Nokea
What impact would the removal of a keystone species have in an ecosystem?
- A. Lead to a decrease in competition among other species
- B. Cause a slight increase in primary productivity
- C. Have a minimal impact on the overall ecosystem structure
- D. Disrupt the food web and cause cascading effects on other populations
Correct Answer: D
Rationale: Keystone species play a crucial role in maintaining the balance and structure of an ecosystem due to their significant influence. If a keystone species is removed, it disrupts the delicate food web dynamics and can trigger cascading effects throughout the ecosystem. The disruption in predator-prey relationships can lead to population declines and even extinctions of other species. Options A, B, and C are incorrect because the removal of a keystone species would not decrease competition among other species, cause a slight increase in primary productivity, or have a minimal impact on the overall ecosystem structure. Instead, it would have a profound impact, disrupting the food web and causing cascading effects on other populations.
You may also like to solve these questions
Calcitonin, a hormone that helps regulate calcium levels, is produced by the:
- A. Thyroid gland
- B. Parathyroid gland
- C. Thymus gland
- D. Adrenal gland
Correct Answer: A
Rationale: Calcitonin is a hormone produced by the thyroid gland. It helps regulate calcium levels in the body by inhibiting the breakdown of bone and promoting calcium excretion by the kidneys. The parathyroid gland produces parathyroid hormone (PTH), which works in opposition to calcitonin to regulate calcium levels. The thymus gland is involved in the development of the immune system, and the adrenal gland produces hormones such as cortisol and adrenaline. Therefore, the correct answer is the thyroid gland as it specifically secretes calcitonin for calcium regulation.
Which of the following reagents can be used to convert a primary alcohol to an alkyl halide?
- A. HI
- B. H2O
- C. NaOH
- D. SOCl2
Correct Answer: D
Rationale: SOCl2 (thionyl chloride) is commonly used to convert primary alcohols to alkyl halides through an SN2 mechanism. Thionyl chloride reacts with the alcohol to form an alkyl chloride. HI (hydroiodic acid) is typically used to convert alcohols to alkyl iodides specifically, not alkyl halides in general. H2O (water) and NaOH (sodium hydroxide) are not reagents used for converting alcohols to alkyl halides. Therefore, the correct answer is SOCl2 as it facilitates the conversion of primary alcohols to alkyl halides, unlike the other options provided.
The number of protons in an atom is determined by its:
- A. Atomic mass
- B. Electron configuration
- C. Chemical properties
- D. Atomic number
Correct Answer: D
Rationale: The number of protons in an atom is determined by its atomic number. The atomic number represents the number of protons in the nucleus of an atom, which also determines the element's identity. Therefore, the correct answer is (D) Atomic number. Choices (A) Atomic mass, (B) Electron configuration, and (C) Chemical properties are not directly related to the number of protons in an atom. Atomic mass is the total mass of protons, neutrons, and electrons in an atom. Electron configuration refers to the arrangement of electrons in an atom's energy levels, and chemical properties are determined by the arrangement of electrons in the outermost energy level.
Which compound is a component of baking soda and is important for maintaining pH balance in the body?
- A. Potassium
- B. Sodium
- C. Calcium
- D. Sodium bicarbonate
Correct Answer: D
Rationale: The correct answer is D, Sodium bicarbonate. Sodium bicarbonate, commonly known as baking soda, is a compound that plays a crucial role in maintaining pH balance in the body. When ingested, sodium bicarbonate acts as a buffer, helping to regulate the body's pH levels. It is essential for various physiological functions. Choices A, B, and C are incorrect. Potassium, calcium, and sodium are important minerals in the body but are not components of baking soda or directly responsible for maintaining pH balance in the same way as sodium bicarbonate.
What property best describes the characteristic that nuclear forces are much stronger than electromagnetic forces at the nuclear level?
- A. Short-range interaction
- B. Long-range interaction
- C. Repulsive force
- D. Dependent on charge only
Correct Answer: A
Rationale: The correct answer is A: Short-range interaction. Nuclear forces are much stronger than electromagnetic forces at the nuclear level because they are short-range interactions that act over distances on the order of the size of an atomic nucleus. This short-range nature of nuclear forces allows them to be much stronger than the long-range electromagnetic forces, which weaken with distance according to the inverse square law. Choice B, long-range interaction, is incorrect because nuclear forces are short-range. Choice C, repulsive force, is incorrect as nuclear forces include both attractive and repulsive components. Choice D, dependent on charge only, is incorrect because nuclear forces are not solely determined by charge but also involve other factors like spin and isospin.