Assertion (A): Restriction enzymes are used in recombinant DNA technology. Reason (R): They cut DNA at specific recognition sequences. MCQ with Answer and Explanation

Explanation:
Iron is a trace mineral (micronutrient) needed in small amounts for hemoglobin and myoglobin function. Calcium and phosphorus are macro-minerals required in larger amounts for bones. Sodium is a major extracellular electrolyte. Trace elements include iron, zinc, copper, iodine, selenium, manganese, etc. Iron deficiency causes anemia. Iron is absorbed in duodenum and stored as ferritin.

Explanation:
The nephron is the fundamental structural and functional unit of the kidney. Each kidney contains about one million nephrons. A nephron consists of two main parts: the renal corpuscle (Malpighian body, containing the glomerulus and Bowman's capsule) and the renal tubule (PCT, Loop of Henle, DCT). It is responsible for urine formation.

Explanation:
Carbon-14 (radiocarbon) dating is used to determine the age of organic materials up to about 50,000 to 60,000 years old. Living organisms absorb Carbon-14 from the atmosphere. When they die, absorption stops, and the Carbon-14 decays at a known rate (half-life of 5,730 years). By measuring the remaining Carbon-14, the age of the fossil can be calculated.