Hierarchy of Life

1. CELLS are the most basic unit of life.

2. Groups of similar cells make up TISSUE.

3. Groups of tissue working together make up ORGANS.

4. Organs work together to make up ORGAN SYSTEMS.

5. Organ systems make up the ORGANISM.

6. Groups of the same organism make up a POPULATION.

7. Many different populations make up a COMMUNITY.

8. ECOSYSTEMS include both the biotic (living) and abiotic (nonliving) factors of an area.

Life & Energy

All living things require energy. They get this energy by performing cellular respiration.

Cellular respiration requires oxygen and glucose. Living things are classified in four ways according to how they get their glucose:

Autotroph, Chemotroph, Heterotroph, or Decomposer.

Autotroph

Autotrophs capture the solar energy from sunlight and convert it to the chemical energy of glucose via photosynthesis. 

All plants are autotrophs.

They are also called producers because they produce their own food.

Chemotroph

Chemotrophs get their energy using chemicals from the earth and convert it into useable chemicals for energy.

They are usually extremophiles, meaning they live in extreme places, like hot springs or thermal vents.

Heterotroph

Heterotrophs must get their energy by eating autotrophs, other heterotrophs, or both.

In other words, they eat plants or other animals. For this reason, heterotrophs are also called consumers.

Decomposers

Decomposers recycle dead organisms by breaking them down and returning their nutrients to the soil.

3 Domains of Life

There are 3 Domains of Life:

Bacteria

Archaea

Eukarya

Domain: Bacteria

Bacteria includes only one Kingdom of life within it: eubacteria.

Eubacteria are single-celled. They are what we think of when think of bacteria, and they exist all around us. And inside us.

Domain: Archaea

Archaea includes only one Kingdom of life within it: archaebacteria.

Archaea are single-celled, very ancient, and often extremophiles.

Domain: Eukarya

Eukarya includes four Kingdoms of life:

Protista

Fungi

Plantae

Animalia

3 Domains of Life

Between the 3 Domains of Life there are 6 Kingdoms:

Bacteria - Eubacteria

Archaea - Archaebacteria

Eukarya - Protista, Fungi, Plantae, Animalia

Adaptations

Adaptations are inheritable characteristics that help an organism survive and reproduce. 

Physical adaptations are body structures that help an organism survive and reproduce. 

Behavioral adaptations are actions an organism takes to survive and reproduce.

Enzymes

Enzymes are always proteins.

Since proteins are made of amino acids, enzymes can also be said to be made of amino acids.

Enzymes speed up chemical reactions in the body.

In other words, they increase metabolism.

Enzymes

Enzymes work on a substrate that fits into their active site.

Once the substrate locks into the active site, the enzyme turns the substrate into products.

A change in temperature or pH levels (acidity) may cause the enzyme to change shape and no longer function (the substrate would no longer fit in the active site).

Carbon Cycle

Carbon is part of all biomolecules.

All life on Earth goes through an endless carbon cycle.

There are four steps to the carbon cycle:

1. Carbon enters the atmosphere as CO2.

2. CO2 is absorbed through photosynthesis done by producers (plants).

Carbon Cycle

3. Animals consume plants, thereby taking in their carbon.

4. When animals and plants die, their bodies decompose and their carbon is reabsorbed back into the atmosphere.

Nitrogen Cycle

Nitrogen is a part of two biomolecules: proteins and nucleic acids.

All life on Earth requires nitrogen to survive.

However, you cannot bring nitrogen into your body by breathing.

Nitrogen Cycle

Bacteria 'fix' nitrogen (bring it in from the air).

The bacteria convert the nitrogen to a form that plants can use.

Plants bring nitrogen in through their roots.

Nitrogen Cycle

Animals eat the plants.

When animals excrete waste, nitrogen returns to the soil or the atmosphere.