Biology Chapter 2: Chemical Context of Life

Questions and Answers

Which of the following is a trace element required by most living organisms?

Iron

Magnesium (correct)

Zinc

Copper

What is hydrogen bonding most often seen with?

When hydrogen is covalently bonded to an electronegative atom.

What happens when chemical equilibrium is reached?

The forward and reverse reactions occur at the same rate.

Which property of water allows a paper towel to pick up a puddle of water?

Adhesion Signup and view all the answers

Identify all correct statements about the ionization of water.

Dissociation of water produces equal numbers of OH- and H+. Signup and view all the answers

In the term trace element, what does the adjective trace mean?

The element is required in very small amounts. Signup and view all the answers

What does the reactivity of an atom arise from?

The existence of unpaired electrons in the valence shell. Signup and view all the answers

Which of the following bonds can form between atoms of equal electronegativity?

Van der Waals interactions Signup and view all the answers

What does the term electron orbital describe?

A three-dimensional space where an electron can be found 90% of the time. Signup and view all the answers

What is a true statement about weak bonds?

Weak bonds are transient and easily reversible. Signup and view all the answers

What happens during the decay of radioactive isotopes?

The nucleus decays spontaneously, giving off particles and energy. Signup and view all the answers

What is the half-life?

A parent isotope decays into its daughter isotope at a fixed rate. Signup and view all the answers

What is radiometric dating?

Scientists measure the ratio of different isotopes and calculate how many half-lives have passed. Signup and view all the answers

What is potential energy?

Energy that matter possesses because of its location and structure. Signup and view all the answers

Why are radioactive isotopes useful in scientific research?

Because they can be used as tracers to follow particular atoms and molecules. Signup and view all the answers

What type of bond is formed when valence electrons are shared by two neutral atoms?

Covalent bond. Signup and view all the answers

What is the role of van der Waals interactions in biological molecules?

They help to reinforce the three-dimensional shapes of large molecules. Signup and view all the answers

What is a true statement about chemical reactions?

They involve the making and breaking of chemical bonds. Signup and view all the answers

Study Notes

Trace Elements

Magnesium is a trace element that constitutes about 0.1% by weight in most living organisms.
Trace elements are necessary in very small amounts for different life forms, with iron being essential for all forms of life.

Hydrogen Bonding

Hydrogen bonds occur when hydrogen is covalently bonded to an electronegative atom.
Electronegativity creates a slight positive charge on hydrogen, attracting it to other electronegative atoms, forming bonds.

Chemical Equilibrium

Achieved when forward and reverse reactions occur at the same rate, maintaining constant concentrations of reactants and products.

Properties of Water

Adhesion allows water molecules to stick to other molecules, enabling paper towels to absorb water.
Water's interaction with cellulose in paper towels is similar to its role in water transport within plant cell walls.

Ionization of Water

Water dissociates to produce equal concentrations of hydroxide (OH-) and hydronium ions (H+).
This dissociation is a reversible process, crucial for maintaining pH balance in biological systems.

Reactivity of Atoms

An atom's reactivity is determined by unpaired electrons in its valence shell, influencing its bonding behavior.

Bonds and Interactions

Van der Waals interactions occur between atoms with equal electronegativity, resulting in transient positive and negative charges from electron movements.
Weak bonds, like hydrogen bonds and Van der Waals interactions, are temporary yet play critical roles in biological structures and processes.

Electron Orbitals

An electron orbital represents a 3D space where an electron is likely found 90% of the time.

Radioactive Isotopes

Radioactive isotopes decay spontaneously, emitting particles and energy, useful for tracing atoms in metabolic pathways.

Half-Life and Radiometric Dating

The half-life of a radioactive isotope is the fixed rate at which it decays into its daughter isotope, unaffected by external factors.
Radiometric dating estimates the age of fossils and rocks by measuring isotope ratios and calculating elapsed half-lives.

Energy Concepts

Potential energy refers to the energy possessed by matter due to its position or structure.

Role of Weak Bonds

Weak bonds, while transient, are essential in stabilizing the three-dimensional structures of large biological molecules.
Chemical reactions involve the making and breaking of chemical bonds, which are fundamental to biochemical processes.

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Description

Test your knowledge on the chemical elements essential for life with this flashcard quiz from Chapter 2. Explore concepts such as trace elements, hydrogen bonding, and their significance in biological systems.