Nokea
Which of the following is always true about molecules?
- A. They can travel through all cell membranes
- B. They move from low concentration to high concentration without using energy
- C. They move from high concentration to low concentration without using energy
- D. They cannot move
Correct Answer: C
Rationale: The correct answer is C: 'They move from high concentration to low concentration without using energy.' This statement aligns with the concept of passive transport, where molecules naturally move from areas of higher concentration to lower concentration to reach equilibrium. This process does not require energy input. Option A is incorrect because not all molecules can freely pass through all cell membranes due to factors like size and charge. Option B describes active transport, which involves the movement of molecules against their concentration gradient, requiring energy. Option D is incorrect as molecules are in constant motion.
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Which cell organelle can be functionally compared to a door of a house?
- A. Endoplasmic reticulum
- B. Cell membrane
- C. Nucleus
- D. Cytoplasm
Correct Answer: B
Rationale: The cell membrane can be likened to a door of a house because it functions to regulate what enters and exits the cell, maintaining internal balance (homeostasis) and safeguarding the cell's interior. Just as a door controls access to a house, the cell membrane controls the passage of substances into and out of the cell, thereby playing a crucial role in maintaining the cell's integrity and functionality.
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. Circulatory
- D. Respiratory
Correct Answer: C
Rationale: The circulatory system is responsible for transporting oxygen throughout the body. It consists of the heart, blood vessels, and blood, which work together to deliver oxygen from the lungs to cells and tissues, facilitating cellular respiration. The skeletal system provides structural support and protection for the body but is not involved in oxygen transport. The lymphatic system helps maintain fluid balance and immune function, not oxygen transport. The respiratory system is responsible for gas exchange in the lungs but relies on the circulatory system to transport oxygen to cells and tissues.
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.
Which of the following options best represents 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 guanine (G) pairs with cytosine (C). This is known as complementary base pairing. The correct answer is 'A and T' because they form a complementary base pair in DNA. Adenine always pairs with thymine via two hydrogen bonds, while guanine pairs with cytosine via three hydrogen bonds. This base pairing specificity is crucial for DNA replication and genetic information transfer.
Which of the following is true of the Krebs cycle?
- A. It is a redox reaction involving proteins produced during glycolysis
- B. It is a redox reaction involving sugars produced during glycolysis
- C. Protons are passed along a gradient to produce ATP
- D. It is also known as the glycolic acid cycle
Correct Answer: B
Rationale: The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that generate energy through the oxidation of acetyl-CoA derived from sugars produced during glycolysis. It is not primarily a reaction involving proteins or protons being passed along gradients to produce ATP. The cycle is distinct from the glycolic acid cycle, which is a separate metabolic pathway. Therefore, the correct answer is B.