troponin-tropomyosin complex. Option c) is incorrect because calcium does not activate motor neurons, but rather is released from the sarcoplasmic reticulum in response to an action potential that travels down the motor neuron to the neuromuscular junction. Option d) is incorrect because calcium is required for muscle contraction, not relaxation. The relaxation of muscles after contraction is due to the active transport of calcium ions back into the sarcoplasmic reticulum, which allows the troponin-tropomyosin complex to return to its resting conformation, blocking the myosin-binding sites on actin and ending the cross-bridge cycle.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science Practice Test 3
Question 1:
What are the five regions of the vertebral column, starting from the top and moving downwards?
A. Cervical, thoracic, lumbar, sacral, coccygeal
B. Thoracic, cervical, lumbar, sacral, coccygeal
C. Lumbar, thoracic, cervical, coccygeal, sacral
D. Sacral, lumbar, cervical, thoracic, coccygeal
The Correct Answer is A.The vertebral column, also known as the spine or spinal column, is a series of bones called vertebrae that extend from the skull to the pelvis. It provides support for the body and protects the spinal cord. The five regions of the vertebral column, starting from the top and moving downwards, are:
- Cervical: This region is made up of seven vertebrae and is located in the neck. The first two cervical vertebrae, the atlas and the axis, are specialized to allow for head movement.
- Thoracic: This region is made up of twelve vertebrae and is located in the upper and middle back. The thoracic vertebrae are larger than the cervical vertebrae and articulate with the ribs.
- Lumbar: This region is made up of five vertebrae and is located in the lower back. The lumbar vertebrae are the largest and strongest of the vertebrae.
- Sacral: This region is made up of five fused vertebrae and is located in the pelvis. The sacrum forms the posterior wall of the pelvis and articulates with the hip bones.
- Coccygeal: This region is made up of four fused vertebrae and is located at the base of the vertebral column. The coccyx, or tailbone, provides atachment points for muscles and ligaments.
 |
Question 2:
Which of the following substances is excreted by the kidneys to regulate blood pressure?
A. renin
B. erythropoietin
C. calcitriol
D. urobilinogen
The Correct Answer is A.Renin is an enzyme that is produced by the kidneys and it acts to elevate blood pressure. When blood pressure falls, the kidneys secrete renin into the bloodstream ³.
 |
Question 3:
What is the difference between innate immunity and adaptive immunity?
A. Innate immunity is present at birth and provides immediate, non-specific protection against pathogens while adaptive immunity is developed over time and provides specific protection against particular pathogens.
B. Innate immunity involves the recognition of specific pathogens while adaptive immunity involves the recognition of general paterns of pathogens.
C. Innate immunity involves the production of antibodies while adaptive immunity involves the activation of phagocytes.
D. Innate immunity is activated by the lymphatic system while adaptive immunity is activated by the circulatory system.
The Correct Answer is A.Innate immunity is the first line of defense against pathogens and is present at birth. It provides immediate, non-specific protection against a wide range of pathogens, including bacteria, viruses, and fungi. Innate immunity involves physical barriers, such as skin and mucous membranes, as well as cellular and molecular components, such as phagocytes and cytokines.
Adaptive immunity, on the other hand, is developed over time and provides specific protection against particular pathogens. It involves the recognition of antigens, which are specific components of pathogens, by immune cells called lymphocytes. The lymphocytes then produce antibodies that are specific to the antigens, allowing for a targeted response to the pathogen. This process takes time to develop, as the immune system needs to encounter the pathogen and mount a response.
Overall, innate immunity provides immediate, non-specific protection while adaptive immunity provides specific protection that is tailored to the particular pathogen. Both forms of immunity work together to protect the body against pathogens.
Question 4:
What is the difference between a monosaccharide and a disaccharide?
A. Monosaccharides are composed of two sugar molecules while disaccharides are composed of a single sugar molecule.
B. Monosaccharides are simple sugars that cannot be further broken down into simpler sugars while disaccharides are composed of two simple sugars.
C. Monosaccharides are only found in plants while disaccharides are only found in animals.
D. Monosaccharides are used for energy storage while disaccharides are used for structural purposes.
The Correct Answer is B.Carbohydrates are one of the main types of biomolecules and are composed of monomers called monosaccharides. Monosaccharides are simple sugars that cannot be further broken down into simpler sugars. They are usually composed of 3 to 7 carbon atoms and have a general formula of (CH2O)n, where n is a number between 3 and 7. Examples of monosaccharides include glucose, fructose, and galactose.
