IMRAN KHAN

Roles of Movements in Our Gut:
a. Peristalsis movement:

Role: Peristalsis is a series of wave-like muscle contractions that move food along the digestive tract. It starts in the esophagus and continues through the stomach, small intestine, and large intestine. These rhythmic contractions push the contents of the gut forward, aiding in the progression of food from one organ to the next and eventually towards elimination.
b. Segmentation movement:

Role: Segmentation movements occur primarily in the small intestine and involve the contraction and relaxation of circular muscles in the intestinal walls. This action divides and mixes the contents, enhancing digestion and absorption by increasing contact with digestive enzymes and the absorptive surfaces of the intestinal lining.
c. Antiperistaltic movement:

Role: Antiperistaltic movements are reverse peristaltic actions that move contents backward through the digestive tract. These movements can occur in response to certain stimuli, such as vomiting or regurgitation, helping to expel harmful or indigestible substances from the body.
d. Churning movement:

Role: Churning movements take place in the stomach and involve the mixing of gastric contents with digestive juices. The stomach's muscular walls contract and relax, breaking down food mechanically and ensuring it is thoroughly mixed with enzymes and acids for chemical digestion. This process converts the ingested food into a semi-liquid form called chyme, which is then gradually released into the small intestine for further digestion and absorption.

Hydrophobic interactions play a crucial role in stabilizing the three-dimensional structure of proteins by influencing the folding and arrangement of nonpolar side chains within the protein. Here’s how this process works:

Mechanism of Hydrophobic Interactions in Protein Folding
Aqueous Environment:

In the cellular environment, proteins are surrounded by water molecules. Water is a polar solvent, meaning it has partial positive and negative charges due to its molecular structure.
Nonpolar Side Chains:

Proteins are composed of amino acids, some of which have nonpolar (hydrophobic) side chains. These side chains do not interact favorably with water because they cannot form hydrogen bonds or engage in ionic interactions with water molecules.
Energetic Considerations:

When nonpolar side chains are exposed to water, it disrupts the hydrogen-bonding network of water molecules. This disruption is energetically unfavorable because it decreases the entropy (disorder) of the water molecules, forcing them into a more ordered arrangement around the nonpolar side chains.
Driving Force for Folding:

To minimize this unfavorable energy state, the protein undergoes conformational changes during folding that bury the hydrophobic side chains in the interior of the protein, away from the aqueous environment. This process increases the overall entropy of the water molecules, making it energetically more favorable.
Formation of Hydrophobic Core:

As the protein folds, the nonpolar side chains aggregate together to form a hydrophobic core. This core is stabilized by van der Waals interactions between the closely packed hydrophobic residues. The aggregation of these nonpolar side chains is driven by the hydrophobic effect, which is the tendency of hydrophobic molecules to avoid contact with water.
Stabilization of Protein Structure:

The formation of a hydrophobic core contributes significantly to the stability of the protein’s three-dimensional structure. This core acts as an internal scaffold that helps maintain the overall shape of the protein.
Summary of the Process:
Hydrophobic side chains are energetically unfavorable when exposed to water.
Folding the protein to position these side chains in the interior minimizes their exposure to water.
This increases the entropy of the surrounding water molecules, making the folded structure more stable.
The resulting hydrophobic core is stabilized by van der Waals interactions.
Example in Practice:
Myoglobin: In myoglobin, a protein that stores oxygen in muscle cells, hydrophobic interactions help stabilize its globular structure by sequestering nonpolar side chains inside the protein, away from the aqueous environment. This allows the polar and charged residues to interact with the surrounding water, maintaining solubility and functionality.
By effectively reducing the exposure of hydrophobic residues to water, hydrophobic interactions ensure that proteins achieve and maintain their functional conformations, which is essential for their biological activity.

Inferior: Refers to a position below or lower than another part of the body; not related to the back.
Ventral: Refers to the front of the body; opposite of the back.
Lateral: Refers to the sides of the body; not specifically the back.
Posterior: Refers to the back of the body.

