Nokea
Which of the following is an example of a weak acid?
- A. Hydrochloric acid (HCl)
- B. Sulfuric acid (H2SO4)
- C. Acetic acid (CH3COOH)
- D. Nitric acid (HNO3)
Correct Answer: C
Rationale: The correct answer is Acetic acid (CH3COOH) because it is a weak acid that only partially dissociates in water, resulting in a lower concentration of H+ ions compared to strong acids like hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3) which completely dissociate in water. Weak acids do not fully ionize in water, leading to a lower concentration of H+ ions in solution. Hydrochloric acid, sulfuric acid, and nitric acid are strong acids that completely dissociate in water, producing a higher concentration of H+ ions. Therefore, they are not examples of weak acids.
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Which property of matter remains constant regardless of changes in gravity?
- A. Mass
- B. Weight
- C. Volume
- D. Density
Correct Answer: A
Rationale: Mass is a measure of the amount of matter in an object and remains constant regardless of changes in gravity. Weight, on the other hand, is the force of gravity acting on an object and can vary depending on the strength of gravity. Volume is the amount of space an object occupies, and density is the mass per unit volume of a substance, both of which can change with changes in gravity. Therefore, mass is the property that remains the same regardless of variations in gravitational force. Choice B, Weight, changes with gravity as it is a force dependent on gravity. Choices C and D, Volume and Density, can be affected by changes in gravity as they are related to the space an object occupies and the mass per unit volume, respectively.
What is the main function of peroxisomes in the cell?
- A. To break down hydrogen peroxide
- B. To synthesize lipids and other cellular components
- C. To package and transport proteins
- D. To store genetic material
Correct Answer: A
Rationale: Peroxisomes are membrane-bound organelles found in eukaryotic cells that contain enzymes involved in various metabolic processes. One of the main functions of peroxisomes is to break down hydrogen peroxide, a toxic byproduct of metabolism, into water and oxygen through the action of the enzyme catalase. This process helps protect the cell from oxidative damage caused by hydrogen peroxide. While peroxisomes are involved in other metabolic functions such as lipid metabolism and the synthesis of bile acids, their primary role is the breakdown of hydrogen peroxide. Choices B, C, and D are incorrect because peroxisomes are not primarily responsible for synthesizing lipids, packaging and transporting proteins, or storing genetic material within the cell.
What is the main consequence of a malfunctioning thyroid gland that produces abnormally low levels of thyroid hormones?
- A. Increased energy levels and weight loss
- B. Decreased heart rate and body temperature
- C. Enhanced muscle growth and bone development
- D. Faster metabolism and heightened alertness
Correct Answer: B
Rationale: The correct answer is B: Decreased heart rate and body temperature. A malfunctioning thyroid gland that produces abnormally low levels of thyroid hormones leads to hypothyroidism, resulting in decreased metabolic activity. This reduction in metabolic rate can cause a decreased heart rate and lower body temperature. Choices A, C, and D are incorrect because hypothyroidism typically manifests as symptoms such as fatigue, weight gain, cold intolerance, bradycardia, and decreased body temperature, rather than increased energy levels, enhanced muscle growth, faster metabolism, or heightened alertness.
What do hair follicles house in the skin?
- A. Blood vessels (Blood vessels are not housed within hair follicles)
- B. Nerve endings (Nerve endings are present but not housed within hair follicles)
- C. Hair shafts and hair roots
- D. Sebaceous glands (These glands are often attached to hair follicles)
Correct Answer: C
Rationale: Hair follicles are structures in the skin that contain the hair shaft (the visible part of the hair) and the hair root (the part of the hair beneath the skin). The hair shaft is the portion of the hair that is visible above the skin, while the hair root is the part that extends below the surface into the follicle. Therefore, the correct answer is that hair follicles house the hair shafts and hair roots. Choices A, B, and D are incorrect because blood vessels are not housed within hair follicles, nerve endings are present but not housed within hair follicles, and sebaceous glands are often attached to hair follicles but not housed within them.
What type of particle carries no charge and mediates the strong nuclear force between protons and neutrons?
- A. Electron
- B. Photon
- C. Gluon
- D. Neutrino
Correct Answer: C
Rationale: The correct answer is C: Gluon. Gluons are the particles responsible for mediating the strong nuclear force between protons and neutrons. They are the carriers of this force. Choice A, Electron, is incorrect as electrons are negatively charged. Choice B, Photon, is incorrect as photons are chargeless particles of light. Choice D, Neutrino, is incorrect as neutrinos are neutral particles with minimal mass and weak interactions with matter, not involved in mediating the strong nuclear force between protons and neutrons.