Use the information below on four different soil bacteria. In the box provided, write the letter that corresponds to each microorganism’s stage in the nitrogen cycle in Fig. 6.1. • Nitrosomonas europaea is an ammonia-oxidising bacterium. • Bacillus cereus is a denitrifying bacterium. • Azospirillum lipoferum lives in the roots of some cereals and grasses and provides fixed nitrogen to plants. • Streptomyces coelicolor is a bacterium that secretes powerful hydrolases to decompose substances such as proteins and cellulose.
Some fungi form mutualistic associations with plant roots. They help the plant take up nutrients, such as phosphates, which are not easily obtained from the soil. Suggest how a higher uptake of phosphate ions will result in increased plant growth.