Nokea
What is the process of breaking down glucose into pyruvate called?
- A. Glycolysis
- B. Gluconeogenesis
- C. Krebs cycle
- D. Oxidative phosphorylation
Correct Answer: A
Rationale: A) Glycolysis is the process of breaking down glucose into pyruvate. This occurs in the cytoplasm of cells and is the first step in cellular respiration.
B) Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources, such as amino acids or glycerol, and is the opposite of glycolysis.
C) The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria and is involved in the oxidation of acetyl-CoA to produce ATP and other energy carriers.
D) Oxidative phosphorylation is the final stage of cellular respiration where ATP is produced through the transfer of electrons in the electron transport chain.
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Which of the following is a common characteristic of alkynes?
- A. They have a triple bond between carbon atoms.
- B. They are saturated hydrocarbons.
- C. They contain only single bonds.
- D. They are aromatic compounds.
Correct Answer: A
Rationale: The correct answer is A. Alkynes are hydrocarbons characterized by at least one triple bond between carbon atoms. This triple bond sets them apart from alkanes, which only have single bonds, and alkenes, which feature at least one double bond. The presence of a triple bond makes alkynes unsaturated hydrocarbons. Choice B is incorrect as alkynes are unsaturated hydrocarbons, not saturated. Choice C is incorrect because alkynes contain at least one triple bond, making them different from compounds with only single bonds. Choice D is incorrect because aromatic compounds have a distinct cyclic structure with resonance stabilization, a feature not shared by alkynes.
In physics, what does the term 'net force' refer to?
- A. Total force acting on an object
- B. Force due to gravity
- C. Force in motion
- D. Force of friction
Correct Answer: A
Rationale: In physics, the term 'net force' refers to the total force acting on an object, considering all individual forces acting on it. It is crucial in determining the object's motion and acceleration as it represents the overall force applied to the object. Choice B, 'Force due to gravity,' is incorrect as it refers to a specific force acting on an object due to gravity. Choice C, 'Force in motion,' is incorrect as it does not define the concept of net force. Choice D, 'Force of friction,' is incorrect as it specifically refers to the force opposing motion when two surfaces are in contact.
Which type of cell has a nucleus but lacks membrane-bound organelles?
- A. Plant cell
- B. Prokaryotic cell
- C. Animal cell
- D. Fungal cell
Correct Answer: B
Rationale: The correct answer is B: Prokaryotic cell. Prokaryotic cells are characterized by having a nucleus that is not enclosed within a membrane (nuclear envelope) and lacking membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus. Plant, animal, and fungal cells are eukaryotic cells, which have a true nucleus enclosed within a nuclear envelope and contain membrane-bound organelles. Therefore, options A, C, and D are incorrect as they all represent eukaryotic cells that possess membrane-bound organelles.
What is the process of breaking down proteins into amino acids called?
- A. Proteolysis
- B. Lipolysis
- C. Carbohydrate catabolism
- D. Nucleic acid catabolism
Correct Answer: A
Rationale: Proteolysis is the specific process of breaking down proteins into amino acids. Lipolysis refers to the breakdown of fats into fatty acids and glycerol, not proteins. Carbohydrate catabolism involves the breakdown of carbohydrates into glucose for energy production, not proteins. Nucleic acid catabolism is the breakdown of nucleic acids into nucleotides, not proteins. Therefore, in the context of breaking down proteins into amino acids, the correct term is proteolysis.
What are isotopes?
- A. Atoms of the same element with different numbers of protons.
- B. Atoms of the same element with different numbers of neutrons.
- C. Atoms of different elements with the same number of protons.
- D. Atoms of different elements with the same number of electrons.
Correct Answer: B
Rationale: Isotopes are atoms of the same element with different numbers of neutrons. While isotopes share the same number of protons, which determines the element, they differ in the number of neutrons. This variance in neutron count results in isotopes having different atomic masses. Choice A is incorrect because isotopes have the same number of protons (same element) but differ in the number of neutrons. Choice C is incorrect as it describes atoms of different elements, not isotopes of the same element. Choice D is also incorrect because isotopes can have different numbers of electrons, but what defines isotopes is the variation in neutron numbers.