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Pearson Edexcel AS/A-level BIOLOGY
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Pearson Edexcel AS/A-level BIOLOGY Pearson Edexcel AS/A-level BIOLOGY Pearson Edexcel AS/A-level BIOLOGY
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Pearson Edexcel AS/A-level BIOLOGYTopic 1 A - ANS -----------------------------------------------------
Ionic bonding - ANS Bonding between a metal and a non-metal
Anion - ANS A negatively charged ion
Cation - ANS A positively charged ion
Ionic bonds - ANS A chemical bond resulting from the attraction between oppositely charged ions.
Covalent bonding - ANS Bonding between 2 non-metals
Dipole - ANS A molecule that has two poles, or regions, with opposite charges
Polar molecule - ANS A molecule in which one side of the molecule is slightly negative and the opposite
side is slightly positive
Dissociation - ANS The separation of ions that occurs when an ionic compound dissolves
ATP - ANS Adenosine triphosphate. Energy.
ADP - ANS (Adenosine Diphosphate) The compound that remains when a phosphate group is removed
from ATP, releasing energy
,What is the angle size between the 2 dipoles in a water molecule? - ANS 104.5
Hydrogen Bonds - ANS Weak electrostatic intermolecular bonds between polar molecules that contain
at least 1 hydrogen atom
What is the importance of water? - ANS - Polar solvent: can dissolve substances.
- Excellent transport medium: substances can dissolve in it and can easily be transported.
- As water cools to 4"C, it reaches max density. As it cools further, molecules become more widely
spaced.
- Water is slow to absorb and release heat. High specific heat capacity. Bonds between hydrogen atoms
need a lot of energy to separate so water in lakes/ sea etc doesn't change temperature throughout the
year.
- Water is a liquid so cannot be compressed.
- Adhesive: bonding of different molecules, makes it attract to other molecules.
- Cohesive: bonding of similar molecules, makes it sticky.
- High surface tension - molecules hold together.
What are organic compounds? - ANS Compounds that always contain carbon. Also contain hydrogen
and oxygen. Form carbohydrates, lipids and proteins.
How many bonds can carbon form? - ANS 4 - usually forming a tetrahedral shape.
Molecular shapes - ANS Straight lines = not facing towards or away from you
Dotted lines = facing away from you
Triangle lines = facing towards you
Monomers - ANS small unit that can join together with other small units to form polymers
, Polymers - ANS large compound formed from combinations of many monomers
Macromolecules - ANS A very large organic molecule composed of many smaller molecules
Carbohydrates - ANS the starches and sugars present in foods
disaccharides - ANS Carbohydrates that are made up of two monosaccharides, sucrose, lactose, maltose.
formula of monosaccharides - ANS (CH2O)n
Tricose - ANS n = 3 : C3H6O3
Hexose - ANS n=6 : C6H12O6
Isomers - ANS Two different molecules that have the same chemical formula e.g. glucose's isomers
include alpha and beta glucose.
condensation reaction - ANS a chemical reaction in which two or more molecules combine to produce
water as a byproduct
Monosaccharides - ANS Single sugar molecules, simple, glucose, fructose, galactose.
glycosidic bond - ANS A glycosidic bond is a covalent bond in which a carbohydrate binds to another
group, which could also be a carbohydrate. E.g a glycosidic bond is found between the two glucose
molecules in maltose.
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