Defining Life and Basic Biochemistry

Question 1

What are the characteristics of life?

Answer 1

Organization, Metabolism, Growth and Development, Reproduction, Homeostasis, Response to Stimuli, Adaptation through Evolution

Question 2

What does ‘organization’ mean in living organisms?

Answer 2

Living things are made of cells, tissues, organs, and systems.

Question 3

What is metabolism?

Answer 3

All chemical reactions in an organism that include energy production and usage.

Question 4

What is homeostasis?

Answer 4

Regulation of internal conditions to maintain stability (e.g., body temperature).

Question 5

How do unicellular organisms maintain homeostasis?

Answer 5

By growing, responding to the environment, transforming energy, and reproducing.

Question 6

How do multicellular organisms maintain homeostasis?

Answer 6

Through specialized cells communicating and performing specific tasks.

Question 7

What is cell specialization?

Answer 7

The process where unspecialized stem cells become specialized for specific functions.

Question 8

What are atoms and elements?

Answer 8

Atoms: Smallest unit of matter, composed of protons, neutrons, and electrons.

Elements: Pure substances made of one type of atom (e.g., Carbon, Oxygen).

Question 9

What are molecules and compounds?

Answer 9

Molecules: Two or more atoms bonded (e.g., H₂O).

Compounds: Molecules with different elements (e.g., CO₂).

Question 10

What are the four major biomolecules and their monomers?

Answer 10

Carbohydrates: Monosaccharides (e.g., glucose).

Lipids: Fatty acids and glycerol.

Proteins: Amino acids.

Nucleic Acids: Nucleotides (sugar, phosphate, nitrogen base).

Question 11

What are the functions of carbohydrates?

Answer 11

Provide energy and structural support (e.g., starch, glycogen, cellulose).

Question 12

What are the functions of lipids?

Answer 12

Long-term energy storage, insulation, forming cell membranes.

Examples: fats, oils, phospholipids, cholesterol.

Question 13

What are proteins, and what are their functions?

Answer 13

Proteins perform enzymatic activities, provide structure, transport molecules, and defend immunity.

Examples: enzymes, hemoglobin, antibodies.

Question 14

What are nucleic acids, and what do they do?

Answer 14

Function: Store and transmit genetic information.

Examples: DNA and RNA.

Question 15

What is the pH scale?

Answer 15

A scale from 0 to 14 measuring acidity or alkalinity:

0–6: Acidic
7: Neutral
8–14: Basic

Question 16

What are buffers, and why are they important?

Answer 16

Buffers stabilize pH levels in organisms by neutralizing acids or bases, essential for maintaining homeostasis.

Question 17

What is the organization of life from smallest to largest?

Answer 17

Atom → Molecule → Cell → Tissue → Organ → Organ System → Organism

Question 18

What are the essential elements of life?

Answer 18

Main elements: Carbon, Hydrogen, Oxygen, Nitrogen.

Others: Phosphorus, Sulfur, and trace elements like iron, iodine, and zinc.

Question 19

What makes carbon important in organic compounds?

Answer 19

Carbon has four valence electrons, forming up to four covalent bonds.

Carbon can create long chains, rings, and double/triple bonds.

Question 20

How are macromolecules formed and broken down?

Answer 20

Dehydration Synthesis: Bonds monomers by removing water.

Hydrolysis: Breaks bonds by adding water.

Question 21

What are the properties of proteins?

Answer 21

Made of amino acids joined by peptide bonds.

Fold into complex shapes: primary, secondary, tertiary, and quaternary. Shape determines function.

Question 22

What are the necessities of life?

Answer 22

Water, food, air, and light.

Question 23

What is adaptation through evolution?

Answer 23

Changes in populations over time to better survive in their environments.

Question 24

What are isotopes and their uses?

Answer 24

Isotopes are forms of elements with varying neutron numbers.

Radioactive isotopes: Used in medicine and fossil dating.

Question 25

What are ions, and how are they formed?

Answer 25

Ions: Atoms with unequal protons and electrons.

Cations: Positive charge (protons > electrons). Anions: Negative charge (electrons > protons).