Nokea
What is the periodic table?
- A. A table of elements that are arranged in order of increasing atomic number.
- B. A table of elements that are arranged in order of increasing atomic mass.
- C. A table of elements that are arranged in order of their reactivity.
- D. A table of elements that are arranged in order of their color.
Correct Answer: A
Rationale: The periodic table is a tabular arrangement of the chemical elements, organized based on their atomic number, electron configurations, and recurring chemical properties. Elements are placed in rows (periods) and columns (groups) with similar properties. The elements are listed in order of increasing atomic number, which is the number of protons in the nucleus of an atom. This arrangement reveals a periodic repetition of chemical properties, forming the basis of the periodic law. Choice B, which suggests arranging elements based on increasing atomic mass, is incorrect because the periodic table is primarily organized by atomic number, not atomic mass. Choices C and D are also incorrect as the periodic table is not based on reactivity or color of elements, but rather on atomic number and properties.
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Why is maintaining good muscle strength and flexibility as we age important?
- A. To prevent headaches
- B. To prevent falls
- C. To reduce anxiety
- D. To avoid the common cold
Correct Answer: B
Rationale: Maintaining good muscle strength and flexibility as we age is crucial to prevent falls. Strong muscles and good flexibility help improve balance and stability, reducing the risk of falls, which can lead to serious injuries, especially in older adults. Falls are a significant concern for the elderly population, and preventing them through muscle strength and flexibility can enhance overall quality of life. Headaches are not directly related to muscle strength and flexibility; they can have various causes such as stress, dehydration, or underlying health conditions. Anxiety is a mental health condition and not directly prevented by muscle strength and flexibility. Similarly, the common cold is a viral infection and is not influenced by muscle strength and flexibility.
What is the feedback mechanism in the endocrine system that helps maintain hormone balance?
- A. Positive feedback, where a hormone stimulates its own release
- B. Negative feedback, where a hormone suppresses its own release
- C. Cascade effect, where one hormone triggers the release of another
- D. Dual hormone system, where two hormones work together
Correct Answer: B
Rationale: In the endocrine system, negative feedback is the mechanism by which hormone levels are regulated. When hormone levels reach a certain threshold, they signal the body to stop producing more of that hormone, thus maintaining a balance. Negative feedback (option B) is the correct answer as it helps in preventing overproduction of hormones by suppressing their own release. Positive feedback (option A) would lead to an excessive production of hormones, disrupting the balance. The cascade effect (option C) involves one hormone triggering the release of another but does not directly regulate hormone levels. The dual hormone system (option D) refers to two hormones working together but does not specifically address the feedback mechanism for maintaining hormone balance.
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 type of muscle tissue contracts involuntarily and is found in organs like the heart and intestines?
- A. Skeletal muscle
- B. Cardiac muscle
- C. Smooth muscle
- D. All of the above
Correct Answer: C
Rationale: Smooth muscle is the type of muscle tissue that contracts involuntarily and is found in organs like the heart and intestines. Skeletal muscle is responsible for voluntary movements, like those involved in skeletal system actions. Cardiac muscle is found in the heart and contracts involuntarily, but it is distinct from smooth muscle. The heart's muscle is specialized and forms the myocardium, which is not the same as the smooth muscle found in organs like the intestines. Therefore, the correct answer is C) Smooth muscle.
What is the stoichiometric coefficient of nitrogen (N2) in the balanced equation for the Haber process: N2 + 3H2 → 2NH3?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: A
Rationale: In the balanced equation for the Haber process: N2 + 3H2 → 2NH3, the stoichiometric coefficient of nitrogen (N2) is 1. This means that one molecule of nitrogen reacts with three molecules of hydrogen to produce two molecules of ammonia. The coefficient '1' indicates the mole ratio of N2 in the reaction. Choice B, 2, is incorrect because it represents the coefficient for ammonia (NH3) in the balanced equation. Choice C, 3, is incorrect as it corresponds to the coefficient of hydrogen (H2). Choice D, 4, is not the correct stoichiometric coefficient for nitrogen (N2) in this equation.