Bio 204 Quiz 1 Practice

Cell

the smallest unit of life

Organelle

A specialized structure within a cell that performs a specific function 

Molecule

A group of two or more atoms bonded together

Atom

The smallest unit of an element, made up of protons, neutrons, and electrons

Non-polar Covalent bond electronegativity range

0.0-0.4

Polar Covalent bond electronegativity range

0.5-1.5

Ionic bond electronegativity range

1.8-3.3

Non-polar Covalent Bond Example

C-C, C-H

Polar Covalent Bond Example

C-O,C-N,H-N,H-O

Ionic Bond Example

LiF, NaCl

How many shells does the 1st electron shell hold

2

How many shells does the 2nd electron shell hold

8

How many shells does the 1st electron shell hold

8

What type of bond forms between two nonmetal atoms with similar electronegativity?

Nonpolar covalent bond (electrons are shared equally).

What type of bond forms between a metal and a nonmetal with a large electronegativity difference?

Ionic bond (electrons are completely transferred from the metal to the nonmetal).

What is the key difference between a polar covalent bond and a nonpolar covalent bond?

Polar covalent bonds involve unequal sharing of electrons resulting in partial charges; nonpolar covalent bonds involve equal sharing with no partial charges.

What are partial charges (δ+ and δ-), and when do they occur?

Partial charges occur in polar covalent bonds when the more electronegative atom pulls shared electrons closer,

What makes a small molecule hydrophilic?

Being polar or charged, allowing it to form favorable electrostatic interactions or hydrogen bonds with water.

What makes a small molecule hydrophobic?

Being nonpolar, meaning it lacks partial or full charges and cannot form hydrogen bonds with water.

Why are carbohydrates generally hydrophilic?

carbohydrates contain abundant polar hydroxyl groups (-OH), which readily form hydrogen bonds with water.

What are the four major classes of biological macromolecules?

Carbohydrates, Lipids, Proteins, and Nucleic Acids.

Which major biomolecule class does NOT consist of true polymers made of repeating monomers?

Lipids (they are large nonpolar molecules composed of glycerol, fatty acids, or steroid rings rather than linked monomers).

What molecule is an exception and is nonpolar

CO2

Hydrogen Bond Example

N-H, O-H, F-H