The process of movement of molecules from high to low concentration without energy is: MCQ with Answer and Explanation

Explanation:
The skin and mucous membranes form the first line of defense (innate immunity), acting as physical barriers that prevent pathogens from entering the body. White blood cells (leukocytes), including phagocytes and lymphocytes, are the cellular components of the immune system that identify, attack, and destroy pathogens. Antibiotics are drugs designed to kill or inhibit the growth of bacteria; they are completely ineffective against viruses, which lack the cellular machinery targeted by antibiotics. Thus, statements 1 and 2 are correct.

Explanation:
BCG (Bacille Calmette-Guérin) is a live attenuated vaccine derived from Mycobacterium bovis, used against tuberculosis, primarily in children. Polio vaccine (OPV/IPV) prevents poliomyelitis, DPT prevents diphtheria, pertussis, tetanus, and MMR prevents measles, mumps, rubella. BCG is often administered at birth in TB-endemic countries.

Explanation:
Lysosomes are single-membrane-bound organelles containing hydrolytic enzymes. Mitochondria, chloroplasts, and the nucleus are double-membrane-bound. Peroxisomes, vacuoles, and the endoplasmic reticulum are also single-membrane structures. The single membrane of lysosomes helps maintain an acidic pH (5.0) for enzyme activity and protects the cell from autolysis.