Biology 1 Notes - Shua PDF

## Macromolecules **Water: Importance** - **Solvent:** Water is a polar molecule, so it can dissolve many substances, making it vital for biochemical reactions in cells. - **Temperature Regulation:** Water has a high specific heat capacity, meaning it can absorb a lot of heat before its temperatur...

## Macromolecules **Water: Importance** - **Solvent:** Water is a polar molecule, so it can dissolve many substances, making it vital for biochemical reactions in cells. - **Temperature Regulation:** Water has a high specific heat capacity, meaning it can absorb a lot of heat before its temperature rises. This helps maintain stable temperatures inside organisms. - **Cohesion & Adhesion:** Water molecules stick together (cohesion) and to other substances (adhesion), important for processes like transport in plants (capillary action). - **Metabolic Reactions:** Water is involved in hydrolysis (breaking down molecules) and condensation reactions (building larger molecules). **Carbohydrates: Monosaccharides, Disaccharides, and Polysaccharides** - **Bond:** glycosidic bond. **Monomer** - **Monosaccharides:** Simple sugars (e.g., glucose, fructose). They are the basic units of carbohydrates. - **Disaccharides:** Formed by two monosaccharides joined together via a glycosidic bond in a condensation reaction (e.g., sucrose = glucose + fructose, lactose = glucose + galactose, maltose = glucose + glucose). - **Polysaccharides:** Long chains of monosaccharides (e.g., starch, glycogen, cellulose). They are formed by condensation reactions, creating glycosidic bonds. **Polymer** **Condensation & Hydrolysis Reactions:** - **Condensation:** Two monosaccharides join, releasing water. - **Hydrolysis:** A disaccharide or polysaccharide is broken down into smaller units by adding water. **Mono/Di** - Instant energy - Not very reactive - Broken easily by hydrolysis - Simple sugars **Poly** - Stored energy - Chemically reactive - Cond & hydrolysis - Many sugars joint by aucecidie bonds ## Lipids: Triglycerides, Saturated vs. Unsaturated - **Triglycerides:** Made from one molecule of glycerol and three fatty acid chains. Formed via condensation reactions, producing ester bonds. - **Saturated Lipids:** Contain no double bonds between carbon atoms (eg., butter). They are solid at room temperature. - **Unsaturated Lipids:** Contain one or more double bonds between carbon atoms (eg., olive oil). They are liquid at room temperature. **Bond:** ester bonds. - Energy storage (fats and oils) - Insulation and protection - Cell membrane structure (phospholipid bilayer) ## Proteins: Amino Acids, Polypeptides, and Structure **Monomer** - **Amino Acid Structure**: Contains an amino group (NH2), a carboxyl group (COOH), a hydrogen atom (H), and a variable R group (which defines the amino acid). **Polymer** - **Polypeptides:** Formed by the joining of amino acids through peptide bonds (a type of covalent bond) via condensation reactions. - **Protein Structure:** - **Primary Structure:** The sequence of amino acids determines the protein’s shape and function. - **Secondary Structure:** Folding of the polypeptide chain into alpha helices or beta-pleated sheets, stabilized by hydrogen bonds. - **Tertiary Structure:** Further folding into a 3D shape, stabilized by various bonds (eg., hydrogen bonds, disulfide bridges, ionic bonds). - **Quaternary Structure:** Two or more polypeptide chains may join to form a functional protein. Multiple polypeptide chains. - **Bond:** peptide bonds **Globular vs. Fibrous Proteins** - **Globular Proteins:** Compact, spherical shapes (eg., enzymes, antibodies). Soluble in water and have functional roles like catalysis or transport. - **Fibrous Proteins:** Long, thread-like structures (eg., collagen, keratin). Provide structural support and are often insoluble in water. - Enzymes (biological catalysts) - Immune response - Transport (hemoglobin) - Structural (collagen) - Antibodies ## Nucleic Acids **Monomer:** nucleotides (sugar, phosphate, nitrogenous bases) **Polymers:** - **DNA (Deoxyribonucleic Acid):** Contains genetic information. Composed of nucleotides (sugar, phosphate group, nitrogenous base). The structure is a double helix. - **RNA (Ribonucleic Acid):** Involved in protein synthesis. Similar to DNA, but single-stranded, with uracil replacing thymine. **Bond:** phosphodiester bonds (between nucleotides) - **DNA** - Double helix - Deoxyribose - Generic info - **RNA** - Single-stranded - Ribose sugar - Protein synthesis ## Enzymes: Mechanism of Action - **Biological Catalysts:** Enzymes speed up reactions by lowering the activation energy required. - **Active Site:** The region of the enzyme where the substrate binds. The enzyme's specificity is due to the unique shape of the active site. - **Induced Fit Model:** The enzyme’s active site changes shape slightly to accommodate the substrate more tightly. - **Lock & Key Model:** The substrate fits perfectly into the enzyme’s active site (outdated but still useful for understanding enzyme specificity). - **Factors Affecting Enzyme Activity:** Temperature, pH, and substrate concentration all affect enzyme function. If these factors are not optimal, the enzyme may denature (lose its shape and function). ## DNA **Remember:** - **DNA** - A - T - **RNA** - A - U **Basic Structure of Mononucleotides and DNA:** - **Mononucleotide:** A mononucleotide is the basic building block of nucleic acids (DNA and RNA). It consists of: - Phosphate group (PO4) - Pentose sugar (deoxyribose in DNA, ribose in RNA) - Nitrogenous base: - Adenine (A), Thymine (T), Cytosine (C), Guanine (G) (for DNA). - **DNA Structure:** - DNA is a double helix made of two strands of nucleotides. - The backbone consists of alternating sugar (deoxyribose) and phosphate groups. - The nitrogenous bases pair through hydrogen bonds: - Adenine (A) pairs with Thymine (T) (2 hydrogen bonds). - Cytosine (C) pairs with Guanine (G) (3 hydrogen bonds). - The two strands run antiparallel, meaning one runs 5’ to 3’ and the other runs 3’ to 5’. **Why semi conservative?** - 1 original parental strand. - 1 freshly assembled daughter strand. **DNA Replication:** - DNA replication is the process by which DNA makes an identical copy of itself before cell division. **Steps in DNA Replication:** 1. **Unwinding of DNA (H2 bonds break) - by "Helicase"** 2. **New nucleotide joins to new strand by forming H bonds between base pairs.** "DNA Polymerase" 3. **New strand formed. "Ligase" catalyzes formation of phosphodiester bonds between 2 DNA strands.** **Protein Synthesis** - **Gene:** a segment of DNA that codes for a specific protein or RNA molecule. It contains the instructions for building and maintaining an organism’s cells. - **Genetic Code:** the set of rules that defines how the sequence of nucleotides (A, T, C, G) in DNA or mRNA corresponds to the sequence of amino acids in a protein. - **Codons:** A codon is a sequence of three nucleotides that codes for one amino acid. - Example: AUG (adenine-uracil-guanine) is the start codon, which codes for methionine. - There are 64 possible codons, but only 20 amino acids. - The genetic code is universal (same in all organisms) and degenerate (some amino acids are encoded by more than one codon). **Transcription (DNA → mRNA):** - **Transcription:** The process where a mRNA (messenger RNA) molecule is synthesized from a DNA template. - **Nucleus:** DNA polymerase unwinds DNA by breaking H2 bonds. mRNA is formed. - **mRNA (single stranded and small) comes to cytoplasm.** - **Result:** A single-stranded mRNA molecule is produced, which carries the genetic information from the DNA to the ribosome for protein synthesis. **Translation (mRNA → Protein):** - **Translation:** The process by which the sequence of nucleotides in mRNA is translated into a sequence of amino acids, forming a protein. **Key Players:** - **mRNA:** Carries the genetic code from the DNA to the ribosome. - **tRNA (transfer RNA):** Brings amino acids to the ribosome during translation. Each tRNA has an anticodon that is complementary to the mRNA codon. - **Ribosome:** The site of protein synthesis. It has two subunits (large and small) that facilitate the binding of mRNA and tRNA. **Cytoplasm on Ribosomes:** 1. **mRNA attaches to a ribosome.** 2. **tRNA brings aminoacids to ribosome.** (each tRNA has anticodon that pair with mRNA codon) 3. **Amino acids linked by peptide bonds → polypeptide chain.** 4. **Polypeptide folds into functional 3D structure to become a functional protein.** **Result:** The final product is a polypeptide chain (protein), which folds into its functional three-dimensional shape. ## Prokaryotes and Eukaryotes **Prokaryotic Cells (Bacteria)** - Size: Smaller (0.2-2 micrometers). - Nucleus: No true nucleus; DNA is in the nucleoid region (not membrane-bound). - Organelles: No membrane-bound organelles (e.g., no mitochondria, endoplasmic reticulum). - Ribosomes: Smaller (70S). - Cell Wall: Present, made of peptidoglycan (in bacteria). - Plasma Membrane: Present; regulates what enters and exits the cell. - Flagella: Present in some prokaryotes, simpler structure than eukaryotic flagella. - Plasmids: Small circular DNA molecules that carry extra genes (e.g., antibiotic resistance). - Capsule: Some prokaryotes have a protective capsule outside the cell wall. - Pili: Hair-like structures used for attachment or DNA exchange. **Eukaryotic Cells (Plants, Animals, Fungi, Protists)** - Size: Larger (10-100 micrometers). - Nucleus: True nucleus, enclosed by a nuclear membrane; contains genetic material (DNA). - Organelles: Membrane-bound organelles, including mitochondria, endoplasmic reticulum (ER), Golgi apparatus, and lysosomes. - Ribosomes: Larger (80S). - Cell Wall: Present in plant cells (made of cellulose) and fungal cells (made of chitin); absent in animal cells. - Plasma Membrane: Present; regulates material exchange. - Flagella/Cilia: Present in some eukaryotic cells (e.g., sperm, some protists), more complex structure than prokaryotic flagella. - Cytoskeleton: Present (microtubules, microfilaments) for cell shape and movement. **Comparison: Prokaryotic vs Eukaryotic Cells** | Feature | Prokaryotic Cells | Eukaryotic Cells | |---|---|---| | Size | Smaller (0.2-2 µm) | Larger (10-100 µm) | | Nucleus | No nucleus (nucleoid region) | True nucleus (membrane-bound) | | Organelles | None (no membrane-bound) | Membrane-bound organelles | | Ribosomes | 70S | 80S | | Cell Wall | Present (peptidoglycan) | Present in plants & fungi (cellulose/chitin) | | DNA | Circular, no histones | Linear, with histones | | Plasma Membrane | Present | Present | | Flagella | Simple structure | Complex structure | | Plasmids | Present in some | Absent | ## Cell Membrane Structure (Fluid Mosaic Model) - **Phospholipid Bilayer** - They are the basic structural unit of the membrane. - **Hydrophilic Head:** Attracted to water (polar). - **Hydrophobic Tails:** Repel water (non-polar). - **Bilayer Formation:** Phospholipids arrange themselves into a bilayer with the hydrophilic heads facing outward (towards water) and the hydrophobic tails facing inward (away from water). - **Proteins:** - **Integral (Intrinsic) Proteins:** Embedded within the lipid bilayer. These proteins span the membrane and can act as channels or transporters for molecules. - **Peripheral (Extrinsic) Proteins:** Loosely attached to the inner or outer surface of the membrane. They help with cell signaling, structural support, and maintaining shape. - **Cholesterol:** - Found within the phospholipid bilayer. - Reduces membrane fluidity at high temperatures. - Prevents the membrane from becoming too rigid at low temperatures. - **Glycoproteins & Glycolipids:** - **Glycoproteins:** Proteins with carbohydrate chains attached. They play a key role in cell recognition and communication. - **Glycolipids:** Lipids with carbohydrate chains attached. They also contribute to cell recognition and act as receptors for signaling molecules. ## Properties of the Cell Membrane - **Fluidity:** - The fluid mosaic model describes the membrane as a dynamic, fluid structure where lipids and proteins move sideways within the layer. - The fluid nature allows for the movement of proteins, cell signaling, and vesicle formation. - **Selective Permeability:** - The cell membrane is selectively permeable, meaning it controls what enters and exits the cell. - Small non-polar