Industrial uses of algae:
1. Agar, a major medium for laboratory culture, is produced from algae.
2. Sea weeds are major source of fertilizers
3. Algae is used as bio-fuel
4. Algae is used for sewage treatment

External features of dicotyledons:
1. Tap root system
2. Two cotyledons in seeds
3. Reticulate venation in leaves
4. Tetramerous or pentamerous flowers.

1. The main plant body is a sporophyte which is differentiated into true root, stem and leaves. These organs possess well-differentiated vascular tissues.
2. The leaves in pteridophyta are small (microphylls) as in Selaginella or large (macrophylls) as in ferns.
3. The sporophytes bear sporangia that are subtended by leaf-like appendages called sporophylls. In some cases sporophylls may form distinct compact structures called strobili or cones (Selaginella, Equisetum).

Cycas is called the 'relic of the past' It has following properties to justify this
i) Monoxylic wood through secondary growth started
ii) shedding of seed when embryo is still immature.
iii) The arrangement of microsporangia in all defined sori.
Phylogenetically, cycas is related to the pteridosperm (seed ferns) and through them to ferns from which it seems to have evolved. It can be ascertained by the presence of 
i) lead-like megasporophyll
ii) persistence of leaf base.

Red algae The photosynthetic pigments located in the chromatophores are chlorophyll-a, d and \(\alpha \), \(\beta \) -carotenes, xanthophyll and biliproteins.
Green algae   Chromoplasts contain chlorophyll-a, b, carotene and xanthophyll.
Brown algae The chromatophores contain chlorophyll-a, c and \(\beta \),  \(\alpha \)-carotnes and xanthophyll.

Algae.

Male and female cones are borne on the same tree in Pinus.

Flowering plant help pollination to attract them by their flower colour and nectar smell

The Reserve Food Material Of Algae is starch. Algae reserves starch, laminarin, mannitols, and Floridian starch as its food material, Reserve food material is the food that is used when there is a scarcity of food and this reserve food is then used to synthesize energy in the algal cells.

The following reasons explain this
(i) In natural system of classification only related organisms occur in a group as it prevents grouping of unrelated organisms.
(ii) It shows natural relationship among organisms.

The megasspores and microspores germinate and give rise to gametophytes

A small orchid lives underground. it has a mycorrhizal association which help it in obtaining nourishment from decaying organic matter

Rhizoids: Bryophytes have rhizoids that have a root-like structure that helps in absorption of water and anchors the plant.

It indicates the possible origin of diffferent organisms.

Gametophyte is a free - living, small thalloid structure called prothallus. In most ferns, the prothallus is green and autotrophic.

Embro sac of angiosperm develop upto 8 nucleate state prior to fertilization there is a 3 celled egg apparatus, 3 antipodal cells and 2 polar nuclei

Plant kingdom is rich with a large number of species. At every stage of evolutionary development there are interesting examples of new structures coming up to give better tools of survival to the plant
The natural habitat of algae is water, so they can be compared to aquatic animals. As life started in the aquatic environment so algae are the most primitive group of plants. Moreover, their structure is simple with no special organs for special functions.
The way amphibian animals are like a linking point between aquatic and terrestrial life, bryophytes show the same characteristic. Bryophytes need water to facilitate reproduction although they live on soil. In bryophytes we witness some development of leaf-like structures and root like structures. Antheridiopore and Archegoniopore can be compared to flowers of angiosperms
When we analyze Pteridophytes we can see development of vascular tissues for transport of substances. Pteridophytes show true roots as well. While the dominant phase is gametophyte in bryophytes it is sporophyte in Pteridophytes. This is another indication of evolution Gymnosperm look more like a common plant, with well defined roots and stem. Appearance of seeds is another indicator of development. Seeds gave the ability to survive longer durations of adverse conditions. This is a sort of guarantee to continue progeny even after a long spell of adverse environmental conditions.
Angiosperms are more advanced because of many factors. The seed is covered, which means more protection to the embryo. Appearance of flowers was a means to facilitate cross pollination for more variations. Angiosperms can modify almost any part for special purpose. For example, certain plants store excess food in modified leaves or stems or roots.
This essay is an interesting description of how from simple thalloid algae plants have developed into more complicated angiosperms. While algae have a simple thallus to carry out all biological functions, angiosperms have dedicated tissue systems for various functions.

The vascular plants dominate earth and make the planet green everywhere.The features which enable this quality to happen are 
(i) Strong roots capable of penetrating deep into the soil.
(ii) Development of waterproof layer on aerial surfaces especially the leaves to reduce transpiration.
(iii) Presence of strong, woody mechanical tissue to provide mechanical support to aerial parts and allow them to rise to a great height.
(iv) Vascular tissues are present for long distance transport of substances.

Protonemal cell of moss - haploid
Primary endosperm nucleus in dicots - triploid
Leaf cell of moss - haploid
Prothallus cell of ferns - haploid
Gemma cell in Marchantia - haploid
Meristem Cell of monocots - diploid
Ovum of liverworts - haploid
Zygote of ferns - diploid