Nokea
During nuclear transmutation, a target nucleus is bombarded with a particle to create:
- A. A heavier isotope of the same element
- B. A lighter isotope of the same element
- C. An entirely new element
- D. A chain reaction of nuclear fission
Correct Answer: C
Rationale: During nuclear transmutation, a target nucleus is bombarded with a particle to create an entirely new element. This process involves changing the number of protons in the nucleus, resulting in the creation of a different element. Options A and B are incorrect because nuclear transmutation leads to the formation of a new element, not a heavier or lighter isotope of the same element. Option D, a chain reaction of nuclear fission, is incorrect as nuclear transmutation involves the direct conversion of one element into another through bombardment with particles, not the initiation of a fission chain reaction.
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Why is the stratified squamous epithelium found in the skin adapted for?
- A. Absorption
- B. Secretion
- C. Protection
- D. Gas exchange
Correct Answer: C
Rationale: The stratified squamous epithelium found in the skin is adapted for protection. This type of epithelium forms a tough, protective barrier against physical, chemical, and biological damage. Its multiple layers of cells help prevent the entry of pathogens and reduce water loss from the body, making it essential for shielding the underlying tissues. Choices A, B, and D are incorrect because stratified squamous epithelium is not specialized for absorption, secretion, or gas exchange. Instead, its primary function is to protect the underlying tissues and organs from external damage and dehydration.
Where does fertilization, the fusion of sperm and egg, typically occur in the female reproductive system?
- A. Ovary
- B. Fallopian tube
- C. Uterus
- D. Vagina
Correct Answer: B
Rationale: Fertilization typically occurs in the fallopian tube. After ovulation, the egg is released from the ovary and travels through the fallopian tube, where it may encounter sperm for fertilization. The fallopian tube is the site where the sperm fertilizes the egg before the fertilized egg continues its journey towards the uterus for implantation. The ovary is where the egg is produced but not where fertilization occurs. The uterus is where the fertilized egg implants and develops into a fetus, not where fertilization takes place. The vagina is part of the birth canal and not the typical site for fertilization in the female reproductive system.
Which type of muscle is found in the walls of hollow organs, such as the stomach and intestines, and is responsible for involuntary contractions to propel substances through the organs?
- A. Cardiac muscle
- B. Smooth muscle
- C. Skeletal muscle
- D. Striated muscle
Correct Answer: B
Rationale: Smooth muscle is the correct answer. It is found in the walls of hollow organs like the stomach and intestines, where it performs involuntary contractions to move substances through these organs. Cardiac muscle, found in the heart, is responsible for pumping blood. Skeletal muscle is attached to bones and involved in voluntary movements. Striated muscle is a term often used interchangeably with skeletal muscle, which is responsible for voluntary movements but not typically found in the walls of hollow organs like the stomach and intestines.
A light ray travels from air (refractive index 1.00) into water (refractive index 1.33). What happens to its speed and direction?
- A. Speed increases, direction bends towards the normal.
- B. Speed increases, direction bends away from the normal.
- C. Speed decreases, direction bends towards the normal.
- D. Speed and direction remain unchanged.
Correct Answer: C
Rationale: When a light ray travels from air (lower refractive index) to water (higher refractive index), its speed decreases due to the change in the medium. This is because light travels slower in denser mediums. As the light ray enters the denser medium, water in this case, it bends towards the normal (the line perpendicular to the surface of the water). This phenomenon is known as refraction. Choice A is incorrect as the speed of light decreases when entering a denser medium. Choice B is incorrect as the direction bends towards the normal, not away from it. Choice D is incorrect as the speed and direction of the light ray do change when moving from air to water.
What is the role of RNA in the regulation of gene expression?
- A. Provides energy for the process
- B. Controls the timing and location of protein synthesis
- C. Translates the genetic code into amino acids
- D. Stores genetic information
Correct Answer: B
Rationale: A) RNA does not provide energy for the process of gene expression. Energy is typically provided by molecules like ATP. B) RNA plays a crucial role in controlling the timing and location of protein synthesis through processes like transcriptional regulation, RNA splicing, and post-transcriptional modifications. It helps determine when and where specific proteins are produced in the cell. C) While mRNA translates the genetic code into amino acids during the process of translation, this is not the primary role of RNA in the regulation of gene expression. D) RNA does not store genetic information in the same way that DNA does. DNA is the molecule responsible for storing genetic information in the form of genes. Therefore, option B is the most appropriate choice as it accurately describes the role of RNA in regulating gene expression.