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GRADE 9 SCIENCE BIOLOGICAL DIVERSITY FINAL EXAM PREPARATION Name: ____________________________ Homeroom: ______ STUDY GUIDE SPECIES DIVERSITY (Textbook pages 10-23) Variability Diversity refers to differences, in this case differences in living things (biodiversity). The greater the diversity, the healthier the ecosystem. A species is a group of organisms that have the same basic structure and can reproduce with one another. Organisms not of the same species cannot create fertile offspring. Variability refers to the differences in structure and behavior that distinguish one living thing from another. Variability can exist between species (one species looks different from another) but can also exist within a species (a black bear may be black, brown, or even tan). Sometimes these variations are subtle. For example, dogs, wolves and coyotes are each a distinct species yet they are very similar. Probably the best known example of species variability is Sharp, probing bill of an Darwin’s finches. Over years of having to adapt to a variety insect eater of environments and food sources on the Galapagos Islands, the bird’s beaks changed in order to allow them to successfully survive. This was through natural selection. Sharp, probing bill of an insect eater but this one Whereas all of the finches on the islands originally were uses cactus spine as a tool seed eaters, they slowly adapted to other food sources such as leaves, insects, fruit and grubs. The structure of their beaks allows you to infer what their major food Grasping bill of an insect source would have been. The number of different dog eater that feeds on larger breeds is another excellent example of variation within a insects in trees species, although this has been through artificial selection rather than natural selection. Crushing bill of a cactus seed eater. Niches The niche of an organism describes its role. If, through natural selection, an organism can adapt to a niche that others have not, it will have a much better chance at survival. Also, if organisms can adapt to a broader environment (less specified) it increases their chance for survival. Examples of niches are shown below. Organism Rabbit Tree Where it lives Burrow Soil What it consumes Water, grass Water, nutrients Affect on other organisms Feeds coyotes and hawks Feeds consumers and gives 02 Birds in a park ecosystem may have the following niches – seagulls eat the left-overs, ducks have a bill and webbed feet so will stay near a park pond, robins will eat the worms, sparrows will eat seeds, woodpeckers will eat insects from the trees, etc. Adaptations to beaks, feet, flight and nesting behaviour allow the birds to fill different niches. Resource partitioning (i.e. sharing the same niche for food and habitat) also allows more species to survive and thus increases the biological diversity of an ecosystem. Several different species may share a tree by feeding or nesting at different levels. If all organisms wanted the same food source, same habitat, same light, etc. there would be a great deal of interspecies competition and this would lead to less diversity. Interdependencies Food webs or food chains – producers (plants), consumers (animals) and decomposers. Source of oxygen and food – animals need plants which produce oxygen and food (glucose) through photosynthesis and plants need animals for carbon dioxide and organic material for soil. Interdependent organisms are symbiotic which means they depend on each other for one or more parts of their survival. Types of symbiosis include: o Commensalism (+/0) One benefits, other doesn’t notice. Birds nest in trees, fish live in poisonous corals, remora catch a ride on sharks o Mutualism (+/+) Both organisms benefit. Algae and fungus live together as lichen, flowers and pollinators, humans and domesticated animals o Parasitism (+/-) One benefits, the other is harmed. Tapeworms, mosquitoes... o Predation (+/-) Carnivore captures and feeds on prey. o Competition (-/-) when organisms complete, neither benefits. Hawks and coyotes compete for rabbits. The hawk is more successful and the coyote leaves, decreasing biodiversity and making the ecosystem less healthy. The graph below shows a typical predation relationship. If the hare population decreases there will be fewer predators in the future. If the hare population increases, the predator population will begin to rise again. Population Number Legend: Hare (prey) Flower Butterfly Coyote (predator) Years Time Adaptation Variation enables different species to survive in an ecosystem. In Darwin’s finches, those able to adapt survived because they developed beaks that allowed them to find new food sources. Darwin theorized that living things that could adapt new structures to meet their needs in a new environment would be the ones that would survive long enough to reproduce. This is the basis for Darwin’s theory of natural selection. Natural selection in banded snails allows yellow snails to survive in sand while others would