A Level Biology Practice Exam

What is the significance of callose in plants?

1. It provides structural support to roots

2. It is important in the plant response to infection

3. It stores nutrients for the plant

4. It aids in photosynthesis

The correct answer is: It is important in the plant response to infection

Callose is a polysaccharide that plays a crucial role in the plant's response to infection. When plants are attacked by pathogens, such as bacteria or fungi, they produce callose to create a barrier around the affected area. This localized response helps prevent the spread of the pathogen by sealing off the damaged cells and forming a protective matrix. The quick synthesis of callose at the site of infection is part of the plant's innate immune response, allowing it to limit the effects of harmful organisms and enhance its overall resilience. The other options do not accurately represent the primary function of callose. While structural support for roots is primarily provided by lignin and cellulose, nutrient storage typically involves other carbohydrates like starch, and photosynthesis is mainly facilitated by chlorophyll in chloroplasts rather than callose. Thus, the importance of callose lies fundamentally in its role in defensive mechanisms, particularly in response to infection.