Nokea
Aerobic respiration occurs in the presence of what necessary molecule?
- A. Carbon dioxide.
- B. Oxygen.
- C. Water.
- D. Lactic acid.
Correct Answer: B
Rationale:
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Which option demonstrates complementary base pairing in DNA?
- A. A and G
- B. A and C
- C. A and A
- D. A and T
Correct Answer: D
Rationale: In DNA, adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). This is known as complementary base pairing. Adenine always pairs with thymine via two hydrogen bonds, forming a strong bond essential for DNA structure and replication. Therefore, the correct option that demonstrates complementary base pairing in DNA is A and T (D). This pairing is crucial during DNA replication and ensures the accurate transmission of genetic information.
Which characteristic is true of prokaryotic cells?
- A. Have a nucleus
- B. Have a capsule
- C. Have membrane-bound organelles
- D. Cannot move on their own
Correct Answer: B
Rationale: Prokaryotic cells are characterized by the absence of a nucleus; instead, they have a nucleoid region where the genetic material is located. Prokaryotic cells often have a capsule, a protective layer outside the cell wall that plays a role in protection and adherence to surfaces. While eukaryotic cells have membrane-bound organelles, prokaryotic cells lack these membrane-bound structures. Prokaryotic cells are capable of movement, facilitated by structures like flagella or pili.
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.
Why doesn't an antibiotic work for treating flu symptoms in a patient?
- A. The antibiotic is for a different type of infection, not the flu.
- B. The antibiotic is not effective in treating viral infections like the flu.
- C. The antibiotic is not administered in a sufficient dosage to combat the flu.
- D. None of the above
Correct Answer: B
Rationale: Antibiotics are designed to treat bacterial infections, not viral infections like the flu. The flu is caused by a virus, so antibiotics are ineffective in treating flu symptoms. To effectively manage and treat flu cases, antiviral medications specifically designed to target viral infections should be used.
Tonicity refers to the movement of:
- A. Water
- B. Solute
- C. Cells
- D. None of the above
Correct Answer: A
Rationale: Tonicity is a term used to describe the relative concentration of solutes inside and outside of a cell. When a solution is hypertonic, it has a higher concentration of solutes outside the cell, causing water to move out of the cell. When a solution is hypotonic, it has a lower concentration of solutes outside the cell, causing water to move into the cell. Therefore, tonicity primarily affects the movement of water across a cell membrane.