be picked off. Of the snails living in the ground, brown would have the best chance of survival. This adaptation was brought about by natural selection and increased the variability of this particular species, making it much more likely to survive, especially if one group was wiped out through a natural disaster or disease. An ecosystem is an area where living organisms interact with non-living components. All of the different species together in the ecosystem make up the community. All of the members of one particular species makes up a population. Variation plays a role in allowing species to survive under changing environmental conditions. For example, bacteria quickly develop a tolerance to antibiotics because those with immunity survive and reproduce, passing their immunity down to their offspring. In another example, Magpies are being killed off by West Nile Virus. If some Magpies are more immune, they will reproduce and their offspring will be immune, making the species stronger. REPRODUCTION (Textbook pages 27-33, 43-45, 50-54) Asexual Reproduction Asexual reproduction involves only one parent so all offspring are identical - an exact duplicate of the parent. There are several types of asexual reproduction: Binary fission – single celled organisms such as bacteria, amoebas, some algae. Cell splits in two to make exact duplicate. This is the same process as mitosis in multi-cellular organisms. Budding – organisms such as hydra and yeast. Parent produces small bud which is a mini version of itself. It may stay on the organism or it may drop off and become a new individual. THIS IS NOT A FLOWER BUD! Spores (zoospores) – fungus, some algae, mould, ferns. Cell in one parent divides multiple times to produce an individual exactly like the parent. When conditions are right, the spores burst out and are usually carried by the wind or water to a place where they will be able to grow. Vegetative reproduction – most plants are capable of vegetative reproduction where a part of plant can be cut or separated, and a new plant will develop from it without any outside fertilization source. Includes suckers (new tree from tree root), runners (above ground root grows away from plant) or bulbs (underground growth on root). Sexual Reproduction in Animals Sexual reproduction - must be a male and a female involved. Most plants and animals can reproduce sexually. Offspring have a mix of characteristics allowing an increase of variability within a species. Offspring will be different than either parent but will have traits inherited from both parents. There must be two specialized cells called gametes. Male gamete is the sperm, female gamete is the egg (ova). Sperm and egg each have half the normal number of chromosomes. When a sperm and egg combine, it is called fertilization and the resulting zygote has the full compliment of chromosomes for that species. Sexual reproduction in animals includes the following steps: Sperm penetrates egg (fertilization) forming the single-celled zygote. The zygote cell begins to divide through cleavage. Cells continue to divide and grow Multicellular embryo develops. Sexual Reproduction in Plants The male structure is the stamen which consists of the anther and filament. The anther produces the pollen which is the male gamete. The filament holds up the anther so pollinators can reach it. The female structure is the pistil which consists of the stigma, style, ovary and ovules (female gametes). The stigma is sticky so pollen can stick to it. The style leads the growing pollen tube down toward the ovary. The ovary contains and protects the ovules and the ovules are the eggs waiting to be fertilized by the pollen. Pollination occurs when pollen is transferred from the anther to the stigma. Flowers may pollinate themselves or pollen may be carried by butterflies, bees or wind from other flowers. This is called cross-pollination and it helps increase variability within the species of flower. Fertilization occurs when the pollen tube reaches the ovule. A zygote is formed and divides to become an embryo. The embryo is protected inside of a seed. Many plants can reproduce through both vegetative reproduction and pollination, but pollination is the preferred method since it leads to increases diversity of the species. Some animals, such as the hydra, can also reproduce sexually or asexually. Yeasts can also reproduce by both budding and sexual reproduction. Discrete and Continuous Variation Discrete variations do not have a range. The characteristic is defined as “either/or”. Continuous variation characteristics can occur over a wide range. Discrete Variation Right OR left hand clasp Straight OR Curved thumb Straight OR Pointed hairline (widow’s peak) Blood type – A or B or O or AB Continuous Variation Mass – bone structure from small large Height – short tall Length of arms, legs, hand - short long IQ - from 0 150+ Yes No Attached Earlobe Heritable Versus Non-Heritable Traits Some characteristics are heritable (can be inherited from parents) and some are non-heritable (cannot be inherited from parents). T Examples of Heritable Characteristics Examples of Non-Heritable Characteristics he Eye colour Ability to play instruments envi Skin colour Scars ron Height Dyed hair colour men Bear hibernation Seagulls hanging around dumpsters to feed t can play an important role in certain characteristics (not things like eye colour or blood type since those are independent of environment). Even if you inherited average height and bone structure from parents, you will not attain these averages if you are severely malnourished as are many children in third-world countries. A plant that is kept in the dark will not have a chance to grow to its potential even if it inherited very strong traits from its parents. Weight (mass) is not an inherited trait but is very reliant on environment (you eat too much, you gain weight). How Traits are Inherited Traits are characteristics that are heritable – they can be passed down from generation to generation. Traits include things such as fur colour, eye colour, and skin colour. Genes are responsible for inherited traits. A single gene controls a single trait. Alleles are the “versions” of genes. If there was a jello gene, alleles would determine the flavour of the jello. Some alleles for traits are dominant and some are recessive. Dominant traits show up far more often in the offspring than recessive traits because the presence of a dominant allele always masks the recessive one. Dominant alleles are represented by a capital letter (i.e. A) and recessive by lowercases (i.e. a). Organisms that have inherited the same allele from both parents are called purebred or homozygous dominant (AA) or recessive (aa). If the offspring receives different kinds of alleles from each parent, they are said to be hybrid or heterozygous (Aa). Incomplete dominance occurs when neither trait shows up – instead, the offspring has a combination of the parent traits. For example, if you cross a red sweet pea flower with a white sweet pea flower, the offspring may have pink flowers. Offspring may not have characteristics of either parent. For example, two blue-eyed parents can have a brown-eyed child. Scientists now realize that some inherited characteristics are controlled by multiple genes so it is not always predictable. The following examples show how you can use Punnett squares to determine inheritance patterns in offspring. Genotype refers to the genetic code (alleles) for the gene and phenotype refers to the appearance of the gene trait. For these examples, we will use dog fur colour as the inherited trait. The dominant fur colour is black and this allele will be represented by “F”. The recessive fur colour is white and this allele will be represented by “f”. The mother’s alleles will be along the top and the father’s alleles will be along the side. F F f FF (black) Ff (black) F FF (black) Ff (black) Mother is homozygous dominant (two dominant alleles) Father is heterozygous (one dominant, one recessive allele) Offspring Genotypes: 50% of offspring are homozygous dominant 50% of offspring are heterozygous Offspring Phenotypes: All offspring are black. GENETIC MATERIALS (Textbook pages 39-48, 67-71) DNA A large molecule called DNA (deoxyribonucleic acid), found in the nucleus of every cell, contains a complete set of instructions for making a new individual following the same basic blueprint as the parent. All life is related through the DNA molecule. The arrangement of only four chemicals (A-C-T-G or base pairs) can be combined in billions of different ways to create all life. These chemical molecules make up the “steps” of the DNA ladder and they combine to form the genetic code. This code is similar for all living things but is unique for each individual. DNA is packaged into chromosomes. Chromosomes are twisted into tight coils and contain varying amounts of the genetic code. Humans have 46 chromosomes (23 pairs), each with a set of instructions for specific parts of the human body. Genes are parts of chromosomes (they are a small splice out of the coil). If DNA was the instruction manual for making a human, it would have 46 pages (chromosomes), 100 000 paragraphs (genes), and millions of letters (alleles). Cell Nucleus where all of the DNA is stored Base Pairs (A, C, T, G) are chemical molecules that make up the rungs of the DNA ladder. Their order determines what traits this particular organism will exhibit. Chromosome – “packaged DNA” Gene – a segment of the chromosome responsible for a particular trait – there are 100 000 genes in human DNA. Mitosis and Meiosis Mitosis Single celled organisms can reproduce through mitosis where a cell divides into two parts, replicating all of its DNA in the process so that each new organism has a complete blueprint. Mitosis is also used by multicellular organisms for growth and repair. Meiosis - Only used by organisms using sexual reproduction. It results in four gametes (sperm/pollen and egg/ova) with half the number of chromosomes as normal cells. In this way, when an egg and sperm combine, the zygote has