• Northern Blotting: Detects specific RNA molecules.
• Eastern Blotting: Detects post-translational modifications on proteins.
• Western Blotting: Detects specific proteins.
• Southern Blotting: Detects specific DNA sequences.

The endomembrane system is a group of interacting organelles within eukaryotic cells that work together to modify, package, and transport lipids and proteins. This system compartmentalizes the cell, allowing specific functions to be carried out in distinct areas. It includes:

Nuclear Envelope: Surrounds the nucleus and contains pores that regulate the exchange of materials between the nucleus and the cytoplasm.
Endoplasmic Reticulum (ER):
Rough ER: Studded with ribosomes and involved in protein synthesis and modification.
Smooth ER: Lacks ribosomes and is involved in lipid synthesis, detoxification, and calcium storage.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids received from the ER for secretion or use within the cell.
Lysosomes: Contain digestive enzymes to break down waste materials and cellular debris.
Vacuoles: Storage organelles that can hold various substances, such as nutrients, waste products, or water (notably large central vacuoles in plant cells).
Peroxisomes: Contain enzymes that detoxify harmful substances and break down fatty acids.
Plasma Membrane: Regulates the movement of substances in and out of the cell, providing a barrier and facilitating communication between the cell and its environment.
Transport Vesicles: Membrane-bound sacs that transport materials between the components of the endomembrane system and to the cell's exterior.
The endomembrane system plays a crucial role in the production, processing, and transport of proteins and lipids, as well as in the detoxification of harmful substances and the recycling of cellular components.

ایمانداری کا صلہ ،سزا۔۔۔۔۔۔۔۔۔۔۔۔
(برادرم حسن شہر یار کے ساتھ ہونے والے سلوک سے یاد آیا)
2012میں کالج میں بی اے کا امتحان شروع ہوا۔میں بطور ریزیڈنٹ انسپکٹر فرائض سر انجام دے رہا تھا۔پہلے روز سنٹر گیا تو بہت سارے طلبہ شہری حلیہ اور انجان چہروں کے محسوس ہوئے اور باہر گاڑیاں بھی ایسی کھڑی نظر آئیں جو پہلے کبھی یہاں نہ دیکھی تھیں۔چھوٹا شہر ہونے کی وجہ سے ہم لوگ ایک دوسرے کی پہچان رکھتے ہیں۔میں نے ان کی رول نمبر سلپس چیک کیں تو اکثر لڑکوں کے شناختی کارڈ تو لاہور کے تھے مگر سلپس پر ضلع حافظ آباد کے مختلف دیہات کے ایڈریس لکھے تھے۔جب میں نے ان سے ان کے ایڈریس پر درج دیہات کے نام پوچھے تو ان کو نہیں آتے تھے۔معاملہ مشکوک لگا تو پنجاب یونیورسٹی کے اس وقت کے کنٹرولز ڈاکٹر لیاقت علی کو مطلع کیا۔
اگلے روز انگریزی کا پرچہ تھا۔پہلے سیشن میں 120 سے زائد اُمیدواروں کا پیپر تھا لیکن سنٹر میں صرف بارہ امیدوار امتحان دینے آئے،باقی سب غائب۔اتنی دیر میں ایڈیشنل کنٹرولر بھی لاہور سے آگئے تھے۔پولیس کو بھی بلوا لیا گیا تو دو امیدوار ابھی بھی مشکوک بیٹھے تھے ان سے پوچھ گچھ کی تو انکشاف ہوا کہ لاہور میں ایک گروہ سے ان کی ڈیل ہوئی اور انگریزی کا پیپر پاس کروانے کے لئے ایک لاکھ بیس ہزار روپے طے ہوئے ہیں۔معاملے کی مزید چھان بین ہوئی تو اس میں یونی ورسٹی کے کچھ لوگ بھی ملوث نکلے جنہوں نے دو تین جعلی نگران اس سنٹر میں تعینات کئے تھے ۔مختصر یہ کہ دو ایف آرز کٹوائی گئیں۔اس وقت تو کنٹرولر امتحانات ہماری کارکردگی پر بہت خوش ہوئے اور مجھے زاتی طور پر فون کر کے کہا کہ کسی روز وہ سیلیوٹ کرنے پنڈی بھٹیاں آئیں گے۔۔۔مگر بد قسمتی دیکھئے کہ ہمیں صلہ یہ ملا کہ یونی ورسٹی کا امتحانی سنٹر ہی ختم کر دیا گیا اور طلبہ کو حافظ آباد جا کر امتحان دینا پڑا۔۔ہمارے طلبہ کو صعوبت اٹھانا پڑی۔اس پر میں نے ڈاکٹر لیاقت علی کنٹرولر امتحانات سے براہ راست احتجاج کیا اور بالآخر ہم نے سیاسی دباؤ ڈلوا کر ایک سال بعد یونی ورسٹی کا امتحانی سنٹر بحال کروایا۔۔۔۔۔
اس کے بعد ہمیں بخوبی اندازہ ہو گیا کہ ہر شعبے میں مافیاز کیسے کام کرتے ہیں اور یہ کتنے طاقت ور ہیں کہ خود قابو میں آنے کی بجائے گرفت کرنے والے کو گرفت میں لے آتے ہیں۔۔۔۔۔۔
اسد سلیم شیخ

