Nokea
What is the primary function of white blood cells?
- A. To carry oxygen
- B. To fight infection
- C. To transport nutrients
- D. To transport waste
Correct Answer: B
Rationale: The correct answer is B: "To fight infection." White blood cells are primarily responsible for fighting infections and foreign invaders in the body, making them a critical component of the immune system. Choice A, "To carry oxygen," is incorrect as red blood cells are responsible for oxygen transport. Choice C, "To transport nutrients," is incorrect as this function is mainly attributed to blood plasma and other specialized cells. Choice D, "To transport waste," is also incorrect as waste removal is primarily handled by the kidneys and the lymphatic system, not white blood cells.
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Which of the following is produced by Natural Killer Cells to create pores for target cell rupture?
- A. Interferon
- B. Apoptosis
- C. Perforin
- D. Antibody
Correct Answer: C
Rationale: The correct answer is C, Perforin. Natural Killer cells release perforin, which forms pores in the membrane of target cells, leading to their lysis. Interferon (choice A) is a protein released by cells in response to viral infections, apoptosis (choice B) is programmed cell death, and antibodies (choice D) are produced by B cells to neutralize pathogens but are not directly involved in creating pores for cell rupture like perforin.
Which of the following is an example of an organ?
- A. Skin
- B. Neuron
- C. Brainstem
- D. DNA
Correct Answer: A
Rationale: The correct answer is A, 'Skin.' The skin is the largest organ in the human body and consists of multiple tissue types working together to perform various functions such as protection, sensation, and temperature regulation. Choice B, 'Neuron,' is a specialized cell in the nervous system and not an organ. Choice C, 'Brainstem,' is a part of the central nervous system composed of nerve tissues but is not an organ on its own. Choice D, 'DNA,' is a molecule that carries genetic instructions, not an organ.
Which of the following is not a biological macromolecule?
- A. Glycoproteins
- B. DNA
- C. Phospholipid
- D. Glucose
Correct Answer: D
Rationale: Glucose is a monosaccharide, which is a simple sugar and not a macromolecule. Glycoproteins, DNA, and phospholipids are all examples of biological macromolecules. Glycoproteins are proteins covalently bonded to carbohydrates, DNA is a nucleic acid, and phospholipids are lipids that contain a phosphate group.
What type of bond holds water molecules together?
- A. Covalent bond
- B. Hydrogen bond
- C. Ionic bond
- D. Peptide bond
Correct Answer: B
Rationale: The correct answer is B: Hydrogen bond. Hydrogen bonds are responsible for holding water molecules together. In a water molecule, the oxygen atom is slightly negative, and the hydrogen atoms are slightly positive, creating a partial positive and negative charge. This polarity allows hydrogen bonds to form between adjacent water molecules. Covalent bonds involve the sharing of electrons, ionic bonds involve transfer of electrons between ions, and peptide bonds are specific to linking amino acids in proteins, which are not relevant to water molecule interactions.
Which of the following is an end product of cellular respiration?
- A. Oxygen
- B. ATP energy
- C. Carbon dioxide
- D. Water
Correct Answer: B
Rationale: The correct answer is B: ATP energy. During cellular respiration, glucose is broken down to produce ATP, which is the primary energy currency of cells. While oxygen is required for cellular respiration to occur, it is not an end product but rather a reactant. Carbon dioxide and water are byproducts of cellular respiration, alongside ATP. Therefore, options A, C, and D are incorrect as they are not end products of cellular respiration.