Botany 2022 Paper II 50 marks 150 words Compulsory Write short notes

Q1

Write short notes on the following in about 150 words each: (a) Semi-autonomous cell organelles (10 marks) (b) Multiple factor hypothesis (10 marks) (c) Structure and functions of peroxisomes (10 marks) (d) Cell wall in plants (10 marks) (e) Southern blotting (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणी लिखिए : (a) अर्धस्वायत्त कोशिकांग (10 अंक) (b) बहु कारक परिकल्पना (10 अंक) (c) परऑक्सीसोम्स की संरचना एवं कार्य (10 अंक) (d) पौधों में कोशिका भित्ति (10 अंक) (e) सदर्न शोषण (सदर्न-ब्लॉटिंग) (10 अंक)

Evaluate your answer to this question → See all 2022 Botany questions

Directive word: Write short notes

This question asks you to write short notes. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The directive 'write short notes' demands concise, information-dense responses for each sub-part with equal weighting (10 marks × 5 = 50 marks). Allocate approximately 150 words and 7-8 minutes per sub-part. Structure each note with a precise definition opening, followed by 2-3 key features/mechanisms, and a brief concluding significance. For (a) emphasize endosymbiotic theory and dual genetic control; (b) focus on Nilsson-Ehle's wheat kernel color and additive gene action; (c) detail crystalline core and β-oxidation; (d) cover middle lamella to tertiary wall with plasmodesmata; (e) trace DNA → membrane hybridization steps with probe detection.

Key points expected

(a) Semi-autonomous organelles: Mitochondria and chloroplasts possess own DNA, 70S ribosomes, double membrane; endosymbiotic theory origin; protein import from cytosol; replication independent of nuclear cycle
(b) Multiple factor hypothesis: Nilsson-Ehle's work on wheat kernel color; quantitative inheritance vs Mendelian dominance; additive effects of multiple genes with environmental modification; polygenic inheritance basis
(c) Peroxisomes: Single membrane-bound; crystalline core (urate oxidase in plants); glyoxylate cycle in glyoxysomes; photorespiration in C3 plants; ROS detoxification via catalase
(d) Plant cell wall: Middle lamella (pectin), primary wall (cellulose-hemicellulose-pectin), secondary wall (lignin); plasmodesmata structure; cell wall plasticity and growth; lignification in xylem
(e) Southern blotting: Restriction enzyme digestion, gel electrophoresis, denaturation, capillary transfer to nitrocellulose/nylon membrane, probe hybridization, autoradiography/chemiluminescence detection; DNA fingerprinting applications

Evaluation rubric

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	25%	12.5	For (a) correctly states endosymbiotic origin and dual genetic control; for (b) accurately distinguishes polygenic from monogenic inheritance with correct statistical basis; for (c) precisely differentiates peroxisome and glyoxysome functions; for (d) correctly orders wall layers and their compositions; for (e) accurately sequences all blotting steps without omission	Covers basic definitions for most parts but confuses key details—e.g., states mitochondria have DNA but misses 70S ribosomes; describes quantitative inheritance without naming Nilsson-Ehle; lists peroxisome functions without structural clarity; mentions cell wall components but misorders layers; describes blotting with one step missing or out of sequence	Fundamental errors: claims semi-autonomous organelles lack DNA; conflates multiple factor with multiple allele hypothesis; describes lysosome functions for peroxisomes; confuses cell wall with cell membrane; describes Northern or Western blotting instead of Southern
Diagram / labelling	15%	7.5	For (a) sketches mitochondrion/chloroplast showing cristae/thylakoids with DNA location; for (c) draws peroxisome with crystalline core; for (d) illustrates primary-secondary wall transition with plasmodesmata detailed; for (e) depicts gel-membrane sandwich setup; labels are precise and exam-appropriate	Attempts diagrams for 2-3 parts with basic shapes but incomplete labelling—e.g., draws organelle outline without internal structures; cell wall diagram lacks middle lamella distinction; blotting diagram misses probe hybridization step	No diagrams attempted where essential (peroxisome structure, cell wall layers, Southern apparatus); or diagrams are unlabelled, misleading, or anatomically incorrect
Examples & nomenclature	20%	10	For (a) cites Margulis for endosymbiotic theory; for (b) specifies Nilsson-Ehle and wheat kernel color classes; for (c) names glyoxylate cycle enzymes (malate synthase, isocitrate lyase); for (d) cites Indian examples (jute/linum fiber secondary walls); for (e) mentions E.M. Southern and forensic DNA fingerprinting applications	Mentions some names without precision—e.g., 'discovered by a scientist' for endosymbiosis; 'studied in wheat' without Nilsson-Ehle; lists peroxisome functions without enzyme names; gives generic plant examples; attributes blotting correctly but misses applications	No scientist names or incorrect attributions; no specific organisms cited; confuses terminology (e.g., 'multiple alleles' for multiple factors; 'lysosome' for peroxisome); invents non-existent examples
Process explanation	25%	12.5	For (a) explains protein import mechanism (TOM/TIM complexes or TOC/TIC); for (b) clearly explains additive gene action producing continuous variation; for (c) details β-oxidation pathway and photorespiration coordination; for (d) explains cellulose synthase complex and wall expansion mechanism; for (e) stepwise explains denaturation, transfer, and hybridization chemistry	Describes processes in general terms without mechanistic detail—e.g., states 'proteins are imported' without mentioning transit peptides; describes 'genes add up' without phenotypic ratio explanation; lists peroxisome functions without pathway integration; describes wall growth vaguely; outlines blotting steps without explaining why each occurs	Process descriptions are absent or fundamentally wrong—e.g., claims semi-autonomous organelles synthesize all their proteins; describes dominance inheritance for quantitative traits; confuses peroxisome with mitochondrial β-oxidation; describes animal ECM formation for plant wall; reverses Southern blotting steps
Application / ecology	15%	7.5	For (a) links to cytoplasmic male sterility in crop breeding; for (b) connects to heritability estimation and crop improvement selection; for (c) explains C3-CAM photosynthesis transitions and stress adaptation; for (d) relates lignin modification for biofuel production; for (e) cites forensic identification, paternity testing, and transgene detection in Indian cotton Bt verification	Mentions generic relevance—e.g., 'important in evolution' for organelles; 'useful in breeding' for quantitative traits; 'helps plants survive' for peroxisomes; 'provides support' for cell wall; 'used in research' for blotting—without specific applications	No applications mentioned or irrelevant applications cited—e.g., claims semi-autonomous organelles are targets for gene therapy in humans; describes medical polygenic disease instead of plant breeding; no ecological context for peroxisomes in photorespiration; no biotechnological relevance for cell wall; describes PCR applications for Southern blotting

Practice this exact question

Write your answer, then get a detailed evaluation from our AI trained on UPSC's answer-writing standards. Free first evaluation — no signup needed to start.

Evaluate my answer →