UNIT 2 -- char of living things

Homeostasis

A stable internal environment.

Failure to Maintain Homeostasis

Results in sickness or death.

Metabolism

The sum of all the chemical reactions that occur within the cells of an organism.

Nutrition

Using nutrients for growth, synthesis, repair, and energy.

Autotrophs

Take inorganic materials ($CO_2$, $H_2O$) and convert them into organic nutrients (glucose).

Heterotrophs

Must consume other organisms for nutrients.

Photosynthesis

Process of taking radiant energy from the sun and converting it into chemical energy (organic molecules/glucose).

Chloroplast

The organelle where photosynthesis takes place.

Stomates

Microscopic holes on the underside of leaves that allow for gas exchange ($CO_2$ in, $O_2$ and water vapor out).

Guard Cells

Cells that open and close the stomates to prevent water loss and maintain homeostasis.

Respiration

Process of releasing chemical energy stored in nutrients (glucose) to produce ATP.

Mitochondria

The organelle where aerobic respiration takes place.

Aerobic Respiration

Requires oxygen and yields more ATP per glucose molecule than anaerobic respiration.

Anaerobic Respiration

Does not require oxygen and yields less ATP per glucose molecule.

Synthesis

Combining simple molecules to form more complex molecules (ex: amino acids joined to make a protein).

Transport

The absorption and distribution of materials within an organism.

Diffusion

Passive transport where molecules move from an area of high concentration to an area of low concentration without using energy.

Active Transport

Movement of molecules from an area of low concentration to an area of high concentration, which requires energy (ATP).

Osmosis

The diffusion of water.

Excretion

The removal of metabolic wastes (toxic materials made inside the body, ex: urea, $CO_2$, salt).

Egestion

The removal of undigested waste (feces); this is not metabolic waste.

Regulation

The coordination and control of all life activities.

Stimulus

A change in the environment that an organism responds to.

Neuron

A nerve cell that transmits electrochemical impulses.

Neurotransmitter

A chemical released by a neuron to transmit signals across a synapse to another cell.

Hormone

A chemical messenger secreted by endocrine glands into the blood to target specific cells.

Receptor Molecules

Specifically shaped proteins on the cell membrane that receive chemical signals (hormones or neurotransmitters).

CHON

The four most common elements in living things: Carbon, Hydrogen, Oxygen, and Nitrogen.

Organic Compounds

Molecules that contain both Carbon and Hydrogen (ex: Glucose - $C_6H_{12}O_6$).

Inorganic Compounds

Molecules that do not contain both Carbon and Hydrogen (ex: Water - $H_2O$, Carbon Dioxide - $CO_2$).

Carbohydrates

Organic compounds made of simple sugars (like glucose) that provide energy.

Lipids

Organic compounds made of fatty acids and glycerol that store energy and make up cell membranes.

Proteins

Organic compounds made of amino acids whose specific shape determines their function.

Enzymes

Biological catalysts made of protein that speed up chemical reactions using a lock-and-key fit.

Denaturation

The process where high temperatures or extreme pH change the shape of an enzyme, causing it to lose its function.

pH Scale

A scale from 0-14 that measures the acidity of a solution; 0-6 is acid, 7 is neutral, 8-14 is basic.

Cell Theory

1) All living things are made of one or more cells. 2) Cells are the basic unit of structure and function in living things. 3) All cells come from preexisting cells.

Cell Membrane

A selectively permeable barrier made of lipids and proteins that controls what enters and leaves the cell.

Cell Wall

A rigid outer layer found in plants, fungi, and bacteria that provides structure and support.

Nucleus

The organelle that contains DNA and controls the cell’s activities.

Ribosome

The organelle where protein synthesis occurs.

Vacuole

The organelle used for storage of water, wastes, and nutrients.

Cytoplasm

The fluid-like substance that fills the cell and holds organelles.

Kingdoms

Large groups used to classify organisms based on evolutionary history (ex: plants, animals, fungi, protists, eubacteria, archaebacteria).

Species

The most specific classification level; organisms of the same species can mate and produce fertile offspring.

Scientific Name

The genus and species name of an organism (ex: Homo sapiens).