Biology Test 290

Mother Rh+ve because when mother has Rh +ve then erythroblastosis foetalis is not complete or second progeny is not die. And for erythroblastosis foetalis required condition is mother has Rh-ve and Father has Rh+ve.

DCT maintains the pH and ionic balance in the blood by reabsorption of Na+, water, HCO₃ and selective secretion of H+, K+ and NH₃. Collecting duct plays a role in the maintenance of pH and ionic balance of blood by reabsorption of water, and selective secretion of H+ and K+ ions.

Calcium is present in high level in muscle only during contraction and during muscle contraction "size of A band " remains constant.

The pineal gland, also known as the 'pineal body,' is a small endocrine gland. It is located on the back portion of the third cerebral ventricle of the brain, which is a fluid-filled space in the brain.

The hormones of the pineal gland indirectly support the formation of RBCs as it also contains sleep wake cycle, body temperature, pigmentation, menstrual cycle, metabolism and defence mechanism.

Hence, the correct answer is Option C

The lungs are the primary organ of the respiratory system.

The lungs are situated in the thoracic chamber which is anatomically an air-tight chamber.

The process of exchange of O₂ from the atmosphere with CO₂ produced by the cells is commonly known as respiration.

During respiration, CO₂ and H₂O are removed from our body by the lungs.

Lungs mainly exhale carbon dioxide but also remove a small amount of water vapours (about 400 ml/day).

Eosinophils are 2 - 3 percent and resist infections and associated with allergic reactions.

The correct answer is Option C i.e., "ANF can cause vasoconstriction" because release of ANF causes blood vessels dilation (vasodilation)

Fall in GFR releases renin by activating JG cells.

Angiotensin ii releases aldosterone which increases water and sodium ion absorption.

ADH acts on DCT and CD and increases water reabsorption.

Muscle contraction occurs according to the sliding filanent theory. The active site of actin is masked by troponin. In myosin, the energy for binding of actin is from ATP hydrolysis. Myosin contains ATPase enzyme in its head and is responsible for ATP hydrolysis.

When the signal reaches motor end plate, acetylcholine is released. It binds with the membrane to produce depolarization.

It send neural messages and hence SPR releases Ca²⁺. This Ca²⁺ bind with TnC and the masking of actin is removed. At the same time, ATP molecules bind with the head of meromyosin. Therefore the head of meromyosin get energised.

Actin and myosin binds together (cross arm activity) then a fresh ATP is formed and the cross bridge breaks i.e.,ATP hydrolysis lead to the formation of cross bridge.

As a result size of sacromere decreases, then the ADP and iP are released and cross bridge is broken.

Answer: C.

Solution: Calcium ions play a crucial role in muscle contraction by binding to troponin. This action removes the inhibition that prevents actin and myosin from interacting, thereby facilitating the formation of cross-bridges between these filaments, which is essential for muscle contraction.

Thoracic consists of 12 bones and the bones of last pair (11th and 12th ) are called floating ribs or false bones so 1 and 2 options are right.

options 3 and 4 are wrong because phalanges are 14 and ankle bones are 7.