Nokea
Decomposers in an ecosystem play a vital role by:
- A. Photosynthesizing and producing organic matter
- B. Breaking down dead organisms and returning nutrients to the environment
- C. Preying on herbivores and controlling their populations
- D. Fixing nitrogen from the atmosphere and making it available to plants
Correct Answer: B
Rationale: Decomposers are organisms that break down dead organic matter, such as dead plants and animals, into simpler substances. By doing so, they help to recycle nutrients back into the environment, making them available for other organisms to use. This process is essential for the functioning of ecosystems, as it ensures that nutrients are not lost but instead are continuously cycled through the ecosystem. Photosynthesis (option A) is the process by which plants and some other organisms convert light energy into chemical energy in the form of glucose, and it is not a role of decomposers. Preying on herbivores (option C) is a role typically carried out by predators, not decomposers. Fixing nitrogen from the atmosphere (option D) is a process carried out by nitrogen-fixing bacteria, not decomposers.
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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.
Which property of a substance refers to its ability to undergo a chemical change and form new substances?
- A. Density
- B. Mass
- C. Reactivity
- D. Volume
Correct Answer: C
Rationale: Reactivity is the property of a substance that describes its ability to undergo a chemical change and form new substances through chemical reactions. Density, mass, and volume are physical properties of a substance and do not directly relate to its ability to undergo chemical changes. Density is the mass of a substance per unit volume, mass is the amount of matter present, and volume is the amount of space occupied by the substance. Reactivity specifically deals with how likely a substance is to engage in chemical reactions. Therefore, the correct answer is C - Reactivity.
Which lifestyle practice can weaken the immune system?
- A. Getting enough sleep
- B. Eating a balanced diet rich in fruits and vegetables
- C. Managing stress levels
- D. Frequent smoking
Correct Answer: D
Rationale: Frequent smoking can weaken the immune system by damaging immune cells and impairing their function. Smoking increases the risk of respiratory infections and other illnesses, negatively impacting immune health. Therefore, frequent smoking is a lifestyle practice that can weaken the immune system. Choices A, B, and C are all beneficial practices that support a healthy immune system. Getting enough sleep, eating a balanced diet rich in fruits and vegetables, and managing stress levels are important for maintaining optimal immune function and overall well-being.
Which of the following is NOT a mechanism of evolution?
- A. Natural selection
- B. Genetic drift
- C. Lamarckism
- D. Mutation
Correct Answer: C
Rationale: A) Natural selection is a mechanism of evolution where individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to the next generation.
B) Genetic drift is a mechanism of evolution that occurs due to random changes in allele frequencies in a population.
C) Lamarckism, also known as the inheritance of acquired characteristics, is a discredited theory that suggests organisms can pass on traits acquired during their lifetime to their offspring. This mechanism has been largely rejected by the scientific community.
D) Mutation is a mechanism of evolution that introduces new genetic variation into a population, which can lead to the emergence of new traits and adaptations over time.
What is the term for the number of moles of solute per liter of solution?
- A. Molarity
- B. Molality
- C. Normality
- D. Concentration
Correct Answer: A
Rationale: Molarity is the correct term for the number of moles of solute per liter of solution. It is expressed as moles of solute divided by liters of solution. Molality (B) is similar but is moles of solute per kilogram of solvent. Normality (C) is the number of equivalents of solute per liter of solution, and Concentration (D) is a general term for the amount of solute present in a given quantity of solution. Therefore, the correct answer is A, molarity, as it specifically refers to moles of solute per liter of solution.