Nokea
Which of the following organelles is responsible for producing cell energy?
- A. Mitochondrion and chloroplast
- B. Mitochondrion and nucleus
- C. Chloroplast and nucleus
- D. Chloroplast and lysosome
Correct Answer: A
Rationale: The correct answer is A: Mitochondrion and chloroplast. Mitochondria are known as the powerhouse of the cell as they produce the majority of a cell's energy in the form of ATP (adenosine triphosphate) through aerobic respiration. Chloroplasts, found in plant cells, are responsible for photosynthesis, a process that converts light energy into chemical energy in the form of glucose. Therefore, both mitochondria and chloroplasts play crucial roles in energy production in cells.
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Are all bacteria bad, and do they always cause infections?
- A. TRUE
- B. FALSE
- C. Sometimes
- D. Not sure
Correct Answer: B
Rationale: The misconception that all bacteria are harmful and always cause infections is incorrect. Although some bacteria can lead to diseases, it is essential to note that not all bacteria are harmful. In reality, certain bacteria are beneficial and serve important functions in the body, such as aiding in digestion. Therefore, the correct answer is FALSE.
Cytosine (C) and Thymine (T) are known as:
- A. Purines
- B. Pyrimidines
- C. Both
- D. None of the above
Correct Answer: B
Rationale: Cytosine (C) and Thymine (T) are both pyrimidines. Purines, on the other hand, refer to adenine and guanine. Pyrimidines are characterized by a single-ring structure, while purines have a double-ring structure. Therefore, the correct answer is B: Pyrimidines. Remember, pyrimidines consist of cytosine and thymine, while purines include adenine and guanine.
The cellular membrane consists of a bilayer of which substances?
- A. Nucleic acids
- B. Phospholipids
- C. Proteins
- D. Carbohydrates
Correct Answer: B
Rationale: The cellular membrane is primarily composed of a phospholipid bilayer, forming the structure that regulates entry and exit.
Which type of passive transport uses proteins that change shape to move a target molecule through the membrane?
- A. Diffusion
- B. Carrier proteins
- C. Channel proteins
- D. None of the above
Correct Answer: B
Rationale: Carrier proteins are involved in facilitated diffusion, a type of passive transport where molecules move across the cell membrane with the help of specific carrier proteins that change shape to transport the molecules across. Channel proteins, on the other hand, form pores or channels to allow specific molecules to pass through the membrane via passive transport. Diffusion, while a passive transport process, does not involve proteins changing shape to facilitate the movement of molecules.
Which of the following is not an RNA base?
- A. Adenine
- B. Thymine
- C. Uracil
- D. Cytosine
Correct Answer: B
Rationale: In RNA, the bases are Adenine, Uracil, and Cytosine. Thymine is uniquely found in DNA and not RNA. Adenine pairs with Uracil, while Cytosine pairs with Guanine in RNA. Thus, Thymine is not an RNA base, making it the correct answer.