Characteristics of Life Exam on Thursday What Science is and is not Thinking like a scientist Science as a Way of Knowing Science and Human Values Designing

Characteristics of Life

• Exam on Thursday• What Science is and is not• Thinking like a scientist• Science as a Way of Knowing• Science and Human Values• Designing An Experiment• Publishing and Repeating Investigations• When Experiments Are Not Possible• How A theory Develops• Studying Life• Tools and Procedures• Analyzing Biological Data• Microscopes • Laboratory Techniques



• 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 for energy• Living things respond to their environment• Living things maintain a stable environment• Taken as a group, living things change over time


• Living things are made up of units called cells (multicellular or unicellular organisms)

– Cells are the smallest unit capable of sustaining life

– Cell Theory• All things are made up of cells• All cells come from cells• All cells contain a plasma membrane• All cells contain DNA


• Living things reproduce– Living things produce their own kind

– Living reproduce by two mechanisms• Sexual Reproduction

– The offspring is not identical to its two parents

• Asexual Reproduction– The offspring is identical (clone) to its one parent


• Living things are based on a universal genetic code

• DNA (deoxyribonucleic acid)– Nucleotide (A, G, T, and C)– Sugar group– Phosphate group

3’ end

Sugar-phosphatebackbone

Base pair (joined byhydrogen bonding)Old strands

Nucleotideabout to be added to a new strandA

3’ end

3’ end

5’ end

Newstrands

3’ end

5’ end

5’ end


• Living things grow and develop– Growth

• Increase in size• Replacement of dead cells

– Development• Differentiation – formation of specialized cells

(maturation)


• Living things obtain and use materials for energy– All living things need energy to survive, grow

reproduce and develop– Metabolism – the total of “breaking down”

reactions (catabolic) and “building up” reactions (anabolic) that occur in a cell

• Energy Sources– Photosynthesis– Ingesting other animals and insects (Cellular

Respiration)– Decomposed organisms (Cellular Respiration)


• Living things respond to their environment– Stimulus - a signal to which an organism

responds

• External Stimulus – light, temperature

• Internal Stimulus – glucose level


• Living things maintain a stable environment by keeping internal conditions fairly constant this process is called homeostasis– Positive feedback mechanisms

• Output of stimulus is increased– Blood clotting– Labor contractions

– Negative feedback mechanisms• Output of stimulus is decreased

– Heart rate – Blood pressure


• Taken as a group, living things change over time (evolution)– Populations change over time in response to

their environment– Those traits that are best suited for a certain

environment will be dominant in a population

The Hierarchy of Structural Organization


• Atoms – group of organisms of one type that live in the same area

• Molecules - consists of two or more atoms

• Organelles – are made up of many molecules

• Cells – are made up of organelles (some) and molecules

• Tissues – specialized cells are in a tissue


• Organs – two or more tissues make up an organ

• Organ Systems – two or more organs make up an organ system

• Organism – an individual living thing that may be composed of many organ systems (complex multicellular organisms)


• Population – group of organisms of one type that live in the same area

• Community - populations that live together in a defined area

• Ecosystem – community and its nonliving surroundings

• Biosphere – the part of the earth that contains all ecosystems (any area on the earth that can sustain life)

Documents

Characteristics of Life Exam on Thursday What Science is and is not Thinking like a scientist Science as a Way of Knowing Science and Human Values Designing