Biology Evolution and Adaptations PDF

MYP 4&5 BIOLOGY 2023-2024 UNIT 5 Title Evolution and Adaptations Timeframe 5 Global Context: Orientation...

MYP 4&5 BIOLOGY 2023-2024 UNIT 5 Title Evolution and Adaptations Timeframe 5 Global Context: Orientation in space and time Key Concept: Change Related Concept: Interaction. Environment Statement of Organisms are more likely to survive when they are adapted to interact with their surroundings and Inquiry: respond to changes in their environment. Factual What extraordinary evolutionary adaptations or specialized features can be found in Earth’s changing environment? Conceptual How does the interaction between organisms and their environment lead to the Inquiry Questions development and/or extinction of species? Debatable To what extent should humans artificially support the survival of organisms that are uncapable of adapting to their changing environment? DISCLAIMER The following booklet is a collage of the theoretical content of the following sources: ▪ Biology for the IB MYP 4&5: By Concept. Davis & Deo. Hodder Education. 2015. ISBN: 9781471841705 ▪ Cambridge IGCSE Biology Study and Revision Guide 2nd Edition. Hayward. Hodder Education. 2016. ISBN: 9781471865138 ▪ Oxford IB Study Guides: Biology for the IB Diploma. Allot. Oxford University Press. 2014. ISBN: 9780198393511 ▪ IB Biology Course Book: Oxford IB Diploma Programme. Allot and Mindorff. Oxford University Press. 2014. ISBN: 9780198392118 ▪ Oxford IB Course Preparation: Biology for IB Diploma Programme Course Preparation. Bkerat. Oxford University Press. 2018. IBN:978019842350-8 (1) Evolution Today, it is generally accepted that present-day species have arisen by change from ancestral forms of life. The word ‘evolution’ has several meanings all of which involve the gradual development of something. When we talk about the evolution of species, we mean the gradual development of life over very long periods of time (geological time), from its earliest beginnings to the diversity of organisms we know about today, both living and extinct. Evolution is the development of new types of living organisms from ones that already exist through the gradual build-up of genetic differences. Thus, evolution occurs when heritable characteristics of a species change. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 1  Divergent evolution is the accumulation of differences between closely related populations within a species, leading to speciation. Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor Figure 1 - Schematic representation of the three main types of evolution - divergent, convergent, and parallel. Source: https://www.sparknotes.com/biology/evolution/patternsofevolution/section1/ of those groups. Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure Although it is not possible to prove that organisms on Earth are the result of evolution, there is very strong evidence for this theory. Evolution is supported by four different types of evidence: 1. Fossils. Fossils document the existence of now-extinct past species that are related to present-day species. Figure 2 - Fossil record of whale evolution. Source: https://slideplayer.com/slide/6663302/ Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 2 2. Anatomy. Species may share similar physical features because the feature was present in a common ancestor – homologous structures (see figure 4 and refer to sub-chapter 1-A. Pentadactyl limbs). 3. Molecular biology. DNA and the genetic code reflect the shared ancestry of life. DNA comparisons can show how related species are. The basic idea behind this approach is that two species have the "same" gene because they inherited it from a common ancestor. For instance, humans, cows, chickens, and chimpanzees all have a gene that encodes the hormone insulin, because this gene was already present in their last common ancestor (see figure 3). Amino acid sequences are typically used to compare distantly related species (i.e., different taxa), while DNA or RNA base sequences are often used to compare closely related organisms (e.g., different haplogroups – such as various human ethnic groups) Figure 3 – Bone structure of pentadactyl limbs of turtle, dolphin, horse, human, bird and bat. Source: https://anbiojovem.org.br/evolucao-resumo-o-que-e- evidencias-e-mecanismos/ Figure 4 – Amino acid comparison of the haemoglobin beta chain in different species. Sequence differences accumulate gradually so there is a positive correlation between the number of differences between two species and the time since they diverged from a common ancestor. Source: https://ib.bioninja.com.au/standard-level/topic-5-evolution-and-biodi/54-cladistics/molecular-evidence.html Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 3 4. Biogeography. The global distribution of organisms and the unique features of island species reflect evolution and geological change. This is called adaptive radiation(see note #1) - the diversification of a group of organisms into forms filling different ecological niches. A niche refers to the way in which an organism fits into an ecological community or ecosystem. Note #1: Adaptive radiation is a type of speciation. Please refer to chapter 3., Speciation – Adaptative radiation, for a more in depth understanding. A. Pentadactyl limbs Four groups of vertebrates have limbs: amphibians; reptiles; birds; and mammals. These vertebrates use their limbs in a wide variety of ways, including walking, jumping swimming, climbing, and digging. Despite this, the basic bone structure is the same in all of them. The structure is known as the pentadactyl limb. The most plausible explanation is that all these vertebrates share an ancestor that had pentadactyl limbs. Many different groups have divergently evolved from the common ancestor, but because they adopted different types of locomotion, the limbs developed in widely different ways, to suit the type of locomotion. Structures like the pentadactyl limb that have evolved from the same part of a common ancestor are called homologous structures (see figure 4). Sometimes, organisms have structures that are homologous to important structures in other organisms but that have lost their major ancestral function. These structures, which are often reduced in size, are known as vestigial structures. For example, tailbone of humans (a vestigial tail), the hind leg bones of whales, and the underdeveloped legs found in some snakes. It is important to note that not all physical features that look alike are marks of common ancestry. Instead, some physical similarities are analogous: they evolved independently in different organisms because the organisms lived in similar environments or experienced similar selective pressures. This process is Figure 5 - Diagram that represents how different functions present in several species are considered homologous or analogous. Source: https://ib.bioninja.com.au/standard-level/topic-5- evolution-and-biodi/54-cladistics/structural-evidence.html Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 4 called convergent evolution (see figure 1 and 5) Thus, structural traits are not commonly used to