KCET 2022 Biology C4 Question Paper With Answer Key And Solutions PDF

Step 1: Amniocentesis is a prenatal diagnostic procedure performed between 15–20 weeks of pregnancy.

Step 2: A small amount of amniotic fluid containing fetal cells is extracted using a needle under ultrasound guidance.

Step 3: The fetal cells are cultured and analyzed via karyotyping to detect chromosomal abnormalities, genetic disorders, and sex of the foetus (XX or XY).

Thus, it is used to determine the sex of the foetus. Quick Tip: Amniocentesis is banned in India for sex determination under PCPNDT Act to prevent female foeticide, but allowed for medical diagnosis.

Step 1: The genus Homo evolved from Australopithecus around 2.4 million years ago.

Step 2: Homo habilis (2.4–1.4 mya) is the earliest species of Homo with brain size ~600–700 cm³ and evidence of stone tool use (Oldowan tools).

Step 3: Known as "handy man," it is considered the first human-like being. Homo erectus appeared later (~1.8 mya). Quick Tip: Evolutionary order: Australopithecus → Homo habilis → Homo erectus → Homo sapiens

Step 1: In XO-type (e.g., grasshoppers), females are XO (heterogametic) and males are XX (homogametic).

Step 2: In XY-type, males are XY (heterogametic).

Step 3: The question focuses on XO type, which is a classic example of female heterogamety. Quick Tip: - XY → Male heterogamety (humans)
- XO → Female heterogamety (insects)
- ZW → Female heterogamety (birds)

Step 1: Mendelian disorders involve single-gene mutations.

Step 2: Down’s syndrome is caused by trisomy 21 (nondisjunction), a chromosomal disorder.

Step 3: Cystic fibrosis, haemophilia, thalassemia are Mendelian disorders.

Hence, Down’s syndrome is non-Mendelian. Quick Tip: Non-Mendelian: chromosomal, polygenic, mitochondrial.

Step 1: Klinefelter’s syndrome (47, XXY) affects males.

Step 2: Extra X chromosome causes reduced testosterone and estrogen excess → gynecomastia (breast development in males).

Step 3: Turner’s syndrome affects females; others do not cause gynecomastia. Quick Tip: Klinefelter: XXY → sterile male, gynecomastia, tall stature.

Step 1: Pedigree symbols:

- Males → square

- Females → circle

- Affected → filled

Step 2: Affected male = filled square (■). Quick Tip: Carrier: half-filled; Proband: arrow.

Step 1: Nucleosome = DNA wrapped around histone octamer.

Step 2: H1 histone links nucleosomes.

Step 3: Diagram shows DNA + H1 → nucleosome. Quick Tip: Nucleosome → 11 nm → 30 nm fiber → chromosome

Step 1: Placenta secretes: hCG, hPL, progestogen, relaxin.

Step 2: FSH is secreted by anterior pituitary.

Thus, FSH is not secreted by placenta. Quick Tip: hCG → maintains corpus luteum → progesterone.

Step 1: Bulbil = vegetative propagule in Agave.

Step 2: Gemmules → sponges; Conidia → fungi; Spores → not in sponges.

Thus, Bulbil - Agave is correct. Quick Tip: Vegetative propagation: bulbil (Agave), runner (grass).

Step 1: ART (Assisted Reproductive Technology): IVF, IUI, ZIFT, GIFT — treats infertility.

Step 2: MTP → abortion; RTI → infection; RCH → health program.

Only ART treats infertility. Quick Tip: First test-tube baby: Louise Brown (1978) via IVF.

Step 1: DNA fingerprinting relies on variable number tandem repeats (VNTRs) in satellite DNA.

Step 2: These are highly repetitive, non-coding minisatellite regions with variable repeat counts among individuals.

Step 3: Restriction enzymes cut DNA, and gel electrophoresis separates fragments by size, creating unique banding patterns.

Thus, high degree of repetition in satellite DNA forms the basis. Quick Tip: DNA fingerprinting is used in paternity testing, forensics, and identification.

