chem and bio p1 Flashcards

Enzymes are biological catalysts that speed up chemical reactions. They have an active site with a specific shape that binds to a substrate, forming an enzyme-substrate complex. The reaction occurs, and the products are released. Enzymes are specific to their substrate due to the lock-and-key mechanism.

Set up a water bath at a constant temperature. Add amylase, starch, and buffer solution of a specific pH to a test tube. Start a timer and take samples at regular intervals. Test samples with iodine solution to check for starch presence. Record the time taken for starch to be completely broken down. Repeat with different pH values.

Ionic bonding occurs between metals and non-metals. Metals lose electrons to form positive ions, while non-metals gain electrons to form negative ions. The oppositely charged ions are held together by strong electrostatic forces of attraction, forming a lattice structure.

The graph shows reaction rate increasing with temperature up to the optimum temperature, where the rate is highest. Beyond the optimum, the rate decreases sharply as enzymes denature. Denaturation occurs because high temperatures break bonds in the enzyme's structure, altering the active site shape.

Photosynthesis occurs in chloroplasts of plant cells. Light energy is absorbed by chlorophyll and used to convert carbon dioxide and water into glucose and oxygen. The reaction is endothermic, requiring energy from sunlight.

Cut potato cylinders of equal size and measure their initial mass. Place them in solutions of different concentrations of sugar or salt. Leave for a set time, then remove, dry, and measure their final mass. Calculate percentage change in mass to determine osmosis.

Fractional distillation separates mixtures of liquids with different boiling points. The mixture is heated, and the liquid with the lowest boiling point evaporates first. Vapours rise up the fractionating column, cool, and condense at different levels. Each fraction is collected separately.

Measure a set volume of reactants and place them in a polystyrene cup. Record the initial temperature using a thermometer. Add the second reactant and stir. Record the highest or lowest temperature reached. Calculate the temperature change to determine energy transfer.

Diffusion is the movement of particles from an area of high concentration to an area of low concentration. It occurs down a concentration gradient and does not require energy. Examples include oxygen diffusing into cells for respiration.

Mitosis is a type of cell division that produces two identical daughter cells. It involves stages: prophase, metaphase, anaphase, and telophase. Chromosomes are copied, line up at the equator, are pulled apart, and the cell divides.

Covalent bonding occurs between non-metals. Atoms share pairs of electrons to achieve a full outer shell. The shared electrons form strong bonds, creating molecules. Examples include water (H₂O) and oxygen (O₂).

The graph shows reaction rate increasing as pH approaches the enzyme's optimum pH. At the optimum, the rate is highest. Beyond the optimum, the rate decreases as the enzyme's active site is altered, reducing its ability to bind to the substrate.

Active transport moves substances from a low concentration to a high concentration against the concentration gradient. It requires energy from respiration and uses carrier proteins in the cell membrane. Examples include mineral ions absorbed by plant roots.

Draw a pencil line near the bottom of chromatography paper. Place a small spot of the mixture on the line. Dip the paper into a solvent, ensuring the spot is above the solvent level. Allow the solvent to travel up the paper, separating the components. Measure the distance travelled by each component and calculate Rf values.

At low temperatures, enzyme activity is slow because particles have less kinetic energy, resulting in fewer collisions between enzymes and substrates. As temperature increases, activity rises due to more frequent collisions. At the optimum temperature, enzyme activity is at its peak. Beyond the optimum, enzymes denature as high temperatures break bonds in their structure, altering the active site shape and preventing substrate binding.

During electrolysis, an electric current is passed through a molten ionic compound. Positive metal ions move to the cathode, where they gain electrons (reduction). Negative non-metal ions move to the anode, where they lose electrons (oxidation). This separates the compound into its elements. For example, electrolysis of molten lead bromide produces lead at the cathode and bromine at the anode.

Enzyme has an optimum pH (7) Deviations change hydrogen/ionic bonds Active site shape changes Substrate no longer complementary Fewer enzyme-substrate complexes form Rate decreases

Particles gain kinetic energy Move faster More frequent collisions Faster net movement down concentration gradient

Benedict’s solution not heated Temperature too low Insufficient time Reagents incorrect/expired Low concentration of sugar

More surface for exchange Shorter diffusion distance Faster movement of substances in/out Meets cell demand more efficiently

Cathode: hydrogen (less reactive than sodium) Anode: chlorine (halide ions discharged) Due to reactivity and ion concentration