Exam 2 Bio

Cell

A basic unit of life that performs various functions, such as movement, energy processing, and production of products.

Plasma membrane

A barrier that surrounds the cell and controls the movement of substances in and out of the cell.

Energy

The capacity to cause change.

Kinetic energy

The energy of motion.

Potential energy

Stored energy that an object has because of its location or structure.

Conservation of energy

The principle that energy cannot be created or destroyed, only converted from one form to another.

Heat

A type of kinetic energy contained in the random motion of atoms and molecules.

Entropy

A measure of disorder or randomness in a system.

Chemical energy

Potential energy stored in the arrangement of atoms in molecules, which can be released by a chemical reaction.

ATP (adenosine triphosphate)

A molecule that acts as an energy shuttle, storing and releasing energy for cellular work.

Enzyme

A protein that speeds up chemical reactions without being consumed by the reaction.

Activation energy

The energy required to start a chemical reaction.

Substrate

A specific reactant molecule that an enzyme acts upon.

Enzyme inhibitors

Molecules that bind to an enzyme and disrupt its function, altering its shape.

Membrane proteins

Proteins embedded in the plasma membrane that perform various functions in regulating the flow of materials to and from the cell.

Membrane Proteins

Proteins that are embedded in or associated with the cell membrane and perform various functions.

Diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration.

Passive Transport

The movement of substances across a membrane without the input of energy.

Concentration Gradient

The difference in concentration of a substance between two areas.

Facilitated Diffusion

The assisted transport of molecules across a membrane through protein channels.

Osmosis

The diffusion of water across a selectively permeable membrane.

Solute

A substance that is dissolved in a liquid solvent to form a solution.

Hypertonic Solution

A solution with a higher concentration of solute compared to another solution.

Hypotonic Solution

A solution with a lower concentration of solute compared to another solution.

Isotonic Solution

A solution with an equal concentration of solute compared to another solution.

Osmoregulation

The control of water balance in an organism.

Active Transport

The movement of molecules across a membrane that requires the expenditure of energy.

ATP

Adenosine triphosphate, a molecule that provides energy for cellular processes.

Exocytosis

The process of releasing materials from a cell by fusing vesicles with the plasma membrane.

Endocytosis

The process of taking in materials into a cell by forming vesicles that bud inward.

Phagocytosis

A type of endocytosis where a cell engulfs a particle and forms a food vacuole.

Autotrophs

Organisms that can produce their own organic matter from inorganic nutrients.

Heterotrophs

Organisms that cannot produce organic molecules from inorganic ones and rely on consuming other organisms for food.

Photosynthesis

The process by which plants convert sunlight energy into chemical energy in the form of sugars and other organic molecules.

Producers

Plants and other autotrophs that produce organic matter through photosynthesis.

Consumers

Heterotrophs that obtain their food by eating plants or other animals.

Cellular Respiration

The process by which cells harvest energy from food molecules and convert it into ATP, the main energy currency of cells.

ATP

Adenosine triphosphate, a molecule that stores and releases energy for cellular processes.

Mitochondria

Organelles where cellular respiration occurs and ATP is produced.

Glycolysis

The first stage of cellular respiration, in which glucose is split into two molecules of pyruvic acid.

Citric Acid Cycle

Also known as the Krebs cycle, the second stage of cellular respiration, where pyruvic acid is further broken down to release energy.

Electron Transport Chain

The third stage of cellular respiration, where high-energy electrons from NADH are used to generate ATP.

Oxygen

A gas required for cellular respiration, taken in by cells and used in the electron transport chain.

Carbon Dioxide

A waste product of cellular respiration, released by cells into the environment.

Energy Flow

The transfer of energy from the sun to producers and then to consumers in an ecosystem.

Chemical Cycling

The recycling of nutrients and organic molecules between producers and consumers in an ecosystem.

Glycolysis

The first stage of cellular respiration, in which glucose is broken down into pyruvic acid, producing ATP and NADH.

NADH

Nicotinamide adenine dinucleotide, a coenzyme that carries high-energy electrons during cellular respiration.