Step 1: Plasmodium falciparum causes malignant tertian malaria.

Step 2: It leads to cerebral malaria, high parasitemia, and cytoadherence of infected RBCs to blood vessels.

Step 3: It has the highest mortality rate among malarial parasites.

P. vivax causes benign tertian; P. malariae causes quartan; P. ovale is mild. Quick Tip: Falciparum → cerebral malaria → most fatal.

Step 1: Allergic reactions are Type I hypersensitivity mediated by IgE antibodies.

Step 2: Allergens bind to IgE on mast cells and basophils.

Step 3: This triggers degranulation → release of histamine, serotonin → allergic symptoms.

IgM, IgG, IgA are not involved in immediate hypersensitivity. Quick Tip: Antihistamines block histamine receptors in allergies.

Step 1: Anabolic steroids are synthetic testosterone derivatives.

Step 2: In females, excess androgens cause virilization/masculinisation: deepening of voice, facial hair, menstrual irregularities.

Step 3: Liver damage (cirrhosis) is possible but not specific to females; memory loss and hallucination are not typical. Quick Tip: Anabolic steroids → doping in sports → banned by WADA.

Step 1: Opiate narcotics are derived from opium poppy (Papaver somniferum).

Step 2: Morphine is a natural opiate alkaloid with strong analgesic and sedative effects.

Step 3: LSD (hallucinogen), barbiturates (sedative-hypnotics), amphetamines (stimulants) are not opiates. Quick Tip: Morphine → painkiller → highly addictive → leads to heroin.

Step 1: Swiss cheese is made using Propionibacterium shermanii.

Step 2: This bacterium ferments lactic acid → propionic acid + CO2.

Step 3: Trapped CO2 forms large holes (eyes) during ripening.

No methane or fungus is involved. Quick Tip: Roquefort cheese → Penicillium roqueforti (fungus).

Step 1: Lactic Acid Bacteria (LAB) like Lactobacillus ferment milk into curd.

Step 2: During fermentation, they synthesize Vitamin B12 (cobalamin).

Step 3: Curd is a rich source of B12, especially for vegetarians.

Vitamins E, C, B (general) are not significantly increased. Quick Tip: Curd → probiotic → improves digestion and B12 absorption.

Step 1: Oily stains are lipids (fats).

Step 2: Lipase enzyme hydrolyzes triglycerides into glycerol and fatty acids.

Step 3: It is added to biological detergents to remove oil/grease stains.

Protease (proteins), amylase (starch), renin (not used in detergents). Quick Tip: Biological detergents work best at 30–40°C.

Step 1: Meselson and Stahl (1958) proved semiconservative replication.

Step 2: They used E. coli grown in ¹⁵NH₄Cl (heavy nitrogen).

Step 3: After one replication in ¹⁴N, DNA showed hybrid density → semiconservative model confirmed. Quick Tip: Semiconservative: each new DNA has one old + one new strand.

Step 1: Griffith (1928) used S. pneumoniae (pneumococcus).

Step 2: Smooth (S) strain (virulent) + heat-killed S + Rough (R) strain (non-virulent) → live S strain in mice.

Step 3: Proved transforming principle (later identified as DNA by Avery et al.). Quick Tip: Griffith’s experiment → foundation of molecular genetics.

Step 1: Total codons = 4³ = 64 (U, C, A, G).

Step 2: 3 are stop codons (UAA, UAG, UGA) → no amino acid.

Step 3: 1 start codon (AUG) codes for methionine but is also counted in 6(4).

Thus, 61 codons code for 20 amino acids (degenerate code). Quick Tip: Genetic code: triplet, degenerate, universal, non-overlapping.

Step 1: Vector (e.g., pBR322) has antibiotic resistance genes (amp\^R, tet\^R).

Step 2: Only transformed cells (took up recombinant plasmid) grow on antibiotic medium.

