Standard 11|Plant Kingdom |Pheophyceae | Short Note For NEET BIOLOGY

 

Chapter 3: Plant kingdom

Plant Kingdom |Pheophyceae| Short Note For NEET BIOLOGY| standard 11

Note 4

Three types of algae- 

1. Chlorophyceae – green algae

2. Pheophyceae – brown algae

3. Rhodophyceae – red algae

Pheophyceae - Brown algae

Color---

Brown color due to: Xanthophylls pigment - fucoxanthin 

Other pigments - Chlorophyll a and c : impart green color

Carotenoids: impart red-orange color

Some algae can be olive green in color - because chlorophyll a and c in higher amount than Xanthophylls

Shade of brown depend on amount of fucoxanthin in algae

Habitat--- mainly marine 

Size and form---

Simple branched-

Filamentous forms - Ectocarpus

Profusely branched - Kelps 

Kelps: may reach heights of 100 meters in ocean

Forms large spread which can cause ship wrecks

Food storage---

In form of complex carbohydrates (modified polysaccharides)

Example: Laminarin and Mannitol (both are alcoholic sugars- extra information)

Cell wall---

Cellulosic wall

cover outside the wall - made up of gelatinous coat: algin

Structure of protoplast---

Plastids

Centrally located vacuoles

Nucleus

Structure of plant body---

3 parts

1. Holdfast : attaches body to substratum - function almost like roots of higher plants

2. Stipe : stalk of plant body

3. Frond : photosynthetic organ - leaf like

Reproduction 

Vegetative reproduction: by fragmentation

Asexual reproduction: by zoospores

→Zoospores (in brown algae): pear-shaped (pyriform), biflagellated- 2 unequal flagella which is laterally attached (attached on one side of the spore)

Sexual reproduction: can be isogamous, anisogamous or oogamous

→Gametes: pyriform (pear-shaped), biflagellated-2 laterally attached flagella

Gamete fusion : 

→→may take place in water

→→for oogamous plants - within oogonium

Examples---

Sargassum

Ectocarpus

Laminaria

Fucus 

Dictyota

Happy learning!!

Thank you for reading!

Manish Mevada

Urvi Bhanushali