When two monosaccharides are joined together by a glycosidic bond, they form a disaccharide. Disaccharides are composed of two simple sugars and can be broken down into their constituent monosaccharides by hydrolysis. Examples of disaccharides include sucrose, lactose, and maltose.
Option a) is incorrect because it describes the composition of a disaccharide, not a monosaccharide. Option
c) is incorrect because both monosaccharides and disaccharides can be found in both plants and animals.
Option d) is incorrect because both monosaccharides and disaccharides can be used for energy storage and
structural purposes, depending on their specific structure and function in the organism.
 |
Question 5:
Which of the following is the process by which DNA is copied into RNA?
A. Replication
B. Transcription
C. Translation
D. Mutation
The Correct Answer is B.Transcription is the process by which DNA is copied into RNA. During transcription, the DNA molecule unwinds and RNA polymerase reads the DNA sequence and synthesizes a complementary RNA molecule using the DNA as a template.
Question 6:
What is the name of the valve that separates the left atrium and left ventricle in the heart?
A. Aortic valve
B. Mitral valve
C. Tricuspid valve
D. Pulmonary valve
The Correct Answer is B.The mitral valve is located between the left atrium and left ventricle of the heart and helps to regulate the flow of blood between these chambers. It consists of two leaflets or flaps that open and close in response to changes in pressure as the heart beats.
During diastole, when the heart is relaxed and filling with blood, the mitral valve opens to allow blood to flow from the left atrium into the left ventricle. During systole, when the heart contracts to pump blood out of the left ventricle and into the systemic circulation, the mitral valve closes to prevent backflow of blood into the left atrium.
The mitral valve is one of four valves in the heart that help to ensure the unidirectional flow of blood through the heart and the rest of the circulatory system. Problems with the mitral valve, such as mitral valve prolapse or mitral stenosis, can lead to a range of symptoms and complications, including shortness of breath, fatigue, chest pain, and heart failure.
 |
Question 7:
Which of the following describes the function of ligaments?
A. Ligaments attach skeletal muscles to bone
B. Ligaments attach two bones
C. Ligaments attach bones to tendons
D. Ligaments attach skeletal muscles to tendons
The Correct Answer is B.Ligaments are tough bands of fibrous tissue that connect two bones together in a joint. They provide stability and support to the joint, preventing excessive movement and helping to maintain proper alignment of the bones.
Question 8:
What is the role of the epididymis in sperm maturation?
A. The epididymis produces sperm cells.
B. The epididymis stores and protects sperm cells until ejaculation.
C. The epididymis is responsible for the transport of sperm cells from the testes to the urethra.
D. The epididymis provides nourishment to sperm cells.
The Correct Answer is B.The epididymis is a coiled tube located at the back of each testicle where the sperm mature and are stored until ejaculation. Sperm are produced in the testes and then transported to the epididymis where they undergo maturation and become motile. The epididymis provides a protective environment for the sperm, allowing them to mature and become more resilient to external stressors. During ejaculation, the sperm are transported from the epididymis to the vas deferens and then to the urethra for ejaculation.
 |
Question 9:
Which of the following is responsible for carrying amino acids to ribosomes during protein synthesis?
A. tRNA
B. mRNA
C. rRNA
D. DNA
The Correct Answer is A.Transfer RNA (tRNA) is responsible for carrying amino acids to ribosomes during protein synthesis. Each tRNA molecule has a specific anticodon that matches a codon on the messenger RNA (mRNA) molecule. The tRNA molecule binds to the mRNA codon and brings the corresponding amino acid to the ribosome, where it is added to the growing polypeptide chain.
 |
Question 10:
Which of the following is a chemical property of a substance?
A. Density
B. Melting point
C. Boiling point
D. Reactivity with acid
The Correct Answer is D.Chemical properties are characteristics of a substance that describe its ability to undergo a chemical change or reaction with another substance.
Reactivity with acid is a chemical property because it describes how a substance will react with an acid to produce a new substance. Density, melting point, and boiling point are physical properties that describe how a substance behaves under certain conditions but do not involve a chemical change or reaction.