MENGO SENIOR SCHOOL – BIOLOGY
PAPER 1 (THEORY)
S.5 BCM – END OF TERM I EXAMINATION
Time: 2 hours
Instructions: Attempt all questions. Each scenario is based on real-life situations and
challenges. Use scientific reasoning and biological knowledge to solve the problems
presented. Do not write your name.
1. Scenario: Water Crisis in Kamuli Community
In Kamuli district, the residents of Buwenge village have been facing frequent heatwaves.
The community borehole, which served both domestic use and livestock, dried up for a
week. Many residents reported headaches, dizziness, dry mouths, and fatigue. A local health
worker, Sister Ritah, observed that urine samples from the affected individuals were dark
yellow and highly concentrated. She also noted a rise in cases of constipation and kidney-
related complications.
● a) Identify the biological role of water being highlighted in this community issue.
● b) Explain how lack of water affects the process of excretion in the human body.
● c) State two properties of water that make it suitable for temperature regulation in
living organisms.
● d) Using knowledge of biochemistry, explain why dehydration can affect metabolic
reactions in body cells.
2. Scenario: Kalungi Mixed Farm Report on Animal Diet
At Kalungi Mixed Farm in Mpigi, veterinary officer Mr. Mukiibi decided to review the diet of
young calves and piglets. He noticed that those fed on mostly carbohydrate-rich feeds grew
rapidly in weight but had weak muscles and bloated abdomens. On the other hand, animals
on protein-supplemented feeds developed strong limbs, clear eyes, and active responses.
Blood tests from both groups were compared.
● a) Describe the nutritional imbalance observed in the first group of animals.
● b) Compare the biological roles of carbohydrates and proteins in animal nutrition.
● c) Name the type of biochemical test Mr. Mukiibi could perform to detect presence of
proteins in animal feeds.
● d) Explain how lipids contribute to long-term energy storage and insulation in livestock.
3. Scenario: Strange Structures Seen Under the Microscope
During a microscopy practical at Mengo Senior School, Miss Nakamya asked her S.5 class to
observe cells from onion epidermis and cheek swabs. Moses, a student, observed thread-
like structures in one sample and small green bodies in another. Some students thought
both samples were the same, but their teacher emphasized that the two types of cells had
fundamental differences in structure and function.
● a) Distinguish between the two cell types observed by Moses.
● b) Identify the thread-like structures seen in one of the samples and explain their
function.
● c) Explain why one sample contained green bodies while the other did not.
● d) Discuss the importance of compartmentalization in the cell cytoplasm for efficient
functioning.
4. Scenario: Wandegeya Clinic Heart Monitoring Report
At Wandegeya Clinic, patients with high blood pressure were monitored using ECG
machines. Nurse Amutuhaire recorded pulse readings from three patients after they
climbed three flights of stairs. One patient had a sharp increase in heart rate and reported
chest pain. Another had a low, irregular pulse even at rest. A third patient had a steady
increase in heart rate with exercise but returned to normal shortly after resting.
● a) Identify the role of the heart in maintaining internal balance during exercise.
● b) Suggest a likely heart condition for the patient with irregular pulse and low rate.
● c) Explain how the structure of cardiac muscles supports the continuous function of the
heart.
● d) Describe two ways in which blood pressure is regulated by the body during physical
activity.
5. Scenario: Bukomansimbi Reforestation Project
During a tree-planting campaign in Bukomansimbi, biology students from St. Bruno SS
collected samples of young stems from different plants. Under the microscope, they
observed differences in cell arrangement and thickness of cell walls. The supervisor
explained that these differences were important in enabling plants to survive wind, support
growth, and transport substances. Some cells appeared empty but allowed water to pass
through quickly.
● a) Name the plant tissue responsible for support and transport of water.
● b) Compare the structure of parenchyma and collenchyma tissues and their respective
roles.
● c) Explain how xylem tissue is adapted for its function in a plant stem.
● d) State one reason why the arrangement of tissues in monocots differs from that in
dicots.
