Laboratory Experiments on Diffusion, Photosynthesis, and Respiration

Driving force for diffusion

The difference in concentration that causes particles to move from areas of high concentration to areas of low concentration until evenly spread.

Hypertonic solutions

A solution with a higher solute concentration.

Hypotonic solutions

A solution that has a lower solute concentration than inside of a cell.

Isotonic solutions

A surrounding solution around a cell that has the same solute concentration as inside of the cell.

Effect of 9.0% NaCl on plant cells

Plant cells will shrink and pull away from their walls.

Effect of water on plant cells

Plant cells will swell but stay firm because of their cell walls.

Molecular weight and diffusion

Lighter molecules move more quickly and easily, while heavier molecules move more slowly and take longer to diffuse.

Central vacuole

Organelle that stores solutes to drive osmosis in plant cells.

Semi-permeable membrane

Any barrier that permits diffusion of some molecules but prevents diffusion based on criteria such as size or charge.

Lysis

Bursting of a cell due to the net diffusion of water into the cell.

Crenation

Loss of water that results in this happening to an animal cell.

Concentration gradient

A difference in the amount of solutes between two areas.

Turgor pressure

Net outward force on plant cell walls due to the diffusion of water into the cytoplasm, contributing to how plants maintain their upright position.

Osmosis

The net movement of water down the concentration gradient.

Plasmolysis

The loss of turgor pressure in a cell where the membrane does not collapse and is reversible within a certain amount of time.

Cell wall

A tough outer layer that provides support and protection to plant cells.

Cell membrane

Inside the cell wall, it controls what enters and leaves the cell.

Chloroplast

Organelles that contain chlorophyll for photosynthesis, allowing the plant to make its food.

Vacuole

A large fluid-filled space that stores water, nutrients, and waste.

Cytoplasm

A jelly-like substance inside the cell where cell activities occur.

Mesophyll

The inner tissue where photosynthesis occurs, containing many chloroplasts.

Palisade layer

Column-shaped cells near the top of the leaf that capture sunlight.

Spongy layer

Loosely arranged cells at the bottom of the leaf that allow gas exchange.

Stomata

Small openings on the underside of the leaf that let in carbon dioxide and release oxygen.

Independent variable

Variable that is altered to test for an effect on the dependent variable.

Dependent variable

Variable that is measured during an experiment to determine if a process is affected by a changed condition.

Light intensity and photosynthesis

Low light intensity results in slow photosynthesis, high light intensity increases the rate, and darkness stops photosynthesis while respiration occurs.

Chlorophyll a

Primary photosynthesis pigment.

Chlorophyll B

Accessory pigment that is green and is found in the light-harvesting complex.

Thylakoid membranes

Phospholipid bilayer that is the location of photosystems within chloroplasts.

Carotenoid

Accessory pigment that is orange-yellow and absorbs excess light.

Xanthophyll

An accessory pigment that is yellow and is found in the light-harvesting complex.

Stages of cellular respiration

Glycolysis breaks down glucose into pyruvate, the citric acid cycle releases carbon dioxide and generates ATP, and the electron transport chain produces a large amount of ATP.

Germinating peas

They have a high metabolic rate because they are actively growing and use stored energy for rapid cell division and growth.

Adult plants

Their metabolic rate is generally lower than germinating peas, focusing on maintenance and growth rather than rapid development.

Animal respiration rate

Generally high because they need a constant supply of energy for movement, growth, and maintaining body temperature.

Plant respiration rate

Respire at a lower rate than animals, especially during the day when performing photosynthesis, with increased respiration at night.

Yeast respiration

Respire anaerobically in low oxygen conditions producing ethanol and carbon dioxide, while under aerobic conditions their respiration rate is similar to that of animals.

Heat and cellular respiration

An increase in temperature can speed up metabolic reactions, including cellular respiration, but beyond an optimal range enzymes will denature.

Oxygen

Final electron acceptor in the electron transport chain of mitochondria.

Glucose

Preferred reactant for cellular respiration, a monosaccharide.

CO2

Product of cellular respiration, and what we measured during this experiment.

Pyruvate oxidation

Phase of cellular respiration that generates NADH but no ATP.

Acetyl-CoA formation

Phase of cellular respiration that generates carbon dioxide.

Aerobic

Any chemical reaction that requires oxygen to occur.

Mitochondria

Organelle that is necessary for aerobic cellular respiration.

Tenebrio molitor

Scientific name for mealworms.

FADH2

Cofactor electron carriers generated by pyruvate oxidation, glycolysis, and during the Krebs cycle.

NADH

Cofactor electron carriers only produced during the citric acid cycle.

Sodium dodecyl sulfate

Detergent molecule that helps disrupt plasma membranes.

Sybr green

DNA stain that glows in response to specific colors of light.

Histones

Proteins that help organize DNA double helixes.

Ethanol (95%)

A solution that is used to precipitate DNA.

Loading buffer

A dye solution added to PCR DNA samples to make them heavier and easy to see when added to a gel.

TBE

Clear conductive running buffer for gel electrophoresis.

STR

Repeated blocks of nucleotides that occur randomly in genomes, used for DNA fingerprinting.

Agarose

Seaweed-derived sugar that forms the matrix of DNA gels.

Gel electrophoresis

A technique used to separate DNA fragments by size.

DNA fingerprinting

General field of study/forensics that uses differences in DNA to compare individuals.

Negative charge of DNA

This is the charge of DNA in solution.

Positive charge

This charged electrode attracts DNA.

Polymerase chain reaction

Reaction used to copy DNA for further experiments.

Primers

Small pieces of nucleic acids (20-25 base pairs) used to direct where DNA replication occurs in PCR.

Taq polymerase

Enzyme used in PCR isolated from thermal hot springs bacteria.