Botany (Medical Science)

Acetabularia, a single-celled marine green alga, holds the record for being the largest unicellular organism, with some species reaching up to 5 centimeters in length. Despite being a single cell, it has a complex structure with a cap, stalk, and rhizoid. Funaria is a moss, Nostoc is a cyanobacterium forming colonies, and Colocasia (taro) is a multicellular plant.

The Green Revolution (1940s-1970s) primarily focused on developing high-yield, disease-resistant wheat varieties, with Norman Borlaug's dwarf wheat being the cornerstone. While maize and other crops also saw improvements, wheat benefitted most dramatically, with production increasing by over 300% in some regions. Barley and cotton were not primary Green Revolution crops.

Phosphorus deficiency causes premature leaf fall because phosphorus is essential for energy transfer (ATP) and root development. When deficient, older leaves turn dark green or purplish, then yellow and fall off early as the plant mobilizes phosphorus from older tissues to new growth. Zinc, manganese, and boron deficiencies cause different symptoms like interveinal chlorosis, stunting, or cork formation.

Stomata are microscopic pores primarily found on leaf surfaces that serve two critical functions: gas exchange (CO2 intake for photosynthesis, O2 release) and transpiration (water vapor loss). Option B describes xylem function, and option C describes phloem function. Stomata open and close via guard cells to balance these processes.

Thigmotropism (from Greek 'thigma' meaning touch) is the directional growth movement in response to physical contact or touch. The classic example is the coiling of tendrils around supports. Geotropism is gravity response, hydrotropism is water response, and plagiotropism is growth at an oblique angle to gravity.

Auxin, gibberellin, abscisic acid, and cytokinins are the five major plant hormones that regulate growth and development. Ascorbic acid (Vitamin C) is an antioxidant and enzyme cofactor in plants, but it does not function as a growth hormone like the others.

Option 3 is correct.

In the hierarchical biological classification system, Kingdom is the broadest category, encompassing all related organisms. The hierarchy from broadest to most specific is: Kingdom → Phylum → Class → Order → Family → Genus → Species. Humans belong to Kingdom Animalia, Phylum Chordata, Class Mammalia, etc.

Cisternae are the flattened, disc-like, membrane-bound sacs that comprise the Golgi apparatus (also called Golgi complex or Golgi body). They are stacked together and function in processing, packaging, and modifying proteins and lipids synthesized in the endoplasmic reticulum. The Golgi apparatus is not found in mitochondria (powerhouse of cell), chloroplasts (site of photosynthesis), or nucleolus (site of ribosome synthesis).

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