What is the name of the dome-shaped muscle that plays a key role in breathing?

A. Diaphragm

B. Trachea

C. Bronchus

D. Alveoli

Answer Explanation:

The diaphragm is a dome-shaped muscle that plays a key role in breathing. It separates the thoracic cavity, which contains the heart and lungs, from the abdominal cavity. When the diaphragm contracts, it moves downward and increases the volume of the thoracic cavity, allowing air to ﬂow into the lungs. When it relaxes, it moves upward and decreases the volume of the thoracic cavity, forcing air out of the lungs.

Therefore, the Correct Answer is A.

Q #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
Answer Explanation

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:
1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
Q #2: 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.

Answer Explanation

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.
Q #3: 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.

Answer Explanation

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.
Q #4: 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.

Answer Explanation

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.
Q #5: Which of the following is NOT one of the four primary tissue types found in the human body?

A. Epithelial

B. Nervous

C. Connective

D. Exocrine glandular

Answer Explanation

Exocrine glandular is not one of the four primary tissue types found in the human body. The four primary tissue types are epithelial, nervous, connective, and muscle.
Q #6: Which of the following is a chemical property of a substance?

A. Density

B. Melting point

C. Boiling point

D. Reactivity with acid

Answer Explanation

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.
Q #7: Which of the following is an example of a double-blind study?

A. Participants are randomly assigned to a treatment group or a control group

B. Participants and researchers both know which group participants are assigned to

C. Participants do not know which group they are assigned to, but researchers do

D. Both participants and researchers do not know which group participants are assigned to

Answer Explanation

A double-blind study is a research design in which neither the participants nor the researchers know which group participants are assigned to. This is done to minimize bias and ensure that the results of the study are as objective as possible. In a double-blind study, the treatment and control groups are randomly assigned, and the participants and researchers are unaware of which group each participant is assigned to. Option a) is an example of a randomized controlled trial, which is a common research design, but it is not necessarily double-blind. Option b) is an example of an open-label study, in which both the participants and the researchers know which group each participant is assigned to. Option c) is an example of a single-blind study, in which the participants do not know which group they are assigned to, but the researchers do.
Q #8: What is the chemical formula for water?

A. H2O

B. CO2

C. NaCl

D. C6H12O6

Answer Explanation

The chemical formula for water is H2O. It consists of two hydrogen atoms and one oxygen atom.
Q #9: What is the largest organ in the human body by surface area?

A. Brain

B. Heart

C. Liver

D. Skin

Answer Explanation

The largest organ in the human body by surface area is the skin. It covers the entire external surface of the body and has an average surface area of about 20 square feet in adults.
Q #10: What is the molecular geometry of a molecule of sulphur dioxide (SO2)?

A. Linear

B. Trigonal planar

C. Bent

D. Tetrahedral

Answer Explanation

The molecular geometry of a molecule of sulphur dioxide (SO2) is bent or V-shaped. This is because of the presence of two lone pairs on the sulfur atom, which cause repulsion and distort the bond angles in the molecule.

SO2 has a central sulfur atom bonded to two oxygen atoms by double bonds. The two double bonds and the two lone pairs of electrons on sulfur result in a trigonal planar arrangement of electron pairs around the sulfur atom. However, the repulsion between the lone pairs causes the two oxygen atoms to be pulled closer together, resulting in a bent or V-shaped molecular geometry.

The bent molecular geometry of SO2 aﬀects its properties, such as its polarity and reactivity. SO2 is a polar molecule due to the asymmetric distribution of electrons, which results in a partial positive charge on the sulfur atom and partial negative charges on the oxygen atoms. This polarity makes SO2 a good solvent and reactant in chemical reactions, as well as a contributor to air pollution and acid rain.