Biology Test - 53

Acquired characters do not produce change in the genes of germ cells, so they cannot be inherited.

For example- if tails of mice are cut in the first generation, and then breeding is done, the new mice born will have full tails. The cut tail of mice is an acquired trait which is never passed on to their progeny. This is because cutting of mice tails does not change the genes of their reproductive cells.

Biosphere reserves are multipurpose protected areas of different representative ecosystems which are meant for conservation of biodiversity or wildlife, traditional life style of tribals and their domesticated animals and also plant resources. Each biosphere reserve has a core zone (where no human activity is allowed), a buffer zone (with limited human activity) and manipulation zone (where human activity is allowed without degradation of ecology. Thus, the biosphere reserves protect not just wild varieties but also domesticated varieties of plants of an area.

Transformation of meristematic cells into specific permanent tissues occurs by the process of cell differentiation.

• ​Cells formed by meristematic tissues take up a specific role and lose the ability to divide.
• As a result, they form a permanent tissue.
• This process of taking up a permanent shape, size, and function is called differentiation.
• Cells of meristematic tissue differentiate to form different types of permanent tissue.

Each ductus deferens, at the ampulla, joins the duct from the adjacent seminal vesicle (one of the accessory glands) to form a short ejaculatory duct. Each ejaculatory duct passes through the prostate gland and empties into the urethra.

In angiosperms or flowering plants, the megaspore mother cell produces a functional megaspore that develops into an embryo sac through two distinct processes megasporogenesis (formation of the megaspore in the nucellus, or megasporangium), and megasporogenesis (development of the megaspore into the embryo sac, or megagametophyte).

Anther is a terminal bilobed structure and the wall of anther consist of following layers:

● Endothecium: The cell of endothecium layer have α-cellulosic fibrous bands arising from the inner tangential wall which help in dehiscence of anther due to hygroscopic nature. They are absent in hydrophytes.

● Epidermis: It is the outermost ,singled layered and protective function . The epidermis of Arceuthobium (parasite an develops some fibrous thickenings and called as exothecium).

● Middle layer:Cell of this layer are ephemeral and are 1 to 3 layered, which degenerate at maturity.

● Tapetum: It is the innermost layer of anther wall which surrounds the sporogenous tissue . Tt nourishes the developing pollen grains .Cell of this layer possess dense cytoplasm and generally have more than 1 nucleus and show increase in DNA content.

The term 'clone' cannot be applied to offspring formed by sexual reproduction because offspring do not possess exact copies of parental DNA. Cloning is the process of producing genetically identical individuals of an organism either naturally or artificially. During sexual reproduction, fertilization creates a single-celled zygote which includes genetic material from both gametes.

Middle lamella is mainly composed of calcium pectate.

The middle lamella is a layer rich in pectins which cement the cell walls of adjacent plant cells and forms plasmodesmata connections. This pectin-rich layer is made up of calcium and magnesium pectates. This layer cements the cell walls of two adjacent plant cells. It is the first formed outermost layer (cell plate formed during cell division forms the middle lamella or lamellum).

Aspergillus niger is used for the production of citric acid in industries.

The citric acid (2-hydroxy-propane-1,2,3-tricarboxylic acid) is a tricarboxylic acid that contains three carboxylic functional groups. It is a primary metabolic product formed in the tricarboxylic acid (or Krebs) cycle. Citric acid is the most important organic acid produced in tonnage and is extensively used in the food and pharmaceutical industries. It is produced mainly by submerged fermentation using Aspergillus niger or Candida sp. from different sources of carbohydrates, such as molasses and starch-based media.

Hepcidin inhibits the transfer of iron into enterocytes.

Hepcidin is an iron metabolism regulatory hormone that inhibits iron absorption (transfer of iron into enterocytes). Ascorbic acid (vitamin C) forms soluble complexes with iron and reduces iron from the ferric to the ferrous state, thereby enhancing iron absorption. Tannins, present in tea, form insoluble complexes with iron and lower its absorption.