General Biology Study Guide: Key Concepts and Step-by-Step Guidance

Q1. Describe the five key characteristics of living organisms and basic information about each one as it applies to cells and molecules.

Background

Topic: Characteristics of Life

This question tests your understanding of what defines living organisms, especially at the cellular and molecular level.

Key Terms:

• Cellular organization

• Metabolism

• Homeostasis

• Growth and reproduction

• Response to stimuli/evolution

Step-by-Step Guidance

1. List the five key characteristics that all living organisms share.

2. For each characteristic, briefly describe what it means in general terms.

3. Relate each characteristic to how it appears in cells and molecules (e.g., how metabolism involves biochemical reactions in cells).

4. Think of examples for each characteristic at the molecular or cellular level.

Try solving on your own before revealing the answer!

Final Answer:

The five key characteristics of living organisms are:

1. Cells: All living things are made of cells, which are the basic units of life. Even the simplest organisms are cellular.

2. Replication: Living things can reproduce, making copies of themselves (asexually or sexually).

3. Information: Living organisms process hereditary (genetic) information encoded in DNA, as well as environmental information.

4. Energy: All organisms acquire and use energy to carry out life processes (metabolism).

5. Evolution: Populations of living organisms evolve over time through changes in genetic information.

Each of these characteristics can be observed at the cellular and molecular level, such as DNA replication, metabolic pathways, and cellular responses to environmental signals.

Q2. What are the components of atoms and how are they organized? What are two oversimplifications in the drawings shown in Fig. 2.1a?

Background

Topic: Atomic Structure

This question tests your understanding of atomic structure and the limitations of common atomic models.

Key Terms:

• Protons

• Neutrons

• Electrons

• Nucleus

Step-by-Step Guidance

1. Identify the three main subatomic particles in an atom and where each is located.

2. Describe how these particles are organized within the atom (nucleus vs. electron cloud).

3. Consider what is typically shown in simple atomic diagrams (like Fig. 2.1a) and think about what aspects of real atoms these diagrams might oversimplify.

4. List two ways in which these diagrams do not accurately represent atomic structure.

Try solving on your own before revealing the answer!

Final Answer:

Atoms are composed of protons and neutrons (in the nucleus) and electrons (in orbitals around the nucleus). Two oversimplifications in typical atomic diagrams are: (1) electrons are shown in fixed orbits rather than as probability clouds, and (2) the relative sizes and distances between nucleus and electrons are not to scale.

Q3. Which component of an atom does not vary for a single element? What is the relationship between atomic number and mass number? How is it possible for the mass of an element to vary?

Background

Topic: Atomic Number, Mass Number, and Isotopes

This question tests your understanding of what defines an element and how isotopes arise.

Key Terms:

• Atomic number ($Z$)

• Mass number ($A$)

• Isotopes

Step-by-Step Guidance

1. Recall which subatomic particle determines the identity of an element.

2. Define atomic number and mass number, and explain how each is calculated.

3. Explain how isotopes of an element can have different mass numbers.

4. Think about which subatomic particle varies in isotopes and which does not.

Try solving on your own before revealing the answer!

Final Answer:

The number of protons (atomic number) does not vary for a single element. The atomic number is the number of protons, while the mass number is the sum of protons and neutrons. The mass of an element can vary because the number of neutrons can differ, resulting in isotopes.

Q4. Which are the 4 elements that make up the vast majority of the material in living organisms? What are the next 2 most abundant?

Background

Topic: Elements in Biological Systems

This question tests your knowledge of the most common elements in living things.

Key Terms:

• CHON (Carbon, Hydrogen, Oxygen, Nitrogen)

• Phosphorus, Sulfur

Step-by-Step Guidance

1. Recall the four most abundant elements in living organisms (often remembered by the acronym CHON).

2. Identify the next two most abundant elements commonly found in biological molecules.

3. Think about the roles these elements play in biomolecules (proteins, nucleic acids, etc.).

Try solving on your own before revealing the answer!

Final Answer:

The four most abundant elements are carbon, hydrogen, oxygen, and nitrogen. The next two most abundant are phosphorus and sulfur.

Q5. Describe what happens to the numbers and organization of electrons as you move across rows and down columns in the periodic table. What is the significance of the number of electrons in the outermost shell in an atom, and what does it help you infer about bond formation?

Background

Topic: Periodic Table and Electron Configuration

This question tests your understanding of how electron arrangement relates to chemical properties and bonding.

Key Terms:

• Valence electrons

• Electron shells/energy levels

• Periodic trends

Step-by-Step Guidance

1. Recall how the number of electrons changes as you move from left to right across a period (row) and down a group (column).

2. Describe how electron shells are filled as you move across the table.

3. Explain the importance of the number of electrons in the outermost shell (valence electrons) for chemical reactivity.

4. Relate the number of valence electrons to the likelihood and type of bond formation.

Try solving on your own before revealing the answer!

Final Answer:

As you move across a row, the number of electrons increases and fills the same shell; as you move down a column, new shells are added. The number of valence electrons determines an atom's chemical reactivity and the types of bonds it can form.