molecules (eg., oxygen, carbon dioxide) can pass through easily. - Polar molecules and ions cannot pass through easily and require specific transport proteins. - **Transport Mechanisms:** - **Passive Transport (No Energy Required):** - **Diffusion:** Movement of molecules from high to low concentration. - **Facilitated Diffusion:** Movement of molecules through a membrane protein, down the concentration gradient. - **Osmosis:** Diffusion of water molecules across a selectively permeable membrane. - **Active Transport (Energy Required):** - Molecules move against their concentration gradient, using energy (ATP) and transport proteins (eg., sodium-potassium pump). - **Cell Communication:** - The cell membrane contains receptor proteins that bind to signaling molecules (eg., hormones, neurotransmitters), triggering a cellular response. - **Membrane Asymmetry:** - The outer and inner layers of the membrane have different compositions of lipids, proteins, and carbohydrates. This asymmetry is important for cell recognition and communication. ## Summary - The cell membrane is made up of a phospholipid bilayer with embedded proteins, cholesterol, and glycoproteins/glycolipids. - It is selectively permeable, allowing certain molecules to pass through while blocking others. - The fluid mosaic model highlights the membrane’s fluidity and dynamic nature. - It regulates transport, facilitates communication, and maintains cell integrity. ## Cell Membrane and Transport: Gas Exchange & Respiration Summary **Gas Exchange Surfaces in Living Organisms:** - **Properties of Gas Exchange Surfaces:** - **Large Surface Area:** Maximizes the area for gas exchange. - **Thin Membranes:** Short diffusion distance for faster gas exchange. - **Moist Surface:** Gases dissolve in moisture to diffuse more easily. - **Good Blood Supply:** Maintains concentration gradients by transporting gases away. - **Permeable:** Allows easy movement of gases like oxygen (O2) and carbon dioxide (CO2). - **Mammalian Lung Adaptations:** - **Refer to diagram for structure.** - **Alveoli:** Tiny air sacs with thin walls (one cell thick) to allow efficient gas exchange. - **Capillary Network:** Surrounds alveoli to maintain a concentration gradient of gases. - **Large Surface Area:** Due to the millions of alveoli in the lungs. - **Short Diffusion Path:** Thin epithelial layers of alveoli and capillaries reduce the diffusion distance. - **Ventilation:** Maintains the concentration gradient of O2 and CO2 in the lungs. **Fick’s Law of Diffusion:** - **Fick’s Law:** Describes how the rate of diffusion depends on: $Rate \ of \ Diffusion = \frac{Surface \ Area \times Concentration \ Gradient}{Thickness \ of \ the \ membrane}$ - **Surface Area:** More area increases diffusion rate. - **Concentration Gradient:** Greater difference in concentration between the two sides increases diffusion. - **Thickness:** Thinner membranes allow faster diffusion **Aerobic Respiration** - **Glucose (C6H12O6) + O2 -> CO2 + H2O + ATP** - Glucose is broken down with oxygen to produce carbon dioxide, water, and energy in the form of ATP. ## Respiration as a Multi-Step Process: - **Enzyme-Catalyzed Process:** Each step of respiration is controlled by a specific enzyme, ensuring reactions occur efficiently. **Glycolysis:** - **Location:** cytoplasm - **Anaerobic Process:** Does not require oxygen. - **Process:** - Glucose (6-carbon) is split into two molecules of pyruvate (3-carbon). - Produces a small amount of ATP (2 ATP) and NADH. - **Role in Aerobic Respiration:** Provides pyruvate for the link reaction (next step in aerobic respiration). - **Role in Anaerobic Respiration:** Produces ATP without oxygen, but less efficiently (eg., lactic acid fermentation in animals). **Link Reaction & Krebs Cycle:** - **Link Reaction:** - **Location:** mitochondria - **Converts** pyruvate into Acetyl CoA, releasing CO2 and NADH. - **Krebs Cycle:** - **Location:** mitochondrial matrix. - Acetyl CoA enters the cycle and is further broken down, releasing CO2, ATP, NADH, and FADH2. - **Products:** ATP (produced through substrate-level phosphorylation). - **Products:** High-energy