Chapter 1 Quick Check Answers
Chapter 1
Answers QUICK-CHECK questions
1 What are the special characteristics of the light produced by a synchrotron?
In a synchrotron, electrons are accelerated to very high speeds (almost the speed of light). Light is created when the direction of movement of these electrons is changed (deflected) using magnetic fields. A characteristic of this light is that it is extremely bright.
2 a Explain why ice is less dense than water.
Ice is less dense than liquid water because, as water solidifies, the water molecules form a regular lattice structure in which each molecule is linked by hydrogen bonds to four other water molecules. In liquid water, the hydrogen bonds are less stable and the water molecules pack together more densely. Hence, the molecular arrangement of water in solid form (ice) has more spaces within it and takes up a greater volume than the same number of water molecules in the liquid state. As a result, ice is less dense and so floats on water. b Explain how this difference in density is of vital importance to organisms that live in water.
The fact that ice is less dense than liquid water means that ice in a body of water, such as in a lake or in the sea, floats at the top, rather than sinking to the bottom. So, when a body of water freezes, this takes place from the top down. The ice that forms at the surface acts as an insulating layer so that the underlying water stays above freezing point and organisms living in the water are protected from freezing.
3 a What name is given to a solution that has equal numbers of hydrogen and hydroxide ions?
A solution in which the numbers of hydrogen ions and hydroxide ions are equal is termed a neutral solution. b What general name is given to solutions that have many more hydrogen ions than hydroxide ions?
Solutions that have many more hydrogen ions than hydroxide ions are termed acidic.
4 Name the monomers of carbohydrates, proteins, lipids and nucleic acids.
The monomers (basic building blocks) of
Answers QUICK-CHECK questions
1 What are the special characteristics of the light produced by a synchrotron?
In a synchrotron, electrons are accelerated to very high speeds (almost the speed of light). Light is created when the direction of movement of these electrons is changed (deflected) using magnetic fields. A characteristic of this light is that it is extremely bright.
2 a Explain why ice is less dense than water.
Ice is less dense than liquid water because, as water solidifies, the water molecules form a regular lattice structure in which each molecule is linked by hydrogen bonds to four other water molecules. In liquid water, the hydrogen bonds are less stable and the water molecules pack together more densely. Hence, the molecular arrangement of water in solid form (ice) has more spaces within it and takes up a greater volume than the same number of water molecules in the liquid state. As a result, ice is less dense and so floats on water. b Explain how this difference in density is of vital importance to organisms that live in water.
The fact that ice is less dense than liquid water means that ice in a body of water, such as in a lake or in the sea, floats at the top, rather than sinking to the bottom. So, when a body of water freezes, this takes place from the top down. The ice that forms at the surface acts as an insulating layer so that the underlying water stays above freezing point and organisms living in the water are protected from freezing.
3 a What name is given to a solution that has equal numbers of hydrogen and hydroxide ions?
A solution in which the numbers of hydrogen ions and hydroxide ions are equal is termed a neutral solution. b What general name is given to solutions that have many more hydrogen ions than hydroxide ions?
Solutions that have many more hydrogen ions than hydroxide ions are termed acidic.
4 Name the monomers of carbohydrates, proteins, lipids and nucleic acids.
The monomers (basic building blocks) of