Nokea
What is the Pauli exclusion principle?
- A. The principle that electrons fill orbitals in order of increasing energy.
- B. The principle that electrons cannot occupy the same orbital with the same spin.
- C. The principle that the maximum number of electrons in an orbital is 2n^2, where n is the energy level of the orbital.
- D. The principle that the attractive force between an electron and the nucleus is inversely proportional to the distance between them.
Correct Answer: B
Rationale: The Pauli exclusion principle states that no two electrons in an atom can have the same set of four quantum numbers. This principle leads to the rule that electrons must have opposite spins when occupying the same orbital. Therefore, electrons cannot occupy the same orbital with the same spin, as stated in option B. Option A is incorrect as it refers to the Aufbau principle, which describes the order in which electrons fill orbitals based on increasing energy. Option C is incorrect as it provides the formula for the maximum number of electrons in an orbital based on the energy level, not the Pauli exclusion principle. Option D is incorrect as it describes Coulomb's law, which deals with the electrostatic force between charged particles, not the Pauli exclusion principle.
You may also like to solve these questions
Which statement correctly describes the concept of ionization energy?
- A. The energy required to remove an electron from an outermost shell.
- B. The energy released when an electron bonds with an atom.
- C. The total energy possessed by all electrons in an atom.
- D. The energy needed to change an atom's nucleus.
Correct Answer: A
Rationale: Ionization energy is defined as the energy required to remove an electron from an atom in the gaseous state. This process typically involves removing an electron from the outermost shell of the atom. Therefore, option A accurately describes the concept of ionization energy. The other choices do not accurately describe ionization energy; option B refers to bond formation energy, option C is about the total energy of electrons in an atom, and option D relates to nuclear energy changes, not ionization energy.
Which of the following is an example of aseptic technique?
- A. Washing hands with soap and water before surgery
- B. Coughing into your elbow
- C. Sharing a stethoscope without cleaning
- D. Leaving a wound dressing exposed
Correct Answer: A
Rationale: Aseptic technique refers to practices that help prevent the introduction of harmful microorganisms into a sterile environment. Washing hands with soap and water before surgery is an essential component of aseptic technique as it helps reduce the number of microorganisms on the hands, decreasing the risk of introducing pathogens into the surgical site. Coughing into your elbow is a good hygiene practice to prevent the spread of respiratory infections but is not specifically related to aseptic technique. Sharing a stethoscope without cleaning can introduce microorganisms from one patient to another, compromising aseptic conditions. Leaving a wound dressing exposed can lead to contamination and infection, which is contrary to aseptic technique.
The body's first line of defense against pathogens is the innate immune system. Which of the following is NOT a component of the innate immune system?
- A. Physical barriers like skin and mucous membranes
- B. Phagocytes that engulf and destroy pathogens
- C. Inflammatory response to isolate and contain infection
- D. Production of antibodies specific to a particular pathogen
Correct Answer: D
Rationale: The production of antibodies specific to a particular pathogen is a function of the adaptive immune system, not the innate immune system. The innate immune system provides immediate, non-specific defense mechanisms against pathogens, including physical barriers, phagocytes, and inflammatory responses. Choices A, B, and C are all correct components of the innate immune system. Physical barriers like skin and mucous membranes act as the first line of defense, preventing pathogens from entering the body. Phagocytes are specialized cells that engulf and destroy pathogens, while the inflammatory response helps isolate and contain infections to prevent their spread.
Where is the ball-and-socket joint, allowing a wide range of motion, found?
- A. Upper arm (humerus) and shoulder blade (scapula)
- B. Collarbone (clavicle) and breastbone (sternum)
- C. Two vertebrae in the spine
- D. Ribs and sternum
Correct Answer: A
Rationale: The ball-and-socket joint is located between the upper arm (humerus) and the shoulder blade (scapula). This joint provides a wide range of motion, enabling movements like flexion, extension, abduction, adduction, and rotation. It plays a crucial role in various activities involving the shoulder joint, such as throwing, reaching overhead, and performing rotational movements. Choice B, the collarbone (clavicle) and breastbone (sternum), form the sternoclavicular joint, which is a synovial saddle joint. Choice C, two vertebrae in the spine, typically form gliding or facet joints. Choice D, ribs and sternum, are connected by cartilage, forming cartilaginous joints.
What is the difference between homologous chromosomes and sister chromatids?
- A. Homologous chromosomes have the same genes but may have different alleles, while sister chromatids are identical copies of the same chromosome.
- B. Homologous chromosomes are only found in diploid cells, while sister chromatids are found in both haploid and diploid cells.
- C. Both homologous chromosomes and sister chromatids are genetically identical, but only sister chromatids separate during mitosis.
- D. Both homologous chromosomes and sister chromatids can separate during mitosis, but only homologous chromosomes have different alleles.
Correct Answer: A
Rationale: Rationale:
- Homologous chromosomes are pairs of chromosomes that have the same genes in the same order, one from each parent. While they carry the same genes, they may have different alleles (variants of a gene).
- Sister chromatids are exact copies of each other, formed during DNA replication. They are held together by a centromere and are produced during the S phase of the cell cycle.
- During meiosis, homologous chromosomes pair up and exchange genetic material through crossing over, leading to genetic variation. Sister chromatids separate during mitosis to ensure each daughter cell receives an identical copy of the genetic material.