Plant Physiology Biochemistry

Step 1: Recall nutrient mobility in plants.
- Some nutrients are mobile in plants, meaning they can move both upwards (acropetal) and downwards (basipetal). - Some nutrients are immobile and move only acropetally through xylem.

Step 2: Behavior of Calcium.
- Calcium is absorbed from the soil and transported only upward (acropetal movement) in the xylem. - It is not retranslocated from older to younger tissues, making it immobile in phloem. - Hence, deficiency symptoms appear first in young tissues.

Step 3: Eliminate other options.
- Nitrogen: Mobile, moves through xylem and phloem.
- Sulphur: Semi-mobile, but not strictly acropetal.
- Potassium: Highly mobile nutrient.

Step 4: Conclusion.
The nutrient with acropetal-only movement in xylem is Calcium.

Final Answer:

Step 1: Recall the role of enzymes.
Enzymes are biological catalysts, usually proteins (sometimes RNA molecules), that increase the rate of biochemical reactions in living organisms without being consumed.

Step 2: Analyze the options.
- (1) Provides energy to the cell → Wrong, ATP provides energy, not enzymes.
- (2) Catalyse biochemical reactions → Correct, this is the main function of enzymes.
- (3) Saves the genetic information → Wrong, DNA does this, not enzymes.
- (4) Transmits genetic information generation to generation → Wrong, this is done by DNA/RNA, not enzymes.

Step 3: Conclusion.
Thus, the correct answer is that enzymes catalyse biochemical reactions.

Final Answer:

Step 1: Understanding ATP synthesis.
ATP (adenosine triphosphate) is the energy currency of the cell. It is primarily synthesized during cellular respiration, which occurs in the mitochondria through oxidative phosphorylation.

Step 2: Evaluating the options.
- **Chloroplast**: Involved in photosynthesis in plants, not the main site for oxidative ATP synthesis.
- **Nucleus**: Stores genetic material and regulates cellular activities, but not ATP synthesis.
- **Ribosome**: Responsible for protein synthesis, not energy production.
- **Mitochondrion**: The site of the electron transport chain and oxidative phosphorylation, generating ATP. Known as the powerhouse of the cell.

Step 3: Conclusion.
The correct answer is Mitochondrion.

Final Answer: