| A | B |
|---|
| AIDS | the disease that results when the HIV virus attacks the human immune system |
| antibody | a protein, produced by the immune system, that either attacks invading pathogens or marks them for killing |
| allergy | a condition in which a person's immune system is overly sensitive to environmental substances that are normally harmless |
| antigen | a molecule found on the outer surfaces of cells that the immune system recognizes as either part of the body or as an outside invader |
| ATP | an organic compound that stores respiratory energy in the form of chemical bond energy for transport from one part of the cell to another |
| bacteria | any one of many single-celled organisms without a distinct nucleus, prokaryotes |
| catalyst | a substance that can speed up the rate of a chemical reaction without being changed or used up during the reaction |
| cellular respiration | the process in which nutrients are broken apart, releasing the chemical energy in them |
| chloroplast | the green organelle that contains chlorophyll; site of photosynthesis |
| disease | a condition, other than injury, that prevents the body from working as it should |
| dynamic equilibrium | the constant small corrections that normally occur to keep an organism's internal environment within the limits needed for survival |
| enzyme | proteins that speed up the rate of chemical reactions in living things, organic catalysts |
| feedback mechanism | a cycle in which the output of a system either modifies or reinforces the first action taken by the system |
| fungi | the kingdom of organisms that are mostly multicellular, have cell walls made of chitin, and are heterotrophic |
| gas exchange | the process of obtaining oxygen from the environment and releasing carbon dioxide |
| glucose | a sugar that is a major source of energy for cells |
| guard cells | specialized cells that control the opening and closing of the pores on the surface of a leaf |
| homeostasis | the ability of an organism to maintain a stable internal environment even when the external environment changes |
| immune system | the body's primary defense against disease-causing pathogens |
| insulin | a hormone that prompts glucose to move from the blood into body cells, resulting in a lower glucose level in the blood |
| microbe | any microscopic organism |
| mitochondria | pod-shaped organelles that contain enzymes used to extract energy from nutrients, site of cellular respiration, "powerhouse of the cell" |
| pancreas | an endocrine organ that secretes insulin |
| parasite | an organism that survives by living and feeding on other organisms |
| pathogen | an organism that invades the body, causing disease |
| pH | a measure of whether a substance is acidic, neutral, or basic |
| photosynthesis | the process by which some organisms are able to capture light energy and use it to make food from carbon dioxide and water |
| respiration | the process by which chemical bond energy stored in nutrients is released for use in cells |
| stimulus | any change in the environment that causes an organism to react |
| synthesis | a life process that involves combining simple substances into more complex substances |
| vaccine | a substance made of weakened, killed, or partial pathogens and designed to protect the body from future invasions of the pathogen |
| virus | a nonliving particle of protein and genetic material that reproduces by invading the cell of a living organism |