Step 3: Non-transformed cells die → selection of transformed cells. Quick Tip: Insertional inactivation: recombinant plasmid loses tet^R → white colonies (blue-white screening).

Step 1: RNA interference (RNAi) is a gene silencing mechanism.

Step 2: dsRNA (double-stranded) is introduced → processed by Dicer into siRNA.

Step 3: siRNA + RISC → degrades complementary mRNA → gene silenced. Quick Tip: RNAi used in pest-resistant plants (Bt cotton) and nematode control (flavr savr tomato).

Step 1: Cry-IAC and Cry-IAB genes from Bacillus thuringiensis (Bt).

Step 2: Produce crystal proteins toxic to lepidopteran larvae (bollworm, armyworm).

Step 3: Cry-IAC specifically controls cotton bollworms (Helicoverpa armigera).

Cry-IIAB → corn borer; Cry gene for nematodes not common. Quick Tip: Bt cotton → first GM crop in India (2002).

Step 1: ADA (Adenosine Deaminase) deficiency → SCID (Severe Combined Immunodeficiency).

Step 2: ADA enzyme is required in T-lymphocytes (from bone marrow).

Step 3: Bone marrow transplantation provides healthy stem cells → produce functional ADA.

First gene therapy (1990) also used for ADA deficiency. Quick Tip: Gene therapy: retroviral vector → insert normal ADA gene.

Step 1: Population change = (Births + Immigration) – (Deaths + Emigration)
Step 2:
- Births (natality) = 25
- Deaths (mortality) = 24
- Immigration = 2
- Emigration = 3
Step 3: \[ \Delta P = (25 + 2) - (24 + 3) = 27 - 27 = 0 \]
Hence, net increase = 0. Quick Tip: - Population growth: \(\Delta P = (B + I) - (D + E)\) - Zero growth: \(B + I = D + E\)

Step 1: Restriction enzymes (e.g., EcoRI, HindIII) cut DNA at specific recognition sites.

Step 2: They act as molecular scissors in genetic engineering.

Step 3: Used to cut vector and insert DNA for cloning. Quick Tip: EcoRI → 5'-GAATTC-3' → sticky ends.

Step 1: Sequence: 5'-GAATTC-3' and 3'-CTTAAG-5' → reads same forward and backward on complementary strand.

Step 2: This is a palindromic sequence.

Step 3: Recognized by EcoRI restriction enzyme. Quick Tip: Palindrome: reads same in 5'→3' on both strands.

Step 1: Gel electrophoresis uses agarose gel and electric field.

Step 2: DNA (negatively charged) moves toward anode.

Step 3: Smaller fragments move faster → separation by size. Quick Tip: Ethidium bromide + UV → orange bands.

Step 1: PAR (Photosynthetically Active Radiation) = 400–700 nm.

Step 2: Plants capture only 2–10% of incident solar radiation for photosynthesis.

Step 3: Most energy lost as heat, reflection, or transmission. Quick Tip: GPP = Gross Primary Productivity; NPP = GPP – Respiration.

Step 1: The equation S = cA\^z is the species-area relationship (Alexander von Humboldt).

Step 2: S = species richness, A = area, c and z are constants.

Step 3: Logarithmic form: log S = log c + z log A → straight line on log-log plot.

Thus, the graph represents species-area relationship. Quick Tip: z ≈ 0.1–0.2 (mainlands), 0.2–0.3 (islands).

Step 1: Cuscuta (dodder) is a holoparasitic plant.

Step 2: It grows externally on host, penetrates haustoria into vascular tissue.

Step 3: Lives outside host → ectoparasite (not inside like endoparasite). Quick Tip: Cuscuta → yellow/orange twining stems → no chlorophyll.

Step 1: PM2.5 (≤ 2.5 μm) are fine particulates.

Step 2: They penetrate deep into lungs and enter bloodstream.

Step 3: Cause respiratory and cardiovascular diseases → greatest health risk. Quick Tip: PM10 (>(2).5 μm) → upper respiratory tract; PM(2).5 → alveoli.

