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2.1.1 Biological Molecules

1. Name four functions of water.

As a reactant: in photosynthesis and hydrolysis
As a solvent
For transport of substances, eg. glucose and oxygen
For temperature control ­ carries heat energy away and evaporates

2. Explain why there is polarity in water molecules

Because the shared hydrogen…

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12. Describe the bonding in the primary and secondary structure of proteins

In the primary structure, the amino acids are held together by peptide bonds. In the secondary structure,
hydrogen bonds form (which create the alpha helix or beta pleated sheets)

13. Describe the four different types of bonding in…

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One molecule of glucose with two fatty acids and one phosphate group. The phosphate group is ionised
and so it attracts water molecules

23. Describe the structure of cholesterol (found in cell membranes)

It has a hydrocarbon ring structure attached to a hydrocarbon tail. The hydrocarbon ring has a polar…

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1. What is the function of DNA?

It contains all the genetic information and instructions to grow and develop from a fertilised egg to a fully
grown adult.

2. Describe the structure of DNA

It is a polynucleotide. Each nucleotide contains a deoxyribose sugar, a phosphate group and a varying…

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2.1.3 Enzymes

1. Enzymes are globular proteins. True or false?

True

2. Describe how enzymes speed up a reaction, and thus act as biological catalysts

Enzymes reduce the amount of energy required to start the reaction ­ the activation energy. This speeds up
the reaction. The formation of an enzyme-substrate…

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11. Give two ways in which the rate of an enzyme-controlled reaction can be measured

You can measure how fast the reaction appears or you can measure the disappearance of the substrate

12. Explain how cofactors work

They work by helping the enzyme and substrate bind together. They are not…

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3. Which nutrient is required for growth and repair?

Proteins

4. Give an example of a vitamin and state its function

Vitamin K is needed for blood clotting. Vitamin D is needed for calcium absorption

5. Give an example of mineral and state its function

Iron is needed to make…

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They are at the start of food chains which are then eaten and the energy is used by humans

17. How do fertilisers increase crop production?

They provide minerals that the plants need to grow so that lack of minerals doesn't limit growth of the next
crop

18. How do…

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The low pH of the acidic vinegar reduces enzyme activity so they cannot function properly and their growth
is limited

29. How does heat treatment kill microorganisms?

The food is heated to a high temperature which kills any microorganisms present (eg. pasteurisation)

30. How does irradiation prevent food spoilage?

The…

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Through droplet infection ­ when an infected person coughs or sneezes, the tiny droplets of saliva and
mucus containing bacteria are breathed in by other people

11. Why is malaria, HIV and TB more common in developing countries?

Limited access to good healthcare (drugs not always available and surgical equipment…

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