Diversity of living world - class-XII

Cleidoic eggs have a protective shell, and are laid out of water. The shell is porous to air, and may be flexible or calcareous (hard). The eggs contain all the food the embryo needs to develop into a hatchling. The significance of the cleidoic egg is that it enables reproduction out of, and often away from, water. It is a characteristic of birds and reptiles. Hence, option D is correct.

The notochord is the defining structure forming in all chordate embryos. In humans beings, the notochord is formed in the third week and eventually replaced by the vertebral column. 

Gene banks are a type of biorepository, which preserve genetic material. For plants, this could be by freezing cuttings from the plant, or stocking the seeds (e.g., in a seed bank). For animals, this is the freezing of sperm and eggs in zoological freezers until further need. With corals, fragments are taken which are stored in water tanks under controlled conditions.
Plant genetic material in a 'gene bank' is preserved at $-196^0$C in liquid nitrogen as mature seed (dry).

A biosphere reserve is an ecosystem with plants and animals of unusual scientific and natural interest. It is a title given by UNESCO to help protect the sites. The plan is to promote management, research and education in ecosystem conservation. This includes the 'sustainable use of natural resources'. 
In situ conservation is on-site conservation or the conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of tree species.

Genetic erosion is a process whereby an already limited gene pool of an endangered species of plant or animal diminishes even more, when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population. 

Germplasm is a term used to describe living genetic resources, such as seeds or tissue, maintained for the purpose of breeding, preservation, and other research uses. These resources may take the form of seed collections stored in seed banks, trees growing in nurseries, animal breeding lines maintained in animal breeding programs or gene banks, etc. Germplasm collections can range from collections of wild species to elite, domesticated breeding lines that have undergone extensive human selection.

Genetic diversity refers to the variety of genes within a species. Each species is made up of individuals that have their own particular genetic composition. Within a species there may also be discrete populations with distinctive genes. Speciation is the evolutionary process by which new biological species arise. The biologist Orator F. Cook was the first to coin the term 'speciation' for the splitting of lineages or "cladogenesis," as opposed to "anagenesis" or "phyletic evolution" occurring within lineages.
More diversity will be introduced to gene pool when speciation occurs; as a result of which more and more species will be produced.

Agrobacterium tumefaciens will transfer genes (T-DNA region of Ti plasmid) into the plant that produces its food or nutrient called opines (opines are not needed for plants). Apart from that, it also integrates genes for cell division and proliferation leading to crown gall disease, so that more number of cells result in more production of opines. Because of this reason it is called as a 'natural genetic engineer'.

A staple food, sometimes simply referred to as a staple, is a food that is eaten routinely, and in such quantities that it constitutes a dominant portion of a standard diet in a given population, supplying a large fraction of the needs for energy-rich materials and generally a significant proportion of the intake of other nutrients as well. Most people live on a diet based on just a small number of staples.
Staple foods vary from place to place, but typically they are inexpensive or readily available foods that supply one or more of the three organic macronutrients needed for survival and health: carbohydrates, proteins, and fats.
Wheat (Triticum spp.) is a cereal grain, originally from the levant region of the Near East but now cultivated worldwide. In 2013, world production of wheat was 713 million tons, making it the third most-produced cereal after maize (1,016 million tons) and rice (745 million tons). 

Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of the species. Genetic diversity serves as a way for populations to adapt to changing environments.
In order to capture the maximum genetic diversity of a species, recent, old, wild - all kind of varieties will be considered and taken into account and searched.
Thus, the correct answer is option (D),  'All of the above'.

Extinction of a particular animal or plant species occurs when there are no more individuals of that species alive anywhere in the world - the species has died out. When it does not exist at all , preserving it also not possible.

Genetic erosion is a process whereby an already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population. Low genetic diversity in a population of wild animals and plants leads to a further diminishing gene pool, inbreeding and a weakening immune system and fast tracks that species towards eventual extinction. 