determine a clade - a group of organisms believed to comprise all the evolutionary descendants of a common ancestor - as such features may not necessarily indicate shared heritage. Instead, molecular biology, such as amino acid sequencing and DNA comparison are used. This prevents classifying together animals that look physically alike due to analogous structures. For example, sharks and dolphins are evolutionary more distant than pumas are from dolphins. However, since sharks and dolphins share fins and live-in aquatic environment, they are mis commonly placed together in the same clade. Figure 6 - Using molecular evidence, scientists have discovered that many species thought to be closely related based on shared structural characteristics actually demonstrate distinct evolutionary origins. Such is the case between sharks and dolphins. Source: https://ib.bioninja.com.au/stand ard-level/topic-5-evolution-and- biodi/54-cladistics/structural- evidence.html The chapter above was complemented with information taken from the following sources: Website Evidence for Evolution (Article).” Khan Academy, Khan Academy, www.khanacademy.org/science/biology/her/evolution-and-natural- selection/a/lines-of-evidence-for-evolution. Until here, you can now do the following formative questions at the end of the unit: 1 & 2. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 5 (2) Theory of Evolution by Natural Selection A. Natural selection and variation Variation describes differences in a population. Some variation is inherited (passed on from parents) and some is acquired (developed through life). Animals and plants produced by sexual reproduction will show variation from their parents. Natural selection is the process that results in the adaptation of an organism to its environment by means of selectively reproducing changes in its genotype, or genetic constitution (inherited, not acquired!). When organisms reproduce, many offspring are often produced. However, not all of them are likely to survive because of competition for resources such as food, water, and shelter. The same is true for plants, since they compete for nutrients, light, water, and space. There is a struggle for survival. The individuals with the most favorable characteristics are more likely to survive because they have an advantage over others in the population. For example, a lion cub with bigger muscles in its legs would be able to run more quickly and get food more successfully than its siblings. Thus, in an environment that presents itself with challenges, the individual with the best adaptations to these challenges is most likely to survive to adulthood. The weaker individuals die before having the chance to breed, but the surviving adults breed. In turns, this increases the likelihood of advantageous alleles being passed to the new generation of offspring. Which ultimately reflect in a stronger population, better adapter to a changing environment. Figure 7 - Example of natural selection due to variation. There are two variations for the genotype fur of mice, brown and black. When the phenotype is black, the mice blend in the environment are less likely to be seen and eaten. phenotype is brown, the mice do not blend in the environment, are more likely to be seen and eaten. Source: https://www.khanacademy. org/science/ap- biology/natural- selection/natural-selection- ap/a/darwin-evolution- natural-selection Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 6  B. Sources of Variation Natural selection can only occur if there is variation among members of a species. There are three sources of variation: 1. Mutation. Mutation is considered the original source of variation. New alleles are produced by gene mutation which enlarges the gene pool of a population. Figure 8 - Variation that arises by mutation: sickle cell anaemia. The disease sickle cell anaemia is due to a point mutation (i.e., substitution) of a T for an A at the DNA level, which reflects in the amino acid glutamic acid being replace by valine. Source: https://www.slideshare.net/smullen57/31-genes 2. Meiosis. Meiosis produces new combinations of alleles by breaking up existing combinations in a diploid cell - random assortment of homologous chromosomes. Every cell produced by meiosis in an individual is likely to carry a different combination of alleles. Figure 9 - Representation of two possible combinations of gametes that arise due to meiosis. Homologous chromosomes do not have a fixed spot to take during metaphase I. This means that they can take whichever position, it is a random orientation. Source: https://www.mun.ca/biolo gy/desmid/brian/BIOL20 60/BIOL2060- 20/CB20.html Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 7  3. Sexual reproduction. This type of reproduction involves the fusion and cross-over of male and female gametes. The gametes usually come from different parents, so the offspring has a combination of alleles from two individual. This contributes tremendously to variation between generations, thus species. Figure 10 - One paternal homologous chromosomes (represented as blue) and one maternal homologous chromosome (represented as red) are side-by-side during metaphase I. They are so close that different alleles of the same gene can cross-over, increasing the genetic variation of the future gamete that will arise at the end of telophase II. Source: https://www.khanacademy.org/science/ap- biology/heredity/non-mendelian- genetics/a/linkage-mapping Until here, you can now do the following formative questions at the end of the unit: 3 - 5. C. Charles Darwin - The Origin of Species Charles Darwin developed the theory of evolution by natural selection, which explains how changes in species can occur through variation and selection. Darwin did more than 20 years of research and, during this time, he amassed a wide range of evidence for natural selection. He then published the pioneering work The Origin of Species. This book changed ever the way that biologists think about the living world and the place of humans in it. During his travels around the globe, and in particular during his visit to the Galápagos Islands, Darwin noted that all species showed tremendous variation. He also noticed that populations produced many more individuals than could survive, due to limited resources. He noted that there was a ‘struggle for existence’ where only the most fit survive. On returning to the UK, and after carrying out more extensive research, Darwin developed his Theory of Evolution by Natural Selection: 1. Population number. Species tend to produce more offspring than the environment can support. 2. Competition. There is a struggle for existence in which some individuals survive and some die. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 8  3. Variation. In natural populations there is variation between the individuals. 4. Fitness – Differential survival. Some individuals are better adapted than others. An adaptation is a characteristic that makes an individual suited to its environment and way of life. 5. Fitness – Differential reproduction. Individuals that are better adapted are more likely survive and produce more offspring, while less well adapted individuals are more likely to die or produce fewer offspring, so each generation contains more offspring of better adapted than less well adapted individuals. 6. Inheritance. Individuals that reproduce pass on their ‘more fit’ genotypical traits/characteristics to their offspring. 7. Accumulative change. The frequency of characteristics that make individuals better adapted increases and the frequencies of other characteristics decreases, so species change and become better adapted. When the environment changes, new opportunities for species are generated. The niche - the way in which an organism fits into an ecological community or ecosystem – of a species is everything about where and how it lives. Each species has a unique niche, and so as populations moves into new environments the niche can change. As niche changes, so does the species. If the niche is uncapable of changing, the species is unable to survive. Note that survival of a species is the capacity of a species to reproduce and produce offspring. D. Darwin vs. Lamarck Lamarck’s theory of evolution was based around how organisms (e.g., animals, plants) change during their lifetime, and then pass these changes onto their offspring. For example, Lamarck believed that the giraffe had a long neck because its neck grew longer during its lifetime, as it stretched to reach leaves in high-up trees, meaning that each generation of giraffe had a longer neck than previous generations. At the eyes of Lamarck, there was no difference between inherited and acquired adaptations. He strongly believed that evolution was purely based on how organisms could acquire adaptations to better fit their changing environment (see figure 11). Contrarily, Darwin’s theory refuted Lamarck’s theory. Darwin believed that organisms possessed variation (each individual was slightly different from one another), and these variations led to some being more likely to survive and reproduce than others. Features that made an organism more likely to survive or reproduce are Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 9 therefore more likely to appear to each generation. In terms of the giraffe, Darwin’s theory would state that longer necked giraffes were more likely to survive, because they could eat leaves from taller trees, and therefore more long-necked giraffes will be born, which eventually caused all giraffes to have longer necks. Longer necked giraffes survived because they were a better fit for their environment. It is from this idea that we get the phrase ‘survival of the fittest’. Thus, according to Darwin, organisms do not acquire adaptations to better fit the changing environment. Instead, the changing environment naturally selects those individuals who are genetically more likely to adapt and survive. Figure 11 - Evolution of the giraffe explain under Lamarck's believes and Darwin's believes of what evolution is. Source: http://msandersonbio.weebly.com/evolution.html Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 10 Darwin’s theory became accepted because it had more evidence that supported it. Lamarck’s theory suggest that all organisms become more complicated over time, and therefore doesn’t account for simple organisms, such as single-cell organisms. We also know through observation that characteristics inherited during an individual’s lifetime do not get passed onto their offspring; for example, if someone pierces their ear, it doesn’t mean that their children will be born with pierced ears. Darwin’s theory became even stronger when, many years after his death, the study of genetics and molecular biology emerged. Genetics ultimately showed that all inherited traits were passed on through genes, which are unaffected by outside world, as Lamarck would predict, and are instead naturally varied, as Darwin predicted. Though Darwin didn’t know what genes were, he could see their effect on natural selection. Until here, you can now do the following formative questions at the end of the unit: 6 – 8. The information of the chapter above was taken from the following sources: Website MyTutor. “Explain the Difference between Lamarck's and Darwin's Theory of Evolution? Why Was Darwin's More Successful?” MyTutor, www.mytutor.co.uk/answers/2529/GCSE/Biology/Explain-the-difference-between-Lamarck-s-and-Darwin-s-theory-of-evolution-Why-was-Darwin- s-more-successful/. E. Selective breeding Natural selection occurs in a group of living organisms through the passing on of genes to the next generation by the best-adapted organisms, without human interference. Those with genes that provide an advantage to cope with changes in the environmental conditions are more likely to survive, Figure 12 – Results of selective breeding in cow: a photographic view of the “before while others die before they can breed and pass on and after” improvement in muscle capacity. Source: https://www.quora.com/What- is-the-perspective-of-cow-in-evolution-if-it-is-eaten-by-humans their genes. However, variation within the population remains. Selective breeding are domesticated breeds – animals and plants – that have been developed from wild species, by selecting individuals with desirable traits and breeding from them. The striking differences in the heritable characteristics of domesticated breeds give us evidence that species can evolve rapidly by artificial selection. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 11 Selective breeding is used by humans to produce a variety of animals and plants that have an increased economic importance. It is considered a safe way of developing new strains of organisms and is much faster process than natural selection: ▪ Wild varieties of plants sometimes have increased resistance to fungal diseases but have poor fruit yield. Crossbreeding wheat plants over a number of generations and selecting the organisms with the best features at each stage can result in the formation of varieties that have both high resistance to disease and high seed yield. Crossbreeding is the process or the act of producing offspring particularly through mating two purebred individuals but come from different breeds, varieties, or even species. ▪ A variety of cattle may have a higher-than-average ilk yield. Another variety may have a very high meat yield. If the two varieties are cross bred, the individuals in the next generation with the features are selected to continue breeding until a new breed has been artificially produced with the benefits of both parental varieties (high milk production in females; high meat yield in males). However, selective breeding removes variation from a population, leaving it susceptible to disease and unable to cope with changes in environmental conditions. Potentially, therefore, selective breeding puts a specie at risk of extinction. This will be analysed more in depth in Unit 8 - Biotechnology (3) Speciation – Adaptive radiation For a new species to form, speciation as well as natural selection needs to occur. Speciation is the process by which one or more populations of a species become genetically different enough to form a new species - a group of organisms that can mate and produce young that are themselves able to breed and have their own young. Speciation may occur due to factors like predation, gradual environmental changes and/or abrupt environmental changes, When the latter is the case, geographical isolation of members of a population occurs. Allopatric [(allo) other + (patric) place] speciation occurs when members of a population become geographically isolated from one another, to the extent that genetic exchange, through mating, is prevented or interfered with. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 12 This may be a result of geographical changes, such as the formation of a mountain by a volcano, island formation, habitat separation by glaciers and rivers, or habitat fragmentation caused by human activity. Alternatively, species members may emigrate, resulting in population separation by dispersal. When allopatric speciation of Figure 13 - Beetle speciation due to external factors: predation; and local environmental change. Source: https://schools.aglasem.com/16725 species occurs in a relatively short evolutionary timeframe it is called adaptive radiation. This is the case of the evolution seen in Darwin’s Galapagos’ Finches (see figure 14 and 15). Figure 14 - Adaptive radiation of Darwin's finches, Galapagos' Islands. Source: https://pt.slideshare.net/badaralamdarhashmi/species-and-speciation-63224681 Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 13 Figure 15 - Geographical view of the Galapagos Islands. Source: https://kaiserscience.wordpress.com/biology-the-living-environment/evolution/finches-and-evolution/ Until here, you can now do the following formative questions at the end of the unit: 9 - 24. The chapter above was complemented with information taken from the following sources: Website Editors, BD. “Speciation.” Biology Dictionary, 28 Mar. 2019, biologydictionary.net/speciation/. Website National Geographic Society. “Natural Selection.” National Geographic Society, 7 Sept. 2019, www.nationalgeographic.org/encyclopedia/natural- selection/. (4) Adaptations What makes an organism suited to live in its environment? How can it be possible that some organisms thrive in conditions that seem impossible – or at least dangerous – to live in? For example, why is that one plant, such as a cactus, can survive in a hot, dry dessert while another plant such as a fern, thrives only in a cool, damp forest? Or, why do some animals live together in a large community, like sardines and herring, while other spend most of their lives alone or in a small group, like sharks? The answer to all these questions takes us back to the evolution of the species themselves. Organisms have evolved over time and in different settings to be adapted to live in and respond to their environment. Through the process of natural selection and evolution, different species have passed along different traits as result of their suitability for survival in the time and place the organisms are living. These traits that make organisms well suited Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 14 to live in their habitat are called adaptations - in evolutionary theory, adaptation is the biological mechanism by which organisms adjust to new environments or to changes in their current environment. Organisms can adapt to different environments in three different ways: Figure 17 - Blubber is a fat layer below the skin of Figure 18 – Fangs of snake secreting venom Figure 16 - Hyenas hunt in packs to increase their aquatic mammals that offers insulation chance of obtaining food ▪ Behavioral Adaptations - Actions of an organism that enable them to survive in their environment. This type of adaption could be caused by a change in the surrounding environment or the actions of another species. For example, predatory animals might start hunting in packs - giving them an evolutionary advantage over solo hunters. In addition to changes in a predatory strategy, examples of behavioral adaptations include changes in social patterns, communication methods, feeding habits and reproductive strategy. Figure 19 - Example of a behavioural adaptation: hibernation of a squirrel For example, bears hibernate in winter to escape the cold temperatures and preserve energy. ▪ Structural Adaptations - Physical features of an organism that enable them to survive in their environment. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 15 The physical change is often related to a change in the organism's physical environment. For example, an ecosystem suddenly becoming forested might cause the animals living there to develop suction pads or climbing claws, which would convey a distinct advantage over species that did not change. Other examples of structural changes include developing wings for flight, fins for swimming or powerful legs for jumping. For example, penguins and whales have blubber to protect themself from freezing temperatures. Figure 20 - Example of structural adaptation: succulent plants in extreme dry environments ▪ Physiological Adaptations - Internal and/or cellular features of an organism that enable them to survive in their environment. Physiological adaptations are similar to structural adaptations in the sense that they involve a physical change to the species. However, physiological adaptations are not always seen in an organism's appearance. This type of adaptation may be driven by either a change to the environment or the behavior of another species. For example, a species living in water that suddenly becomes more acidic Figure 21 - Example of physiological adaptation: plants that secrete toxins to prevent being eaten might adapt by slowly shifting its own body chemistry. Other examples of physiological adaptations include developing greater intelligence and improving the senses. For example, snakes produce poisonous venom to ward off predators and to capture prey. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 16 Fully embracing the Theory of Evolution and idea of adaption might cause you to start seeing every characteristic of an organism as an adaptation. However, many attributes of organisms did not develop to better pass on genetic material. Some characteristics may simply be a happenstance of history. Other characteristics might be a by- product of a true adaptation. For example, blood's red color results from the chemical process involved in blood; the color is not, in and of itself, an adaptation. Some characteristics, such as the human appendix, may be outdated adaptations, still hanging on past the point of their usefulness. The chapter above was complemented with information taken from the following sources: Websites Starter), Jill (Teach. “Behavioural, Structural and Physiological Adaptations Teaching Resource.” Teach Starter, 9 Oct. 2019, www.teachstarter.com/au/teaching-resource/behavioural-structural-physiological-adaptations/. National Geographic Society. “Adaptation.” National Geographic Society, 5 June 2019, www.nationalgeographic.org/encyclopedia/adaptation/#:~:text=In evolutionary theory, adaptation is,changes in their current environment.