Evidence of Evolution Lab Report-Biology 11 PDF

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This is a evidence of evolution lab report from Biology 11....

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Evidences for Evolution Lab Introduction: Unfortunately, we cannot repeat nature’s experiments of evolution; however there is a vast amount of evidence, mostly indirect, to support the theory. If modern organisms descended from ancestral organisms then we should see similarities between organisms in the fossil record. Also, we should be able to see more similarities amongst different types of organisms that live today if they have evolved from a common ancestor more recently. Each part of this lab will explore one of the major sources of evidence that support the theory of evolution.

PART A: The Fossil Record and the Age of the Earth Fossils are the remains of long-dead organisms that have escaped decay and become part of the Earth’s crust. Thus, fossils are evidence of organisms that lived long ago. Paleontologists, scientists who study ancient life, use fossils to understand events that happened long ago. They use fossils to determine the kinds of organisms that lived during the past and sometimes to learn about their behaviour. For example, fossil bones and teeth can indicate the size of animals, how they moved, and what they ate. Paleontologists also study fossils to gain knowledge about ancient climate and geography. For instance, if they find a fossil which resembles a present-day plant that lives in a mild climate, they may reason that the ancient environment was also mild. Use the information above and at Station A to answer the following questions: 1. Define fossil: The remains of an animal or plant that has been preserved in the earth’s crust. 2. What normal processes must permanently stop for fossils to form and how can this happen? Decay. This can happen if the remains are isolated from the air or water and decomposing microbes are prevented from breaking them down. 3. Explain how each of the following preservation processes can result in formation of fossils: a. Amber -Gum from conifers traps insects and then hardens b. Tar Pit-Animals fall into and are trapped in mixture of tar and sand. 4. How could fossils be used to determine an animal’s diet? The fossil teeth used to determine an animal’s diet, because teeth are directly involved in the mechanical breakdown of food. 5. Proboscideans’ ancestors were small and trunkless. Why did the group become larger as they evolved? The group become larger because their descendants invaded all continents except Antarctica and Australia. 6. What is meant by a transitional fossil? Transitional fossil is a mixture of traits that are found in two different, but related, taxonomic groups. 7. Recent fossil discoveries support the idea that modern birds evolved from one of the groups of dinosaurs near the end of the Mesozoic Era. Observe the picture of the fossil Archaeopteryx, a prehistoric bird. List 2 Reptilian features and 2 Avian features: Reptilian-1. Breastbone is small and lacks a keel. 2. Forelimb has 3 functional fingers with grasping claws. Avian-1. Impressions of feathers attached to the forelimb. 2. Incomplete fusion of the lower legs bones.

PART B: Embryological Comparisons By the time a new individual has developed from an egg and has grown some recognizable body parts it is called an embryo. These basic structures are due to the most basic genes that even organisms that were ancestral to it must have had in order to begin growth. So, it was assumed that organisms that are closely related must also have similar structures as they develop.

A vertebrate is an animal with a backbone. At this station are photos of various vertebrate embryos at similar stages in development. Use the station info to help you determine the species of each embryo below.

A. Chicken B. Fish C. Human D. Dolphin E. Alien species F. Cat Now look at the actual photographs of some of the embryos and compare them to the diagrams.

Questions: 1. Compare the actual photographs of developing vertebrate embryos. Do you see any similarities between them? Explain. Although these embryos come from different species, but they all have backbones. Their heads all look bigger, and their bodies are all curled up. 2. Explain how embryological comparisons can be used as evidence for the process of evolution. Embryological comparison can be used as evidence of the evolutionary process, because some structures in the organism do not have any obvious function at all, but it seems to be the remains of a common ancestor. For example, gill splits and tails in human embryos. Obviously, these features will disappear when the baby is born. The development of an individual will show the evolutionary stage of the species.

PART C: Anatomical Comparisons

Section 1 – Homologous Structures Homologous organs are ones that are similar in structure but may not be similar in function. For example, a human’s arm has the same basic positioning of bones in the arm as does a cat but a cat does not use its front limbs to grasp. The structure and organs of organisms, (anatomy) is determined by the genes that they inherit. All members of the same species have very similar genes for all structures, which is why they are so similar in appearance. Therefore, by examining the similarities and the differences between homologous organs which have the same embