chapter 2 it’s alive!! or is it? preview · 2014. 8. 20. · chapter 2 section 2 the necessities...

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Section 1 Characteristics of Living Things

Section 2 The Necessities of Life

Chapter 2 It’s Alive!! Or Is It?

Concept Mapping


Section 1 Characteristics of

Living Things

Bellringer

What are four living and nonliving things that you

interact with every day? How do you know whether

each is living or nonliving? Do you know what the

word inanimate means? If so, write out a definition.

Does nonliving mean the same thing as dead?

Explain your answer.

Write your answers in your science journal.

Chapter 2



Living Things

Objectives

• Describe the six characteristics of of living things.

• Describe how organisms maintain stable internal

conditions.

• Explain how asexual reproduction differs from sexual

reproduction.

Chapter 2



Living Things

Living Things Have Cells

• All living things are composed of one or more cells.

• A cell is a membrane-covered structure that

contains all of the materials necessary for life.

• Some organisms are made up of only one cell and

some are made up of trillions of cells. In an organism

with many cells, different kinds of cells perform

specialized functions.

Chapter 2



Living Things

Living Things Sense and Respond to Change

• A stimulus is anything that causes a reaction or

change in an organism or any part of an organism.

• Homeostasis is the maintenance of a stable

internal environment.

• Responding to External Change Organisms must

respond to change in the external environment in

order to maintain their homeostasis.

Chapter 2



Living Things

Living Things Reproduce

• Organisms make other organisms similar to

themselves.

• In sexual reproduction, two parents produce

offspring that will share characteristics of both

parents.

• In asexual reproduction, a single parent produces

offspring that are identical to the parent.

Chapter 2



Living Things Chapter 2

Living Things Have DNA

• The cells of all living things contain the molecule

deoxyribonucleic acid, or DNA.

•DNA controls the structure and function of cells.

•The passing of traits through DNA is called heredity.



Living Things

Living Things Use Energy

Chapter 2

• Organisms use energy to carry out the activities

of life.

• An organism’s metabolism is the total of all of

the chemical activities that the organism performs.



Living Things

Living Things Grow and Develop

• All living things, whether they are made of one cell

or many cells, grow during periods of their lives.

• Living things may develop and change as they grow.

Chapter 2



Bellringer

What do you think your mass would be if there were

no water in your body? What else besides water is

your body composed of? Where do you think you get

the minerals that make up your body mass?

Record your answers in your science journal.

Chapter 2



Objectives

• Explain why organisms need food, water, air, and

living space.

• Describe the chemical building blocks of cells.

Chapter 2



Water

• Your cells and the cells of almost all living organisms

are approximately 70% water. Most of the chemical

reactions involved in metabolism require water.

Chapter 2

Air

• Air is a mixture of several different gases, including

oxygen and carbon dioxide. Most living things use

oxygen in the chemical process that releases energy

from food.



A Place to Live

• All organisms need a place to live that contains all

of the things they need to survive. Space on Earth is

limited, so organisms are often in competition with

each other.

Chapter 2

Food

• All living things need food. Food gives organism

energy and the raw material needed to carry on life

processes.


Section 2 The Necessities of Life Chapter 2

Food, continued

• Making Food Some organisms, such as plants, are

called producers. Producers can make their own food

by using energy from their surroundings.

• Taking Food Other organisms are called

consumers because they must eat (consume) other

organisms to get food. Decomposers are consumers

that get their food by breaking down the nutrients in

dead organisms or animal wastes.



Comparing Consumers and Producers

Chapter 2

Click below to watch the Visual Concept.



Putting It All Together

• All organisms need to break down that food in order

to use the nutrients in it.

• Nutrients are made up of molecules.

• Molecules found in living things are usually made up

of six elements: carbon, hydrogen, nitrogen, oxygen,

phosphorus, and sulfur.

Chapter 2



Proteins

• Proteins are large molecules made up of amino

acids.

•Making Proteins Organisms break down the

proteins in food to supply their cells with amino acids

that are then linked together to form new proteins.

• Proteins in Action Some proteins form structures

that are easy to see. Other proteins help cells do their

jobs. Proteins called enzymes start or speed up

chemical reactions in cells.

Chapter 2



Carbohydrates

• Molecules made of sugars are called carbohydrates.

•Simple Carbohydrates Simple carbohydrates are

made up of one sugar molecule or a few sugar

molecules linked together.

• Complex Carbohydrates Complex carbohydrates

are made of hundreds of sugar molecules linked

together. Organisms store extra sugar as complex

carbohydrates.

Chapter 2



Lipids

• Lipids are compounds that cannot mix with water.

•Phospholipids are the molecules that form much of

the cell membrane.

• Fats and Oils Fats and oils are lipids that store

energy. When an organism has used up most of its

carbohydrates, it can get energy from these lipids.

Chapter 2



ATP

• Adenosine triphosphate, or ATP, is the major energy-

carrying molecule in cells.

• The energy in carbohydrates and lipids must first be

transferred to ATP, which then provides fuel for cellular

activities.

Chapter 2



Nucleic Acids

• Nucleic acids are large molecules made up of

subunits called nucleotides.

• Nucleic acids are sometimes called the blueprints of

life because they have all the information needed for

a cell to make proteins.

• DNA is a nucleic acid.



Nucleic Acid

Chapter 2

Click below to watch the Visual Concept.

Visual Concept

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It’s Alive!! Or Is It?

Concept Mapping

Use the terms below to complete the concept map on

the next slide.

Chapter 2

DNA

sugars

energy

enzymes

living cells

proteins

starches

carbohydrates


Chapter 2 It’s Alive!! Or Is It?

chapter 2 it’s alive!! or is it? preview · 2014. 8. 20. · chapter 2 section 2 the necessities...

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