Which plane divides the body into anterior (front) and posterior (back) halves?
- A. Sagittal/Median Plane
- B. Frontal/Coronal Plane
- C. Transverse/Cross-Section Plane
- D. Horizontal Plane
Correct Answer: B
Rationale: The correct answer is B - Frontal/Coronal Plane. This plane divides the body into anterior (front) and posterior (back) halves. The sagittal plane divides the body into left and right halves, the transverse plane separates the body into superior (upper) and inferior (lower) portions. The horizontal plane is not a standard anatomical term for body division and does not provide division into front and back halves.
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Which muscle is voluntary, striated, and found attached to bones?
- A. Smooth muscle
- B. Skeletal muscle
- C. Cardiac muscle
- D. Epithelial muscle
Correct Answer: B
Rationale: The correct answer is B, Skeletal muscle. Skeletal muscle is both voluntary and striated, as well as attached to bones, allowing for movement. Smooth muscle, on the other hand, is involuntary and typically found in the walls of internal organs, controlling functions like digestion. Cardiac muscle is also striated, but it is involuntary and specifically found in the heart, responsible for cardiac contractions to pump blood. 'Epithelial muscle' is an incorrect term; epithelial tissue is a type of tissue that forms the linings of various body surfaces and structures, not a muscle type.
Which type of blood cell is primarily responsible for fighting infections?
- A. Red blood cell
- B. White blood cell
- C. Platelet
- D. Plasma
Correct Answer: B
Rationale: The correct answer is B: White blood cell. White blood cells are the primary cells responsible for fighting infections and foreign invaders in the body. Red blood cells carry oxygen to tissues, platelets help in blood clotting to prevent excessive bleeding, and plasma is the liquid component of blood that carries cells and nutrients. White blood cells, also known as leukocytes, play a crucial role in the immune system by identifying and destroying pathogens, such as bacteria, viruses, and other harmful substances. Therefore, they are the key players in the body's defense against infections, making them the correct answer in this scenario. While red blood cells, platelets, and plasma have essential functions in the body, they are not primarily responsible for combating infections like white blood cells.
Which of the following types of stem cells can differentiate into any cell type, including forming an entire organism?
- A. Totipotent stem cells
- B. Multipotent stem cells
- C. Pluripotent stem cells
- D. Hematopoietic stem cells
Correct Answer: A
Rationale: Totipotent stem cells possess the unique ability to differentiate into any cell type, including forming an entire organism. These cells have the highest potency level and can give rise to both embryonic and extraembryonic cell types, allowing them to develop into a complete organism. Multipotent stem cells (Choice B) can differentiate into a limited range of cell types within a specific tissue or organ. Pluripotent stem cells (Choice C) can differentiate into any cell type in the body except for those needed to support and develop a fetus. Hematopoietic stem cells (Choice D) are a type of multipotent stem cell that can differentiate into various blood cell types.
What are the components of the male internal genitalia and their functions?
- A. Prostate gland: produces hormones
- B. Testes: produce sperm and testosterone
- C. Epididymis: stores and matures sperm
- D. Urethra: conducts urine and semen out of the body
Correct Answer: B
Rationale: The testes play a crucial role in male reproduction by producing sperm and testosterone. Sperm production is essential for fertility, while testosterone is responsible for the development of secondary sexual characteristics. The epididymis functions to store and mature sperm, allowing them to become motile. The prostate gland, not listed among the choices, secretes fluid that nourishes and protects sperm. The urethra serves the purpose of conducting both urine and semen out of the body, enabling the excretion of waste and reproductive fluids.
What is the structure and function of elastic arteries?
- A. They are the smallest arteries and constrict and dilate frequently.
- B. They are medium-sized arteries that distribute blood to various organs.
- C. They are the largest arteries and stretch and recoil to accommodate blood pressure changes.
- D. They are thin-walled arteries that supply blood to the capillaries.
Correct Answer: C
Rationale: The corrected answer is C. Elastic arteries, like the aorta, are the largest arteries in the body. They possess elastic fibers in their walls, allowing them to stretch and recoil in response to the pulsatile nature of blood flow from the heart. This elasticity helps to maintain blood pressure by absorbing the pressure waves generated by the heart's contractions and ensuring continuous blood flow to the organs. Choices A, B, and D are incorrect because elastic arteries are not the smallest arteries, do not constrict and dilate frequently, are not medium-sized arteries for distributing blood to various organs, and are not thin-walled arteries supplying blood to capillaries. Elastic arteries have a specific structure and function related to their ability to accommodate blood pressure changes due to their elastic properties, which is essential for the cardiovascular system's proper functioning.