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What are isotopes?
- A. Atoms of the same element with different numbers of protons.
- B. Atoms of the same element with different numbers of neutrons.
- C. Atoms of different elements with the same number of protons.
- D. Atoms of different elements with the same number of electrons.
Correct Answer: B
Rationale: Isotopes are atoms of the same element with different numbers of neutrons. While isotopes share the same number of protons, which determines the element, they differ in the number of neutrons. This variance in neutron count results in isotopes having different atomic masses. Choice A is incorrect because isotopes have the same number of protons (same element) but differ in the number of neutrons. Choice C is incorrect as it describes atoms of different elements, not isotopes of the same element. Choice D is also incorrect because isotopes can have different numbers of electrons, but what defines isotopes is the variation in neutron numbers.
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Which condition is characterized by inflammation of the inner lining of the stomach?
- A. Gastroesophageal reflux disease (GERD)
- B. Diverticulitis
- C. Ulcerative colitis
- D. Gastritis
Correct Answer: D
Rationale: Gastritis is the correct answer as it is characterized by inflammation of the inner lining of the stomach. This inflammation can be caused by various factors such as excessive alcohol consumption, prolonged use of nonsteroidal anti-inflammatory drugs (NSAIDs), infections, or autoimmune diseases. Symptoms of gastritis may include abdominal pain, nausea, vomiting, and loss of appetite. Gastroesophageal reflux disease (GERD) is incorrect because it involves the backflow of stomach acid into the esophagus, leading to symptoms like heartburn and regurgitation, not inflammation of the stomach lining. Diverticulitis refers to inflammation or infection of small pouches that can form in the walls of the colon, not the stomach. Ulcerative colitis is a type of inflammatory bowel disease characterized by inflammation and ulcers in the colon and rectum, not the stomach lining.
What is the function of the stratified cuboidal epithelium lining the salivary glands?
- A. Protection
- B. Gas exchange
- C. Secretion
- D. Absorption
Correct Answer: C
Rationale: The correct answer is C: Secretion. The stratified cuboidal epithelium lining the salivary glands is responsible for secretion. This type of epithelium, made of multiple layers of cube-shaped cells, is specialized for secretion and protection. In the salivary glands, these cells secrete saliva to aid in the digestion process. Choice A, Protection, is incorrect because while the epithelium does provide some level of protection, its primary function in the salivary glands is secretion. Choice B, Gas exchange, is incorrect as the salivary glands are not involved in gas exchange processes. Choice D, Absorption, is also incorrect as the main role of this epithelium in the salivary glands is not absorption but rather secretion of saliva.
What do isotopes of the same element have in common?
- A. Identical number of protons and neutrons.
- B. Identical chemical properties.
- C. Identical number of electrons.
- D. Identical mass number.
Correct Answer: D
Rationale: Isotopes of the same element have the same number of protons, which defines the element, but different numbers of neutrons. This difference in neutron count results in isotopes of the same element having different mass numbers. Chemical properties are determined by the arrangement of electrons in an atom, so isotopes of the same element may exhibit slightly different chemical behaviors due to different neutron numbers. The number of electrons can vary in isotopes, affecting their charge. However, the mass number, which is the sum of protons and neutrons, is the same for isotopes of the same element. Therefore, the correct answer is that isotopes of the same element share an identical mass number.
Why is biodiversity important for healthy ecosystems?
- A. Increases stability and resilience to disturbances
- B. Provides stability and resilience to disturbances
- C. Slows down nutrient cycling
- D. Reduces the number of decomposers
Correct Answer: B
Rationale: Biodiversity refers to the variety of living organisms in a particular area. A diverse ecosystem is better able to withstand and recover from disturbances such as natural disasters, climate change, or human impacts. This is because different species play unique roles in the ecosystem, and a higher level of biodiversity means there are more species available to fulfill these roles. For example, if one species is negatively affected by a disturbance, other species may be able to compensate for its loss, maintaining the overall functioning of the ecosystem. Therefore, biodiversity provides stability and resilience to disturbances, making ecosystems healthier and more sustainable. Choice A is incorrect because biodiversity doesn't increase competition for resources but rather helps in maintaining a balance within the ecosystem. Choice C is incorrect as biodiversity does not slow down nutrient cycling; in fact, it enhances nutrient cycling by ensuring a variety of species involved in the process. Choice D is incorrect as biodiversity does not reduce the number of decomposers but instead supports a diverse community of decomposers that are essential for nutrient recycling in ecosystems.
What term describes the bending of waves around obstacles or through openings?
- A. Reflection
- B. Refraction
- C. Diffraction
- D. Absorption
Correct Answer: C
Rationale: The correct answer is C, Diffraction. Diffraction is the phenomenon that explains the bending of waves around obstacles or through openings. When waves encounter obstacles or pass through openings, they spread out and bend around them. Reflection (Choice A) involves waves bouncing back when they encounter a surface without bending, refraction (Choice B) is the bending of waves when passing from one medium to another due to a change in speed, and absorption (Choice D) is the process of a wave being taken in by a material rather than bending or bouncing.