Nokea
In the cardiovascular system, what does the term 'double circulation' refer to?
- A. The separation of oxygenated and deoxygenated blood flow within the heart.
- B. The regulation of blood pressure through vasoconstriction and vasodilation.
- C. The cyclic contraction and relaxation of the heart muscle.
- D. The existence of two separate circulatory pathways, one for the lungs and one for the body.
Correct Answer: D
Rationale: The term 'double circulation' in the cardiovascular system refers to the existence of two separate circulatory pathways, one for the lungs (pulmonary circulation) and one for the body (systemic circulation). Oxygen-poor blood is pumped from the heart to the lungs for oxygenation, and then oxygen-rich blood is pumped from the lungs back to the heart to be circulated to the rest of the body. Choices A, B, and C are incorrect as they do not accurately describe the concept of 'double circulation.' Choice A refers to the separation of oxygenated and deoxygenated blood within the heart, choice B relates to blood pressure regulation mechanisms, and choice C describes the cardiac muscle's contraction and relaxation, none of which define 'double circulation' in the context of the cardiovascular system.
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What is the term for the reaction between an acid and a base to produce water and a salt?
- A. Combustion
- B. Neutralization
- C. Oxidation
- D. Decomposition
Correct Answer: B
Rationale: Neutralization is the correct term for the reaction between an acid and a base to produce water and a salt. During neutralization, the hydrogen ions from the acid react with the hydroxide ions from the base to form water, and the remaining ions combine to form a salt. Combustion involves a reaction with oxygen, oxidation is the loss of electrons, and decomposition is the breakdown of a compound into simpler substances. These processes do not accurately describe the reaction between an acid and a base to produce water and a salt.
What property of matter determines its resistance to changes in shape or size?
- A. Solid
- B. Liquid
- C. Gas
- D. Plasma
Correct Answer: A
Rationale: The correct answer is 'Solid.' Solids have a definite shape and volume, providing them with a strong resistance to changes in shape or size. Liquids and gases do not have a definite shape, making them prone to changing shape or size easily. Plasmas, on the other hand, are ionized gases with high energy levels and lack a definite shape or volume, which does not contribute to resistance against changes in shape or size. Therefore, the properties of solids make them best suited for resisting changes in shape or size compared to liquids, gases, and plasmas.
Which of the following describes the difference between prokaryotic and eukaryotic cells?
- A. Prokaryotic cells have a nucleus, while eukaryotic cells don't.
- B. Eukaryotic cells are simpler in structure than prokaryotic cells.
- C. Prokaryotic cells have membrane-bound organelles, while eukaryotic cells don't.
- D. Eukaryotic cells have a true nucleus and membrane-bound organelles, while prokaryotic cells lack these.
Correct Answer: D
Rationale: Eukaryotic cells have a true nucleus that contains the genetic material, while prokaryotic cells lack a true nucleus. Eukaryotic cells also have membrane-bound organelles such as mitochondria, endoplasmic reticulum, and Golgi apparatus, which are absent in prokaryotic cells.
What enzyme plays a key role in breaking down carbohydrates in the small intestine?
- A. Pepsin
- B. Lipase
- C. Amylase
- D. Trypsin
Correct Answer: C
Rationale: Amylase is the enzyme responsible for breaking down carbohydrates in the small intestine. It specifically targets starches and sugars, breaking them down into smaller molecules like maltose and glucose that can be absorbed by the body. Pepsin is an enzyme that breaks down proteins in the stomach, not the small intestine. Lipase is responsible for breaking down fats, not carbohydrates. Trypsin is an enzyme that breaks down proteins in the small intestine, not carbohydrates.
What is the role of RNA interference in silencing genes?
- A. Increases protein production
- B. Promotes gene mutation
- C. Inhibits the expression of specific genes
- D. Repairs damaged DNA
Correct Answer: C
Rationale: RNA interference (RNAi) is a biological process that involves the silencing of gene expression by inhibiting the translation of mRNA or by degrading mRNA molecules. This mechanism plays a crucial role in regulating gene expression and can be used to selectively silence specific genes. By interfering with the expression of specific genes, RNAi can downregulate protein production from those genes. Therefore, option C, 'Inhibits the expression of specific genes,' is the correct role of RNA interference in silencing genes. Options A, B, and D are incorrect because RNA interference does not increase protein production, promote gene mutation, or repair damaged DNA; its primary function is to inhibit gene expression by degrading or interfering with mRNA.