Botany 11

Respiration is a catabolic process where organic compounds (like glucose) are oxidized (broken down) with oxygen to release energy (ATP), carbon dioxide, and water. Option B correctly states this. Option A is incorrect because respiration produces CO2, not reduces it. Option C is incomplete and reverses the process. Option D describes photosynthesis (the reverse of respiration).

Cytokinins are plant hormones that specifically promote cell division (cytokinesis) and are involved in promoting root formation in tissue culture. They work in conjunction with auxins - high cytokinin to auxin ratio promotes shoot formation, while low ratio (more auxin) promotes root formation. However, cytokinins themselves are directly associated with promoting root initiation in tissue culture experiments. Options A, B, and D are not the primary functions of cytokinins.

A bract is a modified leaf associated with a flower's reproductive structure. Its primary function is to protect the flower bud during development. Bracts are often green and leaf-like but can also be colorful (like in poinsettia or bougainvillea) to attract pollinators. They do not protect terminal buds, axillary buds (those are protected by bud scales), or specifically the calyx (which itself protects the inner flower parts).

Ebractiate is the correct botanical term for a flower that lacks bracts (modified leaves associated with reproduction). The prefix 'e-' means 'without' in botanical terminology. Bracteate flowers have bracts, while heteromerous refers to flowers with different numbers of parts in each whorl.

Roots are positively geotropic (grow downward with gravity) and endogenous in origin (arise from pericycle). They lack nodes and internodes. Roots are negatively phototropic (grow away from light), not positively phototropic, which is why they grow deeper into soil rather than toward light sources.

Kinetin (6-furfurylaminopurine) is a synthetic cytokinin, a class of plant growth regulators that promote cell division. The structure consists of a purine base (adenine) with a furfuryl amino group attached at the 6-position. It was the first cytokinin discovered and is used extensively in tissue culture.

Cuticular transpiration is minimal, not large, because the cuticle is a waxy waterproof layer. Lenticular transpiration is indeed insignificant (less than 1%) compared to stomatal transpiration (90%+). Stomata are correctly described as minute pores on leaf epidermis. Guttation occurs in high humidity/soil moisture conditions, not dry conditions - it happens when transpiration is limited but root pressure continues.

Silk cotton (Bombax ceiba) is a classic example of a palmately compound leaf where leaflets radiate from a single point like fingers on a hand. Cotton has a palmately lobed simple leaf, not compound. Clitoria and Euphorbia have different leaf arrangements - pinnate compound or simple leaves respectively.

Chrysanthemum produces suckers, which are underground shoots that develop from buds and can form new plants. Suckers are vegetative reproductive structures common in many ornamental plants. Bean, Clitoria, and Hibiscus propagate through different methods - seeds, cuttings, or other vegetative means, but not typically through suckers.

 Sprouting of dormant buds of a potato tuber can be induced by GA.

The correct answer is option 3.

Suckers originate from axillary buds located at nodes, which can develop into new aerial shoots that emerge from the base of the plant. They are lateral branches, not arising from terminal buds or stem tips. While they do arise from nodes, the most specific answer is axillary bud since that's the meristematic tissue that actually gives rise to the sucker.

Cytokinins are concentrated in regions of active cell division: embryos (rapidly dividing), developing fruits (cell expansion and division), and root tips (apical meristems). This distribution reflects their primary role in promoting cytokinesis. While present in other tissues, the highest concentrations are found in these metabolically active regions.

Roots lack axillary buds, which are characteristic of stems. Roots have no nodes or internodes, no leaves, and no buds - these are stem features. Root hairs are present in the zone of maturation for water absorption. The absence of axillary buds is a key feature distinguishing roots from stems.

Hibiscus is a classic example of a plant with epicalyx - an additional whorl of bract-like structures below the true calyx. Epicalyx is particularly prominent in the Malvaceae family. Crotalaria, Jasmine, and Launaea do not possess this characteristic epicalyx structure.

Bracteoles are correctly defined as small, thin bract-like structures present on the pedicel (flower stalk). An involucre is a whorl of bracts (not bracteoles) typically found at the base of an inflorescence. Sepals are usually green, not brightly colored - that's the role of petals. Epicalyx is indeed arranged on the thalamus, but the question asks which statement is correct, and only (b) is fully accurate.

Guard cells are the specialized kidney-shaped cells that surround each stoma and control its opening and closing through changes in turgor pressure. Hydathodes are involved in guttation (water secretion), bulliform cells aid in leaf rolling in grasses, and epidermal cells are the general pavement cells forming the outer layer. The distinctive kidney shape is unique to guard cells in dicot leaves.

Gibberellic acid (GA) is a plant hormone that stimulates the production of alpha-amylase enzyme in the aleurone layer of barley seeds during germination. This enzyme breaks down starch into sugars, providing energy for the growing embryo. Pectinase, cellulase, and protease are not induced by GA in this context.

