BPSC TRE 1 PYQ Quiz – Higher Secondary Teacher Exam Subject Botany

EXPLANATION: The dump-heap hypothesis proposes that early plant domestication began when humans discarded waste seeds near settlements, and these plants subsequently grew and were cultivated.

EXPLANATION: Ardil is a synthetic textile fiber produced from groundnut (peanut) protein. It was developed as an alternative to wool.

EXPLANATION: Pyrethrum is a natural insecticide extracted from the dried flower heads of Chrysanthemum cinerariifolium (formerly Pyrethrum cinerariifolium).

EXPLANATION: Cola nitida is the kola nut tree. Its nuts are a natural source of caffeine and are used as a flavoring ingredient and stimulant.

EXPLANATION: The tuft of hairs at the non-embryo end of a wheat grain is specifically called the brush. It is a morphological feature of the caryopsis.

EXPLANATION: Dhurrin is a cyanogenic glycoside found in Sorghum species (e.g., Johnson grass, young sorghum plants), not in Datura, Abrus, or Cannabis.

EXPLANATION: The Respiratory Quotient (RQ) is approximately 1 when carbohydrates are the primary respiratory substrate, as the volume of CO₂ produced equals the volume of O₂ consumed.

EXPLANATION: All three are common TEM techniques. Ultrathin sectioning is for internal details, while negative staining and shadow casting are for surface features of particles.

EXPLANATION: This is incorrect. Prokaryotes have circular DNA, but exocytosis is a eukaryotic process. Furthermore, mitochondria and chloroplasts (eukaryotic organelles) also contain circular DNA.

EXPLANATION: Statements A and B are correct. Eukaryotic flagella/cilia have a 9+2 microtubule array, while centrioles have a 9+0 array. The kinetosome (basal body) is structurally identical to a centriole.

EXPLANATION: Kinases are enzymes that add phosphate groups to specific amino acids. Tyrosine kinases are a major class that phosphorylate tyrosine residues, playing key roles in cell signaling.

EXPLANATION: The movement of a DNA segment within the genome is specifically called transposition, and the mobile segment is a transposon. The listed terms do not define this process.

EXPLANATION: The protein that initiates transcription is RNA polymerase. The options listed are DNA sequences (operator, promoter) or a regulatory protein that blocks transcription (repressor).

EXPLANATION: Degeneracy means most amino acids are coded by more than one codon (multiple triplets for one amino acid). It does not mean a single triplet codes for multiple amino acids (that would be ambiguous)

EXPLANATION: Genetic drift is the change in allele frequency due to random chance, and its effect is strongest in small, isolated populations where inbreeding is common.

EXPLANATION: A test cross is specifically a cross between an individual with a dominant phenotype (but unknown genotype) and a homozygous recessive parent to determine the unknown genotype.

EXPLANATION: The selfing of a heterozygote (Tt) producing a 3:1 phenotypic ratio demonstrates the segregation of alleles during gamete formation, as per Mendel’s first law.

EXPLANATION: Ecological equivalents are different species that fill similar niche roles in different but similar ecosystems or geographical regions (e.g., cacti in America and euphorbias in Africa).

EXPLANATION: Abies (fir) is coniferous, Quercus (oak) is temperate, and Rhododendron is montane. None are typical of tropical dry deciduous forests (which feature Teak, Sal, etc.).

EXPLANATION: The correct fundamental sequence of ecological succession is: Nudation -> Invasion (Migration & Ecesis) -> Competition & Co-action -> Reaction -> Stabilization (Climax). None of the options match this.

EXPLANATION: A primary concern is migration lag. Climate zones are shifting faster than many plant species can disperse or adapt, leading to habitat mismatch and decline.

EXPLANATION: Gross Primary Productivity (GPP) is the total rate of photosynthetic carbon fixation by an ecosystem, before accounting for respiration losses.

EXPLANATION: A key feature of the lytic cycle is the degradation of the host bacterium’s DNA by phage enzymes, redirecting the cell’s machinery to produce new viruses.

EXPLANATION: Temperate viruses (like lambda phage) can undergo lysogeny, where their genome integrates into the host’s DNA and replicates with it without causing immediate lysis.

EXPLANATION: Lophotrichous bacteria have a tuft (multiple) flagella at one or both poles of the cell. A single flagellum at one end is monotrichous.

