Nokea
Which organ produces insulin?
- A. Pancreas
- B. Liver
- C. Stomach
- D. Kidneys
Correct Answer: A
Rationale: Insulin is a hormone that regulates blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. The pancreas, located behind the stomach, is the organ responsible for producing insulin. Within the pancreas, specialized cells known as beta cells synthesize and secrete insulin in response to changes in blood glucose levels. The liver, although vital for metabolism, does not produce insulin. Similarly, the stomach and kidneys do not play a role in insulin production. Hence, the correct answer is the pancreas.
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Which type of white blood cell directly attacks and destroys pathogens like bacteria and viruses?
- A. Neutrophils
- B. Lymphocytes
- C. Monocytes
- D. Eosinophils
Correct Answer: A
Rationale: Neutrophils are a type of white blood cell that plays a crucial role in the immune system's response to infections. They are phagocytes, meaning they engulf and destroy pathogens like bacteria and viruses. Neutrophils are the most abundant type of white blood cell and are known for their rapid response to infections, making them the primary cell type that directly attacks and destroys pathogens. Lymphocytes, although important in adaptive immunity, are not primarily responsible for directly attacking and destroying pathogens. Monocytes are involved in phagocytosis and immune response regulation but are not the primary cell type for direct pathogen destruction like neutrophils. Eosinophils are mainly involved in combating multicellular parasites and are not the primary cell type for targeting bacteria and viruses.
What tool helps scientists identify and classify organisms based on their shared characteristics?
- A. Binomial nomenclature
- B. Cladistics
- C. Dichotomous key
- D. Domain-based classification
Correct Answer: C
Rationale: A) Binomial nomenclature is a system used to give each organism a two-part scientific name (genus and species) but does not help in identifying or classifying organisms based on shared characteristics. B) Cladistics is a method of classification based on evolutionary relationships and shared characteristics, but it is not a tool used for identifying organisms. C) A dichotomous key is a tool that helps scientists identify and classify organisms based on their shared characteristics by presenting a series of choices leading the user to the correct identification. D) Domain-based classification is a system of grouping organisms into three domains (Bacteria, Archaea, Eukarya) based on molecular and genetic similarities, but it is not a tool used for identifying organisms based on shared characteristics.
What is the waxy or oily substance produced by sebaceous glands that helps lubricate the skin and hair?
- A. Keratin
- B. Melanin
- C. Sebum
- D. Sweat
Correct Answer: C
Rationale: Sebum is the waxy or oily substance produced by sebaceous glands. It helps lubricate the skin and hair, keeping them moisturized and protected. Keratin is a protein that makes up hair, skin, and nails, providing structure and strength. Melanin is a pigment that gives color to the skin, hair, and eyes, providing protection against UV radiation. Sweat is a watery fluid produced by sweat glands to help regulate body temperature by cooling the body through evaporation.
What is the net ionic equation for the reaction: 2HCl(aq) + Ba(OH)2(aq) → 2H2O(l) + BaCl2(aq)?
- A. 2H+(aq) + 2OH-(aq) → 2H2O(l)
- B. 2HCl(aq) + Ba(OH)2(aq) → BaCl2(aq) + 2H2O(l)
- C. 2H+(aq) + Ba2+(aq) → Ba2+(aq) + 2H+(aq)
- D. Ba(OH)2(aq) + HCl(aq) → BaCl2(aq) + 2H2O(l)
Correct Answer: A
Rationale: In the given reaction, the complete ionic equation is: 2H+(aq) + 2Cl-(aq) + Ba2+(aq) + 2OH-(aq) → 2H2O(l) + Ba2+(aq) + 2Cl-(aq). Spectator ions (Ba2+ and Cl-) do not participate in the net ionic equation, which simplifies to: 2H+(aq) + 2OH-(aq) → 2H2O(l). This equation represents the significant species involved in the reaction, showcasing the formation of water from the combination of hydrogen ions and hydroxide ions, resulting in the production of water molecules.
What is the function of a cell wall?
- A. To provide structural support for the cell
- B. To transport substances in and out of the cell
- C. To synthesize proteins and lipids
- D. To store genetic material
Correct Answer: A
Rationale: The cell wall is a rigid layer that surrounds the cell membrane in plant cells, fungi, and some bacteria. Its main function is to provide structural support and protection for the cell, helping maintain the cell's shape and preventing it from bursting or collapsing. The cell wall also allows for the passage of water, ions, and other molecules in and out of the cell. Options B, C, and D are incorrect because those functions are typically carried out by other cellular structures. Option B is performed by the cell membrane, option C by ribosomes, and option D by the nucleus, which stores genetic material.