Fig. 1.1 is a diagram of a molecule of haemoglobin.

Which feature of haemoglobin makes it a globular protein?

Most plants are C3 plants and are so-called because their first photosynthetic product is a three carbon compound.

The enzyme ribulose bisphosphate carboxylase/oxygenase (rubisco) catalyses the fixation of carbon dioxide in the Calvin cycle and is used by both C3 and C4 plants.

Each molecule is made up of eight large polypeptides and eight small polypeptides. Fig. 2.1 shows a side view of the molecule.

Which comparative statements concerning biological molecules are correct?

1 A collagen molecule is a fibrous protein that contains many amino acids with hydrophobic R-groups whereas a haemoglobin molecule is a globular protein with no amino acids with hydrophobic R-groups.

2 Sucrose hydrolysis results in glycosidic bond breakage and the production of equal proportions of fructose and $\alpha$-glucose molecules, whereas cellulose hydrolysis results in only $\beta$-glucose molecules.

3 The glycosidic bonds of glycogen have been formed between two $\alpha$-glucose molecules, whereas with amylopectin, the bonds have been formed between an $\alpha$-glucose molecule and a $\beta$-glucose molecule.

Which feature explains why haemoglobin is soluble?

Sugars with a ring structure can also have a linear structure.
Which sugar molecules could be represented by the linear structure shown in the diagram?

Which row correctly matches the functional and structural features of cellulose, collagen, glycogen or triglyceride?

key $\checkmark=$ true $\quad \boldsymbol{\chi}=$ false

What describes a globular protein that is not soluble in water?