Nokea
Which of the following is the main organ responsible for producing antibodies?
- A. Thymus gland
- B. Spleen
- C. Bone marrow
- D. Lymph nodes
Correct Answer: C
Rationale: Antibodies are proteins produced by specialized white blood cells called B lymphocytes (B cells). These B cells mature in the bone marrow, where they undergo a process of differentiation and maturation to become plasma cells that secrete antibodies. The bone marrow is the primary site for the production of B cells and antibodies in the immune system. The thymus gland is responsible for the maturation of T lymphocytes (T cells), not antibody production. The spleen and lymph nodes play roles in filtering and trapping pathogens but are not the main organs responsible for producing antibodies.
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What is the primary function of nervous tissue?
- A. Movement
- B. Protection
- C. Communication and coordination
- D. Nutrient transport
Correct Answer: C
Rationale: The primary function of nervous tissue is communication and coordination within the body. Nervous tissue is composed of neurons that transmit electrical signals and supporting cells known as neuroglia. Movement is primarily controlled by the muscular system, protection is mainly provided by the skeletal system and immune system, and nutrient transport is carried out by the circulatory system. Therefore, choices A, B, and D are incorrect as they do not align with the primary function of nervous tissue.
Which structure in the respiratory system serves as the 'windpipe' that conducts air from the larynx to the bronchi?
- A. Trachea
- B. Larynx
- C. Bronchi
- D. Alveoli
Correct Answer: A
Rationale: The correct answer is the trachea. The trachea, commonly referred to as the 'windpipe,' is a vital structure in the respiratory system that connects the larynx to the bronchi. It is made up of cartilage rings that provide structural support, preventing collapse and ensuring the unobstructed flow of air into the lungs. The trachea plays a crucial role in facilitating the passage of air from the upper respiratory tract to the lower respiratory tract. The larynx is responsible for sound production and is located above the trachea. The bronchi are the two main branches that lead from the trachea into the lungs, further branching into smaller airways. Alveoli are the tiny air sacs where gas exchange occurs in the lungs, but they are not the structure that serves as the 'windpipe' for air passage in the respiratory system.
What is the difference between a germline mutation and a somatic mutation?
- A. Germline mutations are passed to offspring, while somatic mutations are not.
- B. Germline mutations occur in reproductive cells, while somatic mutations occur in body cells.
- C. Germline mutations only affect genes, while somatic mutations can affect any DNA.
- D. Germline mutations are always beneficial, while somatic mutations are always harmful.
Correct Answer: B
Rationale: Rationale:
- Germline mutations are changes in the DNA of reproductive cells (sperm or egg cells) and can be passed on to offspring, affecting all cells in the resulting organism.
- Somatic mutations are changes in the DNA of non-reproductive cells (body cells) and are not passed on to offspring. These mutations only affect the cells that arise from the mutated cell.
- Option A is incorrect because somatic mutations are not passed to offspring.
- Option C is incorrect because both germline and somatic mutations can affect any DNA.
- Option D is incorrect because the effects of mutations, whether germline or somatic, can be beneficial, harmful, or have no significant impact.
What is the breakdown product of ATP (adenosine triphosphate) that provides energy for muscle contraction?
- A. Glucose
- B. Creatine phosphate
- C. ADP (adenosine diphosphate)
- D. Lactic acid
Correct Answer: C
Rationale: ADP (adenosine diphosphate) is the correct breakdown product of ATP that provides energy for muscle contraction. When ATP is hydrolyzed to ADP, energy is released and utilized by the muscles for various cellular processes, including muscle contraction. Glucose serves as an energy source but is not the direct breakdown product of ATP for muscle contraction. Creatine phosphate plays a role in energy storage and transfer, but it is not the immediate breakdown product of ATP. Lactic acid is produced during anaerobic metabolism and is not the direct provider of energy for muscle contraction.
The process by which a single-celled organism divides into two identical daughter cells is called
- A. Conjugation
- B. Binary fission
- C. Endocytosis
- D. Mitosis
Correct Answer: B
Rationale: Rationale:
A) Conjugation is a process in which genetic material is transferred between two bacterial cells through a conjugation tube. It does not involve the division of a single-celled organism into two identical daughter cells.
B) Binary fission is the process by which a single-celled organism, such as a bacterium, divides into two identical daughter cells. This is a common method of reproduction in prokaryotic organisms.
C) Endocytosis is a cellular process in which cells engulf external materials by wrapping them in a vesicle. It is not a method of cell division.
D) Mitosis is a type of cell division that occurs in eukaryotic cells, leading to the production of two daughter cells with identical genetic material. However, the question specifically refers to a single-celled organism, which typically undergoes binary fission for reproduction.