Understanding the Cell Cycle and Plant Anatomy

The Cell Cycle

The cell cycle consists of two main phases: interphase and mitosis (M phase) [3].

Interphase

Interphase is further divided into three phases:

1. G1 phase (Gap 1): During this phase, the cell grows in size and carries out normal metabolic activities [4].
2. S phase (Synthesis): In this phase, DNA replication and chromosome duplication occur [4].
3. G2 phase (Gap 2): The cell continues to grow and prepares for cell division [4].

Mitosis (M phase)

Mitosis is the actual phase of cell division and is divided into four stages:

1. Prophase: Chromosomes condense, the nuclear envelope and nucleolus disappear, and spindle fibers start to appear [4].
2. Metaphase: Chromosomes align at the equatorial plate [4].
3. Anaphase: Centromeres divide, and chromatids move towards opposite poles [4].
4. Telophase: Chromosomes elongate, the nucleolus and nuclear membrane reappear, and cytokinesis begins [4].

Cytokinesis, the division of the cytoplasm, follows mitosis and completes the cell division process [4].

Plant Anatomy

Dicot Leaf

1. TS of a dicot leaf (dorsiventral leaf) shows three main parts:

1. Epidermis
2. Mesophyll cells
3. Vascular systems

Monocot Leaf

1. TS of a monocot leaf (nobilateral leaf) shows three main parts:

1. Epidermis
2. Mesophyll cells
3. Vascular systems

Vascular Cylinder

Technical description of the Vascular Cylinder: Radial, tetrarch, exarch and pith is usually absent.

Reproductive Systems

Male reproductive system:

• Consists of a pair of yellowish ovoid testes, attached to the upper part of kidneys, by mesorchium (Peritoneum or Membrane supporting the testes)
• Vasa efferentia are 10-12 in number arises from the testes.
• Bidder's canal communicates with the urinogenital duct that comes out of the kidneys and opens into the cloaca.

Female reproductive system:

• Includes a pair of ovaries present near the kidneys.
• A pair of oviduct arising from ovaries opens into the cloaca separately.

Phylum: Arthropoda

They are cosmopolitan in distribution, i.e., they are found aquatic, terrestrial and aerial habitats. The body is divisible into head, thorax, and abdomen. In some cases, the head is joined with thorax. They have an organ system grade of organization. Circulation is open type where the white blood (haemolymph) flows within the body cavity is called haemocoel. Respiration takes place by gills, book lungs, or tracheae. Digestive system is complete with having both mouth and anus at opposite ends of the body. Sexes are separate, fertilization is internal, and the development is direct or indirect.