Module 2 Flashcards
What makes water a polar molecule?
Water is polar because electrons are shared unequally within the bonds, with oxygen being more electronegative, giving it a slight negative charge and hydrogen a slight positive charge.
What is the significance of hydrogen bonding in water?
Hydrogen bonding gives water its special properties like being an excellent solvent, having a high latent heat of evaporation, high specific heat capacity, cohesion, and insulating properties in solid form.
Why is water called the “universal solvent”?
Water is an excellent solvent because it can dissolve a wide range of polar molecules and ionic compounds due to its ability to form hydrogen bonds.
What is the role of water’s high latent heat of evaporation?
It allows water to absorb a large amount of heat energy when it evaporates, which helps cool organisms, such as humans sweating to regulate body temperature.
How does water’s high specific heat capacity benefit marine life?
Water’s high specific heat capacity means it can absorb and retain large amounts of heat, making aquatic environments stable in temperature, which is beneficial for marine life.
What does the cohesive property of water mean?
Cohesion refers to the tendency of water molecules to stick to one another, which helps water flow and makes it an effective transport medium in plants and animals.
How does ice help to insulate bodies of water?
Ice is less dense than liquid water and forms an insulating layer on the surface, preventing deeper water from freezing and allowing aquatic organisms to survive.
What are carbohydrates made of?
Carbohydrates are made up of carbon, hydrogen, and oxygen and are formed by linking monosaccharides through condensation reactions.
What is the difference between alpha and beta glucose?
In alpha glucose, the hydrogen atom is above the carbon, while in beta glucose, the hydrogen atom is below the carbon.
What are the main polysaccharides in plants and animals?
In plants, starch (amylose and amylopectin) and cellulose; in animals, glycogen is the main energy storage carbohydrate
What is the structure of amylose?
Amylose is an unbranched, spiraling chain of alpha-glucose molecules, making it compact and efficient for storage
What is the structure and function of cellulose?
Cellulose consists of long, unbranched chains of beta-glucose linked by hydrogen bonds to form strong microfibrils, providing structural support to plant cell walls.
What is the structure of glycogen and its function?
Glycogen is a branched polysaccharide of alpha-glucose that provides energy storage in animals and allows quick breakdown for energy
How are triglycerides and phospholipids similar?
Both are made of glycerol and fatty acids connected by ester bonds, but triglycerides have three fatty acid tails, whereas phospholipids have two fatty acid tails and a phosphate group.
What is the difference between saturated and unsaturated fatty acids?
Saturated fatty acids have only single carbon-carbon bonds, while unsaturated fatty acids contain at least one double bond.
What is the function of triglycerides?
Triglycerides store energy, providing more energy per gram than carbohydrates, and are stored in lipid droplets within cells.
How do phospholipids contribute to cell membranes?
Phospholipids form a bilayer with hydrophobic tails facing inwards and hydrophilic heads facing outwards, creating a barrier that regulates the entry and exit of molecules.
What is the function of cholesterol in cell membranes?
Cholesterol stabilizes and strengthens the cell membrane by making the lipid bilayer more rigid and less permeable.
What are proteins made of?
Proteins are made up of amino acids joined by peptide bonds, and their function depends on their three-dimensional structure
How do peptide bonds form between amino acids?
Peptide bonds form through a condensation reaction, where a water molecule is removed as the amino group of one amino acid bonds with the carboxyl group of another.
What are the four levels of protein structure?
Primary: The linear sequence of amino acids.
Secondary: Local folding into alpha helices or beta-pleated sheets.
Tertiary: Overall 3D shape formed by interactions between R-groups.
Quaternary: Multiple polypeptides interacting, such as in hemoglobin
What are the differences between globular and fibrous proteins?
Globular proteins: Spherical, soluble, functional (e.g., enzymes, hormones).
Fibrous proteins: Long, insoluble, structural (e.g., collagen, keratin).
What is the function of calcium ions (Ca2+) in biological systems?
Calcium ions are essential for muscle contraction, transmission of nerve impulses, blood clotting, and forming bone.
What is the role of sodium ions (Na+) in the body?
Sodium ions are involved in nerve impulse transmission, muscle contraction, and maintaining blood pressure.
How do ammonium ions (NH4+) contribute to plant growth?
Sodium ions are involved in nerve impulse transmission, muscle contraction, and maintaining blood pressure.
How do you test for reducing sugars using Benedict’s solution?
Add Benedict’s solution to the sample, heat it, and observe the color change. A positive result ranges from green to brick red, indicating the presence of reducing sugars.
What is the procedure for testing for starch using iodine?
Add iodine solution to the sample, and a positive result will turn the solution from orange/brown to blue/black, indicating the presence of starch.
What is the Emulsion test for lipids?
Mix the sample with ethanol, then add water. A positive result will show a milky white suspension, indicating the presence of lipids.
How do you test for proteins using Biuret reagent?
Add sodium hydroxide and copper sulfate (Biuret reagent) to the sample, and a color change from blue to purple indicates the presence of proteins.
What is the principle behind biosensors?
Biosensors detect chemicals by using biological molecules (like enzymes) that produce a signal, which is then converted into an electrical signal for analysis.
What is the basic principle of paper chromatography?
Paper chromatography separates mixtures by allowing them to move along a paper in a solvent. Different substances move at different rates, forming separate bands.
How do you calculate the Rf value in chromatography?
The Rf value is calculated as the distance travelled by the substance divided by the distance travelled by the solvent.
