Chapter 1: Exploring Life

1.1 Living Things What do you see that is living when you go outside during the summer?

All of these things are organisms. You are an organism, I am an organism, you pet is an organism. An organism is anything that is living. What makes you the same as your desk or the walls?

The big similarity is that both you and the desks and the walls are all made out of chemicals. Do you know what makes you different from your desk or the walls?

Well the real difference is that you are made out of cells. A cell is the smallest unit of an organism that carries on the functions of life. Organisms can be made up of one or more cells. How these cells are organized will tell which life function they perform.

There are many functions that cells perform. Some are reproduction, homeostasis, growth and development. Organisms reproduce to produce new organisms that are similar to them.

What happens when you run around a lot on a really hot day? This is your body reacting to cool it down. Your body is reacting to a stimulus, which is anything that an organism responds to. As an organism, humans are able to respond to a stimulus and make adjustments to change in their environment.

Any characteristic an organism has that makes it better able to survive in its environment is an adaptation. Adaptations are not immediate. If you have a dog or a cat, their fur is an adaptation. In the summer, they shed their fur to help them stay cool and then they grow more fur during the winter to keep them warm.

Organisms such as humans also adjust to internal changes. Homeostasis is maintaining a steady condition inside of an organism no matter what is going on in the environment outside of the organism. It is the regulation of an organism’s internal environment to maintain conditions that allow it to live. So when it is hot outside and you are running around, your body starts sweating to help keep everything inside of your body cool.

Were you always as tall as you are right now? Why do you think that is? The reason why is because you growing. You started to develop. Development is all the changes that organisms undergo as they grow. You are still developing into the adults you will be someday. You will continue to develop all throughout your life span. Your life span is the length of time that an organism is expected to live. Every organism’s life span is different. Yours could be 80 or 90 years. A fly’s life span is only one day. A trees life span could be thousands of years.

Living things need many things in order to survive. One is energy. You get your energy from food. But the food that you eat gets it energy from something else. The meat products that you eat get their energy from plants. The plants get their energy from the sun. So all organisms get their energy from the sun, directly or indirectly.

Another thing that we need to survive is oxygen. Plants need carbon dioxide to survive. All living organisms need water to survive. All living things also need minerals to survive.

1.3 What is science? So this year you will be learning about life science. There are many types of life scientists. Some of these are zoologists and botanists. Zoologists study animals. Botanists study plants.

These scientists like all other scientists perform experiments to answer questions that they may have about something that they are studying. A zoologist may have a question about a certain behavior a cheetah has. A botanist might have a question about why a certain plant can grow with only air. All of these questions came from observations that they made.

To answer these questions they are going to perform an experiment. To do this they are going to follow a system called the scientific method. In science, it is an organizational tool that takes the form of a series of procedures. There are six parts to the scientific method. The steps are state the problem, gather information, form a hypothesis, perform an experiment, analyze data and report results.

To start the scientific method, a scientist has to observe something that they know nothing about. So they state the problem. The problem is stated in the form of a question. Next the scientist begins to gather information about the problem so that they can understand the problem a little more.

Once they have information, the scientist is going to come up with a hypothesis. A hypothesis is a prediction that can be tested. A hypothesis has to always be something that you can test. After the scientist makes up their hypothesis, he or she is going to perform an experiment to test the hypothesis. A hypothesis is stated in an “If…then…” format.

Next you have to perform an experiment. There some steps that need to be followed that use controlled conditions. There are going to be groups that are tested in every experiment. One is the variable group. This group is the factor that the scientist is testing for in the experiment. The other group is the control group. This group is the standard used to compare with the outcome of a test. The control group is going to have all the same things happening to it as the variable group (experimental group) except for the one factor that you are testing to solve the problem.

The next step is analyze data. The scientist will look at all the data that was collected in the experiment and come up with an answer to the problem. This answer will either prove that the hypothesis is true or false. The last step in the scientific method is to report results. After the scientist has looked at all the data, he or she will tell other scientists about the results of his or her experiment. This will either be written in a scientific paper or presented to other scientists.

The answers to your problems can either be considered a scientific theory or a scientific law. A scientific theory is an explanation of things or events based on many observations. This means that many experiments had to come to the same conclusion. Scientific theories can be changed if new data is found that shows that it is false. A scientific law is based on repeating data that tells us how nature works. Experiments have all had the same conclusions many, many times. A law can also be changed but not as easily as a theory.

Scientists use a system called an SI (International System of Units) to measure things. This chart will show you some of the SI units and will help you to convert one unit to another.

Measurement UnitSymbolEqual to Length1 millimetermm0.001 m 1 centimetercm0.01 m 1 meterm1 m 1 kilometerkm1000 m Volume1 millilitermL1 cm 3 1 literL1000 mL Mass1 gramg1000 mg 1 kilogramkg1000 g 1 tonnet1000 kg = 1 metric ton

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