Nokea
Which combination of cell cycle phase and descriptor is correct?
- A. S phase - the cell synthesizes DNA and doubles its cytoplasm
- B. G� phase - the amount of chromosomes is doubled
- C. GÄ‚‚ phase - the phase prior to the start of mitosis in which the cell continues to grow in size and make proteins
- D. Interphase - the cell increases in mass and number of organelles to prepare for cell division
Correct Answer: C
Rationale: The correct answer is C. The GÄ‚‚ phase is the phase before mitosis within interphase where the cell grows in size and synthesizes proteins needed for cell division. Option A incorrectly describes the S phase, which is primarily for DNA synthesis. Option B is incorrect as the doubling of chromosomes does not occur in GÄ‚� phase. Option D is inaccurate because interphase encompasses GÄ‚�, S, and GÄ‚‚ phases, during which the cell prepares for division by increasing its mass and organelles, rather than specifically focusing on mitosis preparation.
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What type of tissue is fat composed of?
- A. Connective
- B. Muscle
- C. Nervous
- D. Epithelial
Correct Answer: A
Rationale: The correct answer is A: Connective tissue. Fat tissue, also known as adipose tissue, is a type of connective tissue that stores energy in the form of fat. It provides insulation and serves as a reserve of energy. Muscle tissue (choice B) is responsible for movement, nervous tissue (choice C) transmits electrical signals throughout the body, and epithelial tissue (choice D) covers and protects body surfaces.
What is the function of water in photosynthesis?
- A. Combines with carbon dioxide
- B. Absorbs light energy
- C. Supplies electrons in the light reactions
- D. Transports hydrogen ions in the dark reactions
Correct Answer: C
Rationale: In photosynthesis, water plays a crucial role in supplying electrons during the light reactions of the process. When light energy is absorbed by chlorophyll, water molecules are split through photolysis, releasing electrons. These electrons are then used in the photosynthetic electron transport chain to generate ATP and NADPH, essential for the synthesis of sugars during the light-dependent reactions.
What action does an enzyme perform that increases the rate of a biological reaction?
- A. Lowers the activation energy.
- B. Removes the energy barrier.
- C. Changes the substrate.
- D. Alters the active site.
Correct Answer: A
Rationale: Correct Answer: A - Lowers the activation energy.
Rationale:
1. Enzymes lower activation energy needed for a reaction to occur by stabilizing the transition state.
2. This accelerates the reaction rate without being consumed in the process.
3. Choice B is incorrect as enzymes do not physically remove the energy barrier.
4. Choice C is incorrect as enzymes do not change the substrate but rather facilitate the reaction.
5. Choice D is incorrect as enzymes do not alter their active sites during reactions; the sites remain unchanged.
What substances make up the bilayer of the cellular membrane?
- A. Nucleic acids
- B. Phospholipids
- C. Proteins
- D. Carbohydrates
Correct Answer: B
Rationale: The cellular membrane consists of a bilayer of phospholipids. This phospholipid bilayer forms a flexible barrier around the cell, providing structural integrity and fluidity. While proteins and carbohydrates are also present in the cell membrane, the main component of the membrane's structure is the phospholipid bilayer, which plays a crucial role in maintaining the cell's functions.
Which of the following is a protein?
- A. cellulose
- B. hemoglobin
- C. estrogen
- D. ATP
Correct Answer: B
Rationale: Hemoglobin is the correct answer as it is a protein. Proteins are large, complex molecules composed of amino acids that are essential for various structural and functional roles in the body. Hemoglobin, specifically, is a protein found in red blood cells and is responsible for carrying oxygen from the lungs to different parts of the body, highlighting its crucial role in oxygen transportation.