CHARACTERISTICS OF LIVING THINGS LIVING THINGS HAVE CELLS
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CHARACTERISTICS OF LIVING THINGS
LIVING THINGS HAVE CELLS • Cell: a membrane-covered structure that contains all of the materials necessary for life. • Too small to be seen w/naked eye. • Multicellular---organisms made of many cells • Unicellular---organisms made of only one cell---different parts of cell perform different functions.
LIVING THINGS SENSE & RESPOND TO CHANGE • Stimulus: a change that affects the activity of an organism. • Response: How an organisms reacts to a change • Example: Eye is exposed to light (stimulus) and the pupils become smaller (response). • Homeostasis: Maintenance of a stable internal environment. • Outside environment may change; inside stays the same.
LIVING THINGS SENSE & RESPOND TO CHANGE (continued) Responding to external changes…. . Body maintains an internal temperature. Hot—body sweats! Cold—muscles twitch to warm you! (aka, “shivering”) • Other animals have to control their body temp by moving from one environment to another. • •
LIVING THINGS REPRODUCE • Sexual reproduction: – 2 parents – produce offspring that share characteristics of both parents. – Offspring do not look exactly like parents. • Most animals/plants reproduce this way. • Asexual reproduction: – single parent – produces offspring that are identical to the parent. • Most single-celled organisms reproduce this way. (Ex: hydra—forms buds that break off and grow into new individuals. )
LIVING THINGS HAVE DNA • Deoxyribonucleic acid (DNA) • Controls structure & function of cells • Organisms reproduce—pass off copies of their DNA to their offspring • Heredity: passing of traits from one generation to the next.
LIVING THINGS USE ENERGY • Living organisms need energy to grow, develop, repair damage, and reproduce • Metabolism: total of all of the chemical activities that an organism performs.
Growth means to get bigger in size
Development involves a change in the physical form or physiological make-up of an organism
Adaptation üA process that enables organisms to become better suited to their environment ü Species obtain adaptations through evolution over great periods of time
An Example of Adaptation Desert plants have succulent waxy leaves and stems to store water and reduce water loss