Category: Biology Second Paper Lecture Sheet

Fern prothallus is a companion plant. That is, male genitalia and female genitalia are produced in the same thallus. Its reproductive process is described.
(i) Spermatogenesis: Inside the antheridium there are 20-50 sperm mother cells or androcytes. Each spermatozoon matures into a multi-flagellated spermatozoon. Spermatozoa break through the cap cells at the top of the antheridium and come out.
(ii) Ovulation: Inside the archegonium there are a few cervical duct cells, a ventral duct cell and a large ovule cell. The ovum develops into an ovum.
(iii) Fertilization: The ducts of mature archegonium are filled with mucilage and malic acid. The sperm reach the archegonium with the help of rain water or dew drops. Archegonium’s malic acid attracts sperm. Sperm and egg unite. Fertilization results in the formation of a zygote.
(iv) Germination: Zygote is enveloped by wall and becomes spore. The spore germinates in a favorable environment and divides repeatedly in the process of mitosis to form a new sporophyte.

Under the anterior groove several female archegonia of pitcher or flax shape are produced. It consists of two parts. Neck and Abdomen. The neck is slightly curved and composed of few neck duct cells. Abdomen contains an ovary and an abdominal duct cell. The cervical duct cells and ventral duct cells of the mature archegonium fuse to form a duct. The alimentary canal is filled with mucilage and malic acid.

On the underside of the thallus several spherical or ovoid stamens antheridia grow. At its base are two ring cells and a lid cell. Inside the antheridium are 20-50 sperm mother cells or androcytes. Each spermatozoon matures into a multi-flagellated spermatozoon.

Thin, filiform, unbranched, colorless and multicellular scales arise from the lower part of the thallus. It attaches the thallus to the soil or other material and absorbs water and mineral salts. Scales protect the thallus from desiccation in unfavorable environments.

Slender, linear, unbranched, colorless and unicellular rhizoids arise from the lower surface of the thallus. Rhizoids are of two types. Smooth and rough rhizoids. Rhizoids anchor the thallus to soil or other material and absorb water and mineral salts.

Fern prothallus is a gametophytic plant. Its body cannot be divided into roots, stems and leaves. That is, they are thallus shaped. The thallus is green, flattened, hemispherical, flattened, multicellular and cordate. It has a large groove at its tip. This is called the anterior notch. Prothallus being green can produce food through photosynthesis.

1. Thallus: Fern prothallus is a gametophytic plant. Its body cannot be divided into roots, stems and leaves. That is, they are thallus shaped. The thallus is green, flattened, hemispherical, flattened, multicellular and cordate. It has a large groove at its tip. This is called the anterior notch. Prothallus being green can produce food through photosynthesis.
2. Rhizoids: Slender, linear, unbranched, colorless and unicellular rhizoids arise from the lower surface of the thallus. Rhizoids are of two types. Smooth and rough rhizoids. Rhizoids anchor the thallus to soil or other material and absorb water and mineral salts.
3. Scales: Thin, filiform, unbranched, colorless and multicellular scales arise from the lower part of the thallus. It attaches the thallus to the soil or other material and absorbs water and mineral salts. Scales protect the thallus from desiccation in unfavorable environments.
4. Genitalia: Pteris is a companion plant. Their male and female genitalia are located in the same thallus. Its male genitalia is called antheridium and female genitalia is called archegonium.
(i) Antheridium: On the underside of the thallus several spherical or ovoid stamens antheridia grow. At its base are two ring cells and a lid cell. Inside the antheridium are 20-50 sperm mother cells or androcytes. Each spermatozoon matures into a multi-flagellated spermatozoon.
(ii) Archegonium: Under the anterior groove several female archegonia of pitcher or flax shape are produced. It consists of two parts. Neck and Abdomen. The neck is slightly curved and composed of few neck duct cells. Abdomen contains an ovary and an abdominal duct cell. The cervical duct cells and ventral duct cells of the mature archegonium fuse to form a duct. The alimentary canal is filled with mucilage and malic acid.

1. It is green and heart shaped.
2. An anterior notch is present on the top of the thallus.
3. Rhizoids arise from the lower part of the thallus.
4. The thallus contains the male antheridium and the female archegonium.

Fern spores germinate in favorable environment to form 4-6 celled protonema. The cells on both sides of the protonema divide repeatedly to form a green, horizontal, hemispherical, flattened and multicellular heart shaped structure called fern prothallus.

Sporangia are produced along the lower margin of the leaves of Pteris. The sporangia together form a brown kidney-shaped sorus. The upper part of sporangium is called capsule. Inside the capsule are sporogenous cells. 16 spore mother cells are produced from sporogenous cells. In the process of meiosis, 64 spores are produced from 16 spore mother cells. The resulting spores are dark brown in color and have the same characteristics. It is double-layered and equipped with germpores. After spore formation, the water holding capacity of the sporangium decreases and becomes dry. This causes tension on the annulus and ruptures the stoma transversely. As a result, the spores are released. Spores germinate to form new gametophyte plants.