Category: Biology Second Paper Lecture Sheet

The capsule of Anthocerotae plants consists of a columella, epidermis with stomata and dividing tissue at the base of the capsule.

1. The plant is haploid in nature.
2. Most plants are thalloid in nature.
3. They have no real roots.
4. They are avascular plants. That is, there is no transport tissue.
5. They are homosporous. ie produces the same type of spores.

1. Bryophyta are green, autophagous and self-sufficient plants.
2. They are multicellular, non-flowering and asexual plants.
3. They are mainly gametophyte (haploid). Gametophytes are large and long lasting.
4. Their bodies are thalloid, i.e. the body cannot be divided into roots, stems and leaves. However, mosses are divided into stems and leaves. Higher bryophyte bodies are divided into colloid (stem-like) and phylloid (leaf-like).
5. They have no roots. Roots are replaced by unicellular rhizoids. Some species have multicellular rhizoids.
6. They do not have transport canals or vascular bundles. That is, they are avascular plants.
7. Their bodies are made up of parenchyma cells only.
8. Their male genitalia are called antheridium and female genitalia are called archegonium.
9. Their antheridium is pear-shaped and archegonium is flask-shaped.
10. Their genitalia are multicellular and covered with a sterile sheath.
11. Their sexual reproduction is ogamous in nature. That is male gametes are small and motile and female gametes are large and stationary.
12. Fertilization occurs in water. That is, the fertilization process is dependent on water.
13. Their spermatozoa are bi-flagellated.
14. In their life cycle multicellular embryos are formed. Embryo development occurs in the venter of the female.
15. They are homosporous or homosporous. That is, they produce identical spores.
16. Several thallus are grouped together to form a rosette.
17. The sporophyte is partially or completely dependent on the gametophyte.
18. Advanced bryophytes are divided into sporophytes, setae and capsules.
19. Their spores germinate directly to form thallus or protonema.
20. In the life cycle of bryophytes there is a clear heteromorphic sequence.

Distribution of bryophytes is global. They are found everywhere except the sea. They usually grow in moist shady environments. Also grows in polar and desert regions. 248 species of 74 genera of 34 tribes have been identified in Bangladesh. Today, 15,600 (according to many, 24,000) species of 960 genera of bryophytes are distributed worldwide.

The word Bryophyta is formed from the Greek words bryon meaning moss and phyton meaning plant. Bryophyta means mossy plants. Bryophytes are green avascular plants composed of parenchyma cells, divided into thalloids or stems and leaves. The division of bryophytes is called Bryophyta. In 1864 scientist Braun first used the term Bryophyta. Plants of the class Bryophyta are called amphibious plants as water is essential for fertilization and life cycle. The smallest bryophyte is Zoopsis argentea. Zoopsis is 5 mm in length. And the largest bryophyte is Dawsonia. The length of Dawsonia is 50-70 cm (Dawsonia superba, Dawsonia longifolia Dawsonia longiseta).

All the plants of the world are divided into two groups based on having flowers. Phanerogams are plants and cryptogams are plants. The non-flowering or cryptogamous are divided into three categories. Thallophyta, Bryophyta and Pteridophyta. Thallophyta are immature cryptogams. Bryophyta and Pteridophyta are hybrid cryptogams. Bryophyta are connecting plants between Thallophyta and Pteridophyta.

Dyspnea is the discomfort or pain that occurs when the breathing rate increases due to any reason. Lack of oxygen, asthma, anemia, epilepsy etc. can cause dyspnea.

A temporary pause in breathing due to any reason is called apnea. Causes of apnea are poisoning, sudden increase in blood pressure, unconscious swallowing of food, immersion in water, electric shock etc.

If the oxygen supply to the cells is low due to any reason, it is called hypoxia. Hypoxia can be caused by asthma, pneumonia, anemia, poisoning, excessive bleeding, mountain climbing etc.

When the oxygen supply to the cells is completely stopped due to some reason, it is called anoxia. It causes body weakness, headaches and dizziness, personality changes and memory loss.