Why are RBCs efficient in their functions though they lack nucleus and mitochondria?

The immediate steps to be taken when a person suffers a heart attack are: P. Loosen the clothes Q. Make the person lie down in an airy place R. Take the person to the hospital S. Encourage conversation (a) P and Q (b) P and S (c) R and S (d) P, Q and R

Pick the odd one out and name the category to which the remaining three belong: (a) Prothrombin, Thrombin, Fibrinogen, Albumin (b) Tonsils, Glomerulus, Spleen, Lymph nodes (c) Neutrophils, Basophils, Monocytes, Eosinophils (d) Leaves, Styrofoam, Grass, Cow dung (e) Pulmonary artery, Renal artery, Coronary artery, Hepatic artery

Arrange the following food chains in a proper sequence. (a) Small fish, Algae, Mosquito larvae, Kingfisher (b) Frog, Snail, Crow, Green leaves

Give two examples of water pollutants.

Name the mineral elements required for: (a) Clotting of blood (b) Synthesis of thyroxine

Mention two structural differences between an artery and a vein.

Give the exact location of: (a) Pericardium (b) Bicuspid valve

Write any two objectives of Swachh Bharat Abhiyan.

State two harmful effects of acid rain on the environment.

Mention two harmful effects of noise pollution.

Assertion (A): Leukoderma is the biological term for blood cancer. Reason (R): An abnormal increase in the number of WBCs causes blood cancer. (a) (A) is true and (R) is false. (b) (A) is false and (R) is true. (c) Both (A) and (R) are true and (R) is the correct explanation of (A). (d) Both (A) and (R) are true and (R) is not the correct explanation of (A).