Nokea
The control center of the cell, containing genetic information (DNA), is the:
- A. Golgi apparatus
- B. Ribosome
- C. Nucleus
- D. Endoplasmic reticulum
Correct Answer: C
Rationale: The correct answer is C, the nucleus. The nucleus is the control center of the cell and houses the genetic information in the form of DNA. The Golgi apparatus (choice A) is responsible for packaging and processing proteins, the ribosome (choice B) is involved in protein synthesis, and the endoplasmic reticulum (choice D) is involved in protein and lipid synthesis. Therefore, choices A, B, and D are not the correct answers as they do not house the genetic information or serve as the control center of the cell.
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What is the primary function of B cells in the immune system?
- A. Directly attacking and engulfing pathogens
- B. Producing antibodies specific to a pathogen
- C. Destroying infected body cells
- D. All of the above
Correct Answer: B
Rationale: B cells are a type of white blood cell that primarily functions by producing antibodies specific to a pathogen. These antibodies play a crucial role in marking pathogens for destruction by other immune cells. While B cells are essential for the immune response, they do not directly attack and engulf pathogens or destroy infected body cells. These functions are carried out by other immune cells like macrophages and cytotoxic T cells. Therefore, the correct answer is B, as it accurately reflects the primary role of B cells in the immune system.
What are polymers?
- A. Large molecules formed by repeating units called monomers
- B. Simple organic molecules with low boiling points
- C. Highly reactive compounds used in industrial processes
- D. Insoluble solids with no definite structure
Correct Answer: A
Rationale: Polymers are large molecules formed by repeating units called monomers. These monomers link together to form long chains or networks, giving polymers their unique properties such as flexibility, strength, and durability. Choice B is incorrect because polymers are not simple organic molecules with low boiling points, but rather complex structures formed by polymerization. Choice C is incorrect as polymers are not necessarily highly reactive compounds, and they are not exclusively used in industrial processes. Choice D is incorrect because polymers can have varying solubilities and structures depending on their composition and properties.
Which element is used in semiconductors like computer chips and solar panels?
- A. Germanium
- B. Silicon
- C. Gallium
- D. Arsenic
Correct Answer: B
Rationale: Silicon is the correct answer. Silicon is widely used in semiconductors for electronic applications because of its unique properties that allow it to be manipulated to conduct or not conduct electricity effectively. Germanium is also used in semiconductors but to a lesser extent compared to silicon. Gallium and arsenic are not as commonly used in semiconductors like computer chips and solar panels, making them incorrect choices for this question.
What is the term for an organism with two different alleles for a gene?
- A. Homozygous
- B. Heterozygous
- C. Dominant
- D. Recessive
Correct Answer: B
Rationale: Homozygous refers to an organism with two identical alleles for a gene, either both dominant or both recessive. Heterozygous, the correct answer, refers to an organism with two different alleles for a gene, one dominant and one recessive. Dominant and recessive describe the relationship between alleles, where dominant alleles are expressed over recessive alleles in heterozygous individuals. Therefore, the term for an organism with two different alleles for a gene is 'heterozygous.'
Which property of matter refers to the amount of space occupied by an object?
- A. Mass
- B. Volume
- C. Weight
- D. Density
Correct Answer: B
Rationale: Volume refers to the amount of space occupied by an object. It is a measure of the three-dimensional space that an object occupies. Mass, on the other hand, refers to the amount of matter in an object, weight is the force of gravity acting on an object, and density is the mass of an object per unit volume. In this context, volume is the most appropriate choice as it directly relates to the amount of space an object occupies.