IGNOU BBYET-141 December 2025 Previous Year Question Paper

Q1.(a) Choose the correct option given in the parentheses : 5x1=5

(i) (Magnification/Resolution) gives a measure of how much bigger an object appears under microscope. Gi) In (Transmission Electron Microscopy/Scanning Electron Microscopy) electron beam moves over the specimen, the molecules get excited and move to higher energy and emit secondary electrons that form image.

(ii) (Endoplasmic reticulum/ Micro- tubule) is a network of short tubular interconnected structures scattered in the cytoplasm.

(iv) Mitochondria are (Semi- autonomous/autonomous) organelles found in the cell.

(v) Cyclin-dependent kinases regulate cell division in (prokaryotes/ eukaryotes).

(b) Define the following : 32158 @) Genome Gi) Synapses

(iii) Catabolite activator proteins

(c) Match the items of Column A with those of Column B: Axi=2 Column A Column B (Gj) DNA

(1) RNA polymerase containing Il enzyme

(ii) Telomerase

(2) folding of peptides Gii) Molecular

(3) regulation of chaperones gene expression

(iv) Gene

(4) holoenzyme silencing

Q2.Differentiate between any two of the following : 2x5=10

(a) Phase Contrast Microscopy and Confocal Microscopy

(b) Paper Chromatography and Thin Layer Chromatography

(c) Density Gradient Centrifugation and Differential Centrifugation

Q3.Describe the different models proposed for the structure of cell membrane with the help of suitable diagrams.

Q4.Discuss the structure and function of chloroplast with the emphasis of its semi- autonomous nature.

Q5.(a) Explain unidirectional and bidirectional replications of DNA. 5

(b) Explain the structure of RNA with the help of a diagram.

Q6.(a) Describe the mechanism of termination of translation. 5

(b) Explain the mechanism of transcription regulation through attenuation.

Q7.Write short notes on any two of the following : 2x5=10

(a) Plant cells

(9) Peroxisomes

(c) Role of regulator molecules of the cell cycle

(d) Griffith’s experiment 5x1=5 2x5=10 2x5=

(10)