PEARSON EDEXCEL AS\A-LEVEL
BIOLOGY EXAM WITH QUESTIONS AND
WELL VERIFIED ANSWERS[GRADED A+]
Topic 1 A
Ionic bonding
Bonding between a metal and a non-metal
Anion
A negatively charged ion
,Cation
A positively charged ion
Ionic bonds
A chemical bond resulting from the attraction between oppositely charged ions.
Covalent bonding
Bonding between 2 non-metals
Dipole
A molecule that has two poles, or regions, with opposite charges
What is the importance of water?
- 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?
Compounds that always contain carbon. Also contain hydrogen and oxygen.
Form carbohydrates, lipids and proteins.
Polar molecule
A molecule in which one side of the molecule is slightly negative and the
opposite side is slightly positive
Dissociation
The separation of ions that occurs when an ionic compound dissolves
ATP
Adenosine triphosphate. Energy.
, ADP
(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?
104.5
Hydrogen Bonds
Weak electrostatic intermolecular bonds between polar molecules that contain at
least 1 hydrogen atom
How many bonds can carbon form?
4 - usually forming a tetrahedral shape.
Molecular shapes
Straight lines = not facing towards or away from you
Dotted lines = facing away from you
Triangle lines = facing towards you
BIOLOGY EXAM WITH QUESTIONS AND
WELL VERIFIED ANSWERS[GRADED A+]
Topic 1 A
Ionic bonding
Bonding between a metal and a non-metal
Anion
A negatively charged ion
,Cation
A positively charged ion
Ionic bonds
A chemical bond resulting from the attraction between oppositely charged ions.
Covalent bonding
Bonding between 2 non-metals
Dipole
A molecule that has two poles, or regions, with opposite charges
What is the importance of water?
- 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?
Compounds that always contain carbon. Also contain hydrogen and oxygen.
Form carbohydrates, lipids and proteins.
Polar molecule
A molecule in which one side of the molecule is slightly negative and the
opposite side is slightly positive
Dissociation
The separation of ions that occurs when an ionic compound dissolves
ATP
Adenosine triphosphate. Energy.
, ADP
(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?
104.5
Hydrogen Bonds
Weak electrostatic intermolecular bonds between polar molecules that contain at
least 1 hydrogen atom
How many bonds can carbon form?
4 - usually forming a tetrahedral shape.
Molecular shapes
Straight lines = not facing towards or away from you
Dotted lines = facing away from you
Triangle lines = facing towards you