the correct number of chromosomes to create a new individual. If an incorrect number of chromosomes is donated to the zygote, you end up with genetic abnormalities such as Down’s Syndrome. Gametes (eggs/ova or sperm/pollen) Advantages and Disadvantages of Reproduction Methods The advantage of sexual reproduction over asexual reproduction is that it increases variability within a species since there are two parents involved. New combinations that are better adapted to a changing environment are possible. The disadvantages are that not many new individuals can be produced and a male and female gamete must be brought together before fertilization can occur. The advantage of asexual reproduction is that you don’t need to find a mate and a large number of new individuals can be reproduced quickly and in great number. However, they are all exact duplicates of the parent so this does not increase the variability of the species or its chance to adapt to changing environments. Artificial Versus Natural Selection Natural selection is the process of survival of the fittest by which organisms that adapt to their environment survive while those that do not adapt disappear. An example would be rabbits whose camouflage allows them to survive. Their fur is white in the winter and brown in the summer. If it were brown in the winter, they would be easy targets for predators. Natural selection of forearms have allowed animals to adapt to many different environments over time (whale fin, horse hoof, lion claw, primate hand, bat wing). Natural selection increases genetic diversity. Artificial selection is the human answer to natural selection. It has been used for hundreds of years by humans. Instead of waiting for the strong to survive, we decide on specific traits that would benefit humans. For example, we want crops that taste better and are more resistant to drought. We want cows that produce more milk and more steak. We want horses that have more stamina and speed. When we decide what trait we want, we begin to breed plants or animals together that possess that particular trait so that their offspring, and subsequence generations, will display that characteristic. Because you are breeding similar traits over and over, artificial selection reduces genetic diversity. Biotechnology Biotechnology is the use of new technology to produce living things that can be used to improve conditions for human beings by manipulating genetic materials. Artificial insemination – any artificial method of joining a male (sperm) and female (egg) gamete. For example, sperm from a desirable bull are artificially inserted into female cows. The bull’s sperm can impregnate more cows this way. Leads to less diversity. In vitro fertilization – many eggs from a prize female and many sperm from a prize male are both removed and placed in a Petri dish where the egg is fertilized by the sperm. The fertilized eggs are placed in several different cows who will give birth naturally. Genetic engineering – any technology that alters the DNA of an organism. Often it involves inserting a gene from one species into another species. For example, bacteria (which reproduce rapidly) have an insulin producing gene inserted so as they multiply, insulin is quickly produced and can be harvested for diabetics. Cloning – Scientist’s attempt to do what plants do naturally – enable animals to reproduce both sexually and asexually, creating an exact duplicate of the parent. Cloning is an issue that will be hotly debated for years to come. Some believe we do not have the right to clone (basically create life) while others see it as a way to solve many of society’s problems. Problems with biotechnology in animals – reduces biodiversity so that animals are less variable. If they do become vulnerable to a disease or environmental change, there will be less likelihood of species survival. Problems with biotechnology in plants – most plants started out as weeds and they can crossbreed back to a half-plant/half-weed form which is resistant to herbicides. Also, because of monoculture (all the same plant grown), a disease can come along and wipe out an entire crop. With more diversity, some of the crop could survive. HUMAN IMPACT ON BIODIVERSITY (Textbook pages 56-71) Relative Abundance of Species The largest diversity of species is among insects since they have an uncanny ability to adapt to any environment and survive. This gives them a great deal of variability. Bacteria have the least number of species because they reproduce through binary fission. That means that they do not have a chance to adapt through natural selection. They just mutate into a new species from time to time. Number of different types of organisms Distance from Equator The more favourable an environment is to survival (for example warm, moist areas with abundant food supplies such as the rain forest or coral reefs), the greater the diversity of life you would expect to find. It is important for a healthy ecosystem to have as many different habitats as possible. The further away from the