electron carriers (NADH, FADH2) **Oxidative Phosphorylation (Electron Transport Chain & Chemiosmosis):** - **Location:** Inner mitochondrial membrane - **Electron Transport Chain (ETC):** - NADH and FADH2 donate electrons to the ETC. - Electrons pass through proteins, releasing energy. - This energy pumps protons (H+) across the inner mitochondrial membrane. - **Chemiosmosis:** - Protons (H+) flow back through ATP synthase, driving the synthesis of ATP from ADP and inorganic phosphate (Pi). - Oxygen acts as the final electron acceptor, combining with protons to form water (H2O). - **ATP Yield:** Around 34 ATP molecules are produced in oxidative phosphorylation. ## Circulatory System - **Overall Structure:** - The heart is a muscular organ located in the thoracic cavity - It is divided into four chambers: - **Right atrium:** Receives deoxygenated blood from the body. - **Left atrium:** Receives oxygenated blood from the lungs. - **Right ventricle:** Pumps deoxygenated blood to the lungs via the pulmonary artery. - **Left ventricle:** Pumps oxygenated blood to the rest of the body via the aorta. - **Heart Valves:** - **Tricuspid valve (right side) and bicuspid/mitral valve (left side):** Prevent backflow of blood into the atria. - **Pulmonary valve and aortic valve:** Prevent backflow into the ventricles. - **Coronary Arteries:** - Supply oxygenated blood to the heart muscle (myocardium). ## Cardiac Cycle - **Phases of the Cardiac Cycle:** - **Atrial Systole (Contraction):** - The atria contract, pushing blood into the ventricles. - AV valves (tricuspid and bicuspid) are open; semilunar valves (pulmonary and aortic) are closed. - **Ventricular Systole (Contraction):** - The ventricles contract, forcing blood into the pulmonary artery (right) and the aorta (left). - AV valves close to prevent backflow into the atria; semilunar valves open to allow blood flow out of the heart. - **Diastole (Relaxation):** - The heart muscle relaxes, the chambers fill with blood. - AV valves open; semilunar valves close to prevent backflow. - **Pressure Changes in the Heart:** - **During systole:** ventricular pressure rises, causing the semilunar valves to open. - **During diastole:** ventricular pressure drops, allowing the atria to refill the ventricles with blood. ## Major Blood Vessels: - **Arteries** - Carry oxygenated blood away from the heart (except pulmonary artery, which carries deoxygenated blood to the lungs). - **Structure:** - Thick, elastic walls with a small lumen (inner diameter) to withstand high pressure. - Smooth muscle allows constriction and dilation to regulate blood flow. - **Veins** - Carry deoxygenated blood to the heart (except pulmonary veins, which carry oxygenated blood from the lungs). - **Structure:** - Thinner walls than arteries, with a larger lumen. - Valves present to prevent backflow of blood, especially in the legs. - **Capillaries** - Smallest blood vessels, where gas and nutrient exchange occurs. - **Structure:** - Very thin walls (one cell thick) for efficient diffusion. - Large surface area for exchange of oxygen, carbon dioxide, nutrients, and waste products. ## Blood Vessels and Their Functions | Blood Vessel | Function | Structure | |---|---|---| | Arteries | Carry oxygenated blood away from the heart (except pulmonary artery). | Thick, elastic walls to handle high pressure, small lumen. | | Veins | Carry deoxygenated blood to the heart (except pulmonary veins). | Thinner walls, large lumen, valves to prevent backflow. | | Capillaries | Exchange of gases, nutrients, and waste products between blood and tissues. | Very thin (one cell thick), large surface area, narrow lumen. | ## Blood Clotting (Coagulation): 1. **Blood vessel constricts to reduce blood flow/limit bleeding.** 2. **Platelets stick to damaged area (release chemicals) - to attract more platelets and forming a temporary plug.** 3. **Clotting factor (factor x/Prothrombinase) convert prothrombin → thrombin.** 4. **Thrombin activates platelets and convert fibrinogen to fibrin, forming fibrin mesh.** 5. **Platelets contract to help close wound. Clot dissolves after healing.