1. What led to the development of the theory of evolution?

1.1 In what ways does a species evolve?

• A random mutation in the DNA produces new gene alleles. Numerous things, such as radiation and chemical exposure, might trigger this mutation. A high number of mutations will either be harmful to the organism or will not affect the phenotype. Fewer mutations will entirely decide the phenotype, although some will have an impact.

• The organism will have higher reproductive success as a result of advantageous mutations. Certain mutations can boost an organism's survival rate and increase its capacity to fight for food and partners.

• The following generation inherits the favourable allele. When the living reproduces, the mutant allele will be inherited by the offspring and manifest itself as a phenotype.

• The frequency of this allele rises over many generations. This is because, as a result of competition from individuals who possess the allele, organisms in the species lacking the advantageous allele have a reduced chance of surviving and having successful reproduction. The greatest features are chosen to be passed on, and those without them will gradually go extinct. This process is known as natural selection.

• The cycle repeats itself when a new gene mutates. A favourable mutation advances the evolution of the species each time it happens. The creatures will eventually diverge from their progenitors to such an extent that a new species emerges.

1.2 Selective breeding and speciation

• It is possible to selectively breed animals and plants to have desired traits.

• Charles Darwin made the first observation of this and pondered whether or not new species could have been created in the wild by the same procedure.

• In order to boost productivity, farmers employ selective breeding; crops and animals with high yields are selected specifically to support this trait.

• Because many of the characteristics that their wild ancestors required to thrive and compete have been bred out of domesticated creatures, selectively produced animals differ greatly from their wild counterparts.

1.3 Species

• A collection of related creatures that are able to reproduce and create viable progeny is referred to as a species.

• A population may occasionally evolve to the point where it is no longer possible for them to mate with their forebears to create fertile offspring, in which case they have created a new species.

• If a portion of the population is isolated, speciation is more likely to happen. For instance, increasing sea levels may cut off an island from the mainland, dividing a species' population between the two locations.

• The two populations will evolve differently and eventually split into two distinct species as a result of disparities in their surroundings and levels of competition.

1.4 Theory of Evolution

• Inspired by the work of Alfred Russel Wallace and Jean-Baptiste Lamarck, a group of scientists led by Charles Darwin formulated the theory of evolution by natural selection in the middle of the 19th century. The following observations served as the foundation for evolution theory:

Fossils

• The existence of fossils lends credence to the idea of evolution because the simplest organisms may be discovered in the earliest rocks, while later fossils comprise more sophisticated animals, demonstrating how organisms have developed to become more complex throughout time.

• It is also evident that creatures have altered and evolved over time from the contrasts between living things and those found in fossils.

Selective breeding

• This technique can result in novel plant and animal kinds as well as desired qualities. This demonstrates how a species' traits can evolve over time.

Dsparities between isolated populations

• Geographical barriers can cause two groups belonging to the same species to become isolated. As a result, as the two groups adjust to their disparate environments, they evolve in distinct ways.

• Darwin saw this firsthand while visiting the Galapagos Islands, where the morphology of the tortoises varied according to the amount of vegetation they could eat. On islands where there was an abundance of food on the ground, tortoises possessed dome-shaped shells because they wouldn't have to raise their heads to eat.

• Darwin considered the fact that all tortoises descended from a single continental progenitor as proof of evolution.

Same anatomy

• A common ancestor is shown by the same bone structures found in many different creatures. The pentadactyl limb is one instance of this, which is a limb, like the human hand and fingers, that has five digits at the end.

• Whales, horses, and bats are among the other creatures that have this appendage.

1.5 Examples of evolution in the modern era

Antibiotic resistance

• Due to natural selection, certain bacterial strains develop resistance to antibiotics. This happens when an allele of the bacterial cell experiences a mutation that renders it resistant to an antimicrobial. As a result, this cell is not killed when that antibiotic is given, but cells that have not developed resistance are.

• The resistant cell is able to endure and proliferate, transferring the resistance allele to generate further resistant bacteria. This demonstrates how bacteria change over time.

DNA comparison

• Even when two species appear to be very different from one another visually, commonalities between them can be discovered by comparing their DNA and gene sequences.

1.6 Contrasting Perspectives on Evolution (Limited to Biology)

• Natural selection and the idea of evolution are continually being supported by new data and observations, which means that the theory of evolution is universally acknowledged as accurate.

• Nonetheless, some individuals reject this theory. This may result from having divergent religious views, not knowing about them, or neither comprehension, the data discovered.

