Plant Anatomy: A Brief Introduction

Anatomy is the branch of science that deals with the study of gross internal structure of plant organs as observed after section cutting.

 

Q1. Which of the following statement is true in relation to plant tissues?

1. The term tissue was given by the scientist Grew
2. Tissue is a group of cells that perform common functions
3. Tissue represent group of cells having common origin
4. Plant tissue can be divided into two groups: meristematic and permanent tissue
5. All of the above

Ans: e

Grew is known as the Father of Plant Anatomy. K. A. chaudhary is known as the Father of Indian Plant Anatomy.

Meristematic tissue (Meristos=divisible) is the one that retains the power of division. The term meristem was given by C. Nageli. On the other hand, permanent tissue is the one that has lost the capacity to divide.

Q2. Which of the following statement is incorrect for meristematic tissue?

1. The cells of meristematic tissue are small sized and having thin cell wall
2. The cells of meristematic tissue are loosely arranged with intercellular spaces
3. The cells of meristematic tissue have dense protoplasm and large nucleus
4. The number of mitochondria in meristematic cells is high
5. Vacuoles are generally absent

Ans: b

The meristematic cells do not possess cholorophyll and plastid, but proplastid (precursor of plastid) is present. Besides, reserve food is also absent in meristematic cells. So, how they obtain food? Well, meristematic cells obtain food from the surrounding cells and to obtain food, they have high surface area. Besides, meristematic cells do not possess ergastic substances (secretary substances such as gums, resins).

Plant Anatomy: Types of Meristematic Tissue

Q3. On the basis of origin, meristematic tissue can be divided into:

1. Primary meristem
2. Secondary meristem
3. Tertiary meristem
4. Both a and b

Ans: d

On the basis of origin, meristem is divided into three classes: PROMERISTEM: aks primordial meristem. They are a group of cells, which represent primary stages of meristematic cells. They are present in small region at the apices of shoots and roots. They give rise to primary meristem. PRIMARY MERISTEM: they originate from promeristem. These cells are always in active state of division and give rise to primary permanent tissue. In most monocots and herbaceous dicots, only primary meristem is present. SECONDARY MERISTEM:  they are meristems developed from primary permanent tissue. They are not present from the very beginning of the formation of an organ, but develop at a later stage and give rise to secondary permanent tissue.

Q4. On the basis of position, meristematic tissue can be divided into:

1. Apical meristem
2. Intercalary meristem
3. Lateral meristem
4. All of the above

Ans: d

Q5. Which of the following statement is correct in relation to primary and secondary meristem?

1. The cells of the primary meristem are derived either from the embryo directly or derivatives of the embryo
2. The cells of the primary meristem differentiate to form primary permanent tissue
3. The secondary meristem is derived from the primary permanent tissue through the process of dedifferentiation
4. The secondary meristem becomes secondary permanent tissue to perform some specific functions through the process of redifferentiation
5. All of the above

Ans: e

The primary meristem is present at the root and shoot apex and involved in increasing the length of the plant organs. They differentiate to form primary permanent tissue to perform certain specific functions. The primary meristem remains present right from the beginning. The function of secondary meristem is to increase the girth (diameter) of the plant.

Q6. Which of the following statement is incorrect in relation to apical meristem?

1. The shoot apical meristem are long (1cm) and terminal in position while the root apical meristem is short (1mm) and subterminal in position
2. The shoot apical meristem cut cells in the basal region while the root apical meristem cut cells in the apex region
3. Both root and shoot apical meristem are primary meristem
4. Both root and shoot apical meristem are involved in the elongation of root and shoot
5. None of the above

Ans: b

Q7. Which of the following statement is true for intercalary meristem?

1. Intercalary meristem is derived from apical meristem
2. Intercalary meristem is so called because it is present between two primary permanent tissue
3. Intercalary meristem can be present above and below the node as well as at the base of the leaf
4. Intercalary meristem is seen in greases
5. All of the above

Ans: e

Intercalary meristem is a primary meristem derived from the apical meristem. It is formed by the separation of the apical meristem and squeezed between two primary permanent tissues. It is present in grasses, mint, pinus and equisetum, etc.

 

Q8. Which of the following statement is correct in relation to lateral meristem?

1. Lateral meristem can either be primary or secondary meristem
2. Intrafascicular / fascicular cambium is the only one tissue which is derived from primary meristem
3. The lateral meristem is only seen in dicots and gymnosperms and absent in monocots
4. Secondary lateral meristem may include interfascicular cambium, cork cambium, vascular cambium and wound cambium, etc
5. All of the above

Ans: e

Intrafascicular cambium is primary meristem but it functions as secondary meristem. Between the vascular bundles there is presence of primary permanent tissue, called MEDULLARY RAYS (made from parenchyma). During the latter stage, the thin cells of medullary rays gain the capacity of division. This leads to the formation of interfascicular cambium through dedifferentiation. The vascular cambium ring cuts cells in both directions (outside and inside). The cells cut outside form secondary phloem and the cells cut inside form secondary xylem.

