CBSE Class 11 Biology Chapter 22: Chemical Coordination and Integration NCERT Solutions

Solution: The correct matching of endocrine glands and their hormones is as follows:

A. Pineal gland secretes Melatonin (2). Melatonin is crucial for regulating biological rhythms, including the sleep-wake cycle.

B. Thyroid gland secretes Tetraiodothyronine (also known as T4) (4). This hormone is vital for regulating metabolism.

C. Ovary secretes Estrogen (3). Estrogen is a primary female sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics.

D. Adrenal medulla secretes Epinephrine (also known as adrenaline) (1). This hormone is part of the 'fight or flight' response.

Therefore, the correct code is (d) 2 4 3 1.

Solution: The anterior pituitary gland, also known as the adenohypophysis, secretes several important hormones. These include Growth Hormone (GH), Follicle Stimulating Hormone (FSH), Adrenocorticotrophic Hormone (ACTH), Thyroid Stimulating Hormone (TSH), Luteinizing Hormone (LH), and Prolactin.

Oxytocin, however, is synthesized in the hypothalamus and released from the posterior pituitary gland (neurohypophysis). It plays a role in uterine contractions during childbirth and milk ejection during breastfeeding.

Therefore, Oxytocin is the hormone listed that is not secreted by the anterior pituitary.

Solution: The symptoms Mary is experiencing – sweating, increased heart rate, and rapid respiration – are characteristic physiological responses to stress, often referred to as the 'fight or flight' response.

These responses are primarily mediated by the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine), which are secreted by the adrenal medulla. These hormones prepare the body to face a perceived threat or stressful situation by increasing blood flow to muscles, raising blood glucose levels, and enhancing alertness.

Estrogen and progesterone are primarily involved in the female reproductive cycle and pregnancy. Oxytocin and vasopressin have roles in childbirth, milk ejection, and water balance, respectively. Insulin and glucagon regulate blood glucose levels.

Thus, adrenaline and noradrenaline are the hormones responsible for Mary's restlessness before the interview.

Solution: The balance of water and electrolytes in the body is crucial for maintaining homeostasis. This balance is significantly regulated by steroid hormones produced by the adrenal cortex.

Aldosterone is a mineralocorticoid, a type of steroid hormone secreted by the adrenal cortex. Its primary function is to regulate the reabsorption of sodium ions and water, and the excretion of potassium ions, in the renal tubules. This action helps maintain blood volume, blood pressure, and electrolyte balance.

Insulin is a peptide hormone regulating blood glucose. Melatonin is a hormone regulating sleep-wake cycles. Testosterone is an androgen, primarily involved in male reproductive functions and secondary sexual characteristics.

Therefore, aldosterone is the steroid hormone responsible for the balance of water and electrolytes.