Nokea
Which of the following structures is not directly involved in translation?
- A. tRNA
- B. mRNA
- C. ribosome
- D. DNA
Correct Answer: D
Rationale: Translation is the process of protein synthesis where mRNA is decoded to produce a specific polypeptide chain. tRNA brings amino acids to the ribosome, and the ribosome is the site where translation occurs. DNA is not directly involved in translation; instead, it serves as the genetic material that stores the instructions for protein synthesis but does not play a direct role in the protein synthesis machinery.
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Human cells need oxygen for respiration. What system of the body is responsible for transporting an oxygen molecule to different locations throughout the body?
- A. Skeletal.
- B. Lymphatic.
- C. Respiratory.
- D. Circulatory.
Correct Answer: D
Rationale:
What is the characteristic of the cell membrane consisting of a bilayer of phospholipids with proteins, cholesterol, and glycoproteins that creates a hydrophobic region between two layers of lipids?
- A. Impermeable
- B. Permeable
- C. Selectively permeable
- D. Selectively impermeable
Correct Answer: C
Rationale: The correct answer is 'C: Selectively permeable.' The cell membrane is selectively permeable because it allows certain molecules to pass through while restricting the passage of others. The hydrophobic region formed by the lipid bilayer makes it selectively permeable by controlling the movement of substances in and out of the cell. This selective permeability is vital for cellular functions, as it regulates the transport of essential molecules and maintains the internal environment required for proper cell operation and overall cellular homeostasis.
By what process do sex cells reproduce?
- A. Cytokinesis.
- B. Meiosis.
- C. Mitosis.
- D. Fission.
Correct Answer: B
Rationale:
Do all bacteria have negative effects and cause infections?
- A. TRUE
- B. FALSE
- C. Sometimes
- D. Not sure
Correct Answer: B
Rationale: Not all bacteria have negative effects and cause infections. While some bacteria can lead to infections, many bacteria are beneficial and essential for various processes in nature and our bodies. Bacteria have diverse roles in ecosystems, including positive impacts like aiding digestion and nutrient recycling. Understanding the balance of beneficial and harmful bacteria is crucial for appreciating their significance in our lives.
In the scenario presented in question #49, what type of solution is the egg immersed in?
- A. Hypertonic
- B. Isotonic
- C. Hypotonic
- D. None of the above
Correct Answer: A
Rationale: When an egg is placed in a hypertonic solution, water moves out of the egg into the surrounding solution due to the higher concentration of solutes outside the egg. This results in the egg shrinking or shriveling up as water leaves it, indicating a hypertonic environment.