CBSE Questions for Class 11 Medical Biology Chemical Coordination And Integration Quiz 8 - MCQExams.com

• Cholecystokinin is secreted from the duodenum and causes contraction of gall bladder and secretion of pancreatic juice into duodenum.
• Secretin is secreted from duodenum and stimulates the secretion of pancreatic juice but inhibits the secretion of gastric juices.

$$\textbf{Correct option:D}$$ 

$$\textbf{Solution:}$$

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

$$\bullet$$ Adrenal glands are a pair of endocrine glands situated over the two kidneys in the abdomen. Adrenal is divided into two regions ;cortex and medulla. Cortex secretes three types of hormones aldosterone which regulates sodium homeostasis in the body,cortisol regulates sugar homeostasis and sex corticoids. Adrenal medulla secretes epinephrine and epinephrine at the time of emergency.

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

$$\bullet$$ Parathyroid hormones are two pairs of glands,situated on the anterior side of the thyroid lobes which secretes parathormone in reponse to low level of calcium in the body. It increases the release of calcium from bones and reabsorption of calcium from nephrons and intestines.

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

$$\bullet$$ There are two pairs of testes in males and two pairs of ovaries ,they secrete testosterone and estrogen respectively.Testosterone is required for secondary sexual character and organ development,sperm formation and growth of tissues and bones. Estrogens are primary sexual hormones in females that is required for the secondary sexual characters development, formation of endometrium lining and mammary gland growth.

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

$$\bullet$$ Pituitary forms basal part of the diencephalon ,which secretes trophic hormone from adenohypophysis, melatonin from intermediate lobe of pituitary and release of oxytocin and vasopressin from posterior lobe of pituitary under the stimulation of hypothalmic hormones.

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

• Pancreas is a heterocrine gland as it acts both as endocrine and exocrine gland. It secretes insulin hormone into blood and act as endocrine gland and when it secretes digestive enzymes and juice through pancreatic duct, it acts as exocrine gland.
  
• Adrenal cortex is part of adrenal gland and secretes glucocorticoids (cortisol,) mineralocorticoids (aldosterone) and sexocorticoids (androgens).
• Thyroid gland is situated between the trachea and larynx in the neck and secretes thyroxine hormone which increases oxygen consumption by metabolically active tissues.
  

• Photoperiodism is the physiological reaction to the length of day or night by an organism.
  
• The pineal gland or pineal body (epiphysis or third eye) is a small endocrine gland.
• It secretes melatonin (hormone) which regulates the wake/sleep patterns and photoperiodic functions.
  
• So, the correct answer is 'Pineal body'.

• Membrane bound receptors : These are present on the cell membrane of target cells.
• Intracellular receptors: These are present inside the target cell.

• Erythropoietin is a hormone released by the kidney.
  
• It is a glycoprotein. 
• This hormone helps in the proliferation and differentiation of erythrocyte precursors.
• Thus, they produce red blood cells (RBCs) from the bone marrow cells and this process is also known as erythropoiesis.
• The cells of the kidney that produces erythropoietin are sensitive to low oxygen levels in the blood that travels to the kidney.
• So, the correct answer is 'Glycoprotein'.

• The pineal gland or pineal body (epiphysis or third eye) is a small endocrine gland.
  
• It secretes melatonin (hormone) which regulates the wake/sleep patterns and photoperiodic functions.
  
• Biorhythms or biological rhythms control sleep and wake cycles and other functions such as behaviour and endocrine rhythms. These functions are regulated by the circadian clock.
• The secretion of melatonin is triggered in dark and inhibited by light.
• So, the correct answer is 'Melatonin'.

• Melanin is a pigment produced within the skin in melanocytes or skin cells when they are exposed to the sun. 
  
• The process by which the pigment melanin is formed by the melanocytes is called melanogenesis.
• The colour of the skin is determined by at least 6 genes.
• Thus, skin colour or complexion is controlled by the environment and is also hereditary.
• So. the correct answer is 'Both heredity and environment'.

• Melanin is a pigment produced within the skin in melanocytes or skin cells when they are exposed to the sun. 
• The process by which the pigment melanin is formed by the melanocytes is called melanogenesis.
• The pigment is formed within a small membrane-bound structure called melanosomes.
  
• The skin colour is determined by a bluish-white connective tissue under the dermis or corium and the haemoglobin circulating in the veins of the corium.
  
• The corium is a layer of skin present between the epidermis and the subcutaneous tissues of the skin.
  
• Two types of melanin are formed in the body pheomelanin (red to yellow in colour) and eumelanin (dark brown to black).
  
• Those people with light complexion produce pheomelanin whereas, those with dark complexion produce eumelanin.
• So, the correct answer is 'Melanocytes of corium and incorporated in epidermis'.

• Acidophils: 40%
• Basophils: 10%
• Chromophobes: 50%