Chapter: Life's Structure and Classification

Table of ContentsTable of Contents

Section 1: Living Things

Section 2: How are living things classified?

A. What are living things like?1. Any living thing is called an organism.

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2. Organisms vary in size—from the microscopic bacteria in mud puddles to gigantic oak trees— and are found justabout everywhere.

A. What are living things like?11Living ThingsLiving Things

3. All organisms have some features in common. These features include cells, the ability to grow reproduce, and a need for energy.

B. Living Things Are Organized1. All living things are made of cells, smallest

unit of an organism that carries on the functions of life.

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2.Some organisms are composed of just one cell while others are composed of many cells.

3. Each cell has an orderly structure and contains the instructions for cellular organization and function in its hereditary material.

C. Living Things Grow and Develop1. Growth of a many-celled organism, such as a

human, is mostly due to an increase in the number of cells.

2.In one-cell organisms, growth is due to an increase in the size of cell.

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C. Living Things Grow and Develop

3. Organisms change as they grow. All of the changes that take place during the life of an organism is called development.

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C. Living Things Grow and Develop4. The length of time an

organism is expected to live is its life span.

5. Some organisms have a short life span. Others have a much longer life span.

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6. Some bristlecone pine trees have been alive for more than 4,600 years but a mayfly lives only one day.

D. Living Things Respond1. Living things must interact with their

surroundings. Anything that causes some change in an organism is a stimulus.

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2. All living things interact with their surroundings and respond to stimuli. Often, a response results in movement.

3. An organism must respond to stimuli to carry on its daily activities and to survive.

D. Living Things Respond4. All living things maintain homeostasis, the

regulation of an organism’s internal, life-maintaining condition despite changes in its environment.

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5. Homeostasis is a trait of all living things.

E. Living Things Use Energy1. All living things use energy. The energy used

by most organisms comes either directly or indirectly from the Sun.

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2. Plants and some other organisms use the Sun’s energy, carbon dioxide, and water to make food.

E. Living Things Use Energy3. Organisms that do not get

energy directly from the Sun must take in oxygen in order to release the energy in foods.

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4.Some bacteria can’t use the Sun’s energy to produce food; instead, the bacteria use energy stored in some chemical compounds and carbon dioxide to make food.

F. Living Things Reproduce1. All living things reproduce to make more of

their own kind.

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2. Some bacteria reproduce every 20 minutes, while it might take a pine tree two years to produce seeds.

3. Without reproduction, living things would not exist to replace those individuals that die.

G. What do living things need?

1. All living things need a place to live, water, and food source to survive.

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11Section CheckSection Check

Question 1

A _______ is the smallest unit of an organism that carries on the functions of life.

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Question 2

Any living thing is called a(n) _______.

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Question 3

Which is the smallest unit of an organism that can carry on life functions?

A. cellB. organC. organ systemD. tissue

End of Chapter Summary File