Step 1: Homeostasis = maintenance of stable internal conditions (pH, temperature, ions).

Step 2: Involves feedback mechanisms (negative/positive).

Step 3: Osmoregulation and thermoregulation are parts of homeostasis. Quick Tip: Claude Bernard: "constancy of internal milieu".

Step 1: Diurnal = active during daytime (e.g., humans, birds).

Step 2: Nocturnal = night; Crepuscular = dawn/dusk.

Step 3: Auroral and vesporal are not standard terms. Quick Tip: Diurnal → opposite of nocturnal.

Step 1: Deserts → high temperature, very low rainfall (<25 cm/year).

Step 2: Option 3 says more rainfall and low temperature → incorrect.

Step 3:
- Tundra: cold, low precipitation
- Biomes depend on temp + rainfall
- Grasslands: moderate rain, warm Quick Tip: Desert: <25 cm rain; Tundra: permafrost.

Step 1: Arthropods show diversity in respiration:

- Aquatic: gills (crustaceans)

- Terrestrial: book lungs (scorpions), trachea (insects)

- Some: book gills (horseshoe crabs)

Step 2: Molluscs → ctenidia; Annelids → skin. Quick Tip: Trachea → air tubes in insects.

Step 1: Colchicine is a mitotic poison from Colchicum autumnale (autumn crocus).

Step 2: Inhibits spindle formation → used in polyploidy breeding.

Step 3: Not from tulip, aloe, or asparagus. Quick Tip: Colchicine → doubles chromosomes → polyploid plants.

Step 1: Earthworm (Pheretima) has S-shaped setae for locomotion.

Step 2: Present in all segments except:

- 1st segment (peristomium)

- Last segment (anus)

- Clitellum (14–16 segments, glandular, no setae)

Step 3: Thus, first, last, and clitellum lack setae. Quick Tip: Clitellum → cocoon formation in reproduction.

Step 1: Matthias Schleiden (1838): all plants made of cells.

Step 2: Theodor Schwann (1839): all animals made of cells.

Step 3: Together formulated cell theory (1839).

Robert Brown → nucleus (1831); Hooke → cell (1665). Quick Tip: Cell theory: (1). All organisms cellular, (2). Cell is basic unit.

Step 1: Cotton fibre is made of cell wall material.

Step 2: Plant cell walls are composed of cellulose (β-1,4-glucose polymer).

Step 3: Cotton is >90% cellulose → used in textiles.

Glycogen (animal), starch (plant storage), insulin (protein hormone). Quick Tip: Cellulose → structural polysaccharide; humans cannot digest.

Step 1: Crossing over occurs in pachytene of meiosis.

Step 2: Recombinase (e.g., Spo11, DMC1) mediates DNA strand exchange.

Step 3: Forms chiasmata → genetic recombination.

Endonuclease initiates break; ligase seals. Quick Tip: Synaptonemal complex → holds homologues during crossing over.

Step 1: Kranz anatomy = wreath-like; seen in C4 plants.

Step 2: Bundle sheath cells with chloroplasts surround vascular bundle.

Step 3: Maize is C4 → has Kranz anatomy.

Tomato, potato, pea → C3 plants. Quick Tip: C4 plants: high light, hot climate; Hatch-Slack pathway.

Step 1: RQ = CO₂ produced / O₂ consumed

Step 2: Glucose: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Step 3: RQ = 6 / 6 = (1).0

Fats → 0.7; proteins → 0.9. Quick Tip: RQ > 1 → anaerobic; RQ = 0 → no respiration.

Step 1: Epiglottis = cartilage flap covering trachea during swallowing.

Step 2: Food enters larynx → triggers cough reflex.

Step 3: Improper closure of epiglottis → food in windpipe → coughing. Quick Tip: Choking → Heimlich maneuver.

Step 1: Carolus Linnaeus (1753) in Species Plantarum.

Step 2: Binomial nomenclature: Genus + species (e.g., Homo sapiens).

Step 3: Standardized naming → universal system. Quick Tip: ICBN (plants), ICZN (animals).

Step 1: BSE (Mad Cow Disease) → neurodegenerative.

Step 2: Caused by prions (PrP\^Sc) → misfolded proteins.

Step 3: No nucleic acid → infects brain → spongy appearance. Quick Tip: Prions → Kuru, CJD, Scrapie.

Step 1: Red algae (Rhodophyta) → red pigment phycoerythrin.

Step 2: Store food as floridean starch (similar to glycogen).

Step 3: Found in deep water → absorb blue light. Quick Tip: Agar from Gelidium, Gracilaria.

Step 1: Menstrual cycle = shedding of uterine lining (menstruation).

Step 2: Seen in primates (humans, apes, monkeys).

Step 3: Others have estrous cycle (no bleeding). Quick Tip: Human cycle: 28 days; apes similar.

Step 1: Dioecious = male and female flowers on separate plants.

Step 2: Papaya → male and female trees.

Step 3: Cucurbita, coconut, mango → monoecious. Quick Tip: Date palm, Marchantia → dioecious.

Step 1: Stamen = male reproductive organ of flower.

Step 2: Consists of anther (pollen sac) and filament (stalk).

Step 3: Filament supports anther.

Peduncle (inflorescence stalk), pedicel (flower stalk), petiole (leaf stalk). Quick Tip: Androecium = all stamens.

Step 1: Ovule = integumented megasporangium.

Step 2: Contains nucellus (megasporangium tissue).

Step 3: Produces megaspore via meiosis from megaspore mother cell.

Megasporophyll = carpel. Quick Tip: Ovule → seed after fertilization.

Step 1: Polygonum type (most common).

Step 2: 7 cells: egg, 2 synergids, 3 antipodals, 1 central cell (2 polar nuclei).

Step 3: 8 nuclei: central cell has 2 nuclei.

Thus, 8-nucleated, 7-celled. Quick Tip: Embryosac → female gametophyte.

Step 1: Date palm (Phoenix dactylifera) seed from Masada (Israel).

Step 2: Germinated in 2005 → ~2000 years old.

Step 3: Oldest viable seed known. Quick Tip: Lupin seed → 2000-year record (before date palm).

Step 1: Spermatogenesis requires 2–3°C below body temperature.

Step 2: Scrotum keeps testes outside abdomen.

Step 3: Pampiniform plexus regulates temperature.

Sperm stored in epididymis. Quick Tip: Cryptorchidism → undescended testes → infertility.

Step 1: Isthmus, infundibulum, fimbriae → parts of fallopian tube.

Step 2: Labia minora → external genitalia (vulva).

Step 3: Odd one → labia minora. Quick Tip: Fallopian tube: infundibulum → ampulla → isthmus → uterus.

Step 1: Quickening (first fetal movement felt by mother) → 5th month.

Step 2: Lanugo (fine hair on head) appears around 5th month.

Step 3: Heartbeat detectable by 1st month; limbs by 8th week. Quick Tip: Gestation: 9 months = 3 trimesters.

Step 1: Neutrophils → 60–65% of total WBCs.

Step 2: First responders in acute inflammation.

Step 3: Phagocytic; multilobed nucleus.

Basophils (0–1%), eosinophils (2–3%), monocytes (2–8%). Quick Tip: WBC count: 4000–11000/mm(3).

Step 1: Ultrafiltration occurs in glomerulus.

Step 2: High pressure → plasma filters into Bowman’s capsule.

Step 3: Forms glomerular filtrate.

Reabsorption in PCT/DCT; secretion in DCT. Quick Tip: GFR ≈ 125 ml/min.

Step 1: Corpus callosum = bundle of white matter fibers.

Step 2: Connects left and right cerebral hemispheres.

Step 3: Allows communication between hemispheres. Quick Tip: Split-brain patients → corpus callosum severed.