Physical, Chemical, and Energy Changes in Digestion and Homeostasis Unit Review

Why do you think the elements most common in the human body are not the same as the ones in the Earth’s crust?

living things and non-living things have different makeup and needs.

What are the rules for writing chemical symbols?

Elements are represented by 1–3 letters. The first letter is always capitalized. The following letters are always lower case. The letters are always printed.

What is an element?

An element is a pure substance that cannot be broken down into simpler substances. It contains only one type of atom.

Why isn’t sodium chloride listed on the periodic table?

It’s a compound. Only elements are listed on the table.

What is a compound?

A compound is a substance made by chemically combining two or more elements to form a new and different substance, and the bond cannot be broken by physical means.

Is O 2 a compound?

No, because it is made up of only one element. It is considered a molecule because it is two atoms of the same element.

What process does this equation represent?

Photosynthesis

Which of the substances in the photosynthesis equation are elements?

None. They are all compounds or molecules made up of elements.

Which of the substances in the photosynthesis equation are compounds?

CO 2, H 2 O, C 6 H

Which of the substances are molecules?

O2O2

Which elements compose glucose?

Carbon, Hydrogen and Oxygen

What is an organic compound?

Made up carbon atoms bonded to atoms of other elements. Examples are carbohydrates, proteins, lipids, and nucleic acids.

What do the six elements in the human body have in common with the elements in organic compounds?

They are the same

Do you agree or disagree with the following statement? Why or why not? Living things are made of organic compounds.

Agree; all living things contain carbon combined with other elements.

Why would some non-living things contain carbon?

They are made from remains of once living organisms; for example, fossil fuels.

Which system is responsible for chemical regulation?

Endocrine

What are some hormones that the endocrine system uses to regulate the body?

What is homeostasis?

The ability to maintain internal balance

How do responses to stimuli help to maintain balance in organisms?

Living organism must be able to maintain balance in stable internal conditions in response to external and internal stimuli in order to survive.