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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...

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...

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...

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-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 ...

M.Sc. (Zoology) (MSCZOO) Term-End Examination December, 2024 MZOE-002 : ANIMAL BEHAVIOUR AND ANIMAL WELFARE ETHICS Time : 2 Hours| Maximum Marks : 50 Note: (i)  Attempt any five questions.            (ii) All questions carry equal marks. 1. (i) Briefly differentiate between the following pairs of terms: (2+2 Marks) (a) Innate behaviour and Acquired behaviour Innate behaviour is inherited and present in animals from birth. It does not depend on learning or experience. This type of behaviour is automatic, consistent and similar in all members of a species. Examples of innate behaviour include reflex actions like blinking and fixed action patterns such as a spider spinning a web. Acquired behaviour, on the other hand, develops through interaction with the environment and learning. It is not inherited and can change during an animal's life. This behaviour helps animals adjust to new conditions. Examples include training in dogs, birds learning to s...

The cytoskeleton is a network of protein filaments that exists within the cytoplasm of eukaryotic cells. It provides structural support while maintaining cell shape and enabling movement. Additionally, it plays a vital role in cell division and intracellular transport. Made up of microfilaments, intermediate filaments and microtubules, the cytoskeleton is highly dynamic as it continuously reorganizes itself to adapt to the cell's changing needs. Its function is essential for maintaining cell integrity and supporting key cellular processes. Types of Cytoskeleton The cytoskeleton is made up of three main types of filaments: microfilaments, intermediate filaments and microtubules. Each type plays a unique role in maintaining cellular structure and function. 01. Microfilaments Microfilaments also known as actin filaments. Microfilaments are the  thinnest filaments  of the cytoskeleton with a diameter of about  7 nm.  They are composed of  actin protein  and ar...

The plasma membrane or cell membrane is the thin outer layer of a cell that protects it and controls what goes in and out. It is made of  fats (phospholipids), proteins  and  carbohydrates,  which help the cell communicate and function properly. The membrane is  semi-permeable,  meaning it allows some substances to pass while blocking others. It also helps cells recognize each other and send signals. The  fluid mosaic model  describes its flexible and moving structure. Overall, the plasma membrane is essential for keeping the cell stable, interacting with its surroundings and supporting important life processes. Discovery of the Plasma Membrane The discovery of the plasma membrane was a gradual process that spanned centuries. Early scientists observed cells without recognizing their boundaries and with advancements in microscopy and chemistry, the existence and structure of the plasma membrane were eventually established. Understanding the plasma ...