Biology 2 Marks Questions

→ Humans have always depended on nature for food and shelter, but when 'need' turns to 'greed', it leads to over-exploitation of natural resources.
→ Many species extinctions in the last 500 years (Steller's sea cow, passenger pigeon) were due to overexploitation by humans.
→ Presently many marine fish populations around the world are over harvested, endangering the continued existence of some commercially important species.

→ The most important of them are:
(i) Genetic diversity :
→ A single species might show high diversity at the genetic level over its distributional range.
→ The genetic variation shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces.
→ India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango.
(ii) Species diversity :
→ The diversity at the species level, for example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats.
(iii) Ecological diversity :
→ At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.

→ India has a history of religious and cultural traditions that emphasized protection of nature.
→ In many cultures, tracts of forest were set aside, and all the trees and wildlife within were venerated and given total protection.
→ Sacred groves means conservation of plants and animals according to religious beliefs.
Some sacred groves in India :
→ Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya.
→ Aravalli Hills of Rajasthan
→ Western Ghat regions of Karnataka and Maharashtra.
→ Sarguja, Chanda and Bastar areas of Madhya Pradesh.
→ In Meghalaya, the sacred groves are the last refuges for a large number of rare and threatened plants.

→ The broadly utilitarian argument says that biodiversity plays a major role in many ecosystem services that nature provides.
→ The fast dwindling Amazon forest is estimated to produce, through photosynthesis, 20 per cent of the total oxygen in the earth's atmosphere.
→ Some idea by finding out how much your neighborhood hospital spends on a cylinder of oxygen.
→ Pollination (without which plants cannot give us fruits or seeds) is another service, ecosystems provide through pollinators layer - bees, bumblebees, birds and bats.
→ There are other intangible benefits - that we derive from nature-the aesthetic pleasures of walking through thick woods, watching spring flowers in full bloom or waking up to a bulbul's song in the morning.
→ We have a moral duty to care for their well- being and pass on our biological legacy in good order to future generations.

→ Adapting capacity is found more in animals than plants.
→ Animals do locomotion, so they can migrate to protect themselves in unfavourable condition.
→ Animals contain nervous system which control and coordinates different activities. As a result of this, they can respond quickly to adapt themselves with surroundings.
→ Most of the plants cannot migrate and cannot resist in the environment to adapt themselves. So they are at more risk.
→ In animals, due to sexual reproduction and caring of offspring which lead them at higher level.

→ Plants play important role in controlling floods and soil erosion.
→ Plant roots holds the soil tightly which prevents the erosion of soil through water and wind

→ The accelerated rates of species extinctions that the world is facing now are largely due to human activities.
→ There are four major causes:
→ (1) Habitat loss and fragmentation
→ (2) Over-exploitation
→ (3) Alien species invasions
→ (4) Co-extinctions

→ Speciation is generally a function of time.
→ Unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.
→ Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable.
→ Such constant environments promote niche specialisation and lead to a greater species diversity.
→ There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.

→ Yes, there are various kinds of parasites and disease-causing microbes that we deliberately want to eradicate from the Earth.
→ Since these micro-organisms are harmful to human beings.
→ Scientists have been able to eliminate many harmful viruses from the world through the use of vaccinations.
→ This shows that humans deliberately want to make these species extinct.
→ Several other eradication programmes such as polio viruse vaccine and Hepatitis B vaccinations are aimed to eliminate these disease-causing microbes.

→ (i) Genetic diversity
→ (ii) Species diversity
→ (iii) Ecological diversity

→ When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species.
→ The Nile perch introduced into Lake Victoria in east Africa eventually led to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake.
→ The environmental damage caused and threat posed to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eicchornia).
→ The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.

→ Biodiversity knows no political boundaries and its conservation is therefore a collective responsibility of all nations.
→ The historic Convention on Biological Diversity ('The Earth Summit') held in Rio de Janeiro (Brazil) in 1992, called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilization of its benefits.
→ In a follow-up, the World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels.

→ When we conserve and protect the whole ecosystem, its biodiversity at all levels is protected - we save the entire forest to save the tiger.
→ This approach is called in situ (on site) conservation.
→ However, when there are situations where an animal or plant is endangered or threatened (organisms facing a very high risk of extinction.
→ in the wild in the near future) and need urgent measures to save it from extinction, ex situ (off site) conservation is the desirable approach.

→ The ethical argument for conserving biodiversity relates to what we owe to millions of plant, animal and microbe species with whom we share this planet.
→ Philosophically or spiritually, we need to realise that every species has an intrinsic value, even if it may not be of current or any economic value to us.
→ We have a moral duty to care for their well- being and pass on our biological legacy in order to future generations.

→ Humans derive countless direct economic benefits from natural food (cereals, pulses, fruits), firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and products of medicinal importance.
→ More than 25 per cent of the drugs currently sold in the market worldwide are derived from plants and 25,000 species of plants contribute to the traditional medicines used by native peoples around the world.
→ Nobody knows how many more medicinally useful plants are there in tropical rain forests waiting to be explored.
→ With increasing resources put into 'bioprospecting' (exploring molecular, genetic and species-level diversity for products of economic importance), nations endowed with rich biodiversity can expect to reap enormous benefits.

→ Different species are not equally distributed on the earth.
→ Ecologists estimate the total species are based on the polar temperature.
→ For many taxonomic groups, the discovery of species is fulfilled in temperate countries rather than tropical countries.
→ Biologists have compared the statistical data of insects richness in temperate and tropical area as well as the estimated ratio of animals and plants for region.

→ In general, loss of biodiversity in a region may lead to
(a) decline in plant production,
(b) lowered resistance to environmental perturbations such as drought and
(c) increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycles.

→ More than 70 per cent of all the species recorded on the earth are animals.
→ While plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total.
→ Among animals, insects are the most species- rich taxonomic group.
→ Making up more than 70 per cent of the total that means, out of every 10 animals on this planet, 7 are insects.
→ The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles and mammals.
→ Although India has only 2.4 per cent of the world's land area, its share of the global species diversity is an impressive 8.1 per cent.
→ According to Robert May's global estimates, only 22 per cent of the total species have been recorded so far.