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100+ Free BGCSE BSSE Biology 1428 Practice Questions
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2026 Statistics
Key Facts: BGCSE BSSE Biology 1428 Exam
1428
BEC Syllabus Code
Botswana Examinations Council
40
Paper 1 MCQs
BEC Exam Structure
45m
Paper 1 Duration
BEC Exam Timetable
Grade C
Target Benchmark
Botswana Education Standard
100
Practice Questions
OpenExamPrep Question Bank
BGCSE / BSSE Biology 1428 is administered by the Botswana Examinations Council (BEC) for senior secondary students. The assessment tests outcome-based biological principles across cell biology, plant physiology, human organ systems, genetics, ecology, and biotechnology. This 100-question practice bank provides comprehensive preparation aligned with the BEC 1428 syllabus.
Sample BGCSE BSSE Biology 1428 Practice Questions
Try these sample questions to test your BGCSE BSSE Biology 1428 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.
1Which organelle is primarily responsible for generating ATP through aerobic cellular respiration in eukaryotic cells?
A.Ribosome
B.Mitochondrion
C.Golgi apparatus
D.Endoplasmic reticulum
Explanation: Mitochondria are known as the powerhouses of the cell because they perform aerobic respiration to produce ATP from glucose and oxygen. They contain internal cristae and a matrix equipped with respiratory enzymes. Ribosomes synthesize proteins, while the Golgi apparatus modifies and packages molecules.
2Which set of cell structures is present in a plant leaf cell but absent in a human cheek cell?
A.Cell membrane, nucleus, cytoplasm
B.Cell wall, chloroplast, large central vacuole
C.Mitochondria, ribosomes, cell membrane
D.Cytoplasm, nuclear membrane, ribosomes
Explanation: Plant leaf cells possess a cellulose cell wall for structural support, chloroplasts for photosynthesis, and a large central vacuole for turgor pressure. Animal cells lack cell walls and chloroplasts, and usually possess only small, temporary vacuoles. Both cell types share common structures like the nucleus, cell membrane, mitochondria, and cytoplasm.
3What is the primary cellular function of ribosomes?
A.Lipid storage
B.Protein synthesis
C.DNA replication
D.Cellular digestion
Explanation: Ribosomes assemble amino acids into polypeptide chains according to the sequence specified by mRNA, performing protein synthesis. They exist free in the cytoplasm or bound to the rough endoplasmic reticulum. Lipid storage occurs in lipid droplets or smooth ER, while cellular digestion is carried out by lysosomes.
4Osmosis is best defined as the net movement of:
A.Solute molecules from a dilute solution to a concentrated solution across a permeable membrane.
B.Water molecules from a higher water potential to a lower water potential across a selectively permeable membrane.
C.Gas molecules from a low concentration to a high concentration requiring energy.
D.Ions against their concentration gradient using transport proteins and ATP.
Explanation: Osmosis is a specialized form of passive transport involving the net diffusion of water molecules from a region of higher water potential (dilute solution) to a lower water potential (concentrated solution) through a partially permeable membrane. It does not consume metabolic energy (ATP). Solute movement or active ion transport represent distinct processes.
5Which change would cause the fastest increase in the rate of simple diffusion of glucose into a cell?
A.Decreasing the extracellular glucose concentration
B.Increasing the temperature and increasing the extracellular glucose concentration
C.Decreasing the surface area of the cell membrane
D.Increasing the thickness of the cell membrane barrier
Explanation: Fick's law dictates that diffusion rate is directly proportional to surface area and concentration gradient, and inversely proportional to diffusion distance. Increasing temperature increases kinetic energy of molecules, and increasing extracellular glucose concentration steepens the gradient, both increasing diffusion rate.
6Active transport differs from passive transport because active transport:
A.Moves substances down their concentration gradient without carrier proteins.
B.Requires ATP energy to move particles against a concentration gradient.
C.Occurs only in dead cells with permeable cell walls.
D.Transports only water molecules across a fully permeable membrane.
Explanation: Active transport uses cellular metabolic energy (ATP) and carrier proteins embedded in the cell membrane to move ions or molecules from a region of lower concentration to a region of higher concentration. Passive processes like diffusion move particles down their concentration gradient without consuming ATP.
7What happens when a fresh red onion epidermal cell is placed in a concentrated (hypertonic) sucrose solution?
A.Water enters the cell by osmosis, causing it to burst (lysis).
B.Water leaves the cell by osmosis, causing the cytoplasm to pull away from the cell wall (plasmolysis).
C.Sucrose enters the vacuole by active transport, turning the cell turgid.
D.No net water movement occurs because the cell wall prevents osmosis.
Explanation: In a hypertonic sucrose solution, the solution has a lower water potential than the cell sap inside the onion cell. Water leaves the cell vacuole by osmosis across the selectively permeable cell membrane. As the vacuole shrinks, the cell membrane and cytoplasm pull away from the rigid cell wall, a process called plasmolysis.
8According to the lock-and-key model of enzyme action, the 'key' represents the:
A.Enzyme active site
B.Specific substrate molecule
C.Product of the reaction
D.Co-enzyme factor
Explanation: In the classic lock-and-key model, the enzyme's active site acts as the rigid 'lock', and the specific substrate molecule acts as the fitting 'key'. The substrate shape is complementary to the active site, allowing an enzyme-substrate complex to form.
9Why does heating an enzyme to 70 °C drastically reduce its rate of catalysis?
A.The substrate molecules gain kinetic energy and move too fast to bind.
B.High temperature breaks hydrogen and ionic bonds, altering the active site shape (denaturation).
C.Heat converts the protein into carbohydrates, destroying the active site.
D.High temperature increases activation energy requirement beyond cell limits.
Explanation: Enzymes are proteins whose tertiary structure is maintained by hydrogen bonds, ionic bonds, and disulfide bridges. High temperatures (above optimum) cause thermal agitation that breaks these bonds, causing the active site to lose its complementary shape (denaturation). Substrates can no longer bind.
10Pepsin operates efficiently in the stomach at pH 2. What is the most likely reason pepsin becomes inactive when it enters the duodenum at pH 8?
A.Stomach acid converts pepsin into trypsin.
B.Alkaline pH changes the electrical charges and hydrogen bonding of pepsin, denaturing its active site.
C.Duodenal bile coats pepsin molecules so substrates cannot reach it.
D.Low temperature in the duodenum slows down collision frequency.
Explanation: Each enzyme has an optimum pH. Extreme changes in pH alter H+ and OH- ion concentrations, disrupting ionic and hydrogen bonds holding the enzyme's active site in shape. At pH 8, pepsin undergoes denaturation and loses catalytic activity.
About the BGCSE BSSE Biology 1428 Practice Questions
Verified exam format metadata for Botswana BGCSE / BSSE Biology (Syllabus 1428) is pending. The practice questions above remain available while official exam length, timing, passing score, fee, and administrator details are reviewed.