Problem-solving is, by nature, a creative process which, by teaching through the implementation of research and discovery activities, allows students to create their knowledge, revise it and link it to broader systems. The aim of the research was to describe and analyse the process of solving biological problems through activities that are performed during the process of solving them, as well as to study how the implementation of these activities affects the level and quality of student achievement in biology. This study employed a quantitative method research strategy to describe the problem-solving process in biology teaching and determine student achievement. Data collection was by means of survey and testing. A Likert-scale survey and a biology knowledge test were constructed for the purposes of the research. For data analysis, descriptive statistics, factor analysis and the Pearson correlation coefficient were used. The data of eighth-grade students were collected from September 2016 to February 2017, in 72 schools in Serbia (565 students). The factor analysis confirmed that problem-solving activities could be grouped into the following five areas: (1) analysing and planning problem-solving; (2) discovering solution(s) to the problem; (3) problem-solving evaluation activities; (4) additional activities involving the discussion of the problem; (5) the degree of student independence in the process of discovering a solution to a problem. The results show that with the increasing frequency of the realisation of the research problem-solving activities, the achievement of students also increases. With regard to achievement quality, a positive but low correlation was found in all three domains--knowledge acquisition, understanding and application.