Wild varieties of plants must be conserved because they are of utmost value to plant breeders for producing improved and favourable varieties of plants by selecting useful genes from a wide range of their wild relatives. In other words, new and improved varieties of crops are derived from their wild relatives by genetic modification. Useful traits are like high yielding, disease resistant, stress resistant etc.

Germplasm is a living tissue from which new plants can be grown. It can be a seed or another plant part like a leaf, a piece of stem, pollen or even just a few cells that can be turned into a whole plant. Germplasm contains the information for a species genetic makeup, a valuable natural resource of plant diversity. 

Shoot tip culture is the culture of terminal part of shoot to a plant in in-vitro condition or in lab called as shoot tip culture. Mostly the shoot tip culture used for obtain disease free plant without genetically changes. The plant which affected by any contaminant mostly by viruses have saved by shoot tip culture, because shoot tip of any affected plant is less or free from contamination (viruses, bacteria, fungus). 

Norman Borlaug developed a special breed of dwarf wheat that resisted a wide spectrum of plant pests and diseases and produced two to three times more grain than the traditional varieties. During the period from 1949-55, M S Swaminathan undertook research on potato, wheat, rice and jute genetics, after which he worked on Mexican dwarf wheat varieties.

Vavilov worked on global genetic diversity of cultivated plants throughout his life, from which he developed several major theories that have played an important role in the development of botany, genetics and plant breeding. One such theory among several is "Theory of centres of origin of cultivated plants" (1920).

Genetic erosion is a process, whereby an already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population. The term is sometimes used in a narrow sense, such as when describing the loss of particular alleles or genes, as well as being used more broadly, as when referring to the loss of varieties or even whole species.
Genetic erosion occurs because each individual organism has many unique genes which get lost when it dies without getting a chance to breed. Low genetic diversity in a population of wild animals and plants leads to a further diminishing gene pool inbreeding and a weakening immune system can then "fast track" that species towards eventual extinction.

Vavilov collected not less than 26,000 varieties of wheat alone, were kept in cultivation at Leningrad. These collections formed the basis for new theories on the origin of cultivated plants and laid the foundation for the future improvement of crop plants and of one of the largest and oldest seed banks in the world today.

Germplasm is a term used to describe living genetic resources such as seeds or tissue, maintained for the purpose of breeding, preservation, and other research uses. These resources may take the form of seed collections stored in seed banks, trees growing in nurseries, animal breeding lines maintained in animal breeding programs or gene banks, etc. Germplasm collections can range from collections of wild species to elite, domesticated breeding lines that have undergone extensive human selection.
Holstein-Friesian (HF) gene bank collections were established in France  to conserve genetic diversity for this breed. The cryobanks have captured substantial amounts of genetic diversity for the HF compared with the current populations. A substantial part of the US, French, and Dutch collections seems to be genetically similar. On the other hand, the US collection in particular represents an interesting reservoir of HF genes of the past. Gene banks can play an important role in conserving genetic diversity within livestock breeds over time, and may support industry in the future when needed.

The Rht - B1b and Rht - D1b are dwarfing genes, derived from Norin - 10. Norin - 10, which was a semi - dwarf variety bred in Japan and released in 1935. Norin - 10 was used in order to improve lodging resistance in winter wheat. 

Ecological hot spots are large areas of Earth's land surface which have high concentrations of plant endemism and also experience high rates of habitat loss. In India, 4 ecological hot spots are presently identified. The Himalayas, the Western Ghats, the Indo-Burma region and the Sundaland constitute the biodiversity hot spots in our country. One of the major features of these places is the presence of numerous endemic species.

• A biodiversity hotspot is an area which has lost at least 70 per cent of its primary native vegetation 

• It contains at least 1,500 species of vascular plants which are endemic.

• There are currently 36 recognized biodiversity hotspots.

• These are Earth’s most biologically rich yet threatened terrestrial regions.