** ## ECG - **ECG (Electrocardiogram):** A test that measures the electrical activity of the heart. - **Purpose:** To monitor the heart's rhythm, detect abnormalities, and diagnose heart conditions (eg., arrhythmias, heart attacks, and other cardiovascular diseases). **How to Interpret a Blood Pressure Graph:** 1. **Systolic Pressure:** The highest pressure when the heart contracts and pumps blood (top number). 2. **Diastolic Pressure:** The lowest pressure when the heart relaxes between beats (bottom number). 3. **Pulse Pressure:** The difference between systolic and diastolic pressures. 4. **Normal Range:** Typical blood pressure is around 120/80 mmHg. 5. **Graph Features:** - **Rising Systolic Pressure:** Represents the contraction phase (systole). - **Lower Diastolic Pressure:** Reflects the relaxation phase (diastole). **Normal Electrical Activity of the Heart:** 1. **Sinoatrial (SA) Node:** The heart’s natural pacemaker, located in the right atrium, generates electrical impulses. 2. **Atria:** The impulse spreads through the atria, causing them to contract (P wave). 3. **Atrioventricular (AV) Node:** Receives the electrical impulse and delays it briefly to allow the atria to empty before ventricular contraction. 4. **Bundle of His and Purkinje Fibers:** Transmit the electrical impulse to the ventricles, causing them to contract (QRS complex). 5. **Ventricular Relaxation:** After contraction, the ventricles relax and the heart’s electrical activity returns to baseline (T wave). **Use of Electrocardiograms (ECGs):** 1. **Recording the Heart’s Electrical Activity:** An ECG graph shows the electrical impulses generated by the heart during each heartbeat: - **P Wave:** Atrial depolarization (atria contract). - **QRS Complex:** Ventricular depolarization (ventricles contract). - **T Wave:** Ventricular repolarization (ventricles relax). 2. **Diagnosing Heart Conditions:** - **Arrhythmias:** Irregular heartbeats, such as tachycardia (fast heart rate) or bradycardia (slow heart rate). - **Heart Attacks (Myocardial Infarction):** Abnormalities in the ECG, like ST-segment elevation, can indicate a heart attack. - **Electrolyte Imbalances:** Changes in the ECG can reveal imbalances in electrolytes like potassium or calcium. ## Risk Factors for Cardiovascular Disease (CVD) 1. **Genetics:** - **Family history:** Individuals with a family history of CVD are at higher risk due to inherited genetic traits (eg., high cholesterol levels, tendency for hypertension). 2. **Diet:** - **High in saturated fats and cholesterol:** Can lead to arterial plaque formation (atherosclerosis), increasing the risk of heart disease. - **Excessive salt intake:** Raises blood pressure, which increases the risk of stroke and heart attacks. - **Low fiber intake:** A poor diet lacking in fruits, vegetables, and whole grains may contribute to obesity and heart disease. 3. **Age:** - **Older age:** Risk increases with age, as blood vessels lose elasticity and plaque builds up over time. 4. **Gender:** - Men tend to have a higher risk of heart disease at a younger age, though the risk for women increases after menopause due to decreased estrogen levels. 5. **High Blood Pressure (Hypertension):** - Elevated blood pressure puts strain on the heart and blood vessels, leading to damage and an increased risk of heart attack, stroke, and kidney disease. 6. **Smoking:** - Nicotine and carbon monoxide in cigarette smoke damage blood vessels, raise blood pressure, reduce oxygen in the blood, and increase the likelihood of blood clots, all of which increase the risk of heart disease. 7. **Physical Inactivity:** - Lack of exercise contributes to obesity, high blood pressure, and elevated cholesterol, all of which increase the risk of CVD. ## Benefits and Risks of Treatments for CVD 1. **Antihypertensive Drugs:** - **Benefits:** Lower blood pressure, reduce the risk of heart attacks, strokes, and kidney damage. - **Risks:** Side effects such as dizziness, fatigue, and potential kidney issues in some patients. 