The hormone aldosterone, which acts on the distal convoluted tubule and collecting duct to increase sodium reabsorption and potassium excretion, is secreted by the: MCQ with Answer and Explanation

Explanation:
Chlorophyll a and b absorb red and blue light and reflect green, giving leaves their color. Carotenoids are yellow/orange, anthocyanins red/purple.

Explanation:
COVID-19 is caused by SARS-CoV-2, a novel coronavirus. Tuberculosis is bacterial (Mycobacterium). Influenza is caused by influenza viruses (Orthomyxoviridae), not coronavirus. Pneumonia can be bacterial or viral, but the question specifies Streptococcus which is bacterial. COVID-19 emerged in 2019, causing a global pandemic, primarily affecting the respiratory system.

Explanation:
Gel electrophoresis, especially agarose gel electrophoresis, separates DNA, RNA, or protein fragments based on size and charge under an electric field. Smaller fragments move faster through the gel matrix. Centrifugation separates by density, chromatography by differential partitioning, spectrophotometry measures light absorption. Electrophoresis is a fundamental tool in molecular biology.