Growth is an irreversible (permanent) increase in the size of an organ, its parts, or even a single cell. It happens through cell division and cell enlargement, and is usually helped by metabolism (the plant uses energy and makes new protoplasm). Memory hook: growth = "size goes up and cannot come back down" (irreversible + permanent).
Growth in plants = cell division plus cell enlargement, giving an irreversible, permanent increase in size that needs energy (metabolism). A reversible change is not growth.
Your doubts, answered
Why is growth called 'irreversible' and 'permanent'?
Because true growth adds new protoplasm and new cell material. Once the cell divides or lays down a new wall, the plant does not go back to the old smaller size. This is why a leaf or stem does not shrink back after it has grown. A wilted leaf swelling with water again is NOT growth, because that change is reversible.
Does growth only mean cell division?
No. Growth has two parts: (1) cell division (more cells) and (2) cell enlargement (each cell gets bigger, mainly by taking in water into the vacuole and adding new wall material). Both together give an irreversible increase in size. For NEET, remember growth = cell division + cell enlargement, not division alone.
Is every increase in size counted as growth?
No. Only an IRREVERSIBLE increase in size is growth. If a dry seed swells by soaking up water (imbibition), that is reversible and is not growth. Growth must be permanent and is usually joined by metabolic activity (using energy to make new material).
Can a single cell show growth?
Yes. NCERT clearly defines growth as an irreversible increase in size of an organ, its parts, OR even of an individual cell. So growth is not only at the whole-plant level. This exact wording is a common NEET one-liner, so learn it word for word.
Why is growth an important character of a living being?
Growth is one of the most basic and visible signs of life. It shows the plant is making new protoplasm and new cells using energy from metabolism. This is why NCERT begins the chapter by asking 'What is growth?' and links it to metabolic processes.
⚠️ The NEET trap ✗ Any increase in the size of a plant part is called growth. ✓ Only an IRREVERSIBLE (permanent) increase in size is growth. A reversible change, like a seed or cell swelling due to water uptake, is NOT growth. 🧠 NTA loves the word 'irreversible'. If the size can come back down, it is not growth.
Real NEET questions
2023
Which of the following statements is not correct?
A · Plant growth is generally determinate. ✓
B · Plant growth is measurable.
C · Phase of cell elongation of plant cells is characterized by increased vacuolation.
D · Cells in the meristematic phase of growth exhibit abundant plasmodesmatal connections.
Solution: Plant growth is generally INDETERMINATE, not determinate, because meristems give plants the power of unlimited (open) growth throughout life. So statement A is not correct. The other three are true: growth is measurable, the elongation phase shows increased vacuolation, and meristematic cells have many plasmodesmatal connections. This question was repeated across NEET 2016, 2017, 2019, 2020, 2021 and 2023.
2020
The process of growth is maximum during
A · Senescence
B · Dormancy
C · Log phase ✓
D · Lag phase
Solution: In geometric (sigmoid) growth, the rate of growth is maximum during the log (exponential) phase, because both new cells keep dividing at an exponential rate. Lag phase is slow, while senescence and dormancy show declining or suspended growth, so they are wrong.
Solved Plant Growth and Development NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Growth can be defined as an irreversible permanent increase in size of an organ or its parts or even of an individual cell. It is generally accompanied by metabolic processes that use energy.
Is plant growth reversible?
No. Growth is irreversible and permanent. A reversible size change, such as water uptake by a cell, is not growth.
What two processes cause growth?
Cell division (making more cells) and cell enlargement (each cell getting bigger by water uptake into the vacuole and new wall deposition).
Can a single cell grow?
Yes. NCERT says growth can occur in an organ, its parts, or even an individual cell, so growth is not limited to the whole plant.
Why is growth important for NEET?
The definition, the word 'irreversible', and the fact that growth needs metabolism are direct one-mark points that NTA tests in statement-based and assertion questions.