&text=The idea of natural selection,organisms of the same species. King, Susan. “What Is Adaptation Theory?” Sciencing, 2 Mar. 2019, sciencing.com/adaptation-theory-5105998.html. (5) Surface-area to volume ratio (SA:V) The surface-area-to-volume ratio (SA:V), is the amount of surface area per unit volume of an object or collection of objects. Surface area refers to the outside area of a cell (units2), while volume refers to the amount of space inside the cell (units3). The outside surface of a cell is the cell membrane, and substances diffusing into or out of the cell can pass through at any point in this surface area. If the surface area is increased, more substances can enter or leave in a given time. After entering the cell, these substances can move into the cytoplasm, again by diffusion, where they can be used in the cell's processes such as respiration. This space has a certain volume. If its volume were increased, it would take longer for substances to get to the center of the cell. So, the processing of a cell's requirements depends on a balance between the external area and the internal volume. As cells grows, volume (units3) increases faster than surface area (units2), leading to a decreased SA:V ratio. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 17 Figure 22 - Surface area to volume ratio in cubes of different sizes. Source: https://ib.bioninja.com.au/standard-level/topic-1-cell-biology/11-introduction-to-cells/sa-- vol-ratio.html Cells need to be small because they rely on diffusion for getting substances into and out of their cells. When a cell grows, there is comparatively less membrane for the substances to diffuse through resulting in the entre of the cell not receiving the substances that it needs. Diffusion is less efficient; cell processes slow down and the ell stops growing. The cell then needs to divide into two smaller cells, which each have a larger SA:V ratio and can diffuse materials more efficiently again. ▪ In unicellular organisms. Their small size means that they have a large SA:V ratio and is adequate for the many materials to move into and out of the cell by diffusion and active transport. But it does limit the organism’s size. Once they get too big, they must divide. ▪ In multicellular organisms. By being multicellular, plants and animals have overcome the problem of small cell sizes. Each cell has a large SA:V ratio but they have evolved features such as gas exchange organs (lungs) and circulatory system (blood) to speed up and aid the movement of materials into and out of the organism. Until here, you can now do the following formative questions at the end of the unit: 25. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 18 (6) Specialized structures in larger animals The environment that an organism is adapted to can include many different factors – temperature, the availability of water, the amount of sunlight food – depending on the type of organism and the way it lives. Adaptations may be outwardly visible, while others are hidden within the body. A. Outside the body Temperature Control. The fur of some animals keeps a layer of warm air close to the body; sweat glands in the skin also keep the body cool. Defense against parasites. Animals with scales and shells have some extra protection against small parasites that try to enter through their skin. Defense against poisonous plants. Oils from plants such as poison ivy irritate the skin. The fur of animals keeps the oily irritant away from the skin until the oil breaks down over time. Defense against sunburn. Ultraviolet rays from the sun can damage skin. Tropical animals such as monkeys and parrots are protected from sunburn by their hair and feathers. Defense against predators. The skin of the puffer fish and the porcupine has sharp spines that repel predators. The backbone of the turtle is a scale-covered shell that provides defensive protection. Warning to predators. Poison arrow frogs and monarch butterflies have toxic substances in their bodies that can kill or repel a predator. Their bright warning colors turn predators away before they attack. Skunks have a bold black and white warning pattern because most animals that prey on them only have black and white vision. Mimicry. Some organisms have coloring, distinctive patterns or other behaviors which resemble other organisms that may be dangerous, poisonous, or unpleasant to eat. Predators avoid these organisms because they think these counterfeits are the real thing. For example, viceroy butterflies that are not toxic to predators mimic the coloration of monarch butterflies that are poisonous. Two or more unpalatable species may also resemble each other, providing increased protection for both against predators. Camouflage from predators. The patterns on some insect skins mimic leaves, bark and even bird droppings. Animals like zebras have patterns that help them blend into tall grass. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 19 Deceiving predators. False heads or large, fake eyes can startle predators momentarily, allowing the prey to escape. They can also lead the predator to strike a non-vital area, such as attacking the animal 's tail instead of its head. Attraction of a mate. Some birds and butterflies have brightly colored wings to attract potential mates. Until here, you can now do the following formative questions at the end of the unit: 26 & 27. The chapter above was complemented with information taken from the following sources: Website King, Susan. “What Is Adaptation Theory?” Sciencing, 2 Mar. 2019, sciencing.com/adaptation-theory-5105998.html. B. Within the body Organisms need a variety of different substances to keep functioning, and to maintain life processes. Oxygen and glucose are needed for cellular respiration, and a variety of nutrients are needed to sustain metabolic processes. Thus, the surviving of organisms depends on their capacity and efficiency to uptake these substances. Diffusion is the movement of molecules from higher to lower concentration. Various factors speed up the rate at which substances can move into organisms. A fast rate of diffusion can be achieved by: 1. Increasing surface area. The larger the surface area, the faster molecules can move into (or out from) an organism. For example, the folds in the lining of the small intestine (the villi) allow digested food molecules to move into the blood at a rate that is fast enough to maintain life processes. Further folds on the membranes of the cells lining the intestine (microvilli) further increase the surface area. Figure 23 - Magnification of the increased surface area of absorption of the intestines Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 20  Figure 24 - Representation of the decreased thickness of diffusion surface between a mother and her developing fetus 2. Decreasing the thickness of the diffusion surface. A small diffusion distance is needed as the thicker the surface, the longer it will take for molecules to cross it. For example, there is a small distance between the mother’s blood and that of the embryo, ensuring that the embryo gets food and oxygen quickly enough. 3. Maintaining a concentration gradient. A concentration gradient is needed so that molecules can move from a higher to lower concentration. For example, in the lungs, oxygen is removed from the alveoli by the blood which maintains the difference between the oxygen concentration in air in the alveoli and the blood oxygen concentration. Figure 25 - Representation of how the concentration gradient of the lungs is maintained. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 21  Formative Questions for Unit 7 – Evolution and Adaptations 1. Outline what are the four sources of evidence for evolution. 2. Explain how homologous and an analogous structure can induce to error when it comes to tracing back the common ancestor between living things. 3. Outline the three sources of variation within a sexually reproductive organism. 4. Read the following text about Sea turtles’ race for survival and then answer the questions related to the text: An adult female sea turtle lays on average 110 eggs. The mother sea turtle nests on beaches and returns to the sea; leaving her nest and the eggs on their own to develop, hatch, and enter the sea. When baby turtles (known as “hatchlings”) hatch, they use the natural light horizon (the moon), which is usually over the ocean, along with the white crests of the waves to reach the water when they emerge from the nest. However, any other light sources such as beachfront lighting, streetlights, light from cars, campfires etc. can lead hatchlings in the wrong direction. Watching a hatchling struggle out of the nest and make its way to the sea is an emotional experience. Everything is an obstacle. On the beach, hatchlings must escape natural predators like birds, crabs, raccoons, and foxes to make it to the sea. Once in the water, hatchlings are consumed by seabirds and fish. It's estimated that only 1 in 1,000 hatchlings will survive to adulthood. a. Why do sea turtles produce far more offspring than can possibly survive? b. The presence of human beings by the coastline (coastal cities like Miami, for example) are affecting which factor of natural selection? c. In your own words, explain how the presence of human beings can lead to the extinction of sea turtles? 5. Explain the Theory of Evolution by Natural Selection by stating at least three points/factors – meaning, how the environment is key to evolution. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 22 6. Describe how species evolve based on Lamarck’s theory. 7. Lamarck’s work is now quoted as “used it or lose it”. While Darwin’s work is now quoted as “survival of the fittest”. In your own words, compare and contrast how Lamarck justified the evolution of long necks in giraffes vs. how Darwin justified it. 8. Outline two reasons that criticise Lamarck’s theory of evolution, thus supporting Darwin’s theory of evolution. 9. Five hundred cockroaches of one species were sprayed with a new insecticide. Twenty-four hours later nearly all the cockroaches were dead. A few, however, survived. This outcome illustrates which one of Darwin’s key ideas about natural selection and variation? a. All living things come from preexisting living things b. Animals adapt to new environments. c. There is variation among individuals within a species. d. New species develop from survivors. 10. A scientist is studying the fossils of giraffes from different regions and different time periods. What would the scientist be most likely to learn about? a. How the color of giraffes changed over time. b. How the spots on giraffes changed over time. c. How the height of giraffes changed over time. d. How the behavior of giraffes changed over time. 11. The fossilized jawbones in the diagram below show the changes in organisms over time. According to the diagrams, which of the following is a likely conclusion? a. These fossils provide evidence that evolution occurs rapidly. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 23  b. These fossils provide evidence that evolution occurs over long periods of time. c. These fossils belonged to organisms that were large and slow moving. d. These fossils lack similar characteristics in their structural design. 12. The diagram below shows the beaks of five species of birds that developed over time from one parent species. The five species of birds can be found living in the different areas. Which of the following BEST explains why the beak shape of each species of bird developed differently? a. Birds in different areas were able to make different birdcalls and songs. b. Birds in different areas were exposed to different food sources. c. Birds in different areas had different materials to make nests. d. Birds in different areas had different predators to defend or hide from. 13. A certain reptile species is an herbivore and exists only on an isolated island. Which of the following would most likely result in the extinction of the reptile species over a period of twenty thousand years? a. The reptile species produces many offspring with many unique traits, and the vegetation remains constant. b. The reptile species produces few offspring with some unique traits, and the vegetation remains constant. c. The reptile species produces few offspring with no unique traits, and the vegetation changes quickly. d. The reptile species produces many offspring with some unique traits, and the vegetation changes slowly. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 24 14. Chameleons can change color to match the color of their surroundings. If a chameleon was born unable to change color, why would it be unlikely to pass on this trait? a. The chameleon would be unlikely to survive long enough to reproduce and pass on the trait. b. The chameleon would have to find another chameleon with the same trait to pass the trait on. c. The trait would change over time as the chameleon learns to change color. d. The trait would not be present in any of the offspring of the chameleon, so it would not be passed on. 15. Moths are a type of insect similar to butterflies. A species of moth lived in a forest made up of a mixture of dark- and light-colored trees. Some of the moths were dark-colored and some were light- colored. The coloring of these moths is inherited from parent to offspring. The dark moths were hidden from predators on the dark trees, and the light moths were hidden on the light trees. When the light-colored trees were killed by a disease, the forest was suddenly made up almost entirely of dark-colored trees. Generations later, almost all the moths had the dark coloring. Which of the following gives a correct explanation? a. The light moths that survived did not mate and have offspring because they saw that their offspring would easily be seen and eaten by predators. b. The light moths that survived had dark offspring because the change in the environment caused the parents to have offspring that would do better in the changed environment. c. The light moths saw that the dark moths were less likely to be eaten by predators, so they made themselves dark as well. d. The dark moths were better hidden from predators, so more of them survived. Because dark parents outnumbered light parents, there were many more dark offspring than light offspring in the next generation. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 25 16. Fossils of the Dorudon, an aquatic mammal that lived over 40 million years ago, show a whale-like animal that had small, underdeveloped hind limbs. Which best explains how fossils like the Dorudon support the theory that plant and animal life has evolved over time? a. They confirm that many animals have not evolved. b. They show that some animals evolved from other animals. c. They prove that all animals evolved from a single ancestor. d. They demonstrate that animals that don't evolve will die out. 17. The different finches found in the Galapagos Islands developed very different beaks, depending on the type of food available on each of the islands. Finches that eat seeds have large crushing beaks made to crack the shells of seeds. Other finches have developed beaks for drilling holes in wood, eating cactus, or even drinking the blood of other birds. If a storm hits and causes the death of nearly all of the cacti on the islands, which of the following will be the most likely outcome for the Cactus ground finch? a. They will be unable to eat and will die out. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 26  b. They will evolve into a different species of finch. c. They will adapt to eating a different source of food. d. They will form a social group with other finches to collect food. 18. Charles Darwin made a number of observations and inferences during his travels. He studied island finches during a long period of time. Which statement is an inference? a. Individual birds have different colored feathers. b. Island finches have a large number of offspring. c. Individual birds of an island finch species have many differences d. Island finches share a common ancestry with mainland finch species. 19. In the early days of antibiotic use, penicillin and sulfonamide were used to successfully treat a variety of bacterial infections. In later years, stronger antibiotics were needed because some bacteria were either resistant to or not affected by these same antibiotics. This situation is best explained? a. By the lack of quality control in drug companies b. As the result of poor nutrition. c. By doctors prescribing the wrong antibiotic d. By the process of natural selection 20. Scientists found that, over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities? a. The original species became extinct. b. Species in the older community died from old age. c. The abiotic characteristics of the habitat changed. d. Diseases that killed the older organisms disappeared. 21. Which of these best illustrates natural selection? a. An organism with favorable genetic variations will tend to survive and breed successfully. b. A population monopolizes all of the resources in its habitat, forcing other species to migrate. c. A community whose members work together utilizes all existing resources and migratory routes. d. The largest organisms in a species receive the only breeding opportunities- Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 27 22. Earth has undergone some catastrophic changes from time to time. Which of these most likely explains why life on Earth continued following these catastrophes? a. Dominant species had a slow mutation rate. b. Many species filled the same niche. c. A strong species had many different characteristics. d. A wide diversity of species existed. 23. A species of finch has been studied on one of the geographically isolated Galapagos Islands for many years. Since the island is small, the lineage of every bird for several generations is known. This allows a family tree of each bird to be developed. Some family groups have survived, and others have died out. The groups that survive probably have… a. Interbred with other species. b. Inherited some advantageous variations. c. Found new places on the island to live. d. Been attacked by more predators. 24. Natural selection is the process by which organisms with favorable traits will survive and reproduce, increasing those favorable traits in a population. Which of the following is the best example of a favorable trait which helps with survival that was developed by natural selection? a. A frog eating a fly. b. A wolf hunting a deer. c. A mouse burrowing a hole. d. A moth blending with a tree. 25. For the four cubes below, measure (in cm) each with a ruler, and calculate the surface area, the volume, and the surface area to volume ratio. Reduce the SA:V ratio so that it the "V" is = 1. a. What trend do you notice as the size of the cells increases? b. Why can the trend identified in the question a. compromise living cells? c. What can cells do to ‘fight’ a decrease in SA:V ratio? Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 28  (Visualize for question 26.) (Visualize for question 27.) 26. The photograph above, on the left, shows a musk ox. The musk ox lives in the Artic. An adult musk ox is 2.5m long and 1.4m high at the shoulder. Adults usually have a mass of about 400kg. Use this information and the information from the photograph to explain two ways in which a musk ox is adapted for survival in the Artic a. State one adaptation that the musk ox has for its environment b. How does your stated adaptation (25. a.) help the musk ox to survive in the Artic Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 29  c. State a second adaptation that the musk ox has for its environment. d. How does your stated adaptation (25. c.) help the musk ox to survive in the Artic 27. The photograph above, on the right, shows swallows. Swallows migrate between Britain and South Africa every year. The photograph to the right shows swallows. Swallows can fly very quickly and feed on flying insects. They spend the summer in Britain and then migrate to South Africa in the autumn a. Use the information from the photograph to give one way in which the swallow is adapted for flying very quickly. b. Suggest one reason why swallows do not stay in Britain in the winter Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 30  MARKSCHEME of Formative Questions 1. Outline what are the four sources of evidence for evolution. The four sources of evidence of evolution are: ▪ Fossils. Fossils document the existence of now-extinct past species that are related to present-day species. ▪ Anatomy. Species may share similar physical features because the feature was present in a common ancestor (homologous vs. analogous structures). ▪ Molecular biology. DNA and the genetic code reflect the shared ancestry of life. DNA comparisons can show how related species are. ▪ Biogeography. The global distribution of organisms and the unique features of island species reflect evolution and geological change. 