equator one goes, the less diverse and hospitable the habitats become and the number of different species that can exist decreases proportionally. Extinction and Extirpation The Oldman River Dam project in southern Alberta had a significant affect on the species living in and near the river. This area now has a large reservoir above the dam and a decreased, intermittent water flow below the dam. Several plant and animal species that relied on a normal river system have now had to leave the area altogether. The grizzly bear and wolf used to roam the Alberta Prairies but now they are completely gone from this habitat, only existing in the Rocky Mountains. When an animal permanently disappears from an area it is said to be extirpated. Even this range is being destroyed thanks to building of roads, housing, and oil and gas exploration. The Y2Y project is designed to give these animals a corridor where they can roam from Yellowstone National Park in Wyoming to the Yukon and find new populations to breed with. This is vital since variability of the genetic pool improves a specie’s chance at survival. Extinction is the total disappearance of a species from the face of the Earth. Extinction is a normal part of evolution, occurring over a long period of time through natural selection as a species simply isn’t able to adapt quickly enough to environmental changes. We have also had several mass extinctions due to natural disasters such as asteroid hits, volcanoes and ice ages. Some species succumb to starvation or disease. The problem is that the extinction rate is currently increasing. This is decreasing our level of biodiversity and is largely due to loss of habitat and pollution of breeding sites with pesticides and herbicides. Some species become endangered (in immanent danger of extinction) because their food source becomes extirpated. This is especially true of species that have overspecialized food or habitats so they cannot move to another area and adapt. Possible Solutions to Decreasing Biodiversity Study plots are used to calculate the populations of an area. A measured area is marked out and number of individuals counted. This area is then multiplied by the larger area to arrive at an estimate of species or individuals in an ecosystem. Canada does not allow any product made from endangered species into the country. In-situ conservation involves creating protected areas, such as Y2Y for species with large ranges like bears and wolves, allowing their breeding gene pool to increase. Restoration of destroyed habitat – Canada is striving to restore wetlands, wildlife corridors and natural habitats. Controlling spread of exotic (non-native) species – purple loosestrife is forcing out native species and steps have been taken to eliminate it. Ex-situ conservation – conservation outside of a natural habitat (usually zoos). For example, some Vancouver Island marmots (an endangered species) were recently born at the Calgary zoo. Seed and sperm/egg banks are now storing the gametes for most species, including endangered and non-endangered, to ensure that genetic diversity in plants and animals can be maintained. Issues Patented crop varieties, in particular those requiring extensive chemical or genetic treatment, are an issue for many people. Much of our food is now genetically altered without our knowledge and there are scientists who believe we have not yet studied the long term possible effects in enough detail. The only way to be sure your food is not altered is to purchase organically grown produce. Selective breeding in game farming and in rearing fish stocks is another issue. The traits of these animals are being artificially selected by people and the animals are then released into the natural environment. Many scientists are concerned that this will have an unbalancing effect on natural selection in populations that are affected. BIOLOGICAL DIVERSITY VOCABULARY WORD SUMMARY 1. Darwin is most famous for his theory of natural selection which allows an organisms to survive long enough to pass on its traits while others die. 2. Dog breeders have influenced what characteristics dogs will have through the process of artificial selection. 3. A species is a group of organisms that have the same basic structure and can reproduce viable offspring. 4. A species that has a wide variety of adaptations, allowing it to live in different environments is said to have species variability. 5. Dichotomous keys are used as a classification tool to identify species. 6. Living things interact with non-living things in an ecosystem. 7. All of the same species sharing the same resources makes up a population. 8. Different species sharing the same resources make up a community. 9. A finch and a sparrow both eating the same type of seed would be an example of interspecies competition. 10. Interspecies competition leads to a decrease in biodiversity since a few strong species would win out. 11. An organisms that can find a unique niche is less likely to have a problem with interspecies competition. 