Nokea
Which process involves the body's natural defense against inhaled dust and allergens?
- A. Cellular respiration
- B. Gas exchange
- C. Ciliary action
- D. Bronchoconstriction
Correct Answer: C
Rationale: Ciliary action refers to the process where tiny hair-like structures called cilia in the respiratory tract help to sweep away inhaled dust and allergens, preventing them from entering deeper into the lungs. This is a crucial part of the body's natural defense mechanism against respiratory irritants. Cellular respiration (A) is the process where cells use oxygen to produce energy, not a defense mechanism against inhaled particles. Gas exchange (B) involves the exchange of oxygen and carbon dioxide in the lungs, not specifically targeting inhaled dust and allergens. Bronchoconstriction (D) is the narrowing of the airways in response to irritants or allergens, which can lead to breathing difficulties, but it is not the primary defense mechanism against these particles.
You may also like to solve these questions
Which of the following is the antiparticle of a neutron?
- A. Antineutrino
- B. Positron
- C. Antiproton
- D. Electron
Correct Answer: C
Rationale: The antiparticle of a neutron is an antineutron, which is composed of an antiproton and an antineutrino. The antineutrino (choice A) is not the antiparticle of a neutron. A positron (choice B) is the antiparticle of an electron, not a neutron. An electron (choice D) is a fundamental particle, not an antiparticle. Therefore, the correct answer is an antiproton (choice C), as it forms an antineutron when combined with an antineutrino.
What is the process of making copies of DNA called?
- A. Transcription
- B. Translation
- C. Replication
- D. DNA repair
Correct Answer: C
Rationale: A) Transcription is the process of synthesizing RNA from a DNA template. It involves the creation of mRNA molecules from a DNA template.
B) Translation is the process of synthesizing proteins from mRNA. During translation, the genetic code carried by mRNA is decoded to produce a specific sequence of amino acids, forming a protein.
C) Replication is the process of making copies of DNA. This process occurs before cell division and ensures that each daughter cell receives an identical copy of the genetic material.
D) DNA repair is a cellular mechanism that corrects errors in DNA that arise due to various factors such as exposure to mutagens or mistakes during DNA replication. It is essential for maintaining the integrity of the genetic material.
Which structure in the heart is responsible for preventing the backflow of blood from the left ventricle into the left atrium?
- A. Aortic valve
- B. Pulmonary valve
- C. Tricuspid valve
- D. Mitral valve
Correct Answer: D
Rationale: The mitral valve, also known as the bicuspid valve, is located between the left atrium and the left ventricle of the heart. Its primary function is to prevent the backflow of blood from the left ventricle into the left atrium during ventricular contraction. The aortic valve (A) prevents the backflow of blood from the aorta into the left ventricle, the pulmonary valve (B) prevents the backflow of blood from the pulmonary artery into the right ventricle, and the tricuspid valve (C) prevents the backflow of blood from the right ventricle into the right atrium. Understanding the functions of these heart valves is crucial in maintaining proper blood flow through the heart and preventing regurgitation of blood into the wrong chambers.
Which statement accurately describes cytokinesis in animal cells?
- A. Which statement accurately describes cytokinesis in animal cells?
- B. A cell plate forms in the center of the dividing cell, eventually separating the cytoplasm into two daughter cells.
- C. A cell plate forms in the center of the dividing cell, eventually separating the cytoplasm into two daughter cells.
- D. The nucleus elongates and pulls apart, physically dividing the cytoplasm into two.
Correct Answer: B
Rationale: A) This statement is a duplicate of option C and does not accurately describe cytokinesis in animal cells.
B) In animal cells, during cytokinesis, a cleavage furrow forms in the center of the dividing cell. This furrow deepens and eventually pinches the cytoplasm into two daughter cells. This process is distinct from plant cells, where a cell plate forms.
C) This statement is a duplicate of option A and does not accurately describe cytokinesis in animal cells.
D) This statement describes the process of nuclear division (mitosis) rather than cytokinesis, which is the division of the cytoplasm.
What is the oxidation state of carbon in CH4?
- A. +1
- B. -1
- C. +2
- D. -4
Correct Answer: D
Rationale: In CH4 (methane), carbon is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Since the overall charge of CH4 is 0, the oxidation state of carbon must be -4 to balance the charges. Each hydrogen contributes an oxidation state of +1, resulting in a total of +4 from hydrogen atoms. To achieve a total oxidation state of 0 for the molecule, carbon must have an oxidation state of -4 to offset the contribution from hydrogen. Therefore, the correct answer is -4. Choices A, B, and C are incorrect: +1 is the oxidation state of hydrogen, -1 is not the oxidation state of carbon in methane, and +2 is not the correct oxidation state of carbon in CH4.