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Apoptosis is a  programmed cell death  process that removes damaged, old or unnecessary cells in a controlled way. It is essential for growth, immune system function and preventing diseases like cancer. The process includes cell shrinkage, chromatin condensation, DNA fragmentation and membrane blebbing. The cell breaks into small apoptotic bodies, which are quickly cleared by surrounding cells to prevent inflammation. Apoptosis occurs through two main pathways:  the intrinsic (mitochondrial) pathway  (which is triggered by internal stress) and  the extrinsic (death receptor-mediated)) pathway  (that is activated by external signals). This process ensures proper development, maintains tissue balance, and protects the body from harmful cells. Note -  besides the intrinsic and extrinsic pathways, there are additional apoptotic pathways, including: Perforin/Granzyme Pathway –  Used by cytotoxic T cells and natural killer (NK) cells to induce apoptosis...

Intermediate filaments (IFs) are an essential component of the cytoskeleton that provide structural support and mechanical strength to cells. With a diameter of 8–12 nm, they are intermediate in size between microfilaments and microtubules. These filaments are composed of various proteins, including keratins, vimentin and lamins, which help maintain cell integrity, resist mechanical stress and preserve cellular shape. Unlike microtubules and actin filaments, Intermediate filaments are highly stable and do not undergo dynamic polymerization. They play a crucial role in cell adhesion, organelle positioning and nuclear structure. Found in both the cytoplasm and nucleus of eukaryotic cells, Intermediate filaments contribute to tissue-specific functions and enhance cellular resilience. Structure of Intermediate Filaments Intermediate filaments (IFs) are one of the three main components of the cytoskeleton, along with microtubules and actin filaments. They provide structural support to cells...

SAQ 1 i) In the Protenor mode of the sex determination, males are a) homogametic and have two sex chromosomes b) heterogametic and have two sex chromosomes c) homogametic and have one sex chromosome d) heterogametic and have one sex chromosome Answer: d) heterogametic and have one sex chromosome ii) Female is heterogametic in a) Humans b) most birds c) Drosophila d) C. elegans Answer: b) most birds iii) Which of the following chromosomal mode of sex determination is exhibited by Drosophila? a) XX/XO mode b) XX/XY mode c) ZZ/ZW mode d) ZZ/ZO mode Answer: b) XX/XY mode iv) The sex in C. elegans are a) males and females b) males and hermaphrodites c) Hermaphrodites only d) Hermaphrodites and females Answer: b) males and hermaphrodites v) During self-fertilisation in hermaphrodites, ratio of sex in progenies is a) 50% females and 50% male b) 50% males and 50% hermaphrodites c) All hermaphrodites d) Majorly hermaphrodites, occasionally males Answer: d) Majorly hermaphrodites, occasionally ...

SAQ 1 1. (a) Write answers to the following questions in brief. i.  What is the longest phase of the cell cycle? The longest phase of the cell cycle is  Interphase,  which occupies about 90% of the total duration of the cycle. It is a highly active stage where the cell prepares for division. Interphase has three sub-phases: G1 phase, where the cell grows and synthesizes proteins; S phase, where DNA replication takes place; and G2 phase, where the cell checks for DNA errors and prepares for mitosis. Though no visible division occurs in interphase, it is crucial for the success of mitosis or meiosis. Cells that do not divide frequently may remain in G1 or enter a resting state called G₀ phase. ii.  During which phase of interphase does DNA replication occur?  DNA replication occurs during the S phase (Synthesis phase) of Interphase. In this phase, the entire genetic material of the cell is duplicated so that each daughter cell formed after cell division will recei...

What is Electromagnetic radiation (EMR)? Electromagnetic radiation (EMR) is a type of energy that moves through space in waves. It is made up of  electric  and  magnetic  fields that travel together at the speed of light (3 × 10⁸ meters per second). EMR comes in many forms, depending on its  wavelength  (the length of each wave) and  frequency  (how many waves pass a point in a second). The types of EMR include radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays and gamma rays. We encounter Electromagnetic radiation every day. For example, sunlight is Electromagnetic radiation that helps plants make food through photosynthesis and allows us to see. Infrared radiation is felt as heat, while radio waves are used for communication like in radios and phones. X-rays help doctors see inside our bodies and ultraviolet light from the sun can cause sunburn. Electromagnetic radiation (EMR) can act like a wave, spreading o...

