Biology Test 252

Chlorella is a genus of microscopic single-celled freshwater green algae. It is an incredibly sustainable food source which provides us with a broad array of many important nutrients, coupled with a high value of chlorophyll, complete proteins and nucleic acids.

Keber’s organs otherwise known as the pericardial gland are excretory organs in bivalve molluscans, e.g. Unio. These are large, reddish-brown glandular mass, situated anterolateral to the pericardium. It discharges waste products into the pericardial cavity, collected by the kidneys (organ of Bojanus).

Bird’s eggs are surrounded by two-shelled membranes, constituted mainly by calcium carbonate crystals stabilised by a protein matrix. The structure and composition of avian egg shell is to provide protection against damage, contamination, desiccation, etc.

Tortoises are animals belonging to class Reptilia. Its body is covered by a protective shell which in turn consists of a dorsal carapace and ventral plastron.

Angiosperms are highly evolved and well-adapted land plants. They have certain attributes which make capable of adapting in diverse habitats, e.g. advanced vascular system, highly developed sex organs, flowers to attract pollinators, etc.

Pteridophytes are sometimes referred to as ‘botanical snakes’ or ‘snakes of plant kingdom’. This is because like reptiles, pteridophytes are considered as the first true land plant that evolved after bryophytes.

Capsid is the protein coat or shell composed of capsomeres (protein subunits), which encloses the viral nucleic acid. The capsid also helps in binding of viral cells to a host’s cell surface in the absence of envelope.

Plant succession on a bare rock (i.e. primary succession) is initiated by pioneer species like lichens. These lichens secrete acids to cause the weathering of the rocks to form soil. The pioneer species then get replaced by plants better suited to these conditions like grasses.

Aptenodytes forsteri, the emperor penguins found in Antarctica are aquatic birds. They cannot fly, but are excellent swimmers.

Pavo cristatus (peacock), is considered one of the largest flying birds.

Passer (a genus of sparrows), Corvus (a genus of crows) are both capable of flying.

In dicot stem, the vascular bundles are definite in number. They are obtusely wedge-shaped. Each vascular bundle consists of phloem on outside, xylem on inner side with a strip of cambium between them.