Morphology is a branch of biology dealing with the study of the form and structure of organisms and their specific structural features.

Polymer is a substance which has a molecular structure built up chiefly or completely from a large number of similar units bonded together, e.g. many synthetic organic materials used as plastics and resins.

All chordates are characterized by four features at different stages of their life:

• Notochord– It is a longitudinal, cartilaginous rod running between the nerve cord and the digestive track. It acts as a support for the nerve cord. In vertebrates, it is replaced by vertebral column after the embryonic stage.
• Dorsal nerve cord–It is a bundle of nerves which runs along the “back” and splits into the brain and the spinal cord
• Pharyngeal slits–They are the openings which allow the entry of water through the mouth without entering the digestive system i.e., they connect mouth and throat.
• Postanal tail–It is an extension of the body to the ****. In chordates, the tail is composed of skeletal muscles which help in locomotion in fish-like species.

Other features of chordates include:

• Bilaterally symmetrical, triploblastic, coelomic and segmented body.
• The body design is complex and well-differentiated.
• The body has organ system level of organization.

difference between Plasmodium falciparum and Plasmodium vivax:

• P. vivax produces benign tertian malaria, but P. falciparum produces malignant tertian malaria.
• P. vivax lifecycle includes sporozoites that remain as hypnozoites, but there are no dormant stages in P. falciparum.
• In P. falciparum, merozoites enter new RBCs, whereas P. vivax merozoites can invade RBCs of all ages.
• P. falciparum causes more severe infection on human than the P. vivax does.

A symbiont is an organism that is very closely associated with another, usually larger, organism. This larger organism is called a host. A symbiont can live on, in or sometimes very near its host.

Symbiosis relationships can be obligate, meaning that one or both of the symbionts entirely depend on each other for survival. For example, in lichens, which consist of fungal and photosynthetic symbionts, the fungal partners cannot live on their own.

Homeostasis - the most successful genes would be those that express for traits and behaviors that promote survival of the organism long enough to reproduce and ensure that its offspring survives to do the same.
Stress - We commonly think of stress as being a state of mental or emotional overwhelm, usually as a result of work deadlines, lack of financial security, or problematic relationships.

Heterocyst are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc punctiforme, Cylindrospermum stagnale, and Anabaena sphaerica. They fix nitrogen from dinitrogen (N₂) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis. Nitrogenase is inactivated by oxygen, so the heterocyst must create a microanaerobic environment. The heterocysts' unique structure and physiology require a global change in gene expression.

For example heterocysts:

Produce three additional cell walls, including one of glycolipid that forms a hydrophobic barrier to oxygen

Produce nitrogenase and other proteins involved in nitrogen fixation

De-grade photosystem II, which Produces oxygen .

Up-regulate glycolytic enzymes.

Produce proteins that scavenge any remaining oxygen.

Contain polar plugs composed of cyanophycin which slows down cell-to-cell diffusion.