The element that is a component of the hormone thyroxine is: MCQ with Answer and Explanation

Explanation:
Rhizobium is a symbiotic bacterium found in legume root nodules that fixes atmospheric nitrogen into ammonia. Yeast (Saccharomyces cerevisiae) undergoes anaerobic respiration, producing CO2 that leavens bread dough. The vast majority of bacteria are harmless or beneficial (e.g., gut flora, decomposers); only a small fraction are pathogenic to humans. Thus, statements 1 and 2 are correct.

Explanation:
DNA contains adenine, guanine, cytosine, and thymine. RNA contains uracil instead of thymine. This is one of the key differences between DNA and RNA. Uracil pairs with adenine in RNA. The base pairing in DNA is A-T and G-C. In RNA, it is A-U and G-C. Uracil lacks the methyl group present in thymine.

Explanation:
Mammalia is the only class of animals that possess mammary glands, which produce milk to nourish their young ones. Other defining features of mammals include the presence of hair on the skin, external pinnae (ear flaps), a four-chambered heart, and being warm-blooded (homeothermic). Examples include humans, whales, and bats.