CBSE Questions for Class 11 Medical Biology Chemical Coordination And Integration Quiz 5 - MCQExams.com

• Thyroid uses iodine, a mineral found in some foods and in iodized salt, to make its hormones.
• The two most important thyroid hormones are thyroxine and triiodothyronine. Thyroid-stimulating hormone (TSH), which is produced by the pituitary gland, acts to stimulate hormone production by the thyroid gland.

• Renin is a hormone produced by the juxtaglomerular cells of the kidney.
• Renin also acts as an enzyme in the conversion of angiotensin-1 to its active form, angiotensin-2 involved in constriction of blood vessels. Hence renin is both a hormone and an enzyme. Hence, renin is both a hormone and enzyme.

• Hormones are chemical messengers of the body which control the animals' growth, development, and behavior. 
• Hormones are produced by specialized glands that make up the endocrine system and are transported via the blood to control the function of different parts of the body. 
• The pituitary gland at the base of the brain is the control center for the endocrine system.

• Testosterone is a 'male hormone' produced by the testes that encourage the development of male sexual characteristics, stimulates the activity of the male secondary sex characteristics and prevents changes in them following castration. 
• Testosterone is the most potent of the naturally occurring androgens. The androgens cause the development of male sex characteristics, such as a deep voice and a beard. 
• They also strengthen muscle tone and bone mass. 

• The thyroid gland is located in the lower part of the neck, below the Adam"s apple, wrapped around the trachea (windpipe). It has the shape of a butterfly: two wings (lobes) attached to one another by a middle part called the isthmus. 

$$\textbf{Correct option:A}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ Thyroxine is secreted from the thyroid gland which promotes prenatal brain development, metabolism and temperature homeostasis.

$$\textbf{Option (B)}$$

$$\bullet$$ Enterokinase is present in succus entericus (intestinal juice) which plays a crucial role in the conversion of Trypsinogen(proenzyme) present in pancreatic juice to trypsin,this trypsin breakdown protein into dipeptides, chymotrypsinogen to chymotrypsin and procarboxypeptidase to carboxypeptidase.

$$\textbf{Option (C)}$$

$$\bullet$$ Pepsinogen is an inactive enzyme that is secreted from the peptic cells /chief cells of the stomach ,this is converted by the hydrochloric acid present in the stomach to pepsin that converts protein to peptones and proteases .

$$\textbf{Option (D)}$$

$$\bullet$$ Insulin is an anabolic hormone that helps in synthesis of protein ,reduces oxidation of fats ,lowering blood sugar by converting it into glycogen which is stored in the liver.

$$\textbf{Hence, the correct option is (A)}$$

$$\textbf{Correct option:D}$$ 

$$\textbf{Solution:}$$

$$\textbf{Option (A)}$$

$$\bullet$$ There are three pairs of salivary glands parotid, sublingual and submandibular which secrete ptyalin (amylase enzyme that helps in initial carbohydrate breakdown .

$$\textbf{Option (B)}$$

$$\bullet$$ Adrenal glands are divided into two parts;adrenal cortex and adrenal medulla. Adrenal cortex secretes aldosterone,cortisol,cortisone ,androgens and estrogens. Adrenal medulla secretes tyrosine derivatives epinephrine and norepinephrine.

$$\textbf{Option (C)}$$

$$\bullet$$ The thyroid hormones secreted by thyroid glands are thyroxine,triiodothyronine,thyrocalcitonin, helps in maintaining energy consumption,metabolism,prenatal brain development and temperature regulation. Thyrocalcitonin helps in calcium metabolism.

$$\textbf{Option (D)}$$

$$\bullet$$ Pituitary hormone also known as master gland under the influence of inhibitory/releasing hormone from the hypothalamus ,secretes trophic hormones that controls the activity and secretion of other endocrine glands.

$$\bullet$$ The anterior pituitary secretes ACTH,TSH ,GH,PH and Gonadotropin hormones .

$$\bullet$$ The intermediate lobe secretes melanotropin that acts on pigmented cells to produce skin colour in certain animals.

$$\bullet$$ The posterior pituitary releases secretion of hypothalamic neurohormones ,oxytocin and vasopressin.

$$\textbf{Hence, the correct option is (D)}$$

• Glucagon is secreted by the alpha cells of the Islets of Langerhans in response to a fall in the blood glucose level. 
• It stimulates the change of glycogen stored in the liver to blood glucose. It also triggers the formation of glucose from amino acids and fats. 
• Both the processes increase the blood-glucose level to provide energy between meals. 
• Estrogen and progesterone are female sex hormones.
• Oxytocin is a hormone and a neurotransmitter that is involved in childbirth and breastfeeding.
  
• Vasopressin or antidiuretic hormone (ADH) causes the kidneys to reabsorb solute-free water from urine.
  

Calcitonin or thyrocalcitonin is a polypeptide hormone produced by the parafollicular cells or the c-cells present in thyroid. This hormone is responsible for regulation of blood calcium and phosphorus. It results in generation of opposite effects of parathyroid hormone. Main effect of calcitonin is to reduce the blood calcium level in blood by inhibiting the bones’ osteoclastic activity, stimulation of osteoblastic activity in bones and promotes excretion of calcium in the urine.