In your notebook, please write this question: “What’s the difference between living and nonliving?”
Below your question in your notebook write three-to-five lines explaining your definition.
If all living things are considered organisms, why do you think scientists chose to use the word, organism. In your notebook, rephrase my question above and write two or three lines about your belief?
All things on Earth are divided into two categories BIOTIC ABIOTIC
Essential Question: What are the characteristics that all biotic organisms share?
Biotic – the root word, bio, means, life. Name a few things that are alive, or biotic 1. 2. 3. 4.
An organism is something that has: • A cellular organization • Contain similar chemicals • Use energy • Respond to their surroundings • Grow and develop • Reproduce
You’ve read about cells in your textbook. Now, in your notebook, write the word cell and its definition.
Abiotic – the root word, bio, means, life, but, the “A” means without Name a few things that have never been alive or abiotic 1. 2. 3. 4.
In the handout, “What is Life,” please note, or underline, or highlight, the words and definitions for unicellular and multicellular. This handout is homework and is due, tomorrow.
In ancient Greece, people thought life was spontaneously generated by nonliving things.
Here’s an example of Spontaneous Generation • Nile River floods every year. • Mud becomes rich silt. • Millions of frogs appeared. • People thought "Frogs come from mud."
Here’s an example of Spontaneous Generation • In the Middle Ages farmers stored grain in wooden buildings. • Buildings had thatched roofs.Mice got in grain. • People thought "Mice come from grain."
Here’s an example of Spontaneous Generation • Salamanders hibernate in and under rotting logs. • When wood was brought indoors and put on the fire, the creatures "mysteriously" appeared from the flames. • A salamander exudes a milky substance when frightened. This makes its skin very moist. • People thought "Salamanders come from fire. They can with stand any heat and even put out fires."
Here’s an example of Spontaneous Generation • No refrigerators during the Middle Ages. • People bought or traded for food everyday. • Butcher shops hung meat outside. • The customer asked for a slice of meat. • The butcher chased the flies away and cut off a piece. • The customer didn't use the meat right away and it rotted. • Maggots appeared on the rotten meat. • People thought "Flies come from rotten meat."
Francesco Redi • a 17th Century Italian Francesco Redi scientist, is credited with creating the first controlled experiment.
He created an experiment to prove flies do not come from rotten meat. To do this, he created a controlled experiment.
A controlled experiment is an experiment where you have complete control.
Here is his experiment • He obtained six jars. • In each jar, he placed an equal amount of meat. • Three of the jars he left open, the other three he covered with a piece of cloth. • He placed all six jars outside and waited for the meat to rot.
Results of experiment • Redi noticed flies accumulated inside the open jars, but none appeared in the covered jars. • Then, he noticed maggots on the rotting meat in the open jars and none in the covered jars. • He then covered the open jars and soon noticed the maggots developed into flies. • The jars that remained covered throughout the experiment did not develop flies.
Follow-up • Later, Redi uncovered the three jars that had been covered the entire time, and soon discovered flies inside those jars. • Of course, the flies landed on the meat, laid eggs, and the eggs developed into maggots, and then flies.
How many of you now believe that life cannot be created from nonliving things?
Well, let me introduce you to • Louis Pasteur a 19th Century French chemist and microbiologist who was one of the most important founders of medical microbiology. He is remembered for his remarkable breakthroughs in the causes and preventions of diseases.
Here’s how he disprovedspontaneous generation He took jars with swan-necked tube openings. This type of flask permits air to flow in, but, no solid objects. He poured a broth mixture into each flask.
Here’s how he disprovedspontaneous generation Nothing happened. Air could flow in and out of the flasks, but, nothing else. Therefore, there was no life in the flasks.
Here’s how he disprovedspontaneous generation • Then, he broke the neck off one flask and observed what happened. • Bacteria grew in the flask, on the broth. • He then broke another flask neck and the bacteria, again, grew. • He broke each successive flask and each flask developed bacterial growth.
Here’s how he disprovedspontaneous generation • Then, he boiled the broth and noticed all the bacteria was killed. • He poured the broth into new swan-necked flasks and noticed new bacteria did not grow. • He discovered pasteurization.
In Redi’s experiment, new flies came from flies that got into the jars and fed on the meat.
Pasteur’s experiment proved that life comes from life, only through direct contact. If the bacteria could not reach the broth, it could not reproduce.
Before we can ask about the origin of life, we must decide what is it that all life needs to survive?
All living things share six important characteristics: • All living things are made of cells. • The cells of living things are made of similar chemicals. • All living things use energy. • All living things grow and develop. • All living things respond to their surroundings. • All living things reproduce. All living organisms on Earth are divided in pieces called cells.
Living Things Are Made of Cells • All living things are made of cells. Cells are so small, you need a microscope to see them. Some organisms are made of only one cell and are called unicellular organisms. If a living thing is made of only one cell, that one cell has all of the parts necessary to live. (We will learn more about unicellular organisms when we study pond life.)
Living Things Are Made of Cells • Living things that are made of more than one cell are called multicellular organisms. Multicellular organisms often have many, many cells. You are a multicellular organism and your body contains trillions of cells! Each type of cell is responsible for carrying out different functions to keep you alive.
Chemicals of Life • The cells of living things are made of specific types of chemicals. • Water is the most abundant chemical in cells. It is important for you to drink plenty of water throughout the day so that your body's cells can do their work. • Other chemicals in cells include carbohydrates, or carbs, which provide your cells with energy; proteins and lipids, which are the building materials of cells; and nucleic acids, which provide instructions for cellular activities.
Cells Use Energy • The cells of organisms use energy to do what living things must do, such as grow, "breathe," move, think, digest food, and repair injured parts. • Food is your source of energy. It is very important that you eat a nutritious breakfast in the morning so that you can think and work at school. When you do not eat, you will begin to feel tired, irritable, and will have difficulty focusing. You make school harder when you come to school without having had breakfast.
All Living Things Grow and Develop • When living things are born, they will be smaller than their parents. Over the course of time, the organism will grow larger and larger. Human babies, for example, are much smaller than adult humans. It usually takes about eighteen years for a human to grow to full size. Other organisms grow over relatively short periods of time. Cats are considered full grown after only one year.
All Living Things Grow and Develop • Living things also develop over that course of their lives. This means that the organism will become more complex. In the case of an oak tree, it starts out as an acorn and becomes a tree with branches, leaves, a trunk, and a root system underground. It is a much more complex organism when full-grown than when it first began to grow.
All Living Things Respond to Their Surroundings • All organisms will respond to certain stimuli in their environment. A stimulus is a change in a living thing's surroundings that causes it to respond. A response is an action or a change in behavior.
All Living Things Respond to Their Surroundings • Your body responds to certain kinds of stimuli. Pretend you have just gotten home from school and, as you walk in the door, you smell the amazing scent of freshly baked cookies. Your mouth will begin to water and your stomach may begin to growl. The scent of cookies is the stimulus that causes your body's reaction of a watering mouth and a growling stomach.
All Living Things Respond to Their Surroundings • Simpler organisms also react to stimuli. A plant, for example, will turn its leaves toward a sunny window to catch as much sunlight as possible. Why? The leaves need sunlight to produce food through the process of photosynthesis. If you turn the plant around so that the leaves no longer face the window, the leaves will eventually tilt to face the window again. The stimulus is you turning the plant's leaves away from the window, and the response is when the plant tilts its leaves back toward the window again.