1. What is the scientific term for the involuntary rhythmic contraction and relaxation of the heart muscle?

A. Peristalsis
B. Myogenesis
C. Myocardial contractility
D. Systole and diastole

Correct answer: D

Rationale: The correct answer is D: Systole and diastole. Systole refers to the phase of the heartbeat when the heart muscle contracts and pumps blood out, while diastole is the phase when the heart muscle relaxes and fills with blood. This rhythmic contraction and relaxation of the heart muscle is crucial for maintaining blood circulation throughout the body. Peristalsis (option A) is the involuntary constriction and relaxation of the muscles of the gastrointestinal tract that pushes contents forward. Myogenesis (option B) is the formation of muscle tissue. Myocardial contractility (option C) refers to the ability of the heart muscle to contract. Therefore, the most appropriate term for the described process is systole and diastole.

2. Lymph nodes are small, bean-shaped structures found along lymphatic vessels. What is their primary function?

A. To store excess lymph fluid
B. To produce red blood cells
C. To filter lymph and fight infection
D. To transport lymph to the heart

Correct answer: C

Rationale: The correct answer is C. Lymph nodes are crucial components of the immune system. Their primary function is to filter lymph, which is a clear fluid containing white blood cells, and to fight off infections. Lymph nodes contain specialized cells that help trap and destroy pathogens, such as bacteria and viruses, that may be present in the lymph fluid. This process helps to prevent the spread of infections throughout the body and plays a key role in maintaining overall immune function. Therefore, option C, 'To filter lymph and fight infection,' is the most appropriate description of the primary function of lymph nodes.

3. What is the acceleration due to gravity near the Earth's surface?

A. 9.8 meters per second squared (m/sÃ‚Â²)
B. 6.3 meters per second squared (m/sÃ‚Â²)
C. 5.0 meters per second squared (m/sÃ‚Â²)
D. 12.5 meters per second squared (m/sÃ‚Â²)

Correct answer: a

Rationale: The acceleration due to gravity near the Earth's surface is approximately 9.8 m/sÃ‚Â²

4. Identify the spectator ions in the reaction: 2KCl + Pb(NO3)2 â†’ 2KNO3 + PbCl2.

A. K+ and NO3-
B. K+ and Cl-
C. Pb2+ and NO3-
D. Pb2+ and Cl-

Correct answer: B

Rationale: Rationale: - In the reaction, potassium ions (K+) and chloride ions (Cl-) are present on both sides of the equation. They are not involved in the formation of the products and remain unchanged. - Lead ions (Pb2+) and nitrate ions (NO3-) are involved in the formation of the products potassium nitrate (KNO3) and lead(II) chloride (PbCl2). - Therefore, the spectator ions in this reaction are K+ and Cl-.

5. The lymphatic system is primarily responsible for:

A. Transporting nutrients throughout the body
B. Removing excess fluids and waste products from tissues
C. Producing red blood cells
D. Regulating body temperature

Correct answer: B

Rationale: The correct answer is B: 'Removing excess fluids and waste products from tissues.' The lymphatic system plays a crucial role in maintaining fluid balance in the body by collecting excess interstitial fluid and returning it to the bloodstream. This system also helps in removing waste products, pathogens, and toxins from tissues, contributing to the body's immune response. Options A, C, and D are incorrect because transporting nutrients, producing red blood cells, and regulating body temperature are primarily the functions of other systems in the body such as the circulatory system, bone marrow, and the thermoregulatory system, respectively.

6. What is the shape of the DNA molecule?

A. Linear
B. Circular
C. Double helix
D. Straight chain

Correct answer: C

Rationale: Rationale: The shape of the DNA molecule is a double helix. This structure was first described by James Watson and Francis Crick in 1953. The double helix shape consists of two strands that are twisted around each other in a spiral. This shape allows DNA to be compactly stored within the cell nucleus and provides stability to the molecule. The other options (A) Linear, (B) Circular, and (D) Straight chain do not accurately describe the shape of the DNA molecule.