EXPLANATION: The direct transfer of DNA between two bacteria via a cytoplasmic bridge (pilus) is called conjugation. The listed processes are other forms of genetic exchange.

EXPLANATION: Botulism is caused by the neurotoxin produced by the anaerobic, spore-forming bacterium Clostridium botulinum.

EXPLANATION: Powdery mildew fungi (Ascomycetes) produce white, cottony or powdery superficial mycelial growth on the surface of leaves and stems.

EXPLANATION: An endemic disease is one that is constantly present at a baseline level in a specific geographic area or population.

EXPLANATION: Several bacterial genera, including Achromobacter, Micrococcus, and Alteromonas, have species known for their ability to biodegrade petroleum hydrocarbons.

EXPLANATION: Nostoc is a nitrogen-fixing cyanobacterium. It is used as a biofertilizer in paddy fields to enrich the soil with nitrogen.

EXPLANATION: The first forests during the Carboniferous period were dominated by giant lycopsids (club mosses) like Lepidodendron.

EXPLANATION: Trichodesmium is a marine, nitrogen-fixing cyanobacterium often found in tropical oceans. Nostoc and Scytonema are common in freshwater.

EXPLANATION: These structures are called tyloses. They are balloon-like outgrowths from adjacent parenchyma cells that block xylem vessels, often in response to injury or infection.

EXPLANATION: A drupe is characterized by a stony endocarp (pit) surrounding the seed, a fleshy mesocarp, and a thin exocarp (skin). Examples are mango, peach, and plum.

EXPLANATION: β-Methylamino-L-alanine (BMAA), a neurotoxic amino acid, is found in cycads, including genera like Cycas and Zamia.

EXPLANATION: Genera Plantarum (1862–1883) is a seminal work on plant classification authored by the British botanists George Bentham and Joseph Dalton Hooker.

EXPLANATION: Free nuclear endosperm development (where nuclei divide without immediate cell wall formation) is common in many plants, including members of families like Proteaceae (Grevillea) and Arecaceae (Areca).

EXPLANATION: In dicots like beans, nutrition is primarily stored in the cotyledons, not the structures listed. The aleurone layer is a protein-rich layer in cereal grains (monocots).

EXPLANATION: Porogamy is the normal fertilization process where the pollen tube enters the ovule through the micropyle.

EXPLANATION: The apical meristem is often virus-free due to high metabolic activity and absence of vascular connections to the infected parts, allowing for meristem culture to produce virus-free plants.

EXPLANATION: Apospory is the development of a gametophyte (and subsequently an embryo) directly from a somatic cell of the sporophyte, such as a nucellus cell, without meiosis or spore formation

EXPLANATION: The Onagraceae family, including the genus Oenothera, is characterized by the Oenothera type (4-nucleate) of embryo sac development.

EXPLANATION: Apomixis is asexual reproduction that produces seeds without fertilization (i.e., without gamete fusion), resulting in clones of the mother plant.

EXPLANATION: In mushrooms (Basidiomycota), the visible above-ground structure is the basidiocarp, which is the fruiting body that bears spores.

EXPLANATION: Both Gelidium and Gracilaria are genera of red algae (Rhodophyta). Ulothrix is a green alga

EXPLANATION: Kigelia africana (sausage tree) is a classic example of chiropterophily (bat pollination). Ficus is pollinated by wasps, and Salvia by bees.

EXPLANATION: Cork cambium (phellogen) is a secondary meristem that arises from mature parenchyma cells and produces cork (phellem) and phelloderm.

EXPLANATION: Companion cells are specialized parenchyma cells associated with sieve tube elements in the phloem of angiosperms, not with vessels, tracheids, or idioblasts.

EXPLANATION: Complementary DNA (cDNA) is synthesized from an RNA template using the enzyme reverse transcriptase, a process central to retroviruses.

EXPLANATION: UAA, UAG, and UGA are all stop codons (nonsense codons) that signal the termination of protein synthesis.

EXPLANATION: Orobanche (broomrape) is a complete root parasite. Rafflesia is a root parasite, and Loranthus is a partial stem parasite. The question asks for “total stem parasite,” and none fit perfectly, but Orobanche is the closest complete parasite listed. Strictly, Cuscuta is a total stem parasite, but it’s not an option. Among the options, Orobanche is a total parasite (though root-based).

EXPLANATION: Monosomy is the condition of having one less chromosome ($1$). None of the given options represent this.

