The theory of chemical evolution of life was proposed by: MCQ with Answer and Explanation

Explanation:
The leavening (rising) of bread dough is caused by the anaerobic respiration (fermentation) of the yeast Saccharomyces cerevisiae (baker's yeast). The yeast ferments the sugars in the dough, producing carbon dioxide (CO2) gas and ethanol. The CO2 gas gets trapped in the dough, causing it to expand and rise, giving bread its light and fluffy texture.

Explanation:
Thigmonasty (seismonasty) is a non-directional, rapid response to touch or vibration, exemplified by the drooping of Mimosa pudica leaves. Thigmotropism is directional growth towards/away from touch (e.g., tendrils). Phototropism is light-directed growth, geotropism gravity-directed.

Explanation:
Xylem vessels and tracheids are dead, hollow cells at functional maturity, providing a continuous tube for water transport. Phloem sieve tube elements are living cells at maturity, though they lack a nucleus, and are responsible for transporting organic nutrients. Cambium (vascular and cork) is a lateral meristem responsible for secondary growth (increase in girth), while apical meristems are responsible for primary growth (increase in length). Thus, statements 1 and 2 are correct.