BSc Third Year (Sem 5 & 6) Botany – Daily Revision MCQ (English Medium)
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In a monohybrid test cross, a heterozygous tall plant (Tt) is crossed with a dwarf plant (tt). What is the phenotypic ratio of the offspring?
Chapter 1: Mendelian Genetics
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Answer: B. 1 tall : 1 dwarf
Tt gives T and t gametes in equal numbers while tt gives only t, so the progeny are ½ Tt (tall) and ½ tt (dwarf).In Nilsson-Ehle's study of kernel colour in wheat controlled by two gene pairs, what is the F2 phenotypic ratio?
Chapter 2: Polygenic and Extranuclear Inheritance
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Answer: D. 1 : 4 : 6 : 4 : 1
Each dominant allele adds equally to the red colour, so the F2 falls into five classes (4, 3, 2, 1, 0 dominant alleles) in the ratio 1 : 4 : 6 : 4 : 1.How does colchicine induce polyploidy in plants?
Chapter 6: Plant Breeding
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Answer: A. It prevents spindle fibre formation, so chromosomes do not separate
Colchicine blocks spindle formation; the duplicated chromosomes stay in one nucleus, doubling the chromosome number.The MS medium, the most widely used plant tissue culture medium, was developed by:
Chapter 7: Plant Tissue Culture and Biotechnology
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Answer: C. Murashige and Skoog
Toshio Murashige and Folke Skoog published the MS medium in 1962; Haberlandt proposed totipotency, and Cohen and Boyer made the first recombinant DNA.What is the median of the data 3, 8, 5, 12, 10?
Chapter 9: Biostatistics
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Answer: B. 8
Arranged in order: 3, 5, 8, 10, 12; the middle (3rd) value is 8. (7.6 is the mean.)Who coined the term 'ecosystem'?
Chapter 12: Ecosystem
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Answer: A. A. G. Tansley
Sir A. G. Tansley introduced 'ecosystem' in 1935; Haeckel coined 'ecology' and Lindeman gave the 10% law of energy transfer.In a vegetation survey, a species was found in 6 out of 20 quadrats studied. What is its frequency?
Chapter 13: Plant Communities and Vegetation Analysis
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Answer: D. 30%
Frequency % = (quadrats in which the species occurs ÷ total quadrats studied) × 100 = 6/20 × 100 = 30%.Pneumatophores (negatively geotropic breathing roots) are a characteristic adaptation of:
Chapter 14: Ecological Adaptations: Hydrophytes, Xerophytes and Halophytes
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Answer: C. Halophytes such as mangroves
Mangrove soil is waterlogged and poor in oxygen, so roots grow upward out of the mud and take in air through lenticels.Late blight of potato is caused by:
Chapter 16: Plant Diseases
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Answer: A. Phytophthora infestans
Phytophthora infestans caused the Irish famine of the 1840s; Puccinia graminis causes wheat rust and Xanthomonas oryzae causes bacterial blight of rice.The concept of 'biodiversity hotspots' was introduced by:
Chapter 19: Biodiversity and Conservation
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Answer: D. Norman Myers
Norman Myers proposed hotspots in 1988 as regions very rich in endemic species and under heavy threat; Rosen coined the word 'biodiversity'.
BSc Third Year (Sem 5 & 6): MCQ in other subjects
All questions are written by PadhaiNotes in our own words from the common syllabus of Maharashtra universities (NEP). Your own university's syllabus may differ a little.