EXPLANATION: During anaphase, sister chromatids (or homologous chromosomes in meiosis I) separate and are pulled towards opposite poles of the cell by spindle fibers.

EXPLANATION: The Respiratory Quotient (RQ) is less than 1 for fats (~0.7) and proteins (~0.8-0.9). Organic acids have variable RQ, often >1.

EXPLANATION: Decarboxylase is a general class of enzymes that remove carboxyl groups. While decarboxylation reactions occur in the Krebs cycle (catalyzed by specific enzymes like isocitrate dehydrogenase), “decarboxylase” itself is not a named enzyme in the standard cycle list.

EXPLANATION: AUG is the universal start codon in the genetic code, which signals the beginning of protein synthesis and also codes for methionine.

EXPLANATION: India hosts four of the world’s biodiversity hotspots: the Himalayas, the Western Ghats, Indo-Burma, and Sundaland (Nicobar Islands).

EXPLANATION: Monotropa (Indian pipe) is a non-photosynthetic, mycoheterotrophic angiosperm that obtains nutrients from decaying organic matter via fungal associates. Neottia is mycoheterotrophic, and Cuscuta is a parasite.

EXPLANATION: Salvinia, Azolla, and Marsilea are all water ferns that are heterosporous (producing microspores and megaspores).

EXPLANATION: Manganese (Mn) is an essential component of the oxygen-evolving complex (OEC) of Photosystem II, which catalyzes the photolysis of water.

EXPLANATION: 2,4-Dichlorophenoxyacetic acid (2,4-D) is a synthetic auxin widely used as a selective herbicide to control broadleaf weeds.

EXPLANATION: The functional megaspore undergoes mitosis to form the female gametophyte (embryo sac), which is not listed. The embryo sac contains the egg cell that, after fertilization, develops into the embryo, and the central cell forms the endosperm.

EXPLANATION: Restriction endonucleases are enzymes that cut DNA at specific recognition sequences, hence they are aptly called “molecular scissors.”

EXPLANATION: Taq polymerase, a heat-stable DNA polymerase essential for PCR, is isolated from the thermophilic bacterium Thermus aquaticus.

EXPLANATION: The International Code of Nomenclature for algae, fungi, and plants (ICN) is founded on six fundamental principles that govern the scientific naming of these organisms.

EXPLANATION: All three—Capsicum annuum (chili), Atropa belladonna (deadly nightshade), and Withania somnifera (ashwagandha)—belong to the Solanaceae family.

EXPLANATION: A magnesium ion (Mg²⁺) is centrally located in the porphyrin ring of the chlorophyll molecule and is essential for its light-absorbing function.

EXPLANATION: Nitrite (NO₂⁻) is oxidized to nitrate (NO₃⁻) by bacteria like Nitrobacter or Nitrospira. Nitrosomonas converts ammonia to nitrite.

EXPLANATION: Photorespiration is a collaborative process involving chloroplasts (initial step), peroxisomes (glycolate metabolism), and mitochondria (glycine decarboxylation).

EXPLANATION: Oceans are considered the most stable ecosystems due to their vast size, constant physical conditions (like temperature and salinity), and high biodiversity which provides great resilience.

EXPLANATION: Soil salinity is measured by an electrical conductivity (EC) meter or a salinometer. The listed instruments measure water uptake (potometer), heat (calorimeter), and stomatal aperture (porometer)

EXPLANATION: Colchicine inhibits spindle fiber formation during cell division, preventing chromosome segregation and leading to polyploidy (chromosome doubling).

EXPLANATION: Selaginella is a heterosporous pteridophyte, and many of its species possess a small, scale-like outgrowth called a ligule at the base of the leaf.

EXPLANATION: Cotton is a surface or seed fiber that grows from the epidermis of the cotton seed. Jute and sunn hemp are bast fibers obtained from stems.

EXPLANATION: Quantasomes are repeating units believed to be present in the thylakoid membranes of chloroplasts, involved in photosynthesis. They are not found in the listed organelles.

EXPLANATION: The hilum is the scar or point of attachment where the funicle (stalk) connects to the ovule (and later, the seed).

EXPLANATION: Capitulum or head inflorescence is the defining characteristic of the family Asteraceae (formerly Compositae), like sunflowers and daisies.

EXPLANATION: RNA contains uracil (U) instead of thymine (T). Thymine is found only in DNA. Guanine is present in both DNA and RNA.