A-level Biology

Welcome to this A-level biology series where we break down complex topics into simple, understandable concepts. This introductory video focuses on the fundamental chemical principles behind biology, starting with the atom. We will explore atomic structure, atomic number, isotopes, and atomic weight, providing a helpful refresher for those familiar with the concepts and a clear overview for newcomers. Understanding these basics is crucial for grasping future biological topics. Elements are composed of a single type of atom, which in turn is made up of three subatomic particles: protons, neutrons, and electrons. Protons carry a positive charge and have a mass of one atomic mass unit. Neutrons have no charge but also a mass of one atomic mass unit. Electrons orbit the nucleus, have a negative charge, and their mass is negligible compared to protons and neutrons. The atomic number, defined by the number of protons, dictates the element. Atomic weight, however, accounts for isotopes, which are atoms of the same element with different numbers of neutrons, by using an abundance-weighted average of their masses. Subscribe to @AxiomTutoringCourses for more educational content.

This video explains covalent bonds by diving into the energy levels and electron configurations of atoms. We explore how elements are arranged on the periodic table based on atom size and electron energy levels, including the concept of electron shells and subshells. Learn about the S, P, D, and F blocks, and the specific rules like the Pauli exclusion principle and Hund's rule that govern electron behavior. We then use carbon as an example to determine its valence electrons and how it forms covalent bonds by sharing electrons to achieve stability. Subscribe to @AxiomTutoringCourses for more educational content.

In this fundamental chemistry for biology lesson, we explore ions and ionic bonds. Learn which elements readily form these bonds, how ions are created, and the mechanism by which they bind together. This video focuses on groups 1 and 2, along with groups 16 and 17 of the periodic table, explaining their propensity for ion formation due to electron configuration. Using sodium and chlorine as examples, we illustrate how atoms gain or lose electrons to achieve stability, resulting in charged ions. Discover how the electrostatic attraction between these oppositely charged ions forms an ionic bond. Subscribe to @AxiomTutoringCourses for more essential chemistry concepts.

This video explains hydrogen bonds, a crucial type of intermolecular force in biology. Discover how they form when hydrogen is bonded to a highly electronegative atom like oxygen, nitrogen, or fluorine, creating partial charges within molecules. Learn how these dipoles interact between molecules, leading to attractions that are essential for the unique properties of water, such as surface tension and its role as a solvent. We also explore their vital function in maintaining the structure of proteins and holding DNA strands together. Subscribe to @AxiomTutoringCourses for more science lessons.

In this video, we explore three essential properties of water: cohesion, adhesion, and surface tension. Understand how the partial charges within water molecules lead to cohesion, enabling vital biological processes like water transport in trees through xylem. Discover how adhesion allows water to interact with different polar or charged molecules, causing effects like the meniscus seen in a glass test tube. Finally, learn how surface tension, a result of water molecules' strong attraction to each other, creates a taut surface capable of supporting small insects and influencing meniscus shapes. Subscribe to @AxiomTutoringCourses for more educational content.

In this video, we dive into the crucial properties of water: specific heat capacity and latent heat capacity, and explore their vital roles in biological systems. Discover how the significant amount of heat energy required to raise water's temperature and change its state contributes to its remarkable ability to regulate environments and organisms. Learn why these properties make water an ideal medium for aquatic life and how our bodies leverage them for temperature control, such as through evaporation. Understanding these concepts is key to grasping water's fundamental importance in life. Subscribe to @AxiomTutoringCourses for more educational content.