2. Explain how homologous and an analogous structure can induce to error when it comes to tracing back the common ancestor between living things. When focusing solely on physical characteristics to understand the evolutionary distance between species, one easily makes the mistakes of overseeing structure by focusing only on function. While certain species share the same function, such as the fin of a shark and the hand of a whale, this does not mean that there is an evolutionary link (common ancestor) between species. Sharks and whales do not share the same fin/hand structure. To trace back common ancestor(s) of species, one needs to focus on structure, such as the hand of a human and a whale. Only a detailed analysis beyond what the eye can see can allows us to understand if species have evolved in a divergent or convergent way. While convergent evolution leads to analogous structures, where function is the same, but structure is not. Divergent evolution leads to homologous structures, where function has differentiated itself over time, but structure remains the same. Thus, focusing on physical characteristics, one is focusing solely on analogous structures; easily leading to error by not detecting homologous structures. 3. Outline the three sources of variation within a sexually reproductive organism. The three sources of variation are: (1) mutation, new alleles are produced by gene mutation which enlarges the gene pool of a population; (2) meiosis because it produces new combinations of alleles by breaking up existing combinations in a diploid cell - random assortment of homologous chromosomes; and (3) sexual reproduction, because this type of reproduction involves the fusion and cross-over of male and female gametes. 4. After reading the provided text: a. Why do sea turtles produce far more offspring than can possibly survive? Answers will vary. Sea turtles produce far more offspring than can possibly survive to increase the likelihood of having at least one offspring surviving. Due to high predation and harsh hatching conditions, a greater Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 31 offspring number increases the chances of how fit each individual offspring can be, thus increases the chance of having more survivors to reach adulthood, reproduce and continue the species. b. The presence of human beings by the coastline (coastal cities like Miami, for example) are affecting which factor of natural selection? The presence of human being by the coastline is affecting the factor “competition”. There is an increase in the struggle for existence, this is because hatchlings become confused towards which direction is the sea/ocean (synthetic lights are brighter than the moon), increasing the likelihood of crawling further away from the sea/ocean and closer to danger. c. In your own words, explain how the presence of human beings can lead to the extinction of sea turtles? Answers will vary but they follow the line of thought of answer 4. b. Please check your answer with your teacher. 5. Explain the Theory of Evolution by Natural Selection by stating at least three points/factors – meaning, how the environment is key to evolution. The Theory of Evolution by Natural Selection states that a changing environment will naturally select the individuals who are (1) most fit to adapt, leading to an (2) increased likelihood of survival of these. If individuals are more likely to survive, then they are (3) more likely to reach reproductive age, thus have (4) offspring. Naturally, the (5) offspring are more likely to inherit the “more fit” adaptation of the parents, thus being more fit themselves. This leads to evolution because there is (6) an accumulative change of genetic characteristics within a population over the years For example, a lion cub with bigger muscles in its legs would be able to run more quickly and get food more successfully than its siblings. Thus, in an environment that presents itself with challenges, the individual with the best adaptations to these challenges is most likely to survive to adulthood. The weaker individuals die before having the chance to breed, but the surviving adults breed. In turns, this increases the likelihood of advantageous alleles being passed to the new generation of offspring. Which ultimately reflect in a stronger population, better adapter to a changing environment. 6. Describe how species evolve based on Lamarck’s theory. Lamarck’s theory of evolution was based around how organisms (e.g., animals, plants) change during their lifetime, and then pass these changes onto their offspring. At the eyes of Lamarck, there was no difference Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 32 between inherited and acquired adaptations. He strongly believed that evolution was purely based on how organisms could acquire adaptations to better fit their changing environment 7. Lamarck’s work is now quoted as “used it or lose it”. While Darwin’s work is now quoted as “survival of the fittest”. In your own words, compare and contrast how Lamarck justified the evolution of long necks in giraffes vs. how Darwin justified it. Lamarck is known for the quote “use it or lose it” because he strongly believed that adaptations could be lost and/or acquired as organisms need. When focusing on the evolution of giraffes’ long necks, Lamarck believed that the giraffe had a long neck because its neck grew longer during its lifetime, as it stretched to reach leaves in high-up trees; meaning that each generation of giraffe had a longer neck than previous generations → “need it? develop, use it!” Contrarily, Darwin’s theory refuted Lamarck’s theory. Darwin believed that organisms possessed variation (each individual was slightly different from one another) that made them less or more fit. The more fit variations led to some organisms being more likely to survive and reproduce than others. Features that made an organism more likely to survive or reproduce are therefore more likely to appear to each generation. In terms of the giraffe, Darwin’s theory would state that longer necked giraffes were more likely to survive, because they could eat leaves from taller trees, and therefore more long-necked giraffes will be born, which eventually caused all giraffes to have longer necks. Longer necked giraffes survived because they were a better fit for their environment → “survival of the fittest, you have it you survive, you don’t, you die” 8. Outline two reasons that criticise Lamarck’s theory of evolution, thus supporting Darwin’s theory of evolution. Two reasons that criticise Lamarck’s theory of evolution are that: ▪ Lamarck’s theory suggest that all organisms become more complicated over time, and therefore doesn’t account for simple organisms, such as single-cell organisms. ▪ Through observation, we know that characteristics inherited during an individual’s lifetime do not get passed onto their offspring; for example, if someone pierces their ear, it doesn’t mean that their children will be born with pierced ears. ▪ Genetics and molecular biology does not support Lamarck’s understanding of inheritance of genetic traits. 9. C 16. B 13. C 10. C 17. A 14. A 11. B 18. D 15. D 12. B 19. D Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 33  22. D 20. C 23. B 21. A 24. D 25. 26. Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 34  27. (a) = first line; and (b) = second line Booklet created by Mrs. Margarida Coimbra Edited for academic year 2023-2024 at Oeiras International School (OIS) | Page: 35