Multiple Choice QuestionsLeghaemoglobin helps in
imparting colour to floral petals
protecting nitrogenase from O2
destroying bacteria
transport of food in plants
Cocoa is the plant from which chocolate is made. Which part is used to extract it?
Flower
Fruits
Seeds
Bark
Assertion : Astigmatism is due to uneven curvature of lens.
Reason : It is treated with cylindrical lenses.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Assertion : Blood coagulate in uninjured blood vessels.
Reason : Uninjured blood vessels release an anticoagulant heparin.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false.
D.
If both assertion and reason are false.
When a blood vessel gets injured, blood platelets get clumped at the injured spot and release certain chemicals called platelet factors, which promote blood coagulation.
Injured tissues or platelets also release coagulation promoting substances called thromboplastins which help in the formation of an enzyme prothrombinase. This enzyme activates inactive protein prothrombin to active thrombin which further promotes the coagulation process.
Blood normally contains an anticoagulant heparin which is released from mast cell granules that prevents the activation of prothrombin in uninjured blood vessels. Blood also contains antithrombin which inhibits any thrombin formed accidentally. Moreover, uninjured tissues do not release thromboplastins, hence blood does not coagulate in uninjured blood vessels.
Assertion : Smaller the organism higher is the rate of metabolism per gram weight.
Reason : The heart rate of a six month old baby is much lower than that of an old person.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Assertion : Torison can be seen in ctenidium.
Reason : Ctenidium acts as the respiratory organ.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Assertion : Secreting hypotonic urine is effective in reducing urinary loss of water.
Reason : Hypotonic urine is more concentrated and higher in osmotic pressure than the blood.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Assertion : Aldosterone is a steroid hormone and is important in the control of sodium and potassium ion concentration in mammals.
Reason : It upgrades sodium ion concentration in the ECF by promoting reabsorption of sodium ions from renal tubules and excretion of potassium ions in urine.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
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