The terms photoautotrophs, chemoautotrophs, photoheterotrophs, chemoheterotrophs, organotrophs, and lithotrophs describe different types of organisms based on their sources of energy, carbon, and electrons. Here is an explanation of each:

Photoautotrophs:

Energy Source: Light
Carbon Source: Carbon dioxide (CO₂)
Examples: Plants, algae, cyanobacteria
Description: Photoautotrophs use light energy to convert CO₂ into organic compounds through the process of photosynthesis.
Chemoautotrophs:

Energy Source: Inorganic chemicals
Carbon Source: Carbon dioxide (CO₂)
Examples: Certain bacteria and archaea, such as those found in deep-sea hydrothermal vents
Description: Chemoautotrophs obtain energy by oxidizing inorganic substances (e.g., hydrogen sulfide, ammonia) and use this energy to fix CO₂ into organic compounds.
Photoheterotrophs:

Energy Source: Light
Carbon Source: Organic compounds
Examples: Some purple non-sulfur bacteria, green non-sulfur bacteria
Description: Photoheterotrophs use light for energy but rely on organic compounds from the environment to obtain carbon for growth and development.
Chemoheterotrophs:

Energy Source: Organic compounds
Carbon Source: Organic compounds
Examples: Animals, fungi, many bacteria and protozoa
Description: Chemoheterotrophs obtain both energy and carbon from organic compounds. They rely on the consumption of other organisms or organic matter for their nutritional needs.
Organotrophs:

Electron Source: Organic compounds
Description: Organotrophs derive electrons from organic compounds. This term can be applied to both chemoheterotrophs and photoheterotrophs, as they utilize organic molecules to obtain electrons for their metabolic processes.
Lithotrophs:

Electron Source: Inorganic compounds
Description: Lithotrophs obtain electrons from inorganic compounds. This term is often used to describe chemoautotrophs and some chemoheterotrophs that use inorganic molecules (e.g., hydrogen sulfide, ammonia) as their electron source.
In summary:

Photoautotrophs: Light for energy, CO₂ for carbon
Chemoautotrophs: Inorganic chemicals for energy, CO₂ for carbon
Photoheterotrophs: Light for energy, organic compounds for carbon
Chemoheterotrophs: Organic compounds for both energy and carbon
Organotrophs: Organic compounds for electrons
Lithotrophs: Inorganic compounds for electrons
These classifications help in understanding the diverse metabolic strategies organisms use to obtain energy, carbon, and electrons for survival and growth.