• The hotspots provide crucial ecosystem services for human life, such as provision of clean water, pollination and climate regulation.
  

• Conservation in the hotspots promotes sustainable management of these essential natural resources and supports economic growth, which also reduces drivers of violent conflict.
  

• So, the answer is in-situ conservation.

• A biodiversity hotspot is a biogeographic region that is both a significant reservoir of biodiversity and is threatened with destruction.
• The term biodiversity hotspot specifically refers to biologically rich areas around the world that have lost at least 70 per cent of their original habitat.
• There are 34 biodiversity hot spots across the globe, among which three occur in India such as the Western Ghats & Sri Lanka, Indo-Burma (North East India) and the Himalayas.
  
• Hence Western ghats & Sri Lanka, Indo Burma and Himalaya are Hot Spots of biodiversity in India.ervo
• So, the correct answer is 'The Western Ghats & Sri Lanka, Indo Burma and Himalaya'.

Ecological hot spots are large areas of Earth's land surface which have high concentrations of plant endemism and also experience high rates of habitat loss. In India, 4 ecological hot spots are presently identified. The Himalayas, the Western Ghats, the Indo-Burma region and the Sundaland constitute the 4 biodiversity hot spots in our country. One of the major features of these places is the presence of numerous endemic species.

If we accept May's global estimates only 22% of the total species have been recorded so far. If May's proposal for discovery of new species is accepted then there are probably more than 1,00,000 plant species and more than 3,00,000 animal species yet to discovered and described.

Species diversity is the variety in the number and richness of the species of a region, Western Ghats have greater amphibian species diversity as compared to eastern ghats.

Vertical distribution of different species occupying different levels is called stratification. For example, trees occupy top vertical strata or layer of a forest, strubs the second and herbs and grasses occupy the bottom layers.

There are four major causes of biodiversity losses which are collectively called as the evil quartet. These are habitat loss and fragmentation, over exploitation, alien species invasion and co-extinctions. 

Alexander Von Humboldt observed that within a region richness increased with increased explored area, but only upto a limit. If a graph is plotted between species richness and area then we get a rectangular hyperbola. ON a log scale, the relationship becomes linear (straight line) and is described by the equation,

Brazil is the country with the highest biodiversity in the world. One-tenth of the world's overall species lives here.

Pines seeds are mainly small and winged, and are anemophilous generally, which means that the seeds are dispersed by wind. However, some seeds are larger and they have only a vestigial wing and are needed to be dispersed by a bird. Thus, If at high altitudes, birds become rare, the plants likely to disappear are Pine plants. Oaks are not generally found at such high altitudes.

The tree line in the Himalayas generally increases in altitude from east to west due to variations in precipitation and temperature, but the Eastern Himalayas are often cited for specific high-altitude vegetation zones; however, this is a complex biogeographical question where the Eastern Himalayas typically host higher biodiversity and distinct altitudinal limits.

Nepenthes khasiana is a pitcher plant endemic to the Khasi Hills in the state of Meghalaya, India.

Moss-Lichen communities, representing tundra vegetation, are predominantly found in high latitude regions ranging from approximately 60 to 80 degrees North or South, where harsh cold climates restrict tree growth.

India is a mega-biodiverse country, and it is estimated to account for approximately 7-8% of the world's recorded species.

Ecological amplitude refers to the range of environmental conditions (tolerance) under which a species can survive and reproduce successfully.

The rate of photosynthesis would be maximum at the equator because the the rate of photosynthesis depends on the light intensity. Maximum intensity of light occurs at the equator, and gradually decreases with increasing distance from the equator to the south and north poles. So the correct answer is 'Equator'.

Biodiversity day or the Biological diversity day is a UN sanctioned day celebrated internationally. It addresses the promotion of biodiversity issues. Currently, the day is held on May 22. Earlier, it was held on December 29 to celebrate the day in which the Convention on Biological Diversity came into action.