Cytokinins are plant hormones that delay senescence (aging) by promoting cell division and preventing protein degradation. They act as anti-aging hormones in plants. Gibberellins promote elongation, auxins regulate growth, and ethylene promotes ripening and senescence.

Ganong's potometer is specifically designed to measure the rate of transpiration by measuring water uptake. Darwin's potometer is used for studying phototropism, respiroscope measures respiration, and auxonometer measures growth movements.

The tap root system develops from the radicle (embryonic root) of the seed, making it embryonic in origin. Fibrous roots develop from the base of the stem (adventitious), and prop roots are adventitious roots providing support.

The Herring embryo test is used for cytokinin (kinetin) bioassay. Gibberella fujikuroi fungus produces gibberellins. Avena curvature test is the classic test for auxin detection. Zeatin was first isolated from Zea mays (corn).

A runner is a weak stem that grows horizontally on the soil surface, producing new plants at nodes (e.g., grass, strawberry). Stolons are similar but grow above ground. Twiners climb by coiling around supports. Suckers grow from the base.

Banana and canna leaves show pinnately parallel venation where veins run parallel but are arranged like a feather (pinnate) from a central midrib. Palmately parallel veins all arise from one point at the leaf base (like grass). Reticulate venation forms a net-like pattern.

Guard cells have thin and elastic outer walls and thick inner walls. When turgid, the thin outer walls stretch and bulge outward, opening the stomatal pore. This asymmetric thickening is essential for stomatal opening and closing.

Kinetin is a cytokinin that specifically promotes cytokinesis (cell division) by activating cell division-related genes. It does not directly cause karyokinesis (nuclear division), cell elongation (auxin function), or differentiation (complex process requiring multiple factors).

Bolting is the rapid elongation of the stem followed by flowering, typically seen in biennial plants like cabbage when exposed to cold (vernalization). It's an adaptation for rapid reproductive growth. Splicing, hardening, and cloning are unrelated processes.

The tap root system is called the normal root system because it develops from the radicle (the normal embryonic root) and is the most common type in dicots. Adventitious roots arise from non-root tissues, prop roots provide support, and fibrous roots are a modification of tap roots.

The radicle is the embryonic root in the seed that emerges first during germination and develops into the primary root system. The plumule becomes the shoot, hypocotyl is the region below the cotyledonary node, and cotyledons are seed leaves.

In palmately compound leaves, all leaflets radiate from a single point at the tip of the petiole (like fingers from a palm). Pinnately compound leaves have leaflets arranged along a central rachis, while the terms reticulate and parallel refer to venation patterns, not leaf arrangement.

A sucker is an underground stem that grows horizontally and produces new plantlets. Stolons are above-ground horizontal stems, offsets are short lateral branches, and twiners are climbing stems that spiral around supports.

When guard cells become turgid due to water uptake, their uneven thickening causes them to bend outward, creating an opening between them. This is the open stomatal pore that allows gas exchange. When flaccid, the stomatal pore closes.

Epicalyx is an additional whorl of bracteoles (small bracts) located just below the calyx, typically found in families like Malvaceae (e.g., hibiscus). Bracts are at the base of the inflorescence, tepals are undifferentiated perianth segments, and sepals form the calyx.

Clitoria (butterfly pea) has pinnately compound leaves with multiple leaflets arranged along a central rachis. Cotton has palmately lobed leaves, silk cotton (Ceiba) has palmately compound leaves, and mango has simple leaves - none are pinnately compound.

Adventitious roots develop from any plant part other than the radicle (embryonic root), such as stems, leaves, or branches. Roots from radicle or primary root are normal roots, not adventitious. The underground part of a plant could be roots themselves or underground stems.

When guard cells have lower (more negative) water potential than adjacent cells, water enters them by osmosis, making them turgid. Turgid guard cells bend outward due to uneven cell wall thickening, opening the stomatal pore. Lower water potential drives water uptake, not closure.

Potassium (K+) ion movement is the primary driver of stomatal movement. K+ ions are pumped into guard cells to open stomata (lowering water potential, causing water uptake) and pumped out to close them (raising water potential, causing water loss). Mg++, Mn++, and Cl- are not involved in stomatal mechanism.

A bisexual (hermaphrodite) flower contains both male (androecium - stamens) and female (gynoecium - pistils/carpels) reproductive parts. Monoecious plants have separate male and female flowers on the same individual, dioecious plants have them on separate individuals, and polygamous refers to plants with multiple sexual conditions.

Tepals are the individual segments of the perianth when sepals and petals are undifferentiated (similar in appearance and color), as in lilies and tulips. Petals are the inner whorl, sepals are the outer whorl, and pistil is the female reproductive organ - none describe perianth segments.

Leaves have limited growth (they stop growing after reaching full size), woody perennials show unlimited growth (continuous growth), IAA (indole-3-acetic acid) is a natural growth hormone, and NAA (naphthalene acetic acid) is a synthetic growth regulator (auxin analog).