Question

Select the total number of correct statement: I. Cell-plate formation occurs in plant cell during cytokinesis. II. During cytokinesis mitochondria and plastid gets distributed between two daughter cells in mitosis. III. Liquid endosperm in coconut is syncytium. IV. Furrow formation occurs in Animal cell during cytokinesis (a) 1 (b) 2 (c) 3 (d) 4

Short answer

The total number of correct statements is 4. So the answer is (d) 4.

Step-by-step solution

Analyze Statement I

Statement I indicates that cell-plate formation is part of cytokinesis in plant cells. Cytokinesis is characterized by the division of the cytoplasm into daughter cells, following the separation of the nucleus (mitosis). In plant cells, this process often involves the formation of a cell plate. Therefore, statement I is correct.

Analyze Statement II

Statement II implies that during the process of mitosis, organelles such as mitochondria and plastids are distributed between the two daughter cells. This is indeed the case as, during cytokinesis, organelles and the cytoplasmic volume are split between the daughter cells. Consequently, statement II is correct.

Analyze Statement III

Statement III refers to the liquid endosperm in coconuts as a syncytium. Syncytium refers to a single cell or cytoplasmic mass containing several nuclei. The liquid endosperm in a coconut is indeed a syncytium because it is a mass filled with fluid containing many nuclei and, thus, statement III is correct.

Analyze Statement IV

Statement IV suggests that furrow formation occurs in animal cells during cytokinesis. Furrow formation is a known model of cytokinesis in animal cells where the plasma membrane pinches inwards to divide the cell into two. This, the final statement IV is also correct.

Key concepts

Cell-plate formation

In plant cells, during cytokinesis, the cell plate is a crucial structure that develops between the two daughter cells. This process happens after the nucleus has already divided in mitosis. Cell-plate formation is unique to plant cells, primarily because of their rigid cell walls, which require a different method of cytokinesis than animal cells.
During the formation, vesicles derived from the Golgi apparatus move to the center of the cell, coalescing to form the new membrane and eventually become the new cell wall separating the two cells.

• This process ensures that each new daughter cell receives a part of the cytoplasm.
• It gives structural integrity to the cells.
• It allows for the continuity of cell division across plant tissues.

This distinct mechanism of cytokinesis ensures the stability and functionality of plant cells after cell division.

Organelle distribution

During cytokinesis, each daughter cell must inherit sufficient organelles to function properly. In both plant and animal cells, this includes the distribution of mitochondria and plastids.
Organelles are not divided evenly, but enough are allocated to ensure each daughter cell remains viable.

• The mitochondria are crucial as they provide the energy needed for cell functions.
• Plastids, important in plants, have various roles including photosynthesis.

By distributing organelles, cells ensure that both new cells can survive and continue to grow.

Syncytium

A syncytium is an interesting cellular phenomenon where a single cell has multiple nuclei within the same cytoplasmic space. This occurs when the nuclei divide but the cell does not undergo complete cytokinesis.
In the context of coconuts, the liquid endosperm is a syncytium.

• It contains many nuclei within a shared cytoplasmic mass.
• This structure supports the growing embryo by providing nutrients.
• It showcases a special adaptation in plants that allows nutrient dispersal.

Syncytial structures can also be found in diverse organisms, including certain animal cells.

Furrow formation

Cytokinesis in animal cells involves a process distinct from plant cells known as "furrow formation." This process does not involve building a new wall or dividing structures but rather utilizing the cell's existing membrane to complete division.
The process involves the following steps:

• The plasma membrane begins pinching inwards at the cell's "equator," creating a cleavage furrow.
• This furrow deepens until the cell is split into two separate daughter cells.

Furrow formation ensures each new cell receives the necessary cellular components and reduces the tension required on structural proteins, making the division energy efficient. It is a dynamic process that highlights the flexibility and adaptability of animal cells during division.