Tag: internal structure of dicot stem

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Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

Select the correct option:

Given are a few peculiar parts/structures found in plants Cucurbita stem, potato tuber, walnut shell, jute fibres.
Identify the tissue responsible for the distinguishing feature in each part respectively and select the correct option

  1. Collenchymatous hypodermis, Parenchyma, Sclerenchyma, Phloem

  2. Collenchymatous hypodermis, Sclerenchyma,Parenchyma, Phloem

  3. Parenchymatous hypodermis, Parenchyma, Sclerenchyma, Xylem

  4. Collenchymatous hypodermis, Parenchyma, Sclerenchyma, Xylem
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  1. Cucurbita stem: Collenchyma is the tissue of primary body. The cell walls show localized thickenings. It occurs chiefly in the hypodermis of dicot stems( e.g. Cucurbita, Helianthus).
    2. Potato tuber: Parenchyma is cell and tissue type in which the cells have only thin primary walls. The cotyledon of many leguminous plants contains protein and starch in their parenchyma cells. Protein and starch are present in the parenchyma of potato tuber.
    3. Walnut shell: Sclerenchyma consists of thick-walled dead cells. It usually occurs in hard parts of plant bodye.g. hard endocarp of Walnut, almond and coconut).
    4. Jute fibres: Phloem fibres are also called bast fibres and most occur in secondary phloem. The fibres of primary phloem have both cellulose and lignified thickenings.
    So, the correct answer is 'Collenchymatous hypodermis, Parenchyma, Sclerenchyma, Phloem'.
Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

Read the following statements and select the correct option.


Statement 1: Annual rings are distinct in plants growing in temperate regions
Statement 2: In temperate regions, the climatic conditions are not uniform through the year

  1. Both statements $1$ and $2$ are correct
  2. Statements $1$ is correct but statements $2$ is incorrect
  3. Statement $1$ is incorrect but statement $2$ is correct
  4. Both statements $1$ and $2$ are incorrect
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

More distinct annual rings are formed in that regions, where climatic variations are sharp. More distinct annual rings are formed in temperate plants as the climatic conditions of temperate regions are not uniform.

Thus, both the statements are correct.
So, the correct option is (A).

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem
Which of the following statements is incorrect?

  1. In a dicot stem, the pericycle is usually multiplayered

  2. Wood is the common name used for secondary xylem

  3. Peripheral cytoplasm, a large vacuole and a prominent nucleus; all are absent in a mature sieve tube element

  4. Lenticels are the aerating pores present in bark of plants and are associated with gaseous exchange
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The cells of the seive tube elements contains protoplasm. a large vacuole however nucleus is lost at maturity. The conduction of food material takes between the cells through seive plants. The flow of food (sucrose), its loading etc is controlled by companion cells. Each seive tube cell is associated with one companion cell.

So, the correct answer is 'Peripheral cytoplasm, a large vacuole and a prominent nucleus; all are absent in a mature sieve tube element'

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

Hypodermis is _______ in sunflower stem and _________ in maize stem.

  1. Parenchymatous, Collenchymatous

  2. Collenchymatous, Sclerenchymatous

  3. Sclerenchymatous, Collenchymatous

  4. Sclerechymatous, Parenchymatous
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Hypodermis is a distinctive layer of mechanical tissue present in some dicot and monocot stems. It is collenchymatous and present as 3-4 layers. It provides mechanical support and elasticity, also stores food.

In maize the hypodermis consists of a few layers of sclerenchymatous cells, interspersed by chlorenchyma cells. It provides mechanical support to the plant.
So, the correct answer is 'Collenchymatous, Sclerenchymatous'

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

The outermost portion of the cortex in stems of flowering plants is ______ and it is ______ in monocotyledonous stems.

  1. (i) General cortex (ii) Parenchymatous

  2. (i) Endodermic (ii) Collenchymatous

  3. (i) General cortex (ii) Sclerenchymatous

  4. (i) Hypodermis (ii) Sclerenchymatous
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cortex is the outermost layer of the stem or root of the plant. It is surrounded by a parenchymatous layer. The cortex is unspecialized cells which help as conducting tissue in the plants.

So,the correct option is '(i) General cortex (ii) Parenchymatous

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

In which structure peripheral vascular bundles are generally smaller than centrally located ones?

  1. Dicot stem

  2. Monocot stem

  3. Dicot root

  4. Monocot root
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

Peripheral vascular bundles are generally smaller than the centrally located ones because the phloem parenchyma is absent and the water containing cavities are present in the vascular bundles which are both in monocot and dicot stem.


So, the correct options are 'Monocot stem' and 'Dicot stem'.

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

Monocot roots differ from dicot roots in having 

  1. Open vascular system

  2. Presence of root hair

  3. Number of xylem / phloem strands

  4. Presence of cortex
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Most of the features of the dicot and monocot roots are similar except the vascular bundles. In the dicot root, there are 2-6 bundles of xylem and phloem alternating whereas in monocots the number of xylem and phloem strands are more than 8. Further, the xylem vessels in dicots are polygonal and those of monocots are oval.

Therefore, the correct answer is option C.

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

In a dicot stem, pericycle gives rise to

  1. Interfascicular cambium

  2. Phellogen

  3. Secondary cortex

  4. Secondary wood
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
  • In dicot stem, the secondary vascular tissues originate as a result of the cambial activity. 
  • The cambial cells divide tangentially again and again and produce secondary tissues. 
  • Some of the cells of single-layered pericycle become meristematic, which divides and form a few layers of cells, phellogen.
  • Hence, In a dicot stem, pericycle gives rise to Phellogen.
  • So, the correct answer is 'Phellogen'.
Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

Actinostele is the modification of

  1. Protostele

  2. Siphonostele

  3. Solenostele

  4. Dictyostele
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The earliest vascular plants had stems with a central core of vascular tissue. This consisted of a cylindrical strand of xylem, surrounded by a region of phloem. Around the vascular tissue, there might have been an endodermis that regulated the flow of water into and out of the vascular system. Such, an arrangement is termed a protostele, which is the simplest type of stele. Actinostele is a variation of the protostele in which the core is lobed or fluted. This stele is found in many species of club moss. Actinosteles are typically exarch  and consist of several to many patches of protoxylem at the tips of the lobes of the metaxylem. Exarch protosteles are a defining characteristic of the lycophyte lineage.

Thus, the correct answer is option A.

Multiple choice botany internal structure of root, stem and leaf internal structure of dicot stem internal structure of stem(dicot and monocot) anatomy of stem

Knots are formed in the wood due to

  1. External injuries

  2. Bases of the branches get buried in main stem

  3. leaf scars

  4. Insect bites
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Knots are common blemishes in trees, often causing lumps or holes within the trunk of the tree itself. In most cases knots are caused by the natural growth of the tree, though the specific circumstances under which they form determines how they will appear. As a tree grows and increases the circumference of its trunk, the growing trunk begins to overtake the branches that grow out from it. Knots form around these branches, building up trunk material as the tree continues to expand. Since, the branches are still growing as they are overtaken by the trunk, the knot that forms is solid and contains living wood throughout. The wood of the knot is typically tougher than the surrounding wood and may form a bulge around the branch emerging from its center. So, knots are formed in wood due to bases of the branches get buried in main stem and not because leaf scars, insect bites and injuries. 
Therefore, the correct answer is option B.