SAQ 1 Fill in the blanks with appropriate words: a) In prokaryotes, genes are organized into ........................ . Answer: operons b) ........................... elements recognize, bind transcription factors and increase the rate of transcription of a gene. Answer: Enhancer c) The enzyme  ............................. is required to bind a promoter to initiate transcription. Answer: RNA polymerase d) The transcription factors bind to specific DNA sequences called .......................... located at the proximal (near) end of the promoter promoter of of a gene or distal end (far) of the gene. Answer: cis regulatory elements e) ........................... is the factor that causes the DNA in the promoter region to bend like the CAP protein in bacteria and helps in the attachment of transcription factor to the promoter. Answer: TFIID or TATA binding protein SAQ 2 Answer in one word a) The factors that bind to specific sequences of DNA upstream of coding genes and promote trans...

SAQ i) Match the items in column I with column II: Answer:  a) → iv;    b) → iii;    c) → vii;    d) → viii;    e) → vi;    f) → i;    g) → ii;    h) → x;    i) → v;    j) → xi;    k) → ix ii) Fill in the blanks: a) Autophagy includes the formation of three different vesicles including ....................., which circularizes to form ......................, which then fuses with a lysosome to form the ..................... . Answer:  phagophore, autophagosome, autolysosome b) Apoptosis can be mediated by two modes or pathways, ....................... or ....................... . Answer:  intrinsic, extrinsic c) Pharmacological inhibitors such as ....................... block the lysosomal proton transport and thus autophagy. Answer:  Bafilomycin A1 d) ...................... is released from the mitochondria upon MOMP and binds to the adapter protein Apaf1 to form the ...

M.Sc. (Zoology) (MSCZOO) Term-End Examination December, 2024 MZOE-003 : AQUACULTURE Time  : 2 Hours |  Maximum Marks : 50 Note: Answer any five questions. All questions carry equal marks. 1. (a) Enumerate the different constraining factors for aquaculture development.   (5 Marks) Aquaculture is a rapidly growing sector that holds promise for food security and economic development. However, several constraints affect its sustainable growth. These constraints can be classified into the following categories: 1. Environmental Constraints Water is the most essential component of aquaculture. But the increasing pollution of natural water bodies, salinity intrusion, water scarcity and eutrophication are major problems. Moreover, climate change leads to unpredictable rainfall, increasing water temperature, and extreme weather events like floods and droughts, all of which disturb aquaculture operations and productivity. 2. Economic Constraints High cost of fish feed, medicines, qu...

M.Sc. (Zoology) (MSCZOO) Term-End Examination December, 2024 MZOE-001 : PARASITOLOGY Time : 2 Hours| Maximum Marks : 50 Note: (i)  Attempt any five questions.            (ii) All questions carry equal marks. 1. (a) What are endoparasites? Give any two examples. (2 Marks) Endoparasites are parasites that live inside the body of their host. They usually infect internal organs like the intestine, liver, lungs, or blood. These parasites depend on the host for nutrients and often cause harm by damaging tissues, stealing nutrients, or releasing toxins. They are commonly found in vertebrates, including humans and may be transmitted through contaminated food, water, or direct contact. Examples: 1. Taenia solium (pork tapeworm) – It lives in the human intestine and causes taeniasis. 2. Plasmodium vivax – A blood parasite that causes malaria in humans, transmitted by female Anopheles mosquitoes. (b) What is the difference between mechanical vector and biologic...

Actin and myosin are two essential proteins that drive muscle contraction, cellular movement and intracellular transport. They are integral to numerous physiological processes such as locomotion, cytokinesis and cytoskeletal organization. Their interaction forms the foundation of the  sliding filament theory,  which explains the mechanism of muscle contraction.  Actin  primarily forms the thin filaments in muscle fibers, providing structural support and a binding site for myosin, while  myosin  constitutes the thick filaments and functions as a molecular motor that generates force. A deeper understanding of these proteins is crucial for advancing research in cell biology, molecular biology, and physiology, as their functions extend beyond muscle activity to fundamental aspects of cell structure and dynamics. Actin Actin is one of the most essential and versatile proteins in eukaryotic cells. It plays a fundamental role in maintaining cellular structure and ...