Why do we breathe oxygen and release CO2?
The primary reason we breathe oxygen and give off carbon dioxide is due to the process of cellular respiration, which occurs in the mitochondria of our cells.
2. Role of Oxygen: Oxygen is essential for the process of aerobic respiration. It acts as the final electron acceptor in the electron transport chain, a series of reactions that generate ATP (adenosine triphosphate), the energy currency of the cell.
3. Glucose Metabolism: During cellular respiration, glucose (C6H12O6) is broken down in the presence of oxygen (O2) to produce energy. The overall chemical reaction can be summarized as:
C6H12O6 + 6 O2 ----------------> 6CO2 + 6H2O + 38ATP
4. Production of Carbon Dioxide: Carbon dioxide (CO2) is a byproduct of the breakdown of glucose. Specifically, it is produced during the Krebs cycle (also known as the citric acid cycle), which is a part of cellular respiration.
5. Gas Exchange in the Lungs: In the lungs, oxygen from the air is absorbed into the bloodstream, and carbon dioxide from the bloodstream is expelled into the air. This gas exchange occurs in the alveoli.
6. Transport in the Blood: Oxygen is transported from the lungs to the cells via hemoglobin in red blood cells. Carbon dioxide, produced by cells, is transported back to the lungs to be exhaled.
7. Final Verification: The process of breathing in oxygen and exhaling carbon dioxide is essential for the production of ATP through cellular respiration, which is necessary for all cellular functions and overall survival.

Allosteric enzymes are a specific type of enzyme that are regulated by molecules that bind to sites other than the enzyme's active site. These molecules, known as allosteric modulators (or effectors), can either increase (activate) or decrease (inhibit) the enzyme's activity. Here is a more detailed explanation of allosteric enzymes and their function:

Characteristics of Allosteric Enzymes:
Allosteric Sites:

Allosteric enzymes have one or more sites distinct from the active site, known as allosteric sites. These sites are where the allosteric modulators bind.
Allosteric Modulators:

Activators: Molecules that bind to the allosteric site and increase the enzyme's activity.
Inhibitors: Molecules that bind to the allosteric site and decrease the enzyme's activity.
Conformational Changes:

Binding of an allosteric modulator induces a conformational change in the enzyme that alters its activity. This change can make the active site more or less effective at catalyzing the reaction.
Cooperative Binding:

Many allosteric enzymes exhibit cooperative binding, meaning the binding of a substrate or allosteric modulator at one site affects the binding affinity at other sites. This is commonly seen in enzymes with multiple subunits.
Examples of Allosteric Enzymes:
Aspartate Transcarbamoylase (ATCase):

ATCase is an enzyme involved in the synthesis of pyrimidine nucleotides. It is regulated by CTP (an inhibitor) and ATP (an activator). CTP binding inhibits the enzyme's activity, while ATP binding activates it.
Phosphofructokinase-1 (PFK-1):

PFK-1 is a key regulatory enzyme in glycolysis. It is allosterically inhibited by ATP and citrate and activated by AMP and fructose-2,6-bisphosphate.
Hemoglobin (though not an enzyme, it exhibits allosteric properties):

Hemoglobin, the oxygen-carrying protein in red blood cells, displays cooperative binding of oxygen. Binding of oxygen to one subunit increases the affinity of the other subunits for oxygen.
Importance of Allosteric Enzymes:
Regulation of Metabolic Pathways:

Allosteric enzymes play a crucial role in regulating metabolic pathways. Their ability to be modulated by various metabolites allows the cell to finely tune enzyme activity in response to changing conditions.
Feedback Inhibition:

Allosteric inhibition is often involved in feedback inhibition, where the end product of a metabolic pathway inhibits an enzyme involved early in the pathway, thus preventing the overproduction of the product.
Mechanisms of Allosteric Regulation:
Homotropic Regulation:

This occurs when the substrate itself acts as an allosteric modulator. Typically, substrate binding to one active site enhances binding and activity at other active sites.
Heterotropic Regulation:

This involves different molecules acting as allosteric modulators. These molecules are not the substrate of the enzyme but can influence its activity.
In summary, allosteric enzymes are regulated by molecules that bind to sites other than the active site, causing conformational changes that affect the enzyme's activity. This regulation is critical for maintaining homeostasis and regulating metabolic pathways in the cell.

