Nokea
What is the formula for calculating molarity?
- A. M = n/V
- B. M = n/L
- C. M = mol/L
- D. M = mol/dm³
Correct Answer: A
Rationale: The correct formula for calculating molarity is M = n/V. In this formula, 'M' represents molarity, 'n' represents the number of moles of solute, and 'V' represents the volume of the solution in liters. Molarity is defined as the number of moles of solute per liter of solution, hence the ratio of moles to volume. Choice B, 'M = n/L', is incorrect because 'L' should represent liters instead of the number of moles. Choice C, 'M = mol/L', is incorrect as it does not include the representation of the number of moles 'n'. Choice D, 'M = mol/dm³', is incorrect because 'dm³' is a volume unit equal to a liter, but the correct representation should be in terms of the volume of the solution in liters. Therefore, the correct answer is M = n/V.
You may also like to solve these questions
Endotoxins are toxic substances released by:
- A. Viruses
- B. Bacteria (gram-positive)
- C. Bacteria (gram-negative)
- D. Parasites
Correct Answer: C
Rationale: Endotoxins are toxic substances that are part of the outer membrane of the cell wall of gram-negative bacteria. These toxins are released when the bacteria are destroyed or during bacterial growth. Endotoxins can cause a variety of harmful effects in the host, including fever, inflammation, and septic shock. Viruses do not produce endotoxins; they are typically associated with producing viral proteins that can be toxic to host cells. Gram-positive bacteria produce exotoxins, which are different from endotoxins found in gram-negative bacteria. Parasites, though capable of causing diseases, are not typically associated with the production of endotoxins.
The tonsils and adenoids are part of the lymphatic system located in the:
- A. Chest cavity
- B. Abdominal cavity
- C. Head and neck region
- D. Pelvic cavity
Correct Answer: C
Rationale: The tonsils and adenoids are lymphatic tissues located in the head and neck region, specifically in the throat area. They are essential components of the immune system, acting as the first line of defense against infections that can enter through the nose and mouth. The tonsils are situated at the back of the throat, while the adenoids are positioned high in the throat behind the nose. Choices A, B, and D are incorrect as they do not correspond to the anatomical location of the tonsils and adenoids. Therefore, the correct answer is the head and neck region.
What is the function of introns in eukaryotic genes?
- A. They code for protein sequences.
- B. They are involved in gene regulation.
- C. They are removed during mRNA processing.
- D. They are non-functional remnants of ancient DNA.
Correct Answer: C
Rationale: A) Introns do not code for protein sequences. Exons are the segments of DNA that code for proteins.
B) While introns can indirectly influence gene regulation, their primary function is not directly involved in gene regulation.
C) Introns are non-coding regions of DNA that are transcribed into pre-mRNA but are removed during mRNA processing through a process called splicing. This allows only the exons to be included in the mature mRNA that will be translated into proteins.
D) While introns were once thought to be non-functional remnants of ancient DNA, research has shown that they can have regulatory functions and play a role in gene expression.
What is the process by which muscle tissue wastes away due to disuse or lack of nutrients?
- A. Hypertrophy
- B. Atrophy
- C. Fibrosis
- D. Rigor mortis
Correct Answer: B
Rationale: Atrophy is the correct term for the process by which muscle tissue wastes away due to disuse or lack of nutrients. It is essential to differentiate atrophy from hypertrophy, which is the increase in muscle size due to exercise or strength training. Fibrosis involves the formation of excess fibrous connective tissue, which is distinct from muscle wasting. Rigor mortis, on the other hand, is the stiffening of muscles that occurs after death and is not related to muscle wasting during life.
Vacuoles are large sacs for storage in plant cells. What is their main function in animal cells?
- A. Protein synthesis
- B. Waste storage and disposal
- C. Photosynthesis
- D. Cellular respiration
Correct Answer: B
Rationale: Vacuoles in animal cells primarily function in waste storage and disposal, helping to maintain cellular homeostasis by storing waste products and aiding in their removal from the cell. Unlike plant cells, animal cells do not typically use vacuoles for storage purposes such as water, nutrients, or pigments. Instead, animal cells rely on other organelles like lysosomes for waste management and maintaining cellular balance. Choices A, C, and D are incorrect because protein synthesis occurs in ribosomes, photosynthesis takes place in chloroplasts (absent in animal cells), and cellular respiration mainly occurs in mitochondria, respectively. Vacuoles in animal cells serve a different purpose compared to plant cells.