Nokea
Which organelle is responsible for controlling the activities of the cell?
- A. Golgi apparatus
- B. Mitochondria
- C. Nucleus
- D. Ribosomes
Correct Answer: C
Rationale: The nucleus is the organelle responsible for controlling the activities of the cell. It contains the cell's genetic material (DNA) and serves as the command center of the cell, regulating gene expression and directing cellular activities. The nucleus plays a crucial role in cell growth, metabolism, and reproduction. While the Golgi apparatus is involved in processing and packaging proteins, the mitochondria are responsible for producing energy in the form of ATP, and ribosomes are involved in protein synthesis, none of these organelles have the primary function of controlling the activities of the cell like the nucleus does. Therefore, the correct answer is the nucleus.
You may also like to solve these questions
In a single displacement reaction, one element takes the place of another element in a compound. Which of the following is an example?
- A. 2H2 + O2 -> 2H2O
- B. Zn + 2HCl -> ZnCl2 + H2
- C. CaCO3 -> CaO + CO2
- D. CH4 + 2O2 -> CO2 + 2H2O
Correct Answer: B
Rationale: Option B demonstrates a single displacement reaction where zinc (Zn) displaces hydrogen (H) in hydrochloric acid (HCl) to produce zinc chloride (ZnCl2) and hydrogen gas (H2). This reaction exemplifies the concept of one element (Zn) replacing another element (H) in a compound (HCl), which is characteristic of single displacement reactions. Choices A, C, and D do not involve a single element displacing another in a compound, making them incorrect. In choice A, hydrogen and oxygen combine to form water, which is not a single displacement reaction. In choice C, calcium carbonate decomposes into calcium oxide and carbon dioxide, not involving displacement of elements. In choice D, methane reacts with oxygen to form carbon dioxide and water, which is a combustion reaction, not a single displacement reaction.
What is the name for the smallest amount of an element that can exist independently and retain its chemical properties?
- A. Atom
- B. Molecule
- C. Compound
- D. Mixture
Correct Answer: A
Rationale: The correct answer is 'Atom.' An atom is the fundamental unit of an element that can exist independently and retain its unique chemical properties. It consists of a nucleus containing protons and neutrons, surrounded by electrons. Choice B, 'Molecule,' is incorrect because a molecule is a combination of two or more atoms bonded together. Choice C, 'Compound,' is incorrect as a compound is a substance formed by the chemical combination of two or more different elements. Choice D, 'Mixture,' is incorrect since a mixture is a blend of two or more substances physically combined, but the individual components retain their properties.
What is the name of the structure that packages DNA in eukaryotic cells?
- A. Nucleosome
- B. Chromatin
- C. Histone
- D. Centromere
Correct Answer: A
Rationale: - A nucleosome is the basic structural unit of DNA packaging in eukaryotic cells. It consists of DNA wrapped around a core of histone proteins.
- Chromatin refers to the complex of DNA and proteins found in the nucleus of a eukaryotic cell, including nucleosomes.
- Histones are the proteins around which DNA is wrapped to form nucleosomes.
- Centromere is a region of a chromosome where the two sister chromatids are joined and to which spindle fibers attach during cell division.
Which white blood cell type is responsible for the initial attack on pathogens?
- A. Red blood cells
- B. Platelets
- C. Phagocytes
- D. Lymphocytes
Correct Answer: C
Rationale: Phagocytes are a type of white blood cell that is crucial in the initial attack on pathogens. These cells have the ability to engulf and digest foreign particles such as bacteria and viruses, thereby preventing infections. Red blood cells primarily function in oxygen transport, platelets are vital for blood clotting, and lymphocytes are involved in the immune response. However, phagocytes are specifically designed to provide the initial defense against pathogens by directly attacking and eliminating them.
Which of the following blood vessels carries oxygenated blood from the lungs to the heart?
- A. Pulmonary vein
- B. Pulmonary artery
- C. Aorta
- D. Vena cava
Correct Answer: A
Rationale: The correct answer is A: Pulmonary vein. The pulmonary vein carries oxygenated blood from the lungs to the heart. It is essential to distinguish between the pulmonary vein (A) and the pulmonary artery (B) in this context. The pulmonary vein transports oxygenated blood, while the pulmonary artery carries deoxygenated blood from the heart to the lungs for oxygenation. The aorta (C) functions as the main artery that delivers oxygenated blood from the heart to the body's tissues, while the vena cava (D) returns deoxygenated blood from the body to the heart.