Identify the correct statement about the cell nucleus: MCQ with Answer and Explanation

Explanation:
Selman Waksman, who discovered streptomycin, coined the term 'antibiotic' in 1942 to describe chemical substances produced by microorganisms that inhibit or kill other microorganisms. Fleming discovered penicillin but did not coin the term. Pasteur developed pasteurization and rabies vaccine, Ehrlich discovered salvarsan (magic bullet) for syphilis.

Explanation:
Greenhouse gases trap heat in the Earth's atmosphere, contributing to the greenhouse effect and global warming. Carbon dioxide (CO2) and methane (CH4) are potent greenhouse gases emitted through human activities like fossil fuel combustion and agriculture. Oxygen (O2) and nitrogen (N2), which make up the majority of the atmosphere, are not greenhouse gases as they do not absorb infrared radiation. Thus, statements 1 and 2 are correct.

Explanation:
Mammals are distinguished by the presence of mammary glands in females that secrete milk for nourishing young. They are warm-blooded, have hair/fur, and most give birth to live young (viviparous), though monotremes like platypus lay eggs. Feathers are characteristic of birds. Cold-blooded refers to ectotherms (reptiles, amphibians, fish). Mammals are endotherms.