The first true cells

Scientists have found fossils that indicate that the first true cells evolved and inhabited Earth as far back as 3.5 billion years ago.

The origin of the first true cells is still unknown today.

The first true cells

  1. Didn’t need oxygen
  2. They were consumers that didn’t produce their own food.
  3. The food that they needed was contained in the pools that the cells lived in.
  4. As the food supply decreased, the cells evolved into producers, or autotrophs.
  5. Autotrophs produce their own food.
  6. Autotrophs are photosynthetic.
  7. Autotrops contain chlorophyll.

Earth today is filled with both consumers and producers.

  1. You are a consumer.
  2. You must eat food in order to obtain energy and important nutrients.
  3. Green plants on the other hand are producers.
  4. Plants use chemicals in their environment and the energy of sunlight to produce their own food.
  5. Green plants produce food in a process called photosynthesis.

This is an extremely important event in the history of Earth. Do you know why?

  • One of the waste materials plants produce during photosynthesis is oxygen.
  • As plants began to perform photosynthesis, they also began to change the atmosphere of Earth.
  • Over millions of years the poisonous atmosphere of Earth changed to contain about 1/5 oxygen.
  • This set the stage for organisms that use oxygen to evolve.

We began with single celled organisms and the fossil record shows that it was some time later that multi-celled organisms came to inhabit the planet.

Characteristics of Living Things

Living things:

  1. Are made of cells
  2. Some are unicellular (made up of one cell).
  3. Some are multicellular ( made up of more than one cell).
  4. Can move
  5. Animals must move to find food and shelter.
  6. Plants bend towards sunlight to capture the sun’s rays.
  1. Perform complex chemical activities
  2. Metabolism-all the chemical reactions that occur in a living thing.
  3. Ingestion-eating
  4. Digestion-process that breaks food down into simpler substances.
  5. Respiration-taking oxygen and using it to make energy.
  6. Excretion-the process of getting rid of waste materials.
  1. Growth and development
  2. Get bigger or more complex
  3. Have a life span (the maximum length of time a particular organism can be expected to live.
  4. Life span varies greatly from one type of organism to another.
  1. Respond to their environment
  2. A stimulus is the signal to which an organism reacts.
  3. A stimulus is any change in the environment that produces a response.
  4. A response is some action, movement, or change in behavior of the organism.
  1. Reproduce
  2. The process by which living things give rise to the same type of living thing is called reproduction.
  3. There are two types of reproduction.
  4. Sexual reproduction
  5. usually requires two parents
  6. most multicellular forms of plants and animals
  7. Asexual reproduction
  8. Only one parent
  9. An organism divides into two parts