Assertion (A): The menstrual cycle ceases during pregnancy. Reason (R): High levels of progesterone and estrogen inhibit FSH and LH release. MCQ with Answer and Explanation

Explanation:
Black stem rust of wheat is caused by the fungus Puccinia graminis tritici, a basidiomycete that produces reddish-brown uredospores and black teliospores. It requires barberry as an alternate host. It is a major disease causing significant crop losses.

Explanation:
Neurons are the excitable cells that generate and transmit electrochemical impulses. Glial cells (neuroglia) provide support, insulation, and nutrients. Fibroblasts form connective tissue, epithelial cells line surfaces. The neuron is the functional unit of the nervous system, connected at synapses.

Explanation:
Glucagon, from the pancreatic alpha cells, raises blood glucose by stimulating glycogenolysis and gluconeogenesis in the liver. Cortisol and growth hormone also raise blood glucose but glucagon is the primary direct antagonist of insulin. Thyroxine increases metabolic rate. The balance between insulin (hypoglycemic) and glucagon (hyperglycemic) maintains glucose homeostasis.