NEET Test 50

Iodine-131 has a half-life of 8 days, which means that after 8 days, the quantity of Iodine - 131 will become half. 
24 days = 3 half lives (since, 3 x 8 days = 24 days)
If A₀ is the initial quantity, then 
After first half-life, the remaining amount = 0.5A₀
After the second half-life, the remaining amount = 0.25 A₀
After the third half-life, the remaining amount = 0.125 A₀
By the end of three half-lives, the 24 days will be gone. 
Thus, we will be left with 0.125 A₀

Here, A₀ = 40 g, 
Thus, 0.125 A₀ = 0.125 x 40 = 5g

• When a bronchus is obstructed, the gas in the alveoli beyond the obstruction is absorbed and the lung segment collapses. Collapse of alveoli is known as Atelectasis.
• The cause of Atelectasis is inactivation of surfactant, the surface-tension-depressing agent normally found in thin fluid lining of alveoli.
• This abnormality is the major cause of failure of the lungs to expand normally at birth.
• Collapse of lungs may also be due to presence in pleural space of air (pneumothorax), tissue fluids (hydrothorax, chylothorax), or blood (hemothorax).

• Granulocytes are of three types Eosinophils, Basophils, and Neutrophils. Eosinophils have bilobed nucleus and take acidic strains and are 2-3%.
• They are originated from the bone marrow and have a life span of about 4-8 hours in the blood and 4 to 5 days in tissues.
• They are non- phagocytic, usually increases during allergic reactions and play an important role in the immunity.
• Basophils are least abundant (0.5-1%) of the total WBCs.
• Neutrophils are the most abundant cells (60-65 percent) of the total WBCs.

• Lymphatic capillaries are present in the intestinal villi, which are known as Lacteals.
• It absorbs fats from the intestine, therefore, release the absorbed fats into blood stream.
• Some other functions of lymph are-

(a) Transport oxygen, nutrients, hormones, etc., to the body cells. 
(b) Brings CO₂ and other metabolic wastes from body cells and pours into the venous system. 
(c) Transports lymphocytes and antibodies from lymph nodes to blood. 
(d) Foreign particles and microorganisms are destroyed by lymphocytes in the lymph nodes.

• Vasopressin and oxytocin are peptide hormones which are lipid insoluble hormones and they cannot pass directly through the membranes of cells and requires extracellular receptors for carrying out their activity.
• Other lipid insoluble hormones are amino acid derivatives like adrenaline and peptide hormones likeinsulin and glucagon.
• Steroids hormones like cortisol, testosterone, estrogen, progesterone, cortisol and estrogen are lipid soluble hormones and can easily pass through plasma membrane of cells and directly enter the cells.