Test: Plant Growth & Development - 2 - NEET MCQ

One single maize root apical meristem can give rise to more than 17,500 new cells per hour.

The tissues that have ability of cell division located in specific area are called meristem. They are located at stem and root tips, nodes of stem and intercalary region.

ABA stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses.Therefore, it is also called the stress hormone.

• All cells of a plant are descendants of the zygote.
• Trees continue to increase in height or girth over some time.
• However, the leaves, flowers and fruits of the same tree appear and fall periodically and sometimes repeatedly.

The type of cambium located between phloem and xylem is classified as vascular cambium.
Explanation:
The vascular cambium is responsible for the secondary growth of plants, which involves the production of additional vascular tissue (xylem and phloem) in the stems and roots. It is a type of lateral meristem, meaning it produces cells that increase the girth of the plant. Here are some key points about vascular cambium:
- Location: The vascular cambium is located between the xylem and phloem in the vascular bundles of plants. It forms a continuous cylinder-like layer.
- Function: The main function of the vascular cambium is to produce new xylem cells towards the center of the stem and new phloem cells towards the outside. This results in the thickening of the stem and root, allowing for the transport of water, minerals, and nutrients throughout the plant.
- Cell Types: The vascular cambium produces two types of cells: xylem and phloem. Xylem cells are responsible for the transport of water and minerals, while phloem cells are responsible for the transport of sugars and other organic molecules.
- Growth Rings: The activity of the vascular cambium produces annual growth rings in woody plants. Each growth ring represents one year of growth and consists of a layer of xylem cells produced during the growing season.
In conclusion, the type of cambium located between phloem and xylem is called vascular cambium. It plays a crucial role in the secondary growth and structural support of plants.

Growth is the permanent and irreversible increase in dry weight, size, mass, volume of cells, organs or organism is called growth.

Gibberellins also promote bolting (internode elongation just prior to flowering) in beet, cabbages and many plants with rosette habit.

• Development is the sum of two processes-growth and differentiation.
• To begin with, it is essential and sufficient to know that the development of a mature plant from a zygote follows a precise and highly ordered succession of events.

The callus (a mass of undifferentiated cells) proliferated only if, in addition to auxins the nutrients medium was supplemented.

In dicotyledonous plants, girth of stem and root increase due to secondary growth. Secondary growth occurs due to cambium formation in stem and root.

Cytokinin is named as anti-ageing hormone.

Auxin and ethylene are the plant hormone that promotes femaleness in flower.

The initial growth is slow (lag phase), and it increases rapidly thereafter – at an exponential rate (log or exponential phase). Here, both the progeny cells following mitotic cell division retain the ability to divide and continue to do so. However, with limited nutrient supply, the growth slows down leading to a stationary phase.

Arithmetic growth is represented by L_t = L₀ + rt where L_t is final growth, L₀ is initial size and rt is the rate of growth and time respectively.

In most of the higher plants, the growing apical bud inhibits the growth ofthe lateral (axillary) buds, a phenomenon called apical dominance.

Rotten fruit produce ethylene gas that hasten the ripening of unripe fruits. So, if a rotten fruit get mixed with unripe fruits the remaining unripe get ripen faster.

The term ‘auxin’ is applied to the indole-3-acetic acid (IAA), and to other natural and synthetic compounds having certain growth regulating properties. They are generally produced by the growing apices of the stems and roots.

Testing of biological activity like growth response of a substance by employing a living material like plant or plant part is called bioassay. It is used to know the effect of substance on plant growth.

Ethylene is highly effective in fruit ripening. It enhances the respiration rate during ripening of the fruits.

GA3 is a gibberellins that help in elongation of stem of the plant. If GA3 plant hormone is applied to the rice seedling the plant will show extra elongation of plant body.

Abscisic acid (ABA)was discovered for its role in regulating abscission and dormancy.

Ethylene promotes female flowers in cucumbers thereby increasing the yield.

• In dicotyledonous plants and gymnosperms, the lateral meristems, vascular cambium and cork cambium appear later in life.
• These are the meristems that cause an increase in the girth of the organs in which they are active.
• This is known as secondary growth of the plant.

Irreversible increase in mass or volume of plant part is called apparent growth. Apparent growth is permanent and cannot be reversed back as it occurs due to increase in cell number.

Auxin was isolated by F.W. Went from tips of coleoptiles of oat seedlings.