Q9. Which of the following options are true in relation to primary permanent tissue?

1. If the tissue originates from apical meristem or intercalary meristem, it is called primary permanent tissue
2. If the tissue originates from lateral meristem, it is called secondary permanent tissue
3. If a permanent tissue consists of only one type of cells, known as simple permanent tissue
4. If a permanent tissue consists of more than one type of cells, known as complex tissue
5. All of the above

Ans: e

Simple permanent tissues are of three types: Parenchyma, collenchymas and schlerenchyma. Complex tissues are though formed of more than one type of cells, but they function together as a unit. The examples are xylem and phloem.

Plant Anatomy: THEORIES OF SHOOT APEX ORGANIZATION

Q10. Which of the following statement is true for apical cell theory in relation to the shoot apex organization?

1. Apical cell theory was given by Hofmeister and Nageli
2. According to the apical cell theory, the shoot apical meristem consists of only one cell that has the capacity to form complete plant body
3. Apical cell theory is applicable for applicable to only simple plants such as algae, bryophytes and pteridophytes
4. All of the above

Ans: d

Apical cell theory is not applicable for gymnosperms and angiosperms.

Q11. Which of the following option is correct for the histogen theory related to the shoot apex organization?

1. Histogen theory was given by Hanstein
2. According to histogen theory, it is composed of three layers: dermatogens, periblem and plerome
3. Histogen theory is applicable for higher plants such as gymnosperms and angiosperms
4. All of the above

Ans: d

Dermatogen (outermost) gives rise to epidermis. Periblem (middle) gives rise to cortex including endodermis. Plerome (innermost) gives rise to vascular bundle and pith.

Q12. In histogen theory, which layer is formed by the plerome?

1. Xylem and phloem
2. Pith
3. Pericycle
4. All of the above

Ans: d

Vascular bundle, pith and pericycle constitute STELE.

Q13. Which of the following statement is true for the Tunica Corpus theory in relation to the shoot apex organization?

1. The Tunica Corpus theory was given by Schmidt
2. The apex shoot consists of only two regions: tunica and corpus
3. Tunica shows anticlinal division while corpus shows both anticlinal and periclinal mode of division
4. Tunica corpus theory is applicable for higher plants
5. All of the above

Ans: e

Tunica is generally single layered. It divides only anticlinally. In multilayered tunica, the outermost layer forms the epidermis and rest of the layers from cortex and leaf primordia.

Corpus is below the tunica. It divides both anticlinally as well as periclinally. Its activity results in the formation of cortex and stele. The cells of corpus are large and divide to result in increase in volume.

ROOT APEX ORGANIZATION

Root apex is having the simplest organization as compared to shoot apex. Root apex is subapical or subterminal in position because of the presence of root cap (CALYPTROGEN) at the apex.

Q14. The histogen theory in relation to the root apex organization says that root is formed of three layers. The outermost layer dermatogen is dicots is responsible for making;

1. The epidermis only
2. The epidermis and root cap
3. The cortex
4. The vascular bundle

Ans: b

In case of shoot apex organization, the histogen theory says that the dermatogen forms only the epidermis, but in case of root apex organization, it forms epidermis and root cap both.

Q15. According to Histogen theory, the different layers are formed in monocots through the root apex organization. These layers include:

1. Dermatogen, periblem, plerome
2. Dermatogen and plerome
3. Dermatogen, periblem, plerome, and calyptrogens
4. Dermatogen, plerome and calyptrogens

Ans: c

On the outer side of the dermatogens, there is formation of calyptrogens responsible for forming the root cap.

Q16. Which of the following statement is true for Korpe-Kappe theory?

1. Korpe-Kappe theory was given by Schuepp
2. Kappe is responsible for forming the epidermis
3. Korpe is responsible for forming the ground tissue and vascular tissue
4. All of the above

Ans: d

Q17. Which of the following option is true for quiescent centre?

1. It is an inverted cup shaped structure present at the root apex
2. The cells of the quiescent centre show low mitotic activity
3. The cells of the quiescent centre have less DNA, RNA and protein content
4. If the root apical meristem is injured, the cells of the quiescent centre take over its function
5. All of the above

Ans: e

Since quiescent centre takes over the function of the main apical meristem, it is also called as reserved meristem.

According to this, there is an inactive centre in the root apex which is called QUIESCENT CENTRE (having low DNA, RNA and proteins) and it acts as reservoir of active initials.

Plant Anatomy