Chapter 2.1 : What is Life

Characteristics of Living Things

(Things that all living organisms share)

1. Cellular Organization

Cell: The basic unit of structure and function in living things, a membrane covered structure that contains all materials necessary for life.

Organisms are made up of either one cell (unicellular) or more than one cell (multicellular)

Though cells perform some of the same functions, cells do not all look the same

All living things are composed of various chemicals such as carbohydrates, proteins, lipids, and nucleic acids (DNA)

2. Chemicals of Life

3. Energy Use - Organisms use energy to carry out the activitiesof life which include making food, breaking down food, building cells, etc.

Metabolism: The total of all chemical activities that an organism performs

4. Response to Surroundings.Stimulus: A change in an organism’s environment that changes the organism’s activity, which is called the response.

Stimulus Response

- bright light - pupil opening becomes smaller

- scared/surprised - fight or flight- sight/sound of food

- mouth waters

- cold temperature - shiver/put on a jacket

Homeostasis: Maintenance of stable internal environment by means of self-regulation.ex. body temp, blood sugar

5. Growth and Development- All organisms grow and develop during periods of their lives.

Growth: increasing the number or size of cells

Development: passing through different stages, becoming more complex (teenager to adult)

6. Reproduction- Organisms produce other organisms like themselves

Asexual Reproduction: A single parent produces offspring identical to the parent

Pro’s:- Faster (more offspring in less time)- All of parent’s genetics are passed on- Do not need a mate

Con’s - All of parent’s genetics are passed on- Offspring genetically identical to parentExample: Hydra, Yeast, Liverwort

Sexual Reproduction: Usually requires two parents to produce offspring. Offspring are a combination of the parents’ traits. (most organisms reproduce by this method)

Pro’s:- Population is diverse because offspring share genetics from both parents- Some of the population should survive environmental change (variability)

Con’s:- Requires a mate/not all males reproduce and they waste resources- Takes a lot of energy/time- Wastes half of parents genes

Life Comes From LifeIt may seem obvious to us now that living things arise from living things through reproduction (biogenesis), but that was not always the case.

Spontaneous generation : The idea that life could arise from nonliving sources.

Flies came from rotting meat.

Mice came from cloth and grain.

Francesco Redi and Louis Pasteur conducted experiments that finally convinced people that spontaneous generation did not occur.

The Needs of Living Things

1. Food:

Food provides organisms with the energy and raw materials to carry out life activities

Autotroph

self feed/nourish

(producers) Organisms that produce their own food. (ex. plants)

Photosynthesis Equation

Water + Carbon Dioxide + Sun Energy Food (Glucose) + Oxygen

Heterotroph:

other

Organisms that rely on other organisms for food

Consumer: eat(consume) other organisms for food (ex. humans)

Decomposer: break down dead organisms or waste to get food (ex. fungus, bacteria)

2. Water

Required for the chemical reactions of metabolism

Living things are made up of about 70% water

Humans can go about 3 days without water, we get water from both fluids and foods

3. Air

Organisms require gasses found in the air

ex. Oxygen is needed for respirationcarbon dioxide is needed for photosynthesis

4. Living Space

Organisms require space in which to live. The size of the space differs with the size and needs of the organism

Chapter 2.2Chapter 2.2 Classifying Organisms Classifying Organisms

ClassificatioClassification:n:Arrangement of organisms into orderly

groups based on similarities. Classifying organisms makes it easier for people to study and answer questions about the organism

Taxonomy:Taxonomy:Science of identifying, classifying, and naming living things.

Aristotle (384-322 B.C.)

• Greek philosopher and scientist.

• Classified living things into two broad categories of plants and animals based on such things as where they lived and size.

Linnaeus categorized organisms based on shared characteristics, and he gave each animal a unique two-part scientific name.

Linnaeus categorized organisms based on shared characteristics, and he gave each animal a unique two-part scientific name.

The naming system is called binomial Nomenclature (two Names)

The naming system is called binomial Nomenclature (two Names)

Swedish botanist/physician who created a new system of classification (1750s) that still is used today.

Swedish botanist/physician who created a new system of classification (1750s) that still is used today.

Scientific NamesScientists use scientific names to identify organisms to avoid confusion and mistakes caused by language differences.

The common name “robin” is used in different parts of the world to describe different species. This could lead to confusion.

But each of these “robins” has a unique scientific name that sets it apart from the others.

Example:Elphus maximus (scientific name is italicized or underlined)

genus species - The genus name is capitalized and the species begins with a lower case letter

The scientific name has two parts, the genus and species. The scientific name is given in Latin because it is a dead language and will not change meaning over time.

Levels of Classification

1. Kingdom

5. Family

4. Order

3. Class

2. Phylum

7. Species

6. Genus

Largest

Smallest

Organisms are put into a series of groups that are progressively more exclusive.

Taxonomy in ActionTaxonomy in Action : Let’s take a look at how this group of organisms is sorted by the classification levels

Kingdom AnimaliaKingdom Animalia : contains all the different phyla of animals

Phylum ChordataPhylum Chordata: contains animals with a hollow nerve cord

Class MammaliaClass Mammalia : contains animals that have a backbone and nurse their young

Order CarnivoraOrder Carnivora : contains animals with a backbone, that nurse their young, and whose ancestors had special teeth for tearing meat.

Family FelidaeFamily Felidae : contains animals with a backbone, that nurse their young, have well developed claws and teeth for tearing meat, and are cats

Genus Genus FelisFelis : contains animals with a backbone, that nurse their young, have well developed claws and teeth for tearing meat, are cats, and cannot roar-only purr.

Species Species Felis domesticusFelis domesticus : contains only one kind of animal, the common house cat. It has all the characteristics of all the levels above it, but it has other unique characteristics

Domains and KingdomsA three-domain system is commonly used to classify organisms. Organisms are placed into domains and kingdoms based on their cell type, their ability to make food, and the number of cells in their bodies.

Domains Archaea EukaryaBacteriaKingdom

sEubacteria Archaeobacteria Animalia

PlantaeFungi

Protista

Dichotomous Key: Specialized guides used to aid in the identification of an unknown species.

Step 1:MAKE OBSERVATIONS

• Make sure they are observations, not inferences (color, child/adult…).

• Make similar observations on each specimen so you can compare them.

• Divide your sheet into a grid for easy reading.

The object has three sides

The object does not have three sides

Step 2:Make a Web

The objecthas 3

equal angles

The objectdoes not have 3

equal anglesThe object is blue.

The object is not blue.

What could you ask here?

Dichotomous Key: Specialized guides used to aid in the identification of an unknown species.

Step 3: Make a dichotomous key