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