Which of the following is responsible for carrying amino acids to ribosomes during protein synthesis?

A. tRNA

B. mRNA

C. rRNA

D. DNA

Answer Explanation:

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.

Therefore, the Correct Answer is A.

Q #1: 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 #2: Which of the following is a function of the respiratory system?

A. Transport of nutrients to the body

B. Pumping of blood to the lungs

C. Exchange of gases between the body and the environment

D. Digestion of food in the stomach

Answer Explanation

One of the main functions of the respiratory system is to facilitate the exchange of gases between the body and the environment. During inhalation, air enters the lungs and oxygen is absorbed into the bloodstream. During exhalation, carbon dioxide is removed from the body and expelled into the environment.
Q #3: What is the name of the hormone that regulates blood sugar levels in the human body?

A. Insulin

B. Glucagon

C. Estrogen

D. Testosterone

Answer Explanation

Insulin is a hormone produced by the pancreas that plays a crucial role in regulating the levels of glucose (sugar) in the blood. After a person eats a meal, the levels of glucose in the blood rise, which stimulates the pancreas to release insulin into the bloodstream. Insulin acts on various cells in the body, particularly those in the liver, muscles, and adipose tissue, to promote the uptake, use, and storage of glucose.

Insulin helps to lower the levels of glucose in the blood by increasing the uptake of glucose by cells, stimulating the liver and muscle cells to store glucose in the form of glycogen, and inhibiting the production and release of glucose by the liver. This process is known as glucose homeostasis, and it helps to keep the levels of glucose in the blood within a normal range.

Deficiencies or abnormalities in insulin production or function can lead to a range of metabolic disorders, including type 1 and type 2 diabetes. In type 1 diabetes, the body does not produce enough insulin, while in type 2 diabetes, the body becomes resistant to the eﬀects of insulin, leading to elevated levels of glucose in the blood.
Q #4: 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 #5: What is the difference between a physical change and a chemical change?

A. A physical change involves the rearrangement of atoms and molecules while a chemical change involves the formation of new substances with diﬀerent chemical properties.

B. A physical change involves the change of one state of mater to another while a chemical change involves the change of one substance into another.

C. A physical change involves the breaking of chemical bonds while a chemical change involves the breaking of intermolecular forces.

D. A physical change involves the release of energy while a chemical change involves the absorption of energy.

Answer Explanation

A physical change is a change that aﬀects the physical properties of a substance, but does not change its chemical identity. Physical changes include changes in state, such as melting or boiling, changes in shape or size, and changes in phase, such as the dissolution of a solid in a liquid. In a physical change, the atoms and molecules of the substance are rearranged, but no new substances are formed.

A chemical change, on the other hand, is a change that results in the formation of new substances with diﬀerent chemical properties. Chemical changes involve the breaking of chemical bonds between atoms and the formation of new bonds to create new compounds. Chemical changes are usually accompanied by a change in color, the formation of a gas or a solid, or the release or absorption of energy.

Overall, the main diﬀerence between a physical change and a chemical change is that a physical change only aﬀects the physical properties of a substance while a chemical change results in the formation of new substances with diﬀerent chemical properties.
Q #6: 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 #7: 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 #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.

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 #9: Which of the following is responsible for carrying amino acids to ribosomes during protein synthesis?

A. tRNA

B. mRNA

C. rRNA

D. DNA

Answer Explanation

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.
Q #10: 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.