Chapter 1 A View of Life. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2 I. How to Define Life 1.Living

Chapter 1

A View of Life

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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I. How to Define Life1. Living things are made of units

called cells.

All living things are made of one or more cells. Cells are made of molecules that contain atoms.

Many microorganisms consist of only a single cell. Animals, plants, and fungi are almost all multi-cellular.


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2. Living Things Reproduce.

Reproduction is the ability of an organism to copy itself or make new organisms like itself.

– Bacteria, protozoans, etc. simply split into two.– Multicellular organisms may pair sperm with

egg; resulting in an immature individual, which develops to become the adult.

– Flies produce flies, dogs produce dogs, roses produce roses.


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3. Living things are based on a universal genetic code.

– Organisms develop as result of blueprint of instructions encoded in their genes.

– Genes are made of long molecules of DNA that specify how the organism is ordered.

– Mutations can occur EX Sickle cell anemia

Heredity= the passing of traits/genes from parent to offspring.


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4. Living things grow and develop. Flies begin life as eggs, then become

maggots, and then become adult flies. An oak tree begins life as an acorn in the

ground, germinates becoming a seedling, and then grows and develops into the mighty oak tree.

You started life as an embryo in the womb, were born as a young baby, and have grown into a teenager/young adult.


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5. Living Things Acquire Materials and Energy.Metabolism is the sum of all chemical reactions

that occur in a cell. Using energy!!– Ultimate source of energy for nearly all life on earth is

the sun through photosynthesis.– Using materials/food organisms obtain

(consume/absorb) from the environment or produce themselves, organisms can build molecules they put into growth and development, and this also takes energy to build something. Organisms also use/release energy when they break molecules down, this too is part of metabolism.


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6. Living Things Respond to their Environment. This ability to respond helps organism survive.– Responses to environment altogether constitute

behavior of organism. – Example: The leaves and stems of plants grow

towards light. 7. Living Things Maintain a Stable

Internal Environment. – Homeostasis:Organisms must remain homeostatic or

keep themselves stable inside their cells and tissues. Temperature, moisture level, acidity, etc. are all factors that need to be maintained by physiology and behavior. EX. Sweating, when too hot, release heat and cools you down.


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8. Taken as a group, living things change over time, they evolve

Natural selection is the mechanism by which species become modified over time.

• A species is a group of interbreeding individuals.

• In natural selection, members may inherit a genetic change that makes them better suited to a particular environment.(Darwin)

• Example: Plants that live in the desert survive because they have become adapted to the dry conditions of the desert.


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Biological OrganizationAll the same type of organisms (species)

inhabiting an area at the same time make up a population.

The populations inhabiting an area at the same time make up a community.

– A community plus its physical environment constitutes an ecosystem.

Documents

Chapter 1 A View of Life. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2 I. How to Define Life 1.Living