Living Things

Biology The study of life to understand the living world Biologists use the scientific method to study living things

Characteristic Examples Living things are made up of units called cells. Many microorganisms consist of only a single cell. Animals and trees are multicellular. Living things reproduce. Maple trees reproduce sexually. A hydra can reproduce asexually by budding. Living things are based on a universal genetic code. Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees. Living things grow and develop. Flies begin life as eggs, then become maggots, and then become adult flies. Living things obtain and use materials and energy. Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat. Living things respond to their environment. Leaves and stems of plants grow toward light. Living things maintain a stable internal environment. Despite changes in the temperature of the environment, a robin maintains a constant body temperature. Taken as a group, living things change over time. Plants that live in the desert survive because they have become adapted to the conditions of the desert.

Cells A collection of living matter enclosed by a barrier that separates the cell from its surroundings Smallest unit of life, but very complex and organized Unicellular organisms consist of only a single cell Plants and animals are multicellular organisms, having many cells of different sizes and shapes, and sometimes different functions

Reproduction All organisms produce new organisms Sexual reproduction = two cells from different parents unite to form the first cell of a new organism Asexual reproduction = a portion from a single parent breaks off and produces a new organism

Growth and Development Life cycles: a pattern of growth and change that occurs over the organism’s lifetime During growth, cells increase in size or number During development, cells increase in number and become different or differentiate

Energy and Materials Need energy and materials to grow, develop, reproduce and stay alive Metabolism = combination of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes Different organisms obtain energy from their surroundings in different ways

Response to Environment Every organism responds to their constantly changing environment in different ways (Ex. Responding to light, water, temperature, seasons)

The Characteristics of Life Living things are made up of units called cells. Living things reproduce. Living things are based on a universal genetic code. Living things grow and develop. Living things obtain and use materials and energy. Living things respond to their environment. Living things maintain a stable internal environment. Taken as a group, living things change over time

Levels of Organization Biology can be studied based on different branches or different levels of organization Each level is a system made up of smaller parts and may be part of a larger system. The levels include molecules, organelles, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems and the biosphere

Basic Needs of Living Things

All living things need air, water, living space and stable internal environment, food.

Internal Balance Homeostasis: the process organisms use to keep their internal conditions relatively stable Homeostasis is constantly being threatened by changes in the environment If homeostasis is disrupted in a major way, an organism cannot survive.