Nokea
Which macromolecule serves as the repository of genetic information in all living organisms?
- A. Ribonucleic acid (RNA)
- B. Deoxyribonucleic acid (DNA)
- C. Protein
- D. Carbohydrate
Correct Answer: B
Rationale: - DNA is the macromolecule that serves as the repository of genetic information in all living organisms. It carries the genetic instructions necessary for the growth, development, functioning, and reproduction of organisms.
- RNA (option A) is involved in various cellular processes, including protein synthesis, but DNA is the primary molecule responsible for storing genetic information.
- Proteins (option C) are essential for various cellular functions but do not serve as the primary repository of genetic information.
- Carbohydrates (option D) are important for energy storage and structural support but do not store genetic information.
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Why are noble gas elements generally unreactive?
- A. They are too large and cannot form bonds easily.
- B. They lack valence electrons in their outermost shell.
- C. They have strong bonds within their own molecules.
- D. They have already achieved stable electron configurations.
Correct Answer: D
Rationale: The correct answer is D. Noble gas elements are generally unreactive because they have already achieved stable electron configurations by having a full outer electron shell. This full shell makes them very stable and unlikely to gain, lose, or share electrons with other elements. Choices A, B, and C are incorrect because noble gases are not unreactive due to being too large to form bonds easily (A), lacking valence electrons in their outermost shell (B), or having strong bonds within their own molecules (C).
What is the term for the small air sacs in the lungs where gas exchange (oxygen and carbon dioxide) takes place?
- A. Bronchi
- B. Alveoli
- C. Trachea
- D. Bronchioles
Correct Answer: B
Rationale: The correct answer is B: Alveoli. The alveoli are the small air sacs in the lungs where gas exchange occurs. Oxygen from the air we breathe passes into the bloodstream through the alveoli, while carbon dioxide from the bloodstream passes out of the body through the alveoli. Choice A, Bronchi, are the main airways in the lungs and not the site of gas exchange. Choice C, Trachea, refers to the windpipe, which is a different structure than the alveoli. Choice D, Bronchioles, are smaller airways branching off from the bronchi and are not where gas exchange primarily occurs.
What is the significance of cell division?
- A. Growth and repair of tissues
- B. Sexual reproduction
- C. Genetic diversity
- D. All of the above
Correct Answer: D
Rationale: Cell division is a fundamental process that serves multiple critical functions in living organisms. It is essential for the growth and repair of tissues by enabling the formation of new cells to replace old or damaged ones. Moreover, cell division plays a pivotal role in sexual reproduction as it is involved in the production of gametes necessary for fertilization. Additionally, cell division contributes to genetic diversity through processes like meiosis, which leads to the formation of genetically distinct gametes. Therefore, the correct answer is D, 'All of the above,' as cell division is significant for growth, repair, sexual reproduction, and genetic diversity. Choices A, B, and C are incorrect because they each represent only one aspect of the significance of cell division, whereas the correct answer encompasses all the essential roles that cell division plays in living organisms.
The immune response can be categorized into two main branches:
- A. Humoral and cellular
- B. Innate and adaptive
- C. Primary and secondary
- D. Active and passive
Correct Answer: A
Rationale: - The immune response can be broadly categorized into two main branches: the humoral immune response and the cellular immune response.
- The humoral immune response involves the production of antibodies by B cells and is primarily responsible for defending against extracellular pathogens such as bacteria and viruses in the bloodstream and tissues.
- The cellular immune response involves the activation of T cells, which can directly kill infected cells or help coordinate the immune response. This branch is crucial for combating intracellular pathogens like viruses and some bacteria.
- Options B, C, and D do not accurately represent the main branches of the immune response and are therefore incorrect.
Which type of muscle tissue contracts involuntarily and is found in organs like the heart and intestines?
- A. Skeletal muscle
- B. Cardiac muscle
- C. Smooth muscle
- D. All of the above
Correct Answer: C
Rationale: Smooth muscle is the type of muscle tissue that contracts involuntarily and is found in organs like the heart and intestines. Skeletal muscle is responsible for voluntary movements, like those involved in skeletal system actions. Cardiac muscle is found in the heart and contracts involuntarily, but it is distinct from smooth muscle. The heart's muscle is specialized and forms the myocardium, which is not the same as the smooth muscle found in organs like the intestines. Therefore, the correct answer is C) Smooth muscle.