Biology exam practice questions

• Viroids are known for their extreme simplicity and small size, and have only been identified in plants, but are suspected of causing some diseases in animals for which no pathogen has ever been isolated.
• Antigenic drift refers to changes to the flu virus that happen slowly overtime, causing the changes to the seasonal flu that require us to get vaccinated against the flu each year.
• Vaccines contain a harmless variation of the pathogen, allowing our immune system to recognize it and respond faster the next time we are exposed to the real pathogen.
• Antigenic shift results when two different flu strains combine and infect the same cell, potentially creating a very severe flu pandemic.
• Prions are disease-causing particles that do not contain DNA or RNA, and cause degenerative brain diseases such as Mad Cow Disease and CJD.
• Some bacteria are photosynthetic and are known as cyanobacteria.
• Streptomycin, tetracycline and vancomycin are common antibiotics that were originally made by bacteria.
• Streptococcus is a genus of bacteria that causes more diseases than any other genus, including Streptococcus pneumoniae, which is an important agent in bacterial pneumonia, Streptococcus mutans, which contributes to dental caries, and Streptococcus pyogenes, which causes the most diseases of any strep.
• The Endosymbiotic Hypothesis is a hypothesis about the origins of mitochondria and chloroplasts, which are organelles of eukaryotic cells.
• Antibiotics inhibit protein synthesis by bacteria, such as Erythromycin and tetracyclins, or inhibit cell wall biosynthesis, such as Penicilins and cephalosporins.
• Cyanobacteria (used to be known as blue-green algae) are ecologically significant because they are the basis of some food chains and release O2 into the environment.
• Gram Negative bacteria have a thin peptidoglycan layer and appear pink in colour.
• Gram Positive bacteria have a thick peptidoglycan layer and stain a dark purple colour.
• Cyanobacteria are thought to have been the first organisms to introduce 02 into Earth's early atmosphere.
• Energy is the ability to do work, or being about change.
• Kinetic energy, the energy of motion, is one form of energy.
• The first law of thermodynamics states that energy cannot be created or destroyed, but it can be changed from one form to another.
• The second law of thermodynamics states that energy cannot be changed from one form to another without a loss of useable energy.
• Exergonic reactions are those where the products have less free energy than the reactants.
• Endergonic actions require an input of energy where the products have more free energy than the reactant, like photosynthesis.
• Exergonic reactions are spontaneous reactions or favourable reactions that release energy to the surroundings.
• Reactants in exergonic reactions have high energy products, while products have low energy.
• Decrease in energy based on the thermal dynamics transfers energy to ATP, making the entire process exergonic.
• Endergonic reactions are unfavourable reactions or non-spontaneous reactions that absorb energy from the surrounding, therefore no energy is produced.
• Metabolic pathways are a series of linked reactions that begin with a specific reactant and produce an end product.
• Enzyme inhibition can occur through feedback inhibition, where metabolic enzymes are often inhibited by the end of the pathway they control.
• Competitive inhibition inhibits an enzyme by blocking binding of substrate to the active site.
• Non-competitive inhibition inhibits an enzyme by attaching at another site known as Auntie side and altering the enzyme so it can't catalyze the reaction.
• Cofactors are molecules which help enzyme function more efficiently, examples include copper and zinc which are inorganic cofactors, and vitamins which are often components of enzyme.
• Isomers are molecules that have the same molecular formula but differ in the arrangement of these atoms. These differences can result in molecules that are very different from one another in their biological activities.
• dehydration synthesis: in this reaction, the monomers, which are being bonded together, have a hydrogen atom on one end and an hydroxyl group 0H group on the other when the molecules join the hydrogen atom and hydroxyl group bond, and are removed as a water molecule The subunits are bonded together by a covalent bond as the water molecule is released
• Hydrolysis: the chemical breakdown of a compound due to reaction with water.
• Catabolic reaction gives out energy. They are exergonic. In a catabolic reaction. Large molecules are broken down into smaller ones hydrolysis are catabolic reactions.
• Anabolic reactions use up energy and they are endergonic . Anabolic reaction small molecules to make large one like the hydration synthesis.
• Cellular Respiration equation C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP
• Photosynthesis reactions equation  6CO2 + 6H2O → C6H12O6 + 6O2
• Free energy is a measure of energy that is available to do work. The free energy of a system changes during energy transfers such as chemical reactions, and this change is referred to as ΔG or Gibbs free energy.
• Entropy refers to the relative amount of disorganization and energy transformations in cells that increase the entropy.
• Cohesion is the linking of like molecules.
• Adhesion is the clinging of one substance to another