Life Science Chapter 2 Characteristics of Life. Bellwork Think and write about the parts of the test you had difficulty with.

Life Science

Chapter 2Characteristics of Life

Bellwork

• Think and write about the parts of the test you had difficulty with.

Early Science

• Spontaneous generation:• Early scientists believed that living things could develop

from non-living matter

Francesco Redi

• In the 17th century, Francesco conducted an experiment that disproved the theory of spontaneous generation

Louis Pasteur

• Following the invention of the microscope, scientists began to see the sudden appearance of “live beasts” on spoiled or decaying food.

• The theory of spontaneous generation was reignited.

Louis Pasteur

• Pasteur conducted an experiment to prove the these “live beasts” were not spontaneous, but travelled through the air and onto other organisms where they begin to grow.

“Life is a germ, and a germ is life”

• Pasteur’s experiment:• One glassware with a swan shaped neck to expel

microorganisms, filled with broth• One glassware with a broken top to allow organisms to

easily enter the glassware, filled with broth• Pasteur boiled both glaswares and waited• That with the swan shaped neck did not develop

microorganisms• That which was broken did develop microorganisms• This proved that microorganisms are not spontaneously

generated, but are present and move through the air

A.I. Oparin and Miller

• A 20th century scientist, Oparin hypothesised that life may have begun during early Earth conditions with high heat, electricity, and extra oxygen

• Stanley Miller tested this hypothesis by mixing hydrogen, methane, and ammonia with water vapor, and passed electricity through it.

• He did produce some substances found in living things, but no organisms

Miller Experiment

Characteristics of life

Characteristics of Life

Made of Cells Reproduce Growth Respond to stimulus Use energy

Characteristics of Life

• Nonliving things may have one or more of the characteristics of life, but not all of the

• All living things have all of the characteristics of life

1. Living things have cells

• Cells build living things and also perform life functions living things need to thrive.

2. Reproduction

• Most plants and animals reproduce through sexual reproduction:– Two parents produce offspring with characteristics of

both parents• Some female fish will release eggs, which the male

will fertilize with his sperm• Some plants have male and female parts on their

flowers. A pollinating insect (such as a bee) will deliver sperm cells to the egg cells and a seed will develop

Fish eggs

Plant reproductive system

Bellwork

• Think about your weekend plans and write possibilities of scientific observations you could make.

Reproduction

• Asexual reproduction: reproduction that involves only one parent and in which the offspring is identical to the parent– Bacteria reproduce by dividing into two parts– Yeast reproduce by forming buds that break off

Bacteria reproduction

Yeast Reproduction

3. All living things grow and develop

• Some living things grow and develop, some only do one or the other

• Development can mean becoming more complex– A Newly conceived child is made of only a few

cells, which will divide and develop into a baby.– Once born that baby will continue to develop

• Give some examples of living things that grow and develop

Living things respond to stimuli

• Work with a partner next to you.• Complete the first two directions on the “try

this” activity on page 33.• Make a hypothesis as to what would be your

response to the last two stimuli.• Record your response after each.• Make a hypothesis as to why you respond the

way you do to each stimulus.

Bellwork 8-26

• Write about some Scientific observations you made this weekend. Don’t ask, “What if I didn’t make any.” ;-)

4. All living things respond to their environment

• Anything that affects the activity of an organism is called a stimulus

• The response can be an action, movement, or behavior change

What stimulates you?

• An alarm clock is a stimulus that wakes you up in the morning.

• List 10 other stimuli that cause you to react during the day.

5. All things use energy

• All living things need energy to survive• Some of the ways they obtain this energy is

through:– Making food, breaking down food, moving material in

and out of cells, and building cells• Some of these activities combine simple substances into more

complex substances• Some break down complex substances into simpler

substances an organism can use

• The sum of all of these chemical processes in a living cell or organism is called Metabolism

Chemical processes

• Before metabolism can take place, living things must take in food or process their own

• Plants process their own food through photosythesis:– They use water, carbon

dioxide, and energy from the sun to make food

Chemical processes continued

• One-celled organisms can engulf their food• Fungi secret enzymes to break food down so

they can absorb it• Sponges eat by filtering food from the water

Metabolism

• Once an organism has food, metabolism begins

• The first step is digestion• Digestion breaks down the food into simpler

substances• Some are used to build more complex

substances, others are stored for energy

Bellwork

• Draw the diagram of the 5 characteristics of living things from memory

Metabolism

• Metabolism also includes respiration:– The process in which living things use gases to

produce energy• Respiration for most living things includes

oxygen.– Animals get energy from combining digested food

with oxygen

Byproducts

• Respiration and digestion both produce byproducts that the living organism doesn’t need– We release carbon dioxide when we breathe out– Plants release oxygen and water

• The process of releasing these byproducts is excretion

• They are all used/recycled in some form

Bellwork 8-28

• Given our lesson yesterday, can you think of another example of a byproduct? Discuss it in your bellwork.

Recycled byproducts

Homeostasis

• To perform metabolism and other chemical activities, all living things must maintain homeostasis:– The ability to maintain a stable internal

environment• When hot, we sweat to cool off• When cold, we shiver to generate heat

The needs of living things

• 1. Food• 2. Water• 3. Certain gases• 4. Space

Needs of living things

• Food: needed for energy and the raw materials needed to perform metabolism

• Living things eat food that contain the chemicals and energy they need

• This helps maintain balance

Living things need water

• You could live for a week or more without food, but you could only live for about 3 days without water.

Water

• Water serves many important needs– Dissolves many substances• Our blood, for example, is mostly water and dissolves

the minerals and nutrients our bodies need and carries them throughout our bodies.• Tree sap, which is mostly water, also dissolves sugars

and nutrients and carries them throughout the tree.• Frogs absorb water through their skin to serve the

same purpose.

