Tag: botany

According to histogen theory by Hanstein, the three principal tissues of the root, vascular cylinder, cortex and epidermis originate from three groups of initial cells or histogens, in the apical meristem plerome, periblem and dermatogen respectively. A fourth histogen, the calyptrogen produces the root cap. 
Thus, the correct answer is option D.

In biology, tissue is a cellular organizational level between cells and a complete organ. A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs are then formed by the functional grouping together of multiple tissues. So, the correct option is "D" (Cells which are similar in origin, form, and function).

In multicellular organisms, most of the tissue of the body is growing by increasing their cell number (means of cell division), but their growth is strictly regulated to maintain a balance between different tissue. Thus, the correct option is A.

Tissues which are made up of more than one type of cells and they work together as a unit are termed as complex tissues; it includes xylem and phloem. Bryophytes are a group of simple and primitive plants that show alteration of generation between two distinct phases namely a haploid gametophytic and a diploid sporophytic phase. The gametophyte is the haploid plant body which is either thalloid or a leafy shoot with stem-like and leaf-like structures and thread-like rhizoids. It lacks vascular tissues xylem and phloem. Zygote represents the first cell of the sporophytic phase which divides and develops into sporogonium. Sporogonium is differentiated into a foot, a seta and a capsule and serve to produce spores. Thus, all bryophytes lack complex tissues.
All gametophytes are the simple haploid stage that develops from spore and lacks vascular tissues, thus no complex tissues. Pteridophytes are the first vascular plants and possess vascular tissues xylem and phloem. The main plant body is sporophyte which is differentiated into true root, stem and leaves having a well differentiated vascular tissue.
The spermatophytes are the seed plants and include gymnosperms and angiosperms both of which have well developed vascular tissues (xylem and phloem).
Thus, the correct answer is option C.

• A group of cells of similar origin that are structurally similar and perform a particular function are called tissue e.g., nervous tissues, blood, etc.

• A tissue is the group of cells of the common origin that are structurally similar or sometimes dissimilar and perform a particular function. 
• Only plant cells are characterized by the distinct cell wall and absent in animal cells.

A tissue is the group of cells of the common origin which are structurally similar and perform a particular function. Whereas organ is the group of tissues and organ system is the group of organs which performs different functions. The molecule is the smallest part of the cell and different molecule performs different functions.

A tissue is the group of cells of the common origin which are structurally similar and perform a particular function. Whereas organ is the group of tissues and organ system is the group of organs which performs different functions.