Glycolysis
Location: Cytoplasm
Net ATP Production: 2 ATP (produced directly by substrate-level phosphorylation)
NADH Production: 2 NADH
Pyruvate Oxidation
Location: Mitochondrial matrix
Net ATP Production: None directly
NADH Production: 2 NADH (one for each pyruvate molecule)
Krebs Cycle (Citric Acid Cycle)
Location: Mitochondrial matrix
Net ATP Production: 2 ATP (produced directly by substrate-level phosphorylation as GTP, which is equivalent to ATP)
NADH Production: 6 NADH (three per cycle, with two cycles per glucose)
FADH2 Production: 2 FADH2 (one per cycle, with two cycles per glucose)
Total NADH and FADH2 Production
Glycolysis: 2 NADH
Pyruvate Oxidation: 2 NADH
Krebs Cycle: 6 NADH and 2 FADH2
Total: 10 NADH and 2 FADH2
Oxidative Phosphorylation
The NADH and FADH2 produced during glycolysis, pyruvate oxidation, and the Krebs cycle are used in oxidative phosphorylation to generate ATP. The electron transport chain (ETC) and ATP synthase are located in the inner mitochondrial membrane.

NADH to ATP Conversion: Each NADH can theoretically produce approximately 3 ATP molecules through the ETC.
FADH2 to ATP Conversion: Each FADH2 can theoretically produce approximately 2 ATP molecules through the ETC.
Calculations
Using the Malate-Aspartate Shuttle (38 ATP)
The malate-aspartate shuttle effectively transfers the electrons from cytoplasmic NADH into the mitochondria without losing any potential ATP. Therefore, each cytoplasmic NADH produces the same amount of ATP as mitochondrial NADH.

2 NADH from glycolysis: 2 x 3 ATP = 6 ATP
8 NADH from pyruvate oxidation and Krebs cycle: 8 x 3 ATP = 24 ATP
2 FADH2 from Krebs cycle: 2 x 2 ATP = 4 ATP
4 ATP directly from glycolysis and Krebs cycle
Total: 6 + 24 + 4 + 4 = 38 ATP

Using the Glycerol Phosphate Shuttle (36 ATP)
The glycerol phosphate shuttle transfers electrons from cytoplasmic NADH to FAD in the mitochondria, effectively reducing the potential yield from these NADH molecules.

2 NADH from glycolysis (converted to FADH2): 2 x 2 ATP = 4 ATP
8 NADH from pyruvate oxidation and Krebs cycle: 8 x 3 ATP = 24 ATP
2 FADH2 from Krebs cycle: 2 x 2 ATP = 4 ATP
4 ATP directly from glycolysis and Krebs cycle
Total: 4 + 24 + 4 + 4 = 36 ATP

Summary
38 ATP is produced if the 2 NADH from glycolysis enter the mitochondria via the malate-aspartate shuttle.
36 ATP is produced if the 2 NADH from glycolysis enter the mitochondria via the glycerol phosphate shuttle.
The malate-aspartate shuttle is more efficient and results in a higher yield of ATP because it ensures that the electrons from NADH produced during glycolysis are transferred into the mitochondria without loss. In contrast, the glycerol phosphate shuttle converts these electrons to FADH2, resulting in a lower yield of ATP.

Net ATP Produced from One Glucose

The oxidation of that 1 glucose through glycolysis, the Krebs and Krebs cycle, and oxidative phosphorylation produces 36 or 38 molecules of ATP.
36 ATP is produced if the 2 NADH molecules produced in the glycolysis enter the mitochondria by the maleic acid-fumarate pathway.
38 ATP is produced if that 2 NADH molecules enter the mitochondria via the malate-aspartate shuttle. Remember that it is in the ideal setting, meaning we are looking for the highest yield of ATP.