Water

Living things need energy

• All living things produce energy through metabolism

• All things use energy differently• A mushroom uses it to grow, a tree uses it to

produce leaves, a bird uses it to build a nest.• What is the original source of the energy for

all these living things?

Living things need certain gases

• Most living things need oxygen to survive (remember respiration!)

• Land animals get this oxygen from the air• Aquatic animals get this oxygen from taking

regular breaths above water, or using dissolved oxygen in the water

Breathing oxygen

Other Gases

• Some species of bacteria live on gases like ammonia, sulfur dioxide, or methane that are poisonous to most other organisms

• Whatever process created Carlsbad and Lechuguilla is largely dormant now. So the team visits a more active and dangerous cavern: Cueva de Villa Luz in Mexico, which emits the toxic, rotten-egg smell of hydrogen sulfide from its entrance. Inside, explorers must wear respirators and carry poison-gas monitors to protect themselves from the hydrogen sulfide that reacts with water in the cave to form caustic sulfuric acid. Deep within, they discover "snottites," mucous-like stalactites of sulfur-eating bacteria that also drip sulfuric acid. Oddly enough, the noxious environment teems with microbes, spiders, insects, crabs, and fish—all thriving in complete darkness.

• As strange as it may seem, sulfuric acid produced by microbial life is the cause of about five percent of all limestone caves, including Cueva de Villa Luz, Carlsbad, and Lechuguilla. Sulfuric acid not only dissolves limestone, it leaves a distinctive chemical residue: gypsum. This process, which is ongoing now in Cueva de Villa Luz, was completed millions of years ago in Carlsbad and Lechuguilla, where microbial activity continues today at a very slow pace.

Bellwork 8-29

• Give and example of each of the “needs of Living Things”

Living things need space

• Habitat: the place in which an organism lives• Living things protect their space from other organisms• Space can only support a certain amount of life• Space offers food, water, air, and shelter• Several microorganisms can flourish in a drop of

water, but a jaguar needs almost 1000 acres• Small trees only grow in open fields because they

cannot compete with taller trees for sunlight and water

• ON your own, read section two about the needs of living things.

• Create a chart, picture, or some other way to categorize the information in this section.

• Be creative, use color, and be thorough.• You will be graded for your effort and final

product

Homework

• Complete the “Needs of Living Things” worksheet. Due tomorrow

The Chemistry of Living Things

• All living things are made of cells

• Cells are made of substances NaCl

• Substances are made of elements

• An element is a pure substance that cannot be broken down into a simpler form

• Example: water is a substance made of the elements hydrogen and oxygen

• Water can be broken down further into two hydrogen atoms and one oxygen atom

• Hydrogen and oxygen cannot be broken down further, they are in their simplest forms

Elements

• Scientists recognize over 100 elements• 91 occur naturally

Compounds

• Compound: pure substance consisting of atoms of two or more elements that are chemically combined in a fixed proportion

=+

Molecule

• Molecule: a particle consisting of two or more atoms chemically tied together is the smallest part of a compound

• Water is a molecule

Compounds

• Most of the substances we see in the world are compounds

• Compounds can be divided into organic and inorganic compounds

• Organic compounds contain carbon ( substances that are or were alive)

• Inorganic compounds contain no carbon

Organic compounds

Inorganic compounds

Living things and compounds

• Living things contain over 3 million organic compounds

• Living things depend on organic compounds to live…our food is made of organic compounds

• Most common organic compounds:– Carbohydrates– Lipids (fats and oils)– Proteins– Nucleic acids

Carbohydrates

• Carbohydrates: organic compounds made of one or more sugar molecules

• Sugars are made from carbon, hydrogen, and oxygen

• Carbohydrates provide and store energy

Simple Carbohydrates

• Simple carbohydrates: made of one or a few sugar molecules linked together– Table sugar, fruit sugars

Complex Carbohydrates

• Complex carbohydrates are starches that are made of many sugar molecules linked together– Bread, pasta, rice,

potatoes

Carb Break Down

• Cells in an organism work to break down carbohydrates into glucose, a simple sugar

• Our bodies use sugar for energy• Glucose not used immediately is stored as

starch

Carbs

• Candy, soft drinks, and other junk food are high in carbohydrates, but provide little to no nutrients

Lipids

• Lipids: organic compounds that are fat and oils• They provide and store energy and make up

most of the membrane of the cell• Most fats are solid at room temperature• Most oils are liquid at room temperature• Carbs are immediately used as energy, while

lipids are used as a reserve supply

Bellwork 9-3

• Discuss a scientific observation you made over the weekend.

Lipids

Lipids

• Made of carbon, hydrogen, and oxygen• Proportions are different than in carbs• Americans and other rich countries eat too

many lipids!

Proteins

• Proteins: organic compounds made of amino acids (Amino acids are organic compounds that combine to form proteins)

• Proteins make structures like muscles, fingernails, antlers, feathers, etc.

• They help repair and build tissues and cells• Proteins also provide some energy• Some carry nutrients through the blood

Protein

Enzymes

• Enzymes: special proteins that speed up chemical reactions in an organism or cell

• They help make metabolism help by speeding up the process

Nucleic Acids

• Nucleic Acids: organic compounds that contain genetic information necessary for an organism to make the protein it needs.

• DNA & RNA are important nucleic acids• DNA (deoxyribonucleic acid) has information needed

to build protein and the info about the organism• RNA (ribonucleic acid “reads” the genetic messages

in the DNA so proteins can be built.• Together these are the genetic blueprints for

organisms

DNA

DNA RNA Protein