A Level Biology Practice Exam

What distinguishes fibrous proteins from globular proteins?

1. Fibrous proteins are soluble, globular proteins are not

2. Fibrous proteins have a structural role, while globular proteins are functional

3. Fibrous proteins can only exist in two dimensions

4. Globular proteins are only found in plants

The correct answer is: Fibrous proteins have a structural role, while globular proteins are functional

The distinction between fibrous and globular proteins is primarily based on their structure and function. Fibrous proteins, such as collagen and keratin, are characterized by their long, parallel chains that form stable structures, providing strength and support to various tissues in the body. Their primary role is structural, making them essential for the integrity of muscles, skin, and connective tissues. Globular proteins, on the other hand, are more compact and folded into spherical shapes. They are involved in a wide array of functions, including transportation (like hemoglobin), catalysis (as enzymes), and regulation (such as hormones). The functional versatility of globular proteins is due to their varied shapes and the presence of active sites that allow for specific interactions with other molecules. The other options do not accurately reflect the key differences between these two classes of proteins. For instance, while it is true that fibrous proteins tend to be less soluble in water compared to globular proteins, the distinction is not solely about solubility. The claim that fibrous proteins can only exist in two dimensions is misleading, as their structure can also have three-dimensional aspects based on the arrangement of their chains. Lastly, the assertion that globular proteins are only found in plants is incorrect; glob