Plant Anatomy, Physiology & Biochemistry

Glycolysis produces a net gain of 2 NADH molecules per glucose. The NADH is formed during the oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, with one NADH produced per each of the two 3-carbon molecules.

Reticulate venation refers to net-like vein patterns in leaves, characteristic of dicot plants. Mango is a dicot with reticulate venation. Grass has parallel venation, while castor and zizyphus are also dicots but mango is the classic example.

Monocarpic perennial plants live for many years but flower only once before dying. Agave is a classic example - it grows for 10-30 years, flowers once, then dies. Tamarind and mango are polycarpic (flower multiple times). Hibiscus is also polycarpic.

Gibberellins were first isolated from the fungus Gibberella fujikuroi, which causes foolish rice disease (excessive elongation). They are plant hormones that promote growth.

Guttation is the loss of water in liquid form through hydathodes (specialized pores) usually from leaf margins. This occurs when transpiration is low and soil moisture is high, creating root pressure. Transpiration is water loss as vapor.

Phosphoglucoisomerase (also called phosphohexose isomerase) converts glucose-6-phosphate to fructose-6-phosphate in glycolysis. This is an isomerization reaction.

Aldolase splits fructose-1,6-bisphosphate into two 3-carbon molecules: glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP). DHAP is then converted to G3P.

Tamarind is a polycarpic perennial - it lives for many years and produces flowers and fruits multiple times throughout its life. Polycarpic means multiple fruitings. Biennials live 2 years, annuals complete lifecycle in one year, monocarpic perennials flower once then die.

Root pressure is measured using a mercury manometer. A potometer measures transpiration rate, anemometer measures wind speed, and auxanometer measures plant growth. Mercury manometer directly measures the pressure developed in roots.

Ferns and gymnosperms lack vessels (evolved in angiosperms) and rely on tracheids as their chief water-conducting elements. Tracheids are long, thin cells with tapered ends that transport water and provide structural support. Sieve elements are for food transport.

Enolase converts 2-phosphoglycerate (2PG) to phosphoenolpyruvate (PEP) by removing a water molecule (dehydration). This is the second-to-last step of glycolysis. PEP then donates its phosphate to ADP via pyruvate kinase.

Placentation is the term for the arrangement and distribution of placenta inside the ovary. Aestivation refers to petal arrangement, vernation to leaf bud arrangement, and polymerisation is a chemical process unrelated to plant anatomy.

Companion cells are specialized parenchyma cells associated with sieve elements in phloem. They are metabolically active and support the sieve elements in transport functions. Sieve plates are porous structures on sieve element end walls.

Phyllotaxy refers to the arrangement of leaves on the stem. Aestivation is the arrangement of petals/sepals in a bud, venation is the arrangement of veins in leaves, and placentation is ovule arrangement in the ovary.

In Asteraceae, the ovary is bicarpellary and syncarpous but unilocular (single chamber). This means the number of carpels (2) differs from the number of locules (1). Most other families have locules equal to carpels.

Meristematic tissue consists of actively dividing cells that perpetuate themselves and give rise to permanent tissues. Permanent tissues have lost the ability to divide. Ground and vascular tissues are types of permanent tissues.

Gibberellins were first discovered from the fungus Gibberella fujikuroi causing foolish seedling disease in rice. Kinetin (a cytokinin) was isolated from herring sperm DNA. Auxins occur naturally in plants, and 2,4-D is synthetic. Ethylene is a gaseous hormone produced by plants.

Monadelphous condition occurs when all stamens are united by their filaments into a single bundle (as in Malvaceae). Diadelphous means two bundles (nine + one in Fabaceae). Syngenesious means fused anthers with free filaments (Asteraceae). Epipetalous means stamens attached to petals.

The placenta is the specialized tissue within the ovary to which ovules are attached. Connective tissue is animal tissue. Vexillum is the standard petal in Fabaceae flowers. Collenchyma is a plant support tissue with thickened corners.

Insertion is a gene mutation involving the addition of nucleotide(s) into DNA sequence, changing the reading frame. Duplication, inversion, and translocation are chromosomal mutations involving changes to large chromosome segments rather than point mutations.

Marginal placentation (a) develops from bicarpellary, syncarpous ovary that becomes unilocular (as in Fabaceae). Parietal placentation (c) develops from multicarpellary, syncarpous, unilocular ovary where ovules attach to the ovary wall. Basal placentation (d) develops from bicarpellary, syncarpous, unilocular ovary with single ovule at base. Axile placentation (b) requires multilocular ovary, not unilocular.

