Biology Questions and Answers


1. What are the chemical elements that form most of living biological matter?

The chemical elements that form most

of the molecules of living beings are

oxygen (O), carbon (C), hydrogen (H)

and nitrogen (N).

2. Living beings are made of

organic and inorganic

substances. According to the

complexity of their molecules

how can each of those

substances be classified?

Inorganic substances, like water,

mineral salts, molecular oxygen and

carbon dioxide, are small molecules

made of few atoms. Organic substances,

in general, like glucose, fatty acids and

proteins, are much more complex

molecules made of sequences of

carbons bound in carbon chains. The

capacity of carbon to form chains is one

of the main chemical facts that

permitted the emergence of life on the


3. What are the most

important inorganic molecular

substances for living beings?

The most important inorganic

substances for living beings are water,

mineral salts, carbon dioxide and

molecular oxygen. (There are several

other inorganic substances without

which cells would die.)

4. What are mineral salts?

Where in living beings can

mineral salts be found?

Mineral salts are simple inorganic

substances made of metallic chemical

elements, like iron, sodium, potassium,

calcium and magnesium, or of non-

metallic elements, like chlorine and


They can be found in non-solubilized

form, as part of structures of the

organism, like the calcium in bones.

They can also be found solubilized in

water, as ions: for example, the sodium

and potassium cations within cells.

5. What are the main

functions of the organic

molecules for living beings?

Organic molecules, like proteins, lipids

and carbohydrates, perform several

functions for living organisms.

Noteworthy functions are the structural

function (as part of the material that

constitutes, delimits and maintains

organs, membranes, cell organelles,

etc.), the energetic function (chemical

reactions of the energetic metabolism),

the control and informative function

(genetic code control, inter and

intracellular signaling, endocrine

integration) and the enzymatic function

of proteins (facilitation of chemical


6. What are some examples of

the structural function of

organic molecules?

Organic molecules have a structural

function as they are part of cell

membranes, cytoskeleton, organ walls

and blood vessel walls, bones, cartilages

and, in plants, of the conductive and

support tissues.

7. What are some examples of

the control and informative

function of organic molecules?

Based on genetic information, organic

molecules control the entire work of the

cell. The nucleic acids, DNA and RNA,

are organic molecules that direct the

protein synthesis, and proteins in their

turn are the main molecules responsible

for the diversity of cellular biological

tasks. In membranes and within the

cell, some organic molecules act as

information receptors and signalers.

Proteins and lipids have an important

role in the communication between cells

and tissues, acting as hormones,

substances that transmit information at

a distance throughout the organism.

8. What are biopolymers?

Polymers are macromolecules made by

the union of several smaller identical

molecules, called monomers.

Biopolymers are polymers present in the

living beings. Cellulose, starch and

glycogen, for example, are polymers of


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