Biology — Plant Kingdom

Bryophytes are called amphibians of the plant kingdom because they can live in soil but are dependent on water for sexual reproduction.

Xylem is the specialized tissue that transports water and dissolved minerals, while phloem transports synthesized food (sugars).

Cycas is considered a living fossil because it has remained virtually unchanged over millions of years and retains primitive characteristics.

Double fertilization is unique to angiosperms where one male gamete fuses with the egg (syngamy) and the other with two polar nuclei (triple fusion).

Gymnosperms (gymnos = naked, sperma = seed) have seeds that are not enclosed within an ovary or fruit.

Rhodophyceae (red algae) contain the accessory pigment phycoerythrin, which masks the green color of chlorophyll.

Lateral meristems (like vascular cambium) are responsible for the secondary growth that increases the thickness or girth of a plant stem or root.

Pteridophytes are the first group of plants to evolve true vascular tissues (xylem and phloem) to transport water and nutrients.

After fertilization, the ovule develops into the seed, while the ovary wall matures into the fruit.

C4 plants possess 'Kranz anatomy', where bundle sheath cells are arranged in a ring, allowing for efficient CO2 fixation and minimal photorespiration.

Suberin is a hydrophobic substance deposited in the cell walls of cork cells, providing protection and preventing water loss.

Lichens represent a symbiotic relationship between an algal component (phycobiont) and a fungal component (mycobiont).

Stomata are small pores that allow for the exchange of gases (CO2/O2) and the regulation of water vapor loss through transpiration.

Magnesium is the central atom in the porphyrin ring of the chlorophyll molecule, essential for photosynthesis.

Biennials are plants that take two years or two growing seasons to complete their biological life cycle.

Ethylene is the gaseous plant hormone known for stimulating the ripening of fruits and the shedding of leaves (abscission).

Monocots are characterized by parallel venation, fibrous root systems, and a single cotyledon in the seed.

Ferns are typical examples of Pteridophytes; they are vascular plants that reproduce via spores rather than seeds.

Starch is the primary polysaccharide used by plants for long-term energy storage, synthesized from excess glucose.

Nepenthes (the Pitcher Plant) is an insectivorous plant that traps insects to supplement nitrogen intake in nitrogen-poor soils.

Thallophyta comprises primitive plants like algae where the body is a thallus, lacking differentiation into distinct roots, stems, or leaves.

Sclerenchyma is composed of dead, thick-walled cells impregnated with lignin, providing structural support and rigidity to the plant.

Pteridophytes produce spores in specialized leaf-like structures called sporophylls, which may form distinct compact structures called strobili or cones.

In gymnosperms, the endosperm is a haploid tissue formed from the female gametophyte, unlike angiosperms where it is triploid and formed post-fertilization.

Xerophytes, such as cacti, possess sunken stomata to reduce transpiration and prevent excessive loss of water in arid environments.

Phototropism is the growth response of a plant part to the stimulus of light, mediated by the hormone auxin.

Angiospermae are the flowering plants and represent the most diverse and widespread group in the plant kingdom.

The root cap protects the delicate growing apical meristem as the root pushes through the soil.

Cytokinins promote cytokinesis (cell division) and are known to delay the aging process (senescence) in leaves.

Halophytes are plants adapted to grow in high-salt environments, such as mangroves and salt marshes.

Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants through pores called hydathodes.

The cell wall, made primarily of cellulose, provides structural support, protection, and a rigid shape to plant cells.

Chlorophyll a is the primary photosynthetic pigment found in all oxygenic photosynthetic organisms, including algae.

Pteridophytes (like ferns) are called vascular cryptogams because they possess vascular tissues (xylem/phloem) but do not produce seeds.

Transpiration is the evaporative loss of water from the aerial parts of a plant, primarily through stomata.

Molybdenum is a crucial micronutrient required for the functioning of nitrogenase and nitrate reductase enzymes.

Bryophytes are called amphibians because they require external water for the motile male gametes to swim to the egg.

Bundle sheath cells surround the vascular bundles in leaves and are especially prominent in C4 plants for carbon fixation.

Like animal cells, plant mitochondria are the sites of cellular respiration and contain their own circular DNA.

In angiosperms, the diploid sporophyte (the vegetative plant body) is the dominant and independent phase of the life cycle.

Pteridophytes are the first land plants to possess vascular tissues (xylem and phloem) but they do not produce seeds; hence they are called vascular cryptogams.

Pteridophytes are often called the 'reptiles' of the plant world because, like reptiles in the animal kingdom, they were the first to adapt to land but still require water for fertilization.

While most pteridophytes are homosporous, genera like Selaginella and Salvinia exhibit heterospory, which is a precursor to the seed habit.

Auxins are primarily responsible for apical dominance and cell elongation in the stems of plants.

The Casparian strip is a band of suberin that blocks the apoplastic movement of water and solutes, forcing them to cross the cell membrane, thereby regulating intake.

Plant cell walls are primarily made of cellulose, while fungal cell walls are composed of chitin.

Plants exhibit a life cycle known as haplodiplontic, where a multicellular diploid sporophyte alternates with a multicellular haploid gametophyte.

Potassium (K+) ions regulate the osmotic potential of guard cells, causing them to swell or shrink, which controls stomatal aperture.

Angiosperms (flowering plants) have seeds enclosed within an ovary (fruit), whereas Gymnosperms have naked seeds.

Collenchyma provides mechanical support and flexibility to young stems and petioles; its cells are living at maturity.