In a simple cyme, the terminal flower develops first and blooms before the lateral flowers, making it the oldest. This is characteristic of determinate inflorescences where the central flower is oldest and peripheral flowers are progressively younger. The other options (head, catkin, umbel) have different flowering patterns.

In monocot stems, the protoxylem (the first-formed xylem) is the innermost xylem and often gets compressed as the stem grows. The disintegration of protoxylem elements creates a cavity called a lacuna. This is a characteristic feature of monocot stem anatomy not seen in dicots.

Vernonia (a genus in Asteraceae) is characterized by having only disc florets and no ray florets. This makes it different from sunflowers, Tridax, or Launaea which typically have both ray and disc florets in their capitulum (inflorescence head).

The rhizodermis is the specialized term for the outermost layer of cells in plant roots, analogous to the epidermis in stems. It is a tubular layer of living cells that protects the root and may develop root hairs for absorption.

A staminode is a sterile stamen that does not produce functional pollen or anther. It is often modified or reduced and may serve other functions like attracting pollinators. Pistillode refers to a sterile pistil, while internode is a stem region and placenta is ovule tissue.

Asteraceae (formerly Compositae) is the largest family of flowering plants with over 32,000 species. It includes sunflowers, daisies, chrysanthemums, lettuce, and many others. Fabaceae is second largest, while Musaceae and Euphorbiaceae are much smaller.

Glycolysis is also called the EMP pathway after Embden, Meyerhof, and Parnas who elucidated the process. It converts glucose to pyruvate. The Calvin cycle fixes CO2, while TCA cycle (also called citric acid cycle) occurs after glycolysis in cellular respiration.

The starch sheath (endodermis) in the dicot stem is morphologically homologous to the endodermis in roots. Both contain starch grains and perform similar functions - regulating transport and serving as a boundary layer. This reflects the anatomical continuity between stem and root tissues.

During glycolysis, one molecule of glucose (6-carbon) is broken down into two molecules of pyruvic acid (each 3-carbon). This is a fundamental fact of cellular respiration - the splitting of glucose into two pyruvate molecules.

Cassia species are known to have staminodes (sterile stamens) in their flowers. These are often petaloid and serve to attract pollinators. Crotalaria, Ravenala, and Hibiscus typically have fertile stamens without staminodes.

Pyrethrum is a natural insecticide extracted from dried flower heads of Chrysanthemum cinerariifolium (now classified as Tanacetum cinerariifolium). It contains pyrethrins which are neurotoxic to insects. Santonin is from Artemisia, ephedrine from Ephedra, and primaquine is synthetic.

In the Asteraceae family, each ovary typically contains only one ovule. This is a characteristic feature of the family - the ovary is inferior and uniovulate. After fertilization, this single ovule develops into an achene (one-seeded fruit).

William Bateson coined the term 'mutation' to describe discontinuous variations in organisms. He used it to describe sudden, heritable changes that were distinct from gradual variations. Darwin and Morgan studied evolution and genetics but did not introduce this specific terminology.

Axile placentation occurs when ovules are attached to a central column formed by the fused margins of carpels. In a pentacarpellary (5 carpels), syncarpous (fused carpels), and pentalocular (5 chambers) ovary, this central arrangement is exactly what creates the axile pattern. Parietal placentation would give a unilocular ovary, while marginal occurs only in monocarpellary conditions.

Parietal placentation characteristically occurs in multicarpellary, syncarpous ovaries where the ovules are borne on the inner walls (periphery) of a single chamber (unilocular). The fusion of carpels creates one large cavity with ovules attached to the walls, unlike axile placentation which has multiple chambers.

Phellogen is the botanical term for cork cambium, the secondary lateral meristem that produces cork (phellem) on the outer side and secondary cortex (phelloderm) on the inner side. Periderm is the complete protective layer including all three tissues, while phellem is just the cork cells produced.

F.W. Went's classic Avena coleoptile experiment (1928) demonstrated that the curvature response was directly proportional to the concentration of auxin. By placing agar blocks containing different auxin concentrations on decapitated coleoptiles, he showed that higher concentrations produced greater curvature - establishing the quantitative relationship between auxin and tropic response.