Biology Class 11 NCERT Solutions: Chapter 6 Anatomy of Flowering Plants Part 1

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Q: 1. State the location and function of different types of meristem.

Answer:

Meristems are specialised regions of plant growth. The meristems mark the regions where active cell division and rapid division of cells take place. Meristems are of three types depending on their location.

Image of the different types of meristem

Image of the Different Types of Meristem

Image of the different types of meristem

Apical meristem

It is present at the root apex and the shoot apex. The shoot apical meristem is present at the tip of the shoots and its active division results in the elongation of the stem and formation of new leaves. The root apical meristem helps in root elongation.

Intercalary meristem

It is present between the masses of mature tissues present at the bases of the leaves of grasses. It helps in the regeneration of grasses after they have been grazed by herbivores. Since the intercalary meristem and the apical meristem appear early in a plant's life, they constitute the primary meristem.

Lateral meristem

It appears in the mature tissues of roots and shoots. It is called the secondary meristem as it appears later in a plant's life. It helps in adding secondary tissues to the plant body and in increasing the girth of plants. Examples include fascicular cambium, interfascicular cambium, and cork cambium

Q: 2. Cork cambium forms tissues that form the cork. Do you agree with this statement? Explain.

Answer:

When secondary growth occurs in the dicot stem and root, the epidermal layer gets broken. There is a need to replace the outer epidermal cells for providing protection to the stem and root from infections. Therefore, the cork cambium develops from the cortical region. It is also known as phellogen and is composed of thin-walled rectangular cells. It cuts off cells toward both sides. The cells on the outer side get differentiated into the cork or phellem, while the cells on the inside give rise to the secondary cortex or phelloderm. The cork is impervious to water, but allows gaseous exchange through the lenticels. Phellogen, phellem, and phelloderm together constitute the periderm.

Q: 3. Explain the process of secondary growth in stems of woody angiosperm with help of schematic diagrams. What is the significance?

Answer

In woody dicots, the strip of cambium present between the primary xylem and phloem is called the interfascicular cambium. The interfascicular cambium is formed from the cells of the medullary rays adjoining the interfascicular cambium. This results in the formation of a continuous cambium ring. The cambium cuts off new cells toward its either sides. The cells present toward the outside differentiate into the secondary phloem, while the cells cut off toward the pith give rise to the secondary xylem. The amount of the secondary xylem produced is more than that of the secondary phloem.

Q 3 Image of Stages Secondary Grouth in Dicot Stem

Q 3 Image of Stages Secondary Grouth in Dicot Stem

Q 3 Image of Stages Secondary Grouth in Dicot Stem

The secondary growth in plants increases the girth of plants, increases the amount of water and nutrients to support the growing number of leaves, and also provides support to plants.