2. What is the impact of asexual and sexual reproduction on evolution?

2.1 Asexual Reproduction

• Asexual Reproduction is a procedure that yields genetically identical offspring, sometimes referred to as clones. Unlike sexual reproduction, only one parent is needed for this.

• Most asexual reproduction happens in plants, although some animals, like starfish, can also reproduce in this manner.

Advantages of Asexual Rproduction

• Only one parent is needed - which is advantageous for creatures that dwell in barren environments where it is challenging to locate a partner.

• Has the ability to reproduce quickly, producing a huge numbers of offspring in a short amount of time that fills a region. This lessens competition from other species and aids in habitat dominance.

• Asexual reproduction requires less energy to complete.

Disadvantages of Asexual reproduction

• There is no genetic variation among the offspring.

• Extinction-prone: Because all created organisms have the same genetic makeup, any sickness that affects one might potentially affect all of them, making it simple for a single pathogen to wipe out an entire community.

• Cannot adopt - organisms are conditioned to a particular environment and are unable to adjust to modifications. They will probably perish if the environment changes, such as the temperature rising.

• Overpopulation: When a population grows too large, an environment may become overcrowded.

2.2 Sexual Reproduction

• Sexual Reproduction calls for two parents. Two gametes, one from each parent, fuse together at their nuclei in order to create a zygote. Genetically, every child is unique.

• Fertilization is the term for the fusing of the gametes.

Avantages of Sexual Reproduction

• Great diversity: every progeny has a distinct genetic makeup.

• Encourages survival: Since every organism is different, resistance to sickness prevents it from spreading as quickly.

• Because every child is born with a unique set of genes, organisms are able to adapt. Those who have a genetic advantage have a higher chance of surviving and passing on their favourable features to their progeny, while those that have a genetic disadvantage are more likely to perish before procreating. This permits natural selection to drive the species' evolution.

Disadvantages of Asexual Reproduction

• Two parents are needed; some species may have trouble finding partners, particularly if there is an imbalance of males to females in the area or if the species is threatened.

• Fewer offspring produced: asexual reproduction is more efficient than sexual reproduction since it takes longer and uses more energy to make offspring.

3. How does the diversity of life on Earth get categorised using our understanding of biology?

3.1 Taxonomy

• In order to facilitate research and comparison of comparable characteristics, organisms are categorised into related groups. Taxonomy refers to the categorization of living things.

• Organisms are divided into a hierarchy known as taxa according to the classification system:

Kingdoms

• The classification system divides all living things into one of five kingdoms as its initial division.

• There are five kingdoms:

  • animals (any animal with several cells)

  • plants (any green plant)

  • fungi (yeast, mushrooms, and moulds)

  • protists, such as Chlorella, Plasmodium, and Amoeba

  • prokaryotes—blue-green algae and bacteria

Phylum

• has a wide variety of creatures and is organised into kingdoms; three examples are given below:

  • Chordata: those have skeletons

  • Arthropods: they have an exoskeleton and joined legs

  • Annelids are worms with segments.

Class

• is an extra sub-division that separates a phylum into, for example, the Chordata phylum into:

  • mammals

  • birds

  • amphibians

  • fish

  • reptiles

Order

• comed after class, and mammals are one example of a group that can be further subdivided into other groupings, including:

  • carnivores

  • primates

Families

• comprise the division of orders. Carnivores can be classified into the following families, to name a few:

  • The Canidae family includes dogs.

  • Cats are in the family Felidae.

Genus

• is the next level below family. Four genus examples make up the subdivided Felidae family:

  • Acinonyx - cheetah

  • Panthera, which includes tigers and lions

  • Neofelis, clouded leopard

  • Felis, or domestic cats

Species

• The last level of classification, where the genus Panthera is split up into the following:

  • Panthera leo, the lion

  • Panthera tigris, the tiger

• There are many ways to remember this order, for example using the mnemonic such as:

  • Kids Prefer Candy Over Fresh Green Salad

  • Kings Play Chess On Fancy Gold Squares

3.2 Impact of Natural Selection on Classification

• Since the 18th century, when the system was first developed, animals were not initially categorised using DNA. As a result, organisms were classified according to their morphological or behavioural traits.

• This approach proved problematic, nevertheless, because many morphologically similar creatures differed greatly genetically.

• For instance, while having similar appearances, hares and rabbits are unable to breed and have different numbers of chromosomes. Natural selection frequently causes organisms that inhabit the same area to morph to resemble one another because it is advantageous to their survival there causing mistakes in the classification of these organisms.

• The same classification system is still in use today, despite numerous modifications brought about by technological advancements, advances in immunology, and advances in genome sequencing.

