ch 1-5 - Biology 1001 Hrincivich I. Chapter 1-An...

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Biology 1001 Hrincivich I. Chapter 1—An introduction to Life on Earth a. Characteristics of Living Things i. Complex, organized structure 1. Mostly organic molecules 2. Life on Earth consists of a hierarchy of structures a. Each level is based on the one below it b. Provides the foundation for the one above it 3. Life is built on a chemical foundation of elements a. An atom is the smallest particle of an element that retains properties of that element b. Molecules of life are called organic molecules c. All cells contain genes units of heredity that provide the information needed to control the life of the cell i. Subcellular structures are called organelles use the info in the genes to keep the cell alive ii. Plasma membrane is a thin sheet surrounding the cell that both holds the cytoplasm and separates the cell from the outside world 1. Related cells combine to form tissues 2. Tissues combine to form organs 3. Organs combine to form organ systems 4. Organ systems combine to form an organism iii. Species population community ecosystem biosphere ii. Respond to stimuli from their environment 1. Animals have evolved elaborate sensory organs and muscular systems
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a. Internal stimuli are perceived by receptors b. External stimuli are things such as which objects to eat iii. Actively maintain their complex structure and internal environment 1. A process called homeostasis a. Regulate body temperature iv. Acquire and use materials and energy from their environment and convert them into different forms 1. Acquire the atoms and molecules they need from air, water, soil, and other living things a. Called nutrients b. Extracted from the environment and incorporated into the molecules of the organism’s body i. The sum of all of the chemical reactions needed to sustain an organism’s life is called its metabolism 2. Organisms obtain energy in one of two basic ways a. Plants use photosynthesis b. Other living organisms consume energy-rich molecules from the bodies of other organisms c. Converted into a form that the organisms can use or store for future use v. They grow and reproduce themselves using DNA 1. Involves the conversion of materials acquired from the environment into the specific molecules of the organism’s body 2. Produce variable offspring 3. Contain their hereditary information within a molecule called deoxyribonucleic acid or DNA a. Mutations produce variety vi. Have the capacity to evolve
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1. Mutations and variable offspring create diversity in the genetic material of a species (they evolve) a. Evolution states that modern organisms descended from preexisting life-forms i. Ultimately all forms of life share a common ancestor b. The most important force in evolution is natural selection i. Process by which organisms with adaptations survive and reproduce more successfully than do others without those traits ii. These traits from genetic mutation are passed on to the next
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ch 1-5 - Biology 1001 Hrincivich I. Chapter 1-An...

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