In the 21st century, the use of student worksheets (LKPD) must be integrated with technological developments or electronic media. Teaching materials are known as e-LKPD. The use of e-LKPD teaching materials can be supported by appropriate learning strategies to support the learner-centered learning process, one of which is the problem-based learning model. This study aims to determine the feasibility of e-LKPD based on the PBL model on the immune system material of students of class XI. The type of research carried out is research and development using the ADDIE model. Data collection techniques using non-test in the form of a closed questionnaire. Questionnaires are used to measure the feasibility of e-LKPD media experts, material experts, and biology teachers, as well as student responses. The data analysis technique used is by calculating the average value (mean) and converted to determine the feasibility category. The results of this study show that the average e-LKPD product feasibility assessment results by material experts 92,192 include the very feasible Category, the average e-LKPD product feasibility assessment by media experts 85.1 including the category is very feasible, the e-LKPD product feasibility assessment by biology teachers 98.24357 includes the very feasible category, and the product feasibility assessment results based on student Responses 96,375 belong to the very feasible category. The conclusion of this study shows that PBL-based e-LKPD teaching materials on body defense system materials are suitable for use in biology learning for class XI students

This study aims to find out: (1) the effectiveness of LKPD mobile learning model problem-based learning on environmental change material used to increase the learning interest of grade X high school students; (2) the effectiveness of LKPD mobile learning model problem-based learning on environmental change material used to improve critical thinking of grade X high school students. This type of research is quasi-experimental with a pre-test design and post-test control group design. The limited trial subjects in this study were 34 grade X students of Senior Hight School 1 Ngabang. The field test subjects consisted of 36 experimental class students and 36 students for the control class in grade X of Senior Hight School 1 Ngabang. Data collection used several instruments, namely interviews, needs analysis questionnaires, assessment questionnaires for material experts, media expert assessment questionnaires, RPP expert assessment questionnaires, syllabus expert assessment questionnaires, biology teacher assessment questionnaires, student response questionnaires, learning interest questionnaires, critical thinking test sheets. Data analysis techniques use the normality test, homogeneity test, T-test, Mann-Whitney test, and n-gain score. The results showed that: (1) LKPD mobile learning model problem-based learning is effective in increasing students' interest in learning. The increase in interest in learning according to the n-gain score that occurred in the experimental class achieved a score of 0.7 in the high category, and (2) LKPD mobile learning problem-based learning model is effective in improving students' critical thinking. The increase in critical thinking according to the n-gain score that occurred in the experimental class achieved a score of 0.8 in the high category.

Abstract. The emphasis on the growth of Phytophthora palmivora was important in order to reduce Pod Rot Disease of cacao (Theobrorna cacao L.) which could harm agriculture sector. Some bacteria had chitinolytic enzyme activity that is potentially used as an antifungal against Phytophthora palmivora, because the cell wall of the fungi composed of chitin. The purpose of this research was to know chitinolytic bacteria from Perna viridis shell which had higher activity of chitinase enzyme, the amount of chitinase enzyme activity of each selected isolate, and to know the effect of chitinolytic bacterial isolates from Perna viridis shell to reduce the growth of Phytophthora palmivora. The bacteria were isolated from Perna viridis shell at Depok Beach, Kretek, Bantul, Yogyakarta. This research was an explorative research which include bacterial characterization and experimental research which include antagonistic test of chitinolytic bacteria against Phytophthora palmivora. The chitinolytic bacteria was isolated using selective chitin agar medium by pour plate method and then screening the isolates that had chitinase enzyme activity by measuring the enzyme activity of each bacterial isolates by spectrophotometric method. Selected bacterial isolates were characterized by macroscopic, microscopic and physiological characters. The bacteria that had been selected tested for their ability to reduce the growth of Phytophthora palmivora by Kirby Bauer modification method. The result showed that there were 10 isolates that had chitinase enzyme activity which two selected isolates had the higher chitinase enzyme activity. There were 7D and 6B isolates. The isolate 7D had 1,258 u/ml chitinase enzyme activity and isolate 6B had 1,212 u/ml chitinase enzyme activity. The result of chitinolytic bacterial antagonist test on Phytophthora palmivora growth showed that both bacterial isolates were potential to antifungal Phytophthora palmivora and showed a real effect in inhibiting the growth of Phytophthora palmivora with significance value < 0,05.Keywords: Chitinolytic Bacteria, Perna viridis, Phytophthora palmivora