The deficiency of vitamin B₁ (thiamine) leads to: MCQ with Answer and Explanation

Explanation:
Mitochondria release cytochrome c and other factors that activate caspases, initiating apoptosis. They have circular DNA and 70S ribosomes.

Explanation:
Rhizopus stolonifer belongs to the class Phycomycetes (or Zygomycetes). These fungi are characterized by a coenocytic (multinucleate, aseptate) mycelium and reproduce asexually by forming motile or non-motile spores in sporangia. Ascomycetes (sac fungi) have septate hyphae and produce ascospores in asci. Basidiomycetes (club fungi) produce basidiospores on basidia. Deuteromycetes are imperfect fungi lacking a known sexual stage.

Explanation:
Photoperiodism is the physiological reaction of organisms, particularly plants, to the length of the day or a dark period. It is the mechanism by which plants measure the relative lengths of light and dark periods to regulate developmental processes, most notably the timing of flowering. Plants are classified as short-day plants, long-day plants, or day-neutral plants based on their flowering response to photoperiod. The photoreceptor pigment phytochrome is crucial in perceiving these light/dark signals.