In lands where ancient olive trees stand tall,
Beneath a sky where stars and shadows fall,
A cry resounds, so mournful and so clear,
The world stands mute, yet what we see is fear.

The children play where dreams should freely soar.
Yet bombs rain down, and laughter is no more.
Their innocence, a candle in the night,
Extinguished by the hate that fuels this fight.

Pregnant mothers, heavy with new life,
Hold on to their dreams amidst the endless strife.
Their hopes, like doves, are shattered in the sky.
While tears of anguish fall and questions arise—why?

The elders, with their wisdom and their grace,
I have witnessed peace and war in this same place.
Now they, too, fall beneath a brutal hand.
Their stories are silenced in this ravaged land.

Young ones, vibrant, full of future's light,
Now face a darkened world of endless night.
Their dreams are dashed upon this ruthless tide.
And still, the world looks on and turns aside.

Oh, humanity, where have you gone astray?
Why do you close your eyes and look away?
The cries of innocents should stir the soul.
Yet silence reigns, and darkness takes its toll.

Injustice casts a shadow on the land.
Yet few will rise or take a righteous stand.
The world’s indifference, a silent scream,
That haunts the hearts of those who dare to dream.

For every life that's lost, a part of us
Falls into darkness, silence, and distrust.
When will we learn that peace is born of love?
Not from the sky, where bombs explode above?

Let our hearts be hardened by the pain.
Let voices rise like thunder in the rain.
For every child, mother, elder, and youth,
Deserves a world of justice, peace, and truth.

In the process of non-cyclic photophosphorylation, which molecule serves as the final electron acceptor?",
a. ATP
b. ADP
c. NADP+
d. FAD

Metabolism is the sum of biochemical reactions within the cells of an organism, including catabolism, which breaks down molecules and releases energy, and anabolism, which synthesizes molecules and uses energy.
Precursor metabolites, often produced in catabolic reactions, are used to synthesize all other organic compounds.
Reduction reactions are those in which electrons are added to a chemical. A molecule that donates an electron is oxidized. If the electron is part of a hydrogen atom, an oxidation reaction is also called dehydrogenation. Oxidation and reduction reactions always occur in pairs called oxidation-reduction (redox) reactions.

Three important electron carrier molecules are nicotinamide adenine dinucleotide , nicotinamide adenine dinucleotide phosphate , and flavin adenine dinucleotide (FAD).
Phosphorylation is the addition of phosphate to a molecule. Three types of phosphorylation form ATP: Substrate-level phosphorylation involves the transfer of phosphate from a phosphorylated organic compound to ADP. In oxidative phosphorylation, energy from redox reactions of respiration is used to attach inorganic phosphate to ADP. Photophosphorylation is the phosphorylation of ADP with inorganic phosphate using energy from light.
Catalysts increase the rates of chemical reactions and are not permanently changed in the process. Enzymes, which are organic catalysts, are often named for their substrates—the molecules on which they act. Enzymes can be classified as hydrolases, isomerases, ligases (polymerases), lyases, oxidoreductases, or transferases, reflecting their mode of action.
Apoenzymes are the portions of enzymes that may require one or more cofactors such as inorganic ions or organic cofactors (also called coenzymes). The combination of an apoenzyme and its cofactors is a holoenzyme. RNA molecules functioning as enzymes are called ribozymes.
Activation energy is the amount of energy required to initiate a chemical reaction.
Substrates fit into the specifically shaped active sites of the enzymes that catalyze their reactions. Active sites change shape slightly to better fit their substrates—a process described as the induced-fit model.

Enzymes may be denatured by physical and chemical factors such as heat and pH. Denaturation may be reversible or permanent.
Enzyme activity proceeds at a rate proportional to the concentration of substrate molecules until all the active sites are filled.
Competitive inhibitors block active sites and thereby block enzyme activity. Noncompetitive inhibitors bind to an allosteric site on an enzyme. This binding alters the active site so that it is no longer functional.
Feedback inhibition (negative feedback) occurs when the final product of a pathway of reactions is an allosteric inhibitor of some previous step in the series. Thus, accumulation of the end product “feeds back” into the pathway as a signal that stops the process.

