ATP-ADP CYCLE (1)
What are the three main components of an ATP molecule?
A. Adenine, glucose, and phosphate
B. Ribose, cytosine, and phosphate
C. Adenine, ribose, and phosphate
D. Guanine, ribose, and phosphate
C
What are the products when ATP is hydrolyzed?
A. ADP, water, and oxygen
B. ADP, phosphate, and energy
C. ATP, phosphate, and glucose
D. ADP, ribose, and adenine
B
Which pigment gives carrots their orange color?
A. Chlorophyll b
B. Carotenoids
C. Xanthophyll
D. Chlorophyll a
B
What molecule provides the electrons for the light-dependent reaction?
A. Carbon dioxide
B. Glucose sugar
C. Oxygen gas
D. Water molecule
D
What is the Calvin Cycle also called?
A. Energy-absorbing reaction
B. Light-dependent reaction
C. Water-splitting reaction
D. Light-independent reaction
D
How are photosynthesis and the ATP–ADP cycle related?
A. It provides energy to reform ATP
B. It prevents ATP from breaking down
C. It stops ADP from being used again
D. It replaces phosphate with oxygen
A
The light reactions of photosynthesis provide energy that converts ADP and Pi into ATP, fueling the Calvin Cycle.
Which statement best describes the ATP–ADP cycle?
A. A single-use energy process
B. A repeated breakdown and formation of ATP
C. A slow and limited reaction
D. A cycle found only in plants
B.
The ATP–ADP cycle is continuous in all living cells, breaking ATP to release energy and reforming it for reuse.
Which color of light does chlorophyll absorb most effectively?
A. Blue and red light
B. Green and yellow light
C. Orange and violet light
D. White and infrared light
A
Chlorophyll strongly absorbs blue and red wavelengths, which are most useful for photosynthesis.
Why is the splitting of water important in the light-dependent reaction?
A. It provides glucose for the plant
B. It creates ATP through diffusion
C. It supplies electrons and oxygen.
D. It absorbs carbon from the air
C
Water splitting, or photolysis, provides the electrons to replace those lost by chlorophyll and releases oxygen as a by-product.
Where does the Calvin Cycle take place in the chloroplast?
A. Thylakoid membrane
B. Chloroplast stroma
C. Cytoplasmic matrix
D. Outer cell wall
B
The Calvin Cycle occurs in the stroma, the fluid-filled area of the chloroplast where enzymes like RuBisCO are located.
What happens during ATP regeneration?
A. ADP combines with oxygen
B. ADP joins with phosphate using energy
C. ATP breaks into glucose molecules
D. ATP forms without any energy input
B
Regeneration occurs when ADP and inorganic phosphate (Pi) combine using energy from food (cellular respiration) or sunlight (photosynthesis).
Why does breaking the last phosphate bond in ATP release energy?
A. The bond is weak and unstable
B. The bond forms more ATP molecules
C. The bond attracts positive charges
D. The bond contains stable electrons
A
The three phosphate groups repel each other due to negative charges, making the bond unstable and full of stored energy.
Why do farmers need to understand the importance of pigments?
A. To increase the oxygen level in soil
B. To improve plant growth under sunlight
C. To reduce the number of plant roots
D. To prevent insects from eating leaves
B
Farmers apply pigment knowledge to ensure crops receive optimal light wavelengths for photosynthesis and growth.
Why are ATP and NADPH important products of the light-dependent reaction?
A. They release oxygen for respiration
B. They form pigments for leaf color
C. They carry carbon to the mitochondria
D. They store chemical energy for the Calvin Cycle
D
ATP and NADPH serve as energy carriers that power the light-independent reactions where glucose is formed.
What happens to most G3P molecules produced in the Calvin Cycle?
A. They are broken down to release oxygen
B. They are converted directly into proteins
C. They are recycled to regenerate RuBP
D. They are stored as starch in vacuoles
C
Most G3P molecules are used to regenerate RuBP using ATP so that the Calvin Cycle can continue.
What would happen if a cell could no longer regenerate ATP?
A. They would continue normal functions
B. They would produce more oxygen
C. They would lose the ability to work
D. They would store extra phosphate
C
Without ATP regeneration, the cell cannot power essential processes, leading to loss of function and eventually cell death.
Which organelle is mainly responsible for ATP production in eukaryotic cells?
A. Mitochondrion
B. Ribosome
C. Golgi apparatus
D. Lysosome
A
The mitochondria perform cellular respiration, where glucose is broken down to produce ATP.
What happens to electrons when chlorophyll absorbs light energy?
A. They split water into hydrogen and oxygen
B. They stay in their ground state
C. They move to a higher energy level
D. They leave the chloroplast membrane
C
When light hits chlorophyll, electrons are excited to a higher energy level, starting the photoexcitation process.
Where do light-dependent reactions take place?
A. Stroma of the chloroplast
B. Thylakoid membrane of the chloroplast
C. Nucleus of the cell
D. Cytoplasm of the cell
B
Light-dependent reactions occur in the thylakoid membranes where chlorophyll absorbs sunlight.
What are the main products of the Calvin Cycle?
A. Glucose, ADP, and NADP⁺
B. Glucose, oxygen, and water
C. Pyruvate, NADH, and CO₂
D. Water, glucose, and oxygen
A
The Calvin Cycle produces glucose as food and regenerates ADP and NADP⁺ for the next light reaction.
Why does the absence of food intake reduce your body’s energy availability?
A. Because oxygen levels rise and slow respiration
B. Because protein synthesis replaces energy production
C. Because excess carbon dioxide blocks enzyme activity
D. Because glucose supply decreases, limiting ATP formation
D
When you skip meals, glucose becomes limited. Since glucose is the main fuel for ATP production, less ATP is formed, leading to tiredness.
Which biochemical event provides the immediate energy required for muscle contraction?
A. The release of carbon dioxide during respiration
B. The conversion of glucose into pyruvate molecules
C. The breakdown of ATP into ADP and inorganic phosphate
D. The production of ATP from stored glycogen
C
Muscle contraction is powered by ATP hydrolysis, which releases energy when ATP splits into ADP and phosphate.
What would happen if chlorophyll pigments stopped absorbing red and blue light?
A. Plants would absorb more oxygen
B. Leaves would turn completely yellow
C. The roots would stop taking water
D. Photosynthesis would slow down drastically
D
Without red and blue light absorption, chlorophyll could not excite electrons efficiently, causing photosynthesis to weaken.
What happens to the excited electrons from chlorophyll during the light-dependent reaction?
A. They move through an electron transport chain
B. They combine with oxygen molecules
C. They remain inside the thylakoid lumen
D. They form carbon dioxide molecules
A
The excited electrons travel through the electron transport chain, producing ATP and NADPH used in the Calvin Cycle.
Why is the Calvin Cycle essential to life on Earth?
A. It releases oxygen needed for cellular respiration
B. It removes nitrogen from the atmosphere
C. It provides the food energy source for living organisms
D. It helps plants absorb minerals from the soil
C
The Calvin Cycle produces sugars that serve as the foundation of food chains, supporting nearly all life on Earth.