Nokea
How does the structure of centromeres contribute to chromosome movement during mitosis?
- A. The centromere provides a binding site for spindle fibers, allowing chromosomes to be attached and manipulated.
- B. The centromere serves as a dividing point between sister chromatids, ensuring their separation during anaphase.
- C. The centromere maintains chromosome stability by preventing chromosomal breaks and rearrangements.
- D. The centromere plays a role in DNA replication, ensuring accurate copying of the genetic material.
Correct Answer: A
Rationale: A) The centromere provides a binding site for spindle fibers, which are microtubules that help move chromosomes during cell division. This attachment allows the chromosomes to be pulled towards opposite poles of the cell during mitosis. Therefore, the structure of centromeres directly contributes to chromosome movement during mitosis by facilitating the attachment and manipulation of chromosomes by the spindle fibers.
B) While the centromere does serve as a dividing point between sister chromatids, ensuring their separation during anaphase, this function is more related to the segregation of chromosomes rather than their movement.
C) The centromere does play a role in maintaining chromosome stability by ensuring proper chromosome segregation, but it is not primarily responsible for preventing chromosomal breaks and rearrangements.
D) The centromere is not directly involved in DNA replication. Its main function is
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What is the term for the process of exchanging gases (oxygen and carbon dioxide) between the blood and the tissues?
- A. Inhalation
- B. Exhalation
- C. External respiration
- D. Internal respiration
Correct Answer: C
Rationale: External respiration is the correct term for the process of exchanging gases (oxygen and carbon dioxide) between the blood and the tissues. It specifically refers to the exchange of gases that occurs in the lungs, where oxygen is absorbed into the bloodstream and carbon dioxide is released from the bloodstream to be exhaled. Inhalation and exhalation, choices A and B, are phases of the breathing process that involve the intake and expulsion of air into and out of the lungs, respectively. Internal respiration, choice D, is the process of gas exchange that happens at the cellular level between the blood and body tissues, not between the blood and the lungs or tissues as in external respiration. Therefore, external respiration is the most appropriate term for the described gas exchange process in the question.
When you push a book across a table, the book experiences an equal and opposite force from the table. Why doesn't the table move as well?
- A. The table is much heavier than the book.
- B. The force on the book acts in a different direction.
- C. The table has a much larger surface area, distributing the force over a wider area.
- D. All of the above
Correct Answer: A
Rationale: The table is much heavier than the book, so it requires a much larger force to accelerate it. The book is lighter and easier to move, so the force applied to it causes it to move without significantly affecting the table due to the table's greater mass. Newton's third law states that for every action, there is an equal and opposite reaction. In this case, the force exerted on the book by the table is countered by an equal force exerted on the table by the book, but the table's greater mass resists movement. Choice B is incorrect because the forces are equal and opposite, acting in the same direction. Choice C is incorrect as the surface area does not affect the movement of the table in this scenario. Therefore, the correct answer is A, as the table's greater mass prevents it from moving easily when a force is applied.
What is the difference between isometric and isotonic muscle contractions?
- A. Isometric involves movement, while isotonic does not.
- B. Isotonic involves shortening of muscle, while isometric maintains length.
- C. Isometric uses more energy, while isotonic uses less.
- D. Isotonic involves smooth muscle, while isometric involves skeletal muscle.
Correct Answer: B
Rationale: The correct answer is B. Isometric contractions occur when the muscle generates tension without changing its length, while isotonic contractions involve the muscle changing length to move a load. In isotonic contractions, the muscle shortens to move a load, whereas in isometric contractions, the muscle contracts to hold a position without movement. Choice A is incorrect because isometric contractions do not involve movement, while choice C is incorrect as isotonic contractions typically require more energy due to movement. Choice D is incorrect because the type of muscle involved (smooth or skeletal) is not the defining factor between isometric and isotonic contractions.
What is the term for the chemical reaction that involves the loss of electrons?
- A. Reduction
- B. Oxidation
- C. Neutralization
- D. Precipitation
Correct Answer: B
Rationale: Oxidation is the process where a substance loses electrons. In an oxidation reaction, the substance being oxidized loses electrons, which are gained by another substance. Reduction is the opposite process, where a substance gains electrons. Neutralization is a reaction between an acid and a base to form a salt and water. Precipitation is the formation of a solid from a solution. Therefore, in the context of a chemical reaction involving the loss of electrons, the correct term is oxidation (Choice B).
Which of the following is the intricate network of blood vessels responsible for transporting blood throughout the body?
- A. Lymphatic system
- B. Circulatory system
- C. Nervous system
- D. Respiratory system
Correct Answer: B
Rationale: The circulatory system, comprising the heart, blood vessels (arteries, veins, and capillaries), and blood, is responsible for transporting blood, oxygen, nutrients, and waste products throughout the body. The lymphatic system aids in maintaining fluid balance and fighting infections; the nervous system transmits signals. The respiratory system facilitates the exchange of oxygen and carbon dioxide in the body, which is distinct from the circulatory system's role in blood transport. Therefore, the correct answer is the Circulatory system (Choice B). Choices A, C, and D are incorrect as they do not pertain to the intricate network of blood vessels responsible for transporting blood throughout the body.