Structures and Functions of Living Things
(Cells and Human Body)
1. cell – the basic unit of structure and function in living things.
2. microscope – an instrument that makes small objects look larger
3. cell theory- a widely accepted explanation of the relationship between cells and living things
4. organelle – a tiny cell structure that carries out a specific function within the cell
5. cell wall – a rigid layer of nonliving material that surrounds the cells of plants and come other
organisms.
6. cell membrane – a cell structure that controls which substances can enter or leave the cell
7. cytoplasm – the region between the cell membrane and the nucleus; in organisms without a nucleus,
the region located inside the cell membrane.
8. nucleus – a cell structure that contains nucleic acids, the chemical instructions that direct all the cell’s
activities.
9. chromatin – material in cells that contains DNA and carries genetic information
10. nucleolus – can be found floating in the nucleus. This is where ribosomes are made.
11. mitochondria- rod-shaped cell structures that produce most of the energy needed to carry out the
cell’s functions.
12. endoplasmic reticulum – a cell structure that forms a maze of passageways in which proteins and
other materials are carried from one part of the cell to another.
13. ribosomes – a small grain-like structure in the cytoplasm of a cell where proteins are made.
14. golgi bodies – a structure in a cell that receives proteins and other newly formed materials from the
endoplasmic reticulum, packages them, and distributes them to other parts of the cell.
15. chloroplasts – a structure in the cells of plants and some other organisms that captures energy from
sunlight and uses it to produce food.
16. vacuoles – a water-filled save inside a cell that acts as a storage area.
17. lysosomes – A small round cell structure that contains chemicals that break down large food particles
into smaller ones.
18. bacteria – a cell that is usually smaller than a plant or animal cell and does not contain a nucleus. The
only other organelles it shares with plants and animals are a cell wall, cell membrane and ribosomes.
19. prokaryote – an organism without a nucleus such as bacteria
20. eukaryote - an organism whose cells DO have a nucleus and other organelles
21. nutrient – substances in food that provide energy for an organism to carry out essential processes
22. amoeba – single celled organism with no fixed shape
23. euglena – single celled organism that can both make its own food like a plant – or consume it
24. volvox – a single celled organism that is a type of algae
25. paramecium – single celled organism found in freshwater, brackish and marine environments
26. cilia – hair-like organelles that provide movement or move fluids and particles along ducts in
multicellular forms.
27. pseudopod – part of a cell’s cytoplasm that allows for movement or food gathering. A “false foot”
28. contractile vacuole –an organelle that pumps excess water out of a cell
29. food vacuole – an organelle where food is digested
30. eye spot - a small, light-sensitive patch of pigment in certain algae and unicellular organisms
31. flagella – a long whip-like structure that acts like a little motor for movement
32. chlorophyll – the green pigment found inside a chloroplast.
33. photosynthesis –the process by which a green plant turns water and carbon dioxide into food when
the plant is exposed to light.
34. autotroph - an organism that creates its own food through photosynthesis
35. heterotroph – an organism that cannot produce its own food and must eat other organisms to survive.
36. tissue – a group of similar cells that perform a specific function in an organism
37. organ – a structure that is composed of different kinds of tissue
38. organ system – a group of organs that work together to perform a major function in the body
39. muscle tissue – a body tissue that contracts or shortens, making body parts move
40. nervous tissue – a body tissue that carries electrical messages back and forth between the brain and
every other part of the body
41. connective tissue – a body tissue that provides support for the body and connects all of its parts
42. epithelial tissue – a body tissue that covers the surfaces of the body, inside and out 43. homeostasis –
the process by which an organism’s internal environment is kept stable in spite of
changes in the external environment.
44. stress – the reaction of a person’s body to potentially threatening, challenging or disturbing events.
45. skeleton – the inner framework made of all the bones of the body
46. vertebrae – the bones that make up the backbone of an animal
47. joint – a place in the body where two bones come together
48. ligaments – strong connective tissue that holds bones together in movable joints
49. cartilage – a connective tissue that is more flexible than none and that protects the ends of bones and
keeps them from rubbing together
50. compact bone – hard, dense bone tissue that is beneath the outer membrane of a bone
51. spongy bone – layer of bone tissue having many small spaces and found just inside the layer of
compact bone
52. marrow – the soft connective tissue that fills the internal spaces in bone.
53. involuntary muscles – a muscle that is not under conscious control
54. voluntary muscles – a muscle that is under conscious control
55. skeletal muscle – a muscle that is attached to the bones of the skeleton and provides the force that
moves the bones
56. tendon – strong connective tissue that attaches muscle to bone
57. striated muscle – a muscle that appears banded; also called skeletal muscle
58. smooth muscle – involuntary muscle found inside many internal organs of the body
59. cardiac muscle – muscle tissue found only in the heart
60. digestion – the process by which the body breaks down food into small nutrient molecules
61. absorption – the process by which nutrient molecules pass through the wall of the digestive system
62. saliva – the fluid released when the mouth waters that plays an important role in both mechanical and
chemical digestion
63. enzymes – a protein that speeds up chemical reactions in the body
64. epiglottis – a flap of tissue that seals off the windpipe and prevents food from entering
65. esophagus – a muscular tube that connects the mouth to the stomach
66. mucus – a thick, slippery substance produced by the body
67. stomach – a J-shaped muscular pouch located in the abdomen
68. small intestine – the part of the digestive system in which most chemical digestion takes place
69. liver – the largest organ in the body; it plays a role in many body processes
70. gallbladder – the organ that stores bile after it is produced by the liver
71. pancreas – a triangular organ that lies between the stomach and first part of the small intestine
72. large intestine – the last section of the digestive system, where water is absorbed into the
bloodstream and the remaining material is eliminated from the body
73. rectum – the end of the large intestine where waste material is compressed into a solid form before
being eliminated
74. anus – a muscular opening at the end of the rectum through which waste material is eliminated from
the body