ATP

Adenosine triphosphate, a molecule that stores and releases energy for cellular processes.

Pyruvic acid

A three-carbon molecule produced during glycolysis.

Citric acid cycle

The second stage of cellular respiration, in which acetic acid molecules are broken down to produce ATP, NADH, and FADH2.

Acetyl CoA

A molecule formed from pyruvic acid that enters the citric acid cycle.

NAD+

Nicotinamide adenine dinucleotide, a coenzyme that accepts electrons during cellular respiration.

FAD

Flavin adenine dinucleotide, a coenzyme that accepts electrons during cellular respiration.

Electron transport chain

A series of electron carrier molecules that transfer electrons and generate ATP during cellular respiration.

ATP synthase

An enzyme complex that produces ATP by utilizing the energy from the flow of protons across the inner mitochondrial membrane.

Fermentation

An anaerobic process that allows cells to produce ATP without oxygen, relying on glycolysis.

Fermentation

The process by which cells produce energy in the absence of oxygen, resulting in the production of lactic acid or ethyl alcohol.

Glycolysis

The first step in cellular respiration, in which glucose is broken down into pyruvic acid, producing a small amount of ATP and NADH.

NADH

A molecule that carries high-energy electrons produced during glycolysis and the Krebs cycle, which can be used to generate ATP.

Lactic acid

A waste product produced during fermentation in human muscle cells when NADH donates electrons to pyruvic acid.

Anaerobic conditions

Conditions in which there is a lack of oxygen.

Pyruvic acid

A three-carbon molecule produced during glycolysis that can be further broken down in the presence of oxygen or converted to lactic acid in the absence of oxygen.

Photosynthesis

The process used by plants, algae, and certain bacteria to transform light energy into chemical energy, using carbon dioxide and water as starting materials and releasing oxygen gas as a by-product.

Autotrophs

Organisms that generate their own organic matter from inorganic ingredients, such as plants and other organisms that perform photosynthesis.

Photoautotrophs

Organisms, like plants, that generate their own organic matter through photosynthesis and serve as the producers for most ecosystems.

Chloroplasts

Light-absorbing organelles found mostly in the interior cells of leaves, where photosynthesis takes place.

Stomata

Tiny pores in leaves where carbon dioxide enters and oxygen exits during photosynthesis.

Grana

Stacks of interconnected membranous sacs called thylakoids, where chlorophyll molecules that capture light energy are built into the chloroplast membranes.

Carbon fixation

The initial incorporation of carbon from the atmosphere into organic compounds, reducing the concentration of carbon dioxide in the atmosphere.

Electromagnetic spectrum

The full range of radiation, including sunlight, which travels through space as rhythmic waves with different wavelengths.

Wavelength

The distance between the crests of two adjacent waves, which determines the color of light.

Chloroplast pigments

Molecules, such as chlorophyll, that selectively absorb light energy during photosynthesis.

Chlorophyll a

A pigment in chloroplasts that participates directly in light reactions and absorbs mainly blue-violet and red light.

Chlorophyll b

A pigment in chloroplasts that does not participate directly in light reactions, but conveys absorbed energy to chlorophyll a.

Carotenoids

A family of yellow-orange pigments in chloroplasts that absorb mainly blue-green light.

Photons

Discrete packets of energy that make up light waves.

Excited electron

An electron in a pigment molecule that gains energy after absorbing a photon.

Ground state

The normal, stable state of an electron after it loses its excess energy.

Fluorescence

The emission of light by a pigment molecule after absorbing photons.

Photosystems

Clusters of pigment molecules, including chlorophylls a and b and carotenoids, organized in the thylakoid membrane that function as light-gathering antennas.

Thylakoid membrane

The membrane in chloroplasts where the light reactions of photosynthesis occur.

ATP

Adenosine triphosphate, a molecule that stores and provides energy for cellular processes.

NADPH

Nicotinamide adenine dinucleotide phosphate, a molecule that carries high-energy electrons for use in the Calvin cycle.

Calvin cycle

The series of reactions in photosynthesis that uses ATP, NADPH, and carbon dioxide to produce sugar molecules.