Consider the following statements about the circulatory system: 1. Arteries carry blood away from the heart. 2. Veins have valves to prevent backflow. 3. Capillaries are thick-walled vessels. Which of the above is/are correct? MCQ with Answer and Explanation

Explanation:
Thyroxine (T4) and Triiodothyronine (T3) are the main hormones secreted by the thyroid gland. They play a crucial role in regulating the basal metabolic rate (BMR), which is the rate at which the body uses energy at rest. They also influence growth, development, and body temperature. Calcitonin, also from the thyroid, regulates blood calcium.

Explanation:
Certain bacteria, like Bacillus megaterium and Alcaligenes eutrophus, accumulate polyhydroxyalkanoates (PHA) such as PHB as intracellular carbon and energy storage under nutrient stress. These are used to make biodegradable plastics. E. coli is engineered for some bioplastics, but natural producers include Bacillus.

Explanation:
Mitosis produces two genetically identical diploid daughter cells (clones) essential for growth, repair, and asexual reproduction. Meiosis involves pairing (synapsis) and crossing over during prophase I, and produces four genetically diverse haploid cells (gametes). The conservation of chromosome number and genetic identity is a hallmark of mitosis.