Identify the correct statement about the circulatory system:
A. Capillaries have valves to prevent backflow.
B. Arteries always carry oxygenated blood.
C. The pulmonary artery carries oxygenated blood.
D. Veins have thin, elastic walls compared to arteries.
Answer: Option D
Solution (By JKExamLibrary)
Veins have thinner walls than arteries and contain valves. The pulmonary artery carries deoxygenated blood, and arteries normally (except pulmonary) carry oxygenated blood.
Explanation:
Lacrimal glands, located above the outer corner of each eye, produce tears that lubricate and protect the eye surface. Parotid and sublingual are salivary glands, ceruminous glands produce ear wax.
Consider statements about biotechnology: 1. PCR can amplify a specific DNA sequence. 2. Gel electrophoresis separates DNA fragments by size. 3. Restriction enzymes join DNA fragments. Which are correct?
Explanation:
Polymerase Chain Reaction (PCR) is a powerful technique used to exponentially amplify a specific segment of DNA using primers and a thermostable DNA polymerase. Gel electrophoresis is a method used to separate DNA, RNA, or protein molecules based on their size and charge by applying an electric field through a gel matrix. Restriction enzymes are molecular scissors that cut DNA at specific sequences; DNA ligase is the enzyme that joins DNA fragments together. Thus, statements 1 and 2 are correct.
Explanation:
Apoptosis is a highly regulated and organized process of programmed cell death that occurs in multicellular organisms. It is crucial for development, maintaining tissue homeostasis, and eliminating damaged or infected cells. Unlike necrosis (accidental cell death), apoptosis does not cause inflammation and involves cell shrinkage and fragmentation.
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