2. **Plant Statins (Cholesterol-lowering drugs):** - **Benefits:** Reduce cholesterol levels, slow the buildup of plaque in arteries, and lower the risk of heart disease and stroke. - **Risks:** Possible side effects include muscle pain, liver damage, and digestive issues. 3. **Anticoagulants (Blood thinners):** - **Benefits:** Prevent blood clots, reducing the risk of strokes and heart attacks. - **Risks:** Increased risk of bleeding, especially in the case of injury or surgery. 4. **Platelet Inhibitory Drugs (Aspirin and other medications):** - **Benefits:** Prevent blood clots by inhibiting platelet aggregation, reducing the risk of heart attack and stroke. - **Risks:** Can cause gastrointestinal bleeding, allergic reactions, or ulcers in some individuals. ## Lifestyle Changes to Reduce CVD Risk 1. **Diet and Obesity Indicators:** - **Body Mass Index (BMI):** A measure of body fat based on weight and height. A BMI over 30 indicates obesity, which increases the risk of CVD. - **Waist-to-Hip Ratio:** A higher ratio (indicating more fat around the abdomen) is associated with a higher risk of CVD. - **Balanced Diet:** A diet rich in fruits, vegetables, whole grains, lean proteins, and healthy fats can help lower cholesterol, blood pressure, and weight. 2. **Exercise:** - Regular physical activity strengthens the heart, lowers blood pressure, and helps manage weight. It also improves blood circulation and reduces the risk of CVD. 3. **Smoking:** - Quitting smoking significantly reduces the risk of developing CVD. It improves blood vessel health, lowers blood pressure, and reduces clotting risk. ## Summary of Key Points - **CVD Risk Factors:** Genetics, diet, age, gender, high blood pressure, smoking, and inactivity all contribute to increased risk. - **Treatment Options:** Antihypertensive drugs, statins, anticoagulants, and platelet inhibitors can help manage CVD but may have side effects. - **Lifestyle Modifications:** A healthy diet, regular exercise, maintaining a healthy weight (using BMI and waist-to-hip ratio as indicators), and quitting smoking are effective strategies to reduce CVD risk. ## Muscles **Muscles, Tendons, Skeleton, and Ligaments in Movement:** 1. **Muscles:** Contract to generate force and allow movement. - **Skeletal Muscles:** Voluntary muscles attached to bones via tendons. 2. **Tendons:** Strong, flexible tissues that attach muscles to bones, allowing muscles to move the skeleton. 3. **Skeleton:** Provides structure and support, acts as a lever system for muscle movement. 4. **Ligaments:** Tough, elastic tissues that connect bones to other bones, stabilizing joints and preventing excessive movement. 5. **Antagonistic Muscle Pairs:** Muscles work in pairs, where one contracts while the other relaxes. - **Example:** The biceps and triceps in the upper arm. - **Biceps (flexor) contracts to bend the arm.** - **Triceps (extensor) relaxes and stretches to allow flexion.** - **When the triceps contracts, the biceps relaxes, causing extension of the arm.** 6. **Flexors and Extensors:** - **Flexors:** Muscles that decrease the angle of a joint (eg., biceps). - **Extensors:** Muscles that increase the angle of a joint (eg., triceps). **Fast and slow twitch muscle fibers:** 1. **Fast Twitch Fibres (Type II):** - **Structure:** Larger, fewer mitochondria, less myoglobin. - **Function:** Designed for quick, powerful bursts of activity (eg., sprinting, lifting). - **Physiology:** Fatigue quickly because they rely on anaerobic respiration. - **Contraction Speed:** Fast, high force production but short duration. - **Energy Source:** Anaerobic, uses glycogen for quick energy release. 2. **Slow Twitch Fibres (Type I):** - **Structure:** Smaller, more mitochondria, more myoglobin. - **Function:** Designed for endurance activities (eg., long-distance running, posture maintenance). - **Physiology:** Fatigue-resistant, as they rely on aerobic respiration for steady energy production. - **Contraction Speed:** Slow, but able to sustain activity over a long period. - **Energy Source:** Aerobic, uses oxygen to produce energy from fat and glucose. ## Key Terms and Relationships in Food Webs 1. **Producer** - Organisms that produce their own food via photosynthesis (eg., plants, algae). - They form the base of the food web. 2. **Consumer** - Organisms that feed on other organisms. - There are different types of consumers: - **Primary consumers (herbivores):** feed on producers. - **Secondary consumers (carnivores):** feed on primary consumers. - **Tertiary consumers:** feed on secondary consumers. 