Practise 33 real Federal Board questions on Bioenergetics from 2023 to 2026. See the answer and explanation as soon as you answer.
Bioenergetics is one of the 15 main chapters in our Federal Board FSC Biology question bank (11th class), and about 7% of its real questions come from it. Tayyari Karo has 33 real questions on this chapter from 2023 to 2026; 7 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 30 medium, 2 hard, 1 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
During anaerobic respiration in human muscles, pyruvate is converted into:
Answer: C. Lactic acid
In oxygen-deprived muscle cells, pyruvate is reduced to lactic acid (lactate) by lactate dehydrogenase, regenerating NAD⁺ so glycolysis can continue.
When energy flows from one trophic level to the next, the amount of energy lost is about:
Answer: C. 90%
Only about 10% of energy is transferred to the next trophic level (the '10% rule'); roughly 90% is lost as heat/respiration/waste at each step.
Which one of the following sequence of reactions is correct regarding Calvin cycle?
Answer: A. 3PGA → 1,3-BPG → G3P
In the Calvin cycle, 3-phosphoglycerate (3PGA) is phosphorylated by ATP to 1,3-bisphosphoglycerate, then reduced by NADPH to glyceraldehyde-3-phosphate (G3P).
Which of the following best describes the role of ATP synthase in cellular respiration?
Answer: C. Utilizes proton gradient to form ATP
ATP synthase uses the energy of protons flowing down their electrochemical gradient (built by the electron transport chain) to phosphorylate ADP into ATP.
Which plant tissue is responsible for the transport of sugars?
Answer: A. Phloem
Phloem (sieve tubes and companion cells) transports organic food (sugars) throughout the plant; xylem transports water and minerals.
Absorption of different wavelengths by photosynthetic pigments is measured by:
Answer: C. Spectrophotometry
A spectrophotometer measures how much light of each wavelength a pigment absorbs, producing its absorption spectrum.
Outline steps of preparatory phase of glycolysis.
1. Glucose is phosphorylated by ATP (using hexokinase) to form glucose-6-phosphate.
2. Glucose-6-phosphate is isomerised to fructose-6-phosphate.
3. Fructose-6-phosphate is phosphorylated by a second ATP to form fructose-1,6-bisphosphate.
4. The enzyme aldolase splits fructose-1,6-bisphosphate into two 3-carbon sugars (DHAP and G3P), which (after isomerisation of DHAP) give two molecules of G3P — consuming a net 2 ATP and preparing the molecule for the energy-yielding (pay-off) phase.
Explain the mechanism of photoperiodism.
Photoperiodism is a plant's physiological response (especially flowering) to the relative length of day and night. Plants perceive the light/dark duration through the pigment phytochrome, which exists in two interconvertible forms: Pr (absorbs red light, ~660 nm) and Pfr (absorbs far-red light, ~730 nm, the biologically active form promoting/inhibiting flowering depending on species). Red light converts Pr → Pfr; far-red light (and slow conversion during darkness) converts Pfr back to Pr. …
The full model answer is in the app.
| Session | Questions |
|---|---|
| 2026 Annual | 6 |
| 2025 1st Annual | 9 |
| 2025 2nd Annual | 7 |
| 2024 Annual | 6 |
| 2023 Annual | 5 |
33 real Federal Board (FBISE) Biology questions on Bioenergetics from 2023 to 2026, for 11th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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