Nokea
What is the primary function of the placenta during pregnancy?
- A. Produce insulin
- B. Facilitate gas exchange between mother and fetus
- C. Excrete waste products from the fetus
- D. All of the above
Correct Answer: B
Rationale: The primary function of the placenta during pregnancy is to facilitate the exchange of oxygen and carbon dioxide between the mother and the fetus. This ensures that the fetus receives oxygen and eliminates carbon dioxide, supporting its growth and development. While the placenta also allows for the transfer of nutrients and waste products between the mother and the fetus, its main role is to ensure proper gas exchange. Therefore, choices A, C, and D are incorrect as the primary role of the placenta is not to produce insulin or excrete waste products from the fetus. Selecting the correct answer, choice B, highlights the crucial role of the placenta in providing oxygen to the fetus and removing carbon dioxide, which are essential for fetal well-being and development.
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Which type of cell is responsible for carrying oxygen throughout the body?
- A. Nerve cell
- B. Muscle cell
- C. Skin cell
- D. Red blood cell
Correct Answer: D
Rationale: The correct answer is D: Red blood cell. Red blood cells, also known as erythrocytes, are specifically designed to carry oxygen throughout the body. They contain hemoglobin, a protein that binds to oxygen in the lungs and transports it to tissues and organs in the body. Nerve cells, muscle cells, and skin cells do not have the specialized function of carrying oxygen like red blood cells do. Nerve cells transmit electrical signals, muscle cells are involved in movement, and skin cells provide a protective barrier and regulate body temperature. Therefore, choices A, B, and C are incorrect in the context of carrying oxygen throughout the body.
Which of the following is NOT a primary producer in an ecosystem?
- A. Grass
- B. Deer
- C. Algae
- D. Mushroom
Correct Answer: B
Rationale: - A) Grass: Grass is a primary producer because it can photosynthesize and convert sunlight into energy, making it the base of the food chain.
- B) Deer: Deer are consumers that feed on primary producers like grass, so they are not primary producers themselves.
- C) Algae: Algae are primary producers that can photosynthesize and produce energy from sunlight.
- D) Mushroom: Mushrooms are decomposers that break down organic matter, so they are not primary producers.
Which part of the male reproductive system is responsible for producing seminal fluid?
- A. Bladder
- B. Urethra
- C. Prostate gland
- D. Kidney
Correct Answer: C
Rationale: The correct answer is the prostate gland (Choice C). The prostate gland, located near the bladder, is responsible for producing seminal fluid. This fluid, along with sperm from the testes, makes up semen. The bladder stores urine, the urethra is a tube that carries urine from the bladder out of the body, and the kidney filters waste from the blood to produce urine. The prostate gland's specific function is to secrete a milky, alkaline fluid that mixes with sperm during ejaculation to form semen. This fluid helps nourish and protect the sperm, aiding in their motility and viability. Therefore, the prostate gland plays a crucial role in male reproductive function by contributing to the composition and quality of semen, essential for fertility.
How many moles of water are produced when 0.5 moles of methane (CH4) react with excess oxygen?
- A. 0.5 moles
- B. 1 mole
- C. 2 moles
- D. 3 moles
Correct Answer: B
Rationale: The balanced chemical equation for the combustion of methane is: CH4 + 2O2 -> CO2 + 2H2O. This equation shows that 1 mole of methane produces 2 moles of water. Therefore, when 0.5 moles of methane react, they will produce 1 mole of water. The ratio of water to methane is 2:1, meaning that for every mole of methane that reacts, it produces 2 moles of water. Since only 0.5 moles of methane are reacting, the amount of water produced will be half of what would be produced if 1 mole of methane reacted, resulting in 1 mole of water being produced. Choice A is incorrect because it does not consider the stoichiometry of the reaction. Choices C and D are incorrect as they do not align with the balanced chemical equation and the stoichiometric ratios involved in the reaction.
How many amino acids can make up a protein?
- A. 10-20
- B. 50-100
- C. 100-500
- D. 1000+
Correct Answer: A
Rationale: Proteins are made up of long chains of amino acids, and there are 20 standard amino acids commonly found in proteins. The sequence and arrangement of these amino acids determine the structure and function of a protein. While proteins can vary in size and complexity, the number of amino acids typically ranges from around 10 to 20 in smaller proteins to hundreds or even thousands in larger proteins. Therefore, the range of 10-20 amino acids is the most accurate representation of the number of amino acids that can make up a protein. Choices B, C, and D are incorrect as they provide ranges that are beyond the typical number of amino acids found in proteins and may lead to confusion. The correct answer is A (10-20).