Sterilization is the eradication of microorganisms and viruses; the term is not usually applied to the destruction of prions.
An aseptic environment or procedure is free of contamination by pathogens.
Antisepsis is the inhibition/killing of microorganisms (particularly pathogens) on skin or tissue by the use of a chemical antiseptic, whereas disinfection refers to the use of agents (called disinfectants) to inhibit microbes on inanimate objects.
Degerming refers to the removal of microbes from a surface by scrubbing.
Sanitization is the reduction of a prescribed number of pathogens from surfaces and utensils in public settings.
Pasteurization is a process using heat to kill pathogens and control microbes that cause spoilage of food and beverages.
The suffixes -stasis and -static indicate that an antimicrobial agent inhibits microbes, whereas the suffixes -cide and -cidal indicate that the agent kills or permanently inactivates a particular type of microbe.
Microbial death is the permanent loss of reproductive capacity. Microbial death rate measures the efficacy of an antimicrobial agent.
Antimicrobial agents destroy microbes either by altering their cell walls and membranes or by interrupting their metabolism and reproduction via interference with proteins and nucleic acids.

Difference b/w Ecology and Environment Biology
The key difference between ecology and environmental biology lies in their focus and scope. Ecology is the branch of biology that deals with the relationship among organisms and their environments. It focuses on relationships at various levels, including individuals, populations, communities, ecosystems, and the biosphere. Ecologists often examine how organisms influence and are influenced by factors like other organisms, the physical environment, and the flow of energy and matter through ecosystems.
Environmental Biology is a broader field that encompasses aspects of ecology but also includes the study of how human activities impact the environment. It integrates knowledge from various biological disciplines to understand and address environmental issues such as pollution, climate change, habitat destruction, and conservation. Environmental biologists work on solutions to mitigate these impacts and often focus on the applied side of science to protect and restore natural systems

The three germinal layers formed during embryonic development are the ectoderm, mesoderm, and endoderm. Each layer gives rise to specific tissues and organs in the body.

1. Ectoderm
Systems and Structures Derived:

Nervous System: Brain, spinal cord, peripheral nerves.
Skin and its Derivatives: Epidermis, hair, nails, sweat glands, mammary glands.
Sensory Organs: Lens of the eye, inner ear, olfactory epithelium.
Mouth and A**s: Oral and a**l ca**l linings.
Pituitary Gland: Both anterior and posterior parts.
Adrenal Medulla: Produces adrenaline and noradrenaline.
2. Mesoderm
Systems and Structures Derived:

Musculoskeletal System: Bones, muscles, cartilage.
Cardiovascular System: Heart, blood vessels, blood cells.
Lymphatic System: Lymph nodes, lymph vessels.
Excretory System: Kidneys, ureters.
Reproductive System: Go**ds (te**es and ovaries), reproductive ducts.
Dermis of the Skin: Deeper layer of the skin.
Adrenal Cortex: Produces steroid hormones like cortisol and aldosterone.
Connective Tissue: Ligaments, tendons, fascia.
3. Endoderm
Systems and Structures Derived:

Digestive System: Lining of the gastrointestinal tract, liver, pancreas.
Respiratory System: Lining of the respiratory tract (trachea, bronchi, lungs).
Urinary System: Urinary bladder, urethra.
Endocrine System: Thyroid gland, parathyroid glands.
Reproductive System: Lining of the urogenital systems.
Other Glands: Thymus, parts of the tonsils.
These germinal layers differentiate into various systems and structures, each playing a crucial role in the development and function of the human body.

پاکستان کو دشمن طاقتوں جن کے لیے پاکستان کا وجود اور بقاء ناقابل برداشت ھے، کے خلاف ایک ناقابلِ تسخیر بنانے والے ہر کردار کو سلام ۔۔
خدا آپ کو آپ کو سلامت رکھے ۔۔
یوم تکبیر مبارک
پروفیسر عمران خان