3. **Herbivore** - A primary consumer that feeds only on plants (eg., rabbits, deer). 4. **Carnivore** - A consumer that feeds on other animals (eg., lions, hawks). 5. **Decomposer** - Organisms (eg., fungi, bacteria) that break down dead organic matter, recycling nutrients back into the ecosystem. 6. **Food Chain** - A linear sequence showing how energy and nutrients flow through an ecosystem (eg., grass → rabbit → fox). 7. **Population** - A group of individuals of the same species living in a particular area. 8. **Community** - All the different populations (species) living and interacting in a particular area. 9. **Habitat** - The physical environment where an organism lives (eg., a forest, ocean). 10. **Ecosystem** - A community of organisms interacting with their abiotic environment (eg., a pond, forest). ## Biotic and Abiotic Factors Influencing Organisms - **Biotic Factors:** Living components that affect organisms (eg., competition, predation, disease). - **Abiotic Factors:** Non-living components that affect organisms (eg., temperature, light, water, soil pH, humidity). - The numbers and distribution of organisms in a habitat are determined by a balance between these biotic and abiotic factors. ## Niche and Its Role in Distribution and Abundance - **Niche:** The role or function of an organism within its ecosystem, including how it obtains food, interacts with other organisms, and contributes to the environment. - **Fundamental Niche:** The potential role of an organism in the absence of competition. - **Realized Niche:** The actual role of an organism when limited by factors like competition or predation. - **The niche concept** explains how species are distributed and why certain species thrive in certain areas based on their adaptations to the environment. ## Biodiversity and Endemism - **Biodiversity:** The variety of life forms in an ecosystem, including the variety of species, genes, and ecosystems. High biodiversity increases ecosystem stability. - **Endemism:** Species that are found only in one specific geographical area and nowhere else (eg., certain species of plants or animals in isolated regions like islands). ## Adaptations to the Environment (Niche and Adaptation) - Organisms have evolved different types of adaptations to survive in their niche. These can be: 1. **Behavioral Adaptations:** - Changes in how an organism behaves to survive (eg., birds migrating to warmer climates during winter, nocturnal behavior to avoid daytime heat). 2. **Anatomical Adaptations:** - Physical features that help an organism survive (eg., thick fur for insulation in cold climates, camouflage for predator avoidance, sharp claws for hunting). 3. **Physiological Adaptations:** - Internal processes that help organisms cope with environmental challenges (eg., desert plants conserve water, some animals produce antifreeze proteins to survive in cold temperatures). ## Visuals to Learn - **Pyramid of Numbers:** An example of a pyramid of numbers for the food chain: (cabbage => caterpillar => bird) - **Pyramid of Biomass:** Pyramid of biomass for the food chain: (cabbages ==> caterpillars ==> birds) - **Pyramid of Energy:** A pyramid of energy showing the amount of energy at each trophic level. ## The Respiratory System - A diagram of the respiratory system with the following labels: - Trachea (wind pipe) - Rings of cartilage - Right lung - Bronchus - Bronchioles - Ribs - Intercostal muscle - Pleural membranes - Pleural cavity fluid - Diaphragm - Larynx - Clavicle (collar bone) - External intercostal muscle - Internal intercostal muscles - Sternum - Sphenoidal sinus - Nasal cavity - Pharynx - Alveoli - Right lung - Diaphragm - Frontal sinus - Nasal conchae - Nose - Larynx - Trachea - Bronchus - Bronchioles - Left lung - **The Respiratory System:** Text label at the bottom of the diagram.