The two types of primitive autotrophs that are found on earth are algae and bryophytes. Both organisms exhibit undifferentiated, thalloid body structure. Algae play an important role in ecosystems such as fresh and marine water, as primary producers and oxygen producers. The most primitive land plants are bryophytes, living in the middle of aquatic and terrestrial environments.
Bryophytes are considered to be evolved from algae. Both algae and bryophytes’ cell walls are made up of cellulose and they lack a vascular system. The main difference that is found between the algae and bryophytes is the division of the plant body, where no division of labor is observed in the plant body of algae whereas the plant body of bryophytes internally divides into photosynthetic and storage zones. Let us learn more about bryophytes and algae.
Algae are the plantlike organisms, which are classified under kingdom Protista. Algae are mostly found in marine, freshwater, and wastewater habitats. They are unicellular. As most of the algae are autotrophs, they contain photosynthetic pigments in their cells. As with other modes of nutrition, the types of algae found are heterotrophic and mixotrophic. Mixotrophic algae use nutrition modes, autotrophy and heterotrophy. In the aquatic food chains, the autotrophic algae serve as the primary producers. Around 70% of breathing oxygen is produced by algae.
All cells in the plant body are capable of growing and reproducing. The size of the algal body varies from microalgae to macroalgae. Cyanobacteria are prokaryotic microalgae. They are called blue-green algae as well. Seaweeds are macroalgae. Algae produce motile spores during asexual reproduction. Sexual reproduction occurs in eukaryotic algae by the fusion of male and female gametes, that are produced in different individuals. Hence, eukaryotic algae are sexually dimorphic.
Bryophytes are the non-vascular land plants, which are classified under the kingdom of Plantae. They are spore-producing plants and the gametophyte stage is the dominant one in the life cycle. Bryophytes are not seed-producing or flowering plants. They are mostly autotrophs. Some of the bryophytes such as liverworts do not contain chlorophyll, hence, they depend on a fungal partner for food. They grow in moist shady places, producing phenolic compounds which deter herbivores. Other plants are also benefited by the water collected by bryophytes.
Bryophytes are the macroscopic plants whose size varies from a millimeter tall to long strands about one meter. Rootlike structures called rhizoids allow the plant to anchor on a surface. Rhizoids are not water-absorbing units. In the plant body, the water is conducted internally which is absorbed by the plant body itself. In bryophytes, asexual reproduction occurs by fragmentation and small aggregations called gemmae. The sperms are carried to the eggs through the water during the process of sexual reproduction. Fertilization of gametes forms the gametophyte with the spore capsules called the sporophyte. The sporophyte produces spores, which are dispersed through the wind.
In biology algae and bryophytes sometimes share common features and few of the characteristics distinguish them. The chloroplast pigments present in bryophytes are similar to that of the green algae. The food material stored in both of them is starch. The main feature which differentiates them is the higher level of organizations and the organs present in the bryophytes.
1. Explain the Classification of Algae?
Ans. Chlorophyta, Rhodophyta, and Phaeophyta are the three morphological types of algae. Chlorophyta is the most diverse group of algae. Chlorophyll, beta carotene, and xanthophylls are the pigments found in Chlorophyta. Hence, Chlorophyta is called green algae. Rhodophyta is red algae, containing phycoerythrin as the main photosynthetic pigment. Phaeophyta is brown algae, containing chlorophyll c and fucoxanthin as the photosynthetic pigments. Laminaria saccharina, which is a brown seaweed.
2. Explain the Classification of Bryophytes?
Ans. Marchantiophyta (liverworts), Bryophyta (mosses) and Anthocerotophyta (hornworts) are the three divisions of bryophytes. Liverworts are flattened mosslike leafy plants. The leaves of the liverworts lack costa. But marginal cilia are present in liverworts. Mosses consist of one cell of thick, simple leaves, which are attached to a stem.
They grow in dense green clumps. Mosses contain costa, which is a midrib, running lengthwise through the leaf. Hornworts consist of a hornlike, elongated sporophyte on the gametophyte.
3. Mention any Two Differences Between Bryophytes and Algae.
Ans: The major difference between bryophytes and algae are:
These are plant-like organisms that are included in kingdom Protista.
These are nonvascular plants included in kingdom Plantae.
They grow in aquatic habitats.
They grow in moist and shady places.