Nokea
What is the most significant contributor to cellular function?
- A. Proteins
- B. Phospholipids
- C. Carbohydrates
- D. Fatty acids
Correct Answer: A
Rationale: The correct answer is A: Proteins. Proteins are the most significant contributor to cellular function as they play crucial roles in almost all biological processes. They act as enzymes that catalyze reactions, are involved in cell signaling pathways, and provide structural support to cells. Phospholipids (Choice B), while important for cell membrane structure, do not have the same diverse functions as proteins in cellular processes. Carbohydrates (Choice C) primarily serve as an energy source and structural components but are not as versatile in cellular functions as proteins. Fatty acids (Choice D) are essential components of cell membranes and energy storage molecules but do not have the same broad range of functions as proteins in cellular processes.
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Which of the following processes produces nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FADH2) for the electron transport chain during cellular respiration?
- A. Electron transport chain
- B. Glycolysis
- C. Citric acid cycle (the Krebs cycle)
- D. None of these
Correct Answer: C
Rationale: The correct answer is C, the citric acid cycle (the Krebs cycle). This cycle generates NADH and FADH2, which play a crucial role in providing electrons to the electron transport chain during cellular respiration. Choice A, the electron transport chain itself, is where NADH and FADH2 donate their electrons, not where they are produced. Choice B, glycolysis, produces NADH but not FADH2. Choice D, 'None of these,' is incorrect as the citric acid cycle specifically produces NADH and FADH2.
Which of the following organelles is known as the cell's transportation center?
- A. Golgi apparatus
- B. Endoplasmic reticulum
- C. Mitochondria
- D. Lysosomes
Correct Answer: B
Rationale: The correct answer is B, Endoplasmic reticulum. The endoplasmic reticulum is involved in the synthesis and transport of proteins and lipids within the cell. The Golgi apparatus is responsible for modifying, sorting, and packaging proteins and lipids for transport. Mitochondria are known as the powerhouse of the cell, producing energy in the form of ATP. Lysosomes are involved in the digestion and recycling of cellular waste.
Where can ribosomes be found inside a cell?
- A. Attached to the endoplasmic reticulum (ER) and in the cytoplasm
- B. Within the cellular membrane
- C. Attached to the Golgi apparatus and in the cytoplasm
- D. Within the nucleus
Correct Answer: A
Rationale: Ribosomes can be found attached to the endoplasmic reticulum (ER) or free-floating in the cytoplasm. The correct answer is A because ribosomes are responsible for synthesizing proteins and are commonly found on the ER or in the cytoplasm. Choice B is incorrect because ribosomes are not typically located within the cellular membrane. Choice C is incorrect as ribosomes are not attached to the Golgi apparatus; instead, they are involved in protein synthesis. Choice D is incorrect as ribosomes are not found within the nucleus but rather in the cytoplasm or attached to the ER.
Which two items react during cellular respiration?
- A. Glucose and water
- B. Carbon dioxide and water
- C. Carbon dioxide and oxygen
- D. Glucose and oxygen
Correct Answer: D
Rationale: The correct answer is D: Glucose and oxygen. During cellular respiration, glucose and oxygen react in the presence of enzymes to produce carbon dioxide, water, and energy in the form of ATP. Choice A (Glucose and water) is incorrect because water is a product of cellular respiration, not a reactant. Choice B (Carbon dioxide and water) is incorrect as carbon dioxide is produced during cellular respiration, not a reactant. Choice C (Carbon dioxide and oxygen) is incorrect because oxygen is a reactant in cellular respiration, not a product.
Which of the following is a group of three RNA nucleotides?
- A. A stop codon
- B. A codon
- C. An anticodon
- D. tRNA
Correct Answer: B
Rationale: The correct answer is B - A codon. A codon is a sequence of three RNA nucleotides that specifies a particular amino acid or a stop signal during protein synthesis. Choice A, a stop codon, is a sequence of three nucleotides that signals the termination of protein synthesis. Choice C, an anticodon, is a group of three nucleotides found in tRNA that pairs with the complementary codon in mRNA. Choice D, tRNA, stands for transfer RNA, which is a type of RNA that carries amino acids to the ribosome during protein synthesis.