12. When members of the same species have slightly different niches that allow them to share a food source or habitat, it is called resource partitioning. 13. One of the reasons bacteria are so successful is because of natural selection. Resistant organisms live to breed and their offspring inherit their resistance. This is called developing tolerance. 14. A bird builds a nest in a tree which benefits the bird and does no harm to the tree. This is an example of commensalism. 15. A parasite needs to obtain its nutrients from a host which is harmed in the process. 16. Lichen consists of algae and fungus living together. The decaying algae is a food source for the fungus and the fungus keeps the algae moist. When two organisms benefit from a relationship, it is called mutualism. 17. A form of reproduction that only involves one individual is called asexual reproduction. 18. Bacteria reproduce when a single cell divides and creates an exact duplicate of itself. This form of asexual reproduction is called binary fission. 19. Yeast and hydra commonly reproduce by replicating mini versions of themselves through budding. 20. Spore are new individuals created by asexual reproduction from organisms such as ferns and fungus. 21. A natural form of cloning occurs when plants reproduce through vegetative reproduction. 22. Vegetative reproduction can include cuttings (plant grows from a piece of a leaf), suckers (plant grows up from old roots), runners (plant grown from root extending on top of the ground) or tubers (plant grows from large, underground roots). 23. Reproduction that involves two parents is called sexual reproduction. 24. Male sperm and female eggs are called gametes. 25. A zygote is the result of fertilization. 26. Sexual reproduction in plants occurs when the anther produces pollen (male) which lands on the sticky stigma. The pollen grain starts to grow down through the style (hollow tube) toward the plant’s ova (eggs) contained in the ovary. 27. Fertilization may occur from pollen produced by the plant itself, or by pollen produced by another plant which is called cross pollination. 28. Traits are characteristics that are inherited from parents. 29. A trait such as eye colour, which can be passed down from generation to generation, is called heritable. 30. Characteristics that have not been passed down but that help identify an individual (i.e., talent, scars, body piercing) are non-heritable. 31. Discrete variations are characteristics defined as “either/or”. For example, you either have attached earlobes or you have unattached earlobes. 32. Continuous characteristics occur over a range. For example, average height may be from 5 feet to 6 feet tall. 33. When an offspring’s trait is a combination of the traits from mom and dad (i.e. white and red flower creates pink offspring), it is call incomplete dominance. 34. DNA contains the entire blueprint for making a new individual. 35. Chromosomes are twisted “chunks” of DNA containing varying amounts of genetic information. 36. Genes are located on chromosomes and contain information for one specific trait. 37. Offspring that inherit the same allele from both parents (i.e. BB) are called homozygous or purebred. 38. Offspring that inherit different alleles from both parents (i.e. Bb) are called heterozygous or hybrid. 39. Traits that always show up if the allele is present are called dominant. 40. Traits that only show up if two of the same alleles are present are called recessive. 41. The genotype describes the alleles of an offspring while the phenotype is the trait appearance. 42. In order for sexually reproduced individuals to have half of the genetic code from each parent, they have to rely on the process of meiosis which results in cells with half of the number of chromosomes as other cells. 43. In order for cells to reproduce exact duplicates of themselves for growth and repair, they must undergo the process of mitosis. 44. When a species disappears from Earth forever, it is extinct. 45. Grizzly bears no longer exist on the prairies and are said to be extirpated. 46. Study plots can be used to do counts of species within a small area and then estimate the numbers in a much larger area. 47. Purple Loosestrife is an exotic (or non-native) species that has taken over the habitat of native plant species living around Alberta wetlands. 48. Inserting desirable sperm into a number of different females is called artificial insemination. 49. Making test tube babies, where egg and sperm are brought together in a Petri dish, is called in-vitro fertilization. 50. when a foreign gene is inserted into the DNA of an organism, the scientific process of genetic engineering is being used. 51. Zoos and seed banks from around the world are attempting to develop a collection of male and female gametes that will increase genetic diversity of plants and animals. This is called ex-situ conservation. 52. The Y2Y project (Yellowstone to Yukon) is an area where animals migrate into new breeding territories so gene pools can increase. It is an example of in-situ conservation.