Thyroxine hormone is produced by the: MCQ with Answer and Explanation

Explanation:
The centrosome, which contains two centrioles, duplicates during the S phase of the cell cycle, concurrent with DNA replication. This ensures that by the time the cell enters mitosis, it has two fully formed centrosomes to organize the mitotic spindle. G1 is for growth, G2 is for preparation for M phase, and M phase is for actual division.

Explanation:
The pituitary, located at the base of the brain, controls many endocrine glands via its hormones, earning the name 'master gland'. Insulin is from pancreas; it is connected to hypothalamus by infundibulum.

Explanation:
Mutualism is a symbiotic interaction where both species benefit (+/+). Examples: Rhizobium-legume association, lichens, mycorrhizae, and oxpecker-rhino. Parasitism benefits one at the expense of the other (+/-), commensalism benefits one without affecting the other (+/0), amensalism harms one without benefit to the other (-/0). Mutualism is crucial for ecosystem functioning.