Tag: biology

In Dryopteris, on the lowerside of the leaflet an outgrowth is present. It consists of a stalk like placenta and a flap, that protects group of sporangia. This is called as true indusium.

In Dryopteris, the annulus and the stomium help in the dehiscence of the sporangium and dispersal of spores. At maturity, the sporangium dehisces by drying action, which exerts pressure on mouth assisted by shrinkage of the annulus. Lastly mouth of sporangium open and spores are liberated.

Gametophytes have sessile jacketed multicellular sex organs. The male is antheridium and female is archegonium. Antheridia form biflagellated (Selaginella, Lycopodium) or multiflagellated (Dryopteris) male gametes. Antheridium producing about 32 anthropoids. Each anthropoid is large antinuclear coiled and multi flagellate.

A resurrection plant is any plant that can survive extreme dehydration and desiccation for years. Selaginella lepidophylla is a  a plant species that is native to America. It is an example of resurrection plant.

In mosses (bryophytes), the sporophyte is dependent on the gametophyte. In pteridophytes (like Selaginella/Ferns), the sporophyte is independent.

Selaginella is the primary example of a heterosporous pteridophyte belonging to the class Lycopsida.

The urinary system produces urine (nitrogenous water) and serves to excrete it to outside the body. Lymphatic system serves in fluid balance, fat absorption and defense. The circulatory system serves in exchange of nutrients and oxygen for waste and carbon dioxide respectively. Respiratory system serves to allow entry of oxygen from the air into blood and exit of carbon dioxide from blood to the air. The integumentary system covers the entire surface of the human body and serves as a barrier, site for waste elimination and temperature control. 

The neopallium (or neocortex) is a part of the brain that is highly developed in mammals, responsible for higher-order brain functions like sensory perception and cognition.

The cytoplasm is the jelly-like substance that fills the cell and contains all organelles except for the nucleus, which is contained within the nuclear envelope.

Plant cells, including onion leaves, lack centrioles, which are typically found in animal cells and lower plants for spindle organization during cell division. Nuclei, cell walls, and endoplasmic reticulum are all present in plant cells.