• This has made it possible to identify genetic commonalities throughout creatures. Because animals in the same group will have a relatively similar physical makeup, this has helped to elucidate the evolutionary links between various organisms and reduces the inaccuracies that come with classifying organisms based solely on physical traits comparable to genome.

• The results of genome sequencing can also reveal how recently speciation happened and whether two distinct groups of creatures had an ancestor.

4. What are the threats to biodiversity, and how can we protect it?

4.1 Biodiversity within the Ecosystem

• The term biodiversity describes the variety and quantity of distinct species found in a given location, as well as the genetic diversity among these organisms. Human actions can have very detrimental effect on the biodiversity:

Chemical Use

• the use of chemicals, like that found in pesticides, can lower biodiversity by eliminating pest species, which in turn lowers the number of species in an ecosystem.

• These substances, along with those in fertilizers, can also be carried into water sources by rain, where they can kill organisms and lead to eutrophication. As less prey is available for other species, who may also perish, this could have a domino effect.

Urbanization and Industrialization

• In addition to significantly raising pollution levels, urbanization and industrialization have caused habitat degradation.

• Acid rain, which corrodes tree leaves and destroys forest ecosystems, and elevated temperatures in certain regions can result from pollution, forcing out species that are unable to adapt.

• Certain factories also contaminate water sources, which kills living organisms. The poisoning of China's industry, which is causing the pink river dolphins to become severely endangered, is one example of this.

Invasive Species

• It is possible for humans to bring invasive species into a region. By feeding on other species, these species lower the biodiversity of a given area. Cane toads in Australia are one example of this.

• In an effort to lessen the number of beetles that were causing damage to sugarcane plantations, toads were initially brought in 1937. On the other hand, these toads proliferated rapidly and feasted on numerous indigenous species in addition to releasing poisonous toxins.

• Numerous other species, such as native lizards, snakes, and crocodiles, have plummeted since their arrival.

4.2 Global Efforts for Biodiversity Conservation

• Both locally and worldwide, efforts are being made to conserve biodiversity in order to address these problems. National parks and nature reserves can support biodiversity conservation and the preservation of endangered species.

• Additionally, farming can be done in a more environmentally friendly manner by using less chemicals and controlling logging and fishing to protect habitats.

• International agreements like the Kyoto Protocol aid in the mitigation of pollution and the control of climate change.

• However, the effectiveness of this varies because some nations, like the USA and China, refuse to sign these treaties. Despite being the most polluting countries, they safeguard their own economies.

4.3 Human Food Security

• The sustainability and accessibility of a food source are referred to as food security. Various factors may put challenges to a food supply, such as:

Growing population

• As a result of improved medical care and rising birth rates, there are more people on the planet who need food.

• Furthermore, the requirement for additional cities and residences results in a decrease in the quantity of farmland that may be used to raise crops and livestock for food.

Dietary changes

• With increasing affluence, dietary preferences in developed nations have shifted towards meat consumption, exacerbating environmental strain and contributing to unsustainable agricultural practices.

• Rapidly developing countries like China are experiencing a surge in meat consumption due to economic growth, further intensifying the strain on global food resources and environmental sustainability.

Emerging pests and diseases

• The emergence of new pests and diseases poses significant threats to global food security by reducing agricultural yields and impacting food production.

• These pests and diseases can cross species barriers, affecting both crops and livestock, thereby exacerbating food shortages and economic instability in affected regions.

Environmental changes

• attributed to global warming, precipitating a surge in severe weather patterns. These manifestations encompass droughts, tropical storms, and flash floods, posing significant threats to agricultural productivity and livestock survival.

• Consequently, the escalating frequency and intensity of these events exacerbate food shortages and economic hardships in affected regions.

4.4 Importance of Sustainable Farming for Biodiversity

• Ensuring food security necessitates the conservation of biodiversity and the adoption of sustainable practices in food production. Practices such as unsustainable farming methods can have enduring repercussions, compromising soil fertility over time.

• For instance, excessive chemical application can result in soil contamination, while over-farming contributes to soil erosion and desertification, rendering land infertile for crop cultivation.

• Sustainable farming practices are indispensable not only for safeguarding food security but also for sustaining the production of raw materials and medicinal ingredients derived from agriculture.

• Moreover, agricultural yields can be enhanced through various methods. Genetic modification allows for the development of resilient plant and animal varieties capable of withstanding adverse environmental conditions, such as frost-resistant strawberries.

• Additionally, selective breeding enables the augmentation of yield per plant or animal by accentuating desirable traits.

• Further optimization is achieved by cultivating crops and livestock under optimal conditions, such as in controlled environments like greenhouses, to maximize growth potential and resource utilization.