A Level Biology WJEC

This subject is broken down into 25 topics in 4 modules:

  1. Basic Biochemistry and Cell Organisation 6 topics
  2. Biodiversity and Physiology of Body Systems 4 topics
  3. Energy, Homeostasis and the Environment 8 topics
  4. Variation, Inheritance and Options 7 topics
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  • 25
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  • 10,287
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  • 1+
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This page was last modified on 28 September 2024.

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Biology

Basic Biochemistry and Cell Organisation

Chemical Elements are Joined Together to form Biological Compounds

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Chemical Elements are Joined Together to form Biological Compounds

Chemical Elements in Biological Compounds

  • The basic elements of life are oxygen, hydrogen, carbon, and nitrogen.
  • Other elements including phosphorus, sulphur, sodium, potassium, calcium, and magnesium also have important roles within living organisms.
  • Trace elements are required in very tiny amounts but are essential for certain cellular functions. These include iron, iodine, copper, zinc, and more.

Formation of Biological Compounds

  • Biological compounds, also known as biomolecules, are typically composed of multiple atoms combined.
  • The vast majority of these biochemical substances are made up macromolecules, which include proteins, nucleic acids, carbohydrates, and lipids.

Role of Carbon

  • Carbon has the unique ability to form stable bonds with other elements, notably itself, which allows it to form a wide variety of functional groups and chains of varying lengths.
  • Since carbon has four valence electrons, it easily bonds with hydrogen and other elements to form compounds necessary for life.

Role of Hydrogen Bonds

  • Hydrogen bonds play a vital role in the structure and function of biological compounds.
  • They contribute to the three-dimensional shape of proteins and nucleic acids and the secondary structure of DNA.

Biomolecules: Protein, Nucleic Acids, Carbohydrates, Lipids

  • Proteins are made up of amino acids, linked by peptide bonds. They serve as enzymes, structural proteins and transport proteins, among other functions.
  • Nucleic acids are made up of nucleotides, which include one of four nitrogenous bases, a phosphate group, and a sugar. DNA and RNA are types of nucleic acids.
  • Carbohydrates, made of simple sugars or polymers of sugars, provide energy and comprise cell structure.
  • Lipids are fat-soluble, nonpolar molecules that serve as cell membrane components, hormones, and energy storage.

Water in Biological Systems

  • Water plays a fundamental role in the constitution and interaction of biomolecules.
  • It allows the correct folding of proteins, the genetic coding by DNA and its transcription to RNA, among other essential functions.

Ionic Compounds in Biological Systems

  • Ionic compounds such as salts are critical for the homeostasis of the body and serve in nerve impulse transmission, muscle contraction and hydration.
  • Ions such as sodium, potassium, and calcium interact with proteins and other organic compounds, thereby influencing numerous bodily processes.

Course material for Biology, module Basic Biochemistry and Cell Organisation, topic Chemical Elements are Joined Together to form Biological Compounds

Biology

Energy, Homeostasis and the Environment

Microbiology

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Microbiology

Microorganisms: An Introduction

  • Microorganisms, or microbes, are minute organisms that cannot be seen with the naked eye due to their extremely small size.
  • They occur virtually everywhere - in air, soil, water, food, and within and on our bodies.
  • Microbes include a wide variety of organisms such as bacteria, viruses, protozoa, algae, and fungi.
  • Most microorganisms are harmless, but some can cause disease, known as pathogens.

Bacteria

  • Bacteria are single-celled prokaryotic organisms. They have a simple cell structure without a nucleus and other membrane-bound organelles.
  • They reproduce asexually by binary fission, a process where one cell divides into two identical cells.
  • Bacteria play a vital role in nitrogen fixation in the soil, making nitrogen available to plants.
  • Numerous bacteria are involved in the fermentation process which is used in food production like in making yoghurt, cheese, and alcoholic beverages.

Viruses

  • Viruses are non-living entities that can only reproduce within a host cell.
  • They infect all types of life forms, from animals and plants to bacteria.
  • Viruses have a simple structure of genetic material (either DNA or RNA) enclosed in a protein coat.
  • They can cause diseases including flu, HIV/AIDS, and COVID-19.

Protozoa

  • Protozoans are single-celled eukaryotic organisms with complex structures.
  • They can move using various methods such as through pseudopodia, cilia, and flagella.
  • Some species are parasites and can cause diseases including malaria and sleeping sickness.

Algae

  • Algae are a diverse group of photosynthetic organisms, ranging from single-celled to multicellular forms.
  • They form the base of the aquatic food chain and help in oxygen production in the atmosphere.
  • Economically important as they can be used to produce biofuels, food additives, and are sources of certain medicines.

Fungi

  • Fungi are eukaryotic organisms that include multicellular moulds and single-celled yeasts.
  • They are important decomposers, playing an essential role in nutrient cycling.
  • They can also cause plant and animal diseases, but also have uses in the production of bread, beer, and antibiotics.

Course material for Biology, module Energy, Homeostasis and the Environment, topic Microbiology

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