Pearson, as an active contributor to the biology learning community, is pleased to provide free access to the Classic edition of The Biology Place to all educators and their students.
The purpose of the activities is to help you review material you have already studied in class or have read in your text. Some of the material will extend your knowledge beyond your classwork or textbook reading. At the end of each activity, you can assess your progress through a Self-Quiz.
To begin, click on an activity title.
Lab 2 Enzyme Catalysis
Mitosis and Meiosis
Plant Pigments and Photosynthesis
6-I Bacterial Transformation
6-II DNA Electrophoresis
Genetics of Organisms
Population Genetics and Evolution
10-I Cardiovascular Fitness
10-II Heart Rate in Daphnia
Biomembranes I: Membrane Structure and Transport
Biomembranes II: Membrane Dynamics and Communication
Cardiovascular System I: The Beating Heart
Cardiovascular System II: The Vascular Highway
Cell Structure and Function
DNA Structure and Replication
From Gene to Protein: Transcription
From Gene to Protein: Translation (Protein Synthesis)
Plant Structure and Growth
Properties of Biomolecules
Restriction Enzyme Digestion of DNA
The lac Operon in E. coli
Concept 2: Valence and Covalent Bonding
Each element has a characteristic valence that determines the number of covalent bonds it can form.
The ability of an atom to combine with other atoms depends on the number of electrons in the outer shells of the atoms. Some elements, the so-called noble gases, have complete outer shells and do not share electrons. Many elements will share electrons with other elements, such that each element completes its outer electron shell capacity.
A shared electron pair is called a covalent bond. The number of covalent bonds that each element can form is called its valence.
The CHNOPS atoms are shown above. Each valence position is represented by a stick protruding from the atom.