CBSE Questions for Class 11 Medical Biology Chemical Coordination And Integration Quiz 15 - MCQExams.com

Hormones which interact with membrane-bound receptors normally do not enter the target cell but generate second messengers( cyclic AMP, IP$$_3$$, etc) which in turn regulate cellular metabolism in figure a.

Hormones which interact with intracellular receptors (e.g. steroid hormones, iodothyronines etc.) mostly regulate gene expression or chromosome function by the interaction of hormone- receptor complex with the genome. cumulative biochemical actions result in physiological and developmental effects.

So, the correct answer is 'A-Generation of a second messenger, B- Biochemical responses, C- Physiological responses'.

Vasopressin hormone is secreted by the posterior pituitary gland. It constricts the blood vessel and increases reabsorption of water from kidney. Hence, it decreases loss of water through urine. Norepinephrine is secreted by adrenal medulla. It increases heart rate and blood pressure. It also increases rate of respiration and alertness. Glucagon hormone is secreted by the alpha cells of Islets of Langerhands. It stimulates glycogenolysis in the liver. It increases amount of glucose in the blood. Prolactin hormone is secreted by the anterior pituitary gland. It promotes the mild formation in females. It also causes growth or enlargement of mammary glands. 

The correct statement is- 'The pineal gland secretes a hormone melatonin which helps to regulate sleep pattern. Parathyroid Gland release hormone which regulates the level of calcium in the blood with the help of calcitonin which is produced in the thyroid gland.'

• Growth hormone affects glucagon and  insulin secretion and is therefore said to be having a diabetogenic effect. 
• In males FSH acts on Sertoli cells to stimulate sperm (male gamete) production and in females it stimulates growth of ovarian follicles. Since it effects both male and female gametes, it is known as gameto kinetic factor. 
• LH triggers the release of an egg (female gamete) from the ovarian follicles and so, is known as the gamete releasing factor. 
• Hormone prolactin stimulates lactation (i.e the mammary glands to produce milk. 
• So, the correct answer is 'A $$\rightarrow$$ iii, B $$\rightarrow$$ i, C $$\rightarrow$$ iv, D $$\rightarrow$$ ii'.

Lipid insoluble hormones such as epinephrine acts or functions on a particular site by binding to it. These hormones have their receptors on the plasma membrane of the target cells. The binding of hormone to the receptor initiates a series of events. These series of events are called as signal transduction. In this, the hormone first binds to the surface receptor. It leads to the activation of the enzyme adenylate cyclase. This enzyme converts the ATP into cyclic AMP or cAMP inside the cell. This cAMP acts as second messenger. This cAMP then activates cAMP-dependent protein kinase called protein kinase A. This proteni kinase A triggers a series of molecular interactions that leads to glycogenolysis. This results in the synthesize of glucose from glycogen.

• Pancreatic secretion contains multiple enzymes to digest proteins, fats, and carbohydrates. The entry of highly acidic food to the small intestine stimulates the secretion of large quantities of water solution of sodium bicarbonate by the pancreatic ductal epithelium as depicted in graph 1. 
• The presence of long-chain fatty acids and peptones in the chyme (partially digested food) results in the secretion of pancreatic digestive enzymes by the acinar cells which are depicted in graphs 2 and 3. 

Thyrocalcitonin (TCT) is secreted when calcium level in blood is high. It then lowers the levels by suppressing  release of calcium ions from bones. Whereas parathyroid hormone increases the blood calcium level by increasing calcium absorption from intestine and mobilising calcium from bones to blood.

The adrenal cortex is responsible for the production of three major classes of steroid hormones: glucocorticoids, which regulate carbohydrate metabolism; mineralocorticoids, which regulate the body levels of sodium and potassium. Thyroid hormone action and mechanisms mediate metabolic regulation, focusing on the interaction among the pathways that regulate lipid and carbohydrate metabolism, and the balance of energy storage and energy expenditure. Hence, both are responsible for carbohydrate or glucose metabolism. 

In mammals, the acrosome reaction releases hyaluronidase and acrosin.