Assertion (A): Plants wilt in salty soil. Reason (R): High salinity causes water to move out of root cells by osmosis. MCQ with Answer and Explanation

Explanation:
Ribosomes are the only organelles common to both prokaryotes and eukaryotes, though sizes differ: 70S in prokaryotes, 80S in eukaryotes. Nuclear membrane, mitochondria, and Golgi are absent in prokaryotes. Ribosomes are the site of protein synthesis. This commonality supports the universal role of protein synthesis in all life forms. Mycoplasma, the smallest prokaryote, also has ribosomes.

Explanation:
Cyanobacteria (blue-green algae) are photosynthetic, oxygenic prokaryotes that play a crucial role in nitrogen fixation in aquatic and terrestrial ecosystems. Mycorrhiza is a mutualistic symbiotic association between a fungus and the roots of a vascular plant, where the fungus aids in nutrient absorption and the plant provides carbohydrates. Nitrosomonas is a nitrifying bacterium that converts ammonia to nitrite; denitrifying bacteria like Pseudomonas convert nitrates to nitrogen gas. Thus, statements 1 and 2 are correct.

Explanation:
The iris contains smooth muscle fibers (sphincter and dilator) that regulate the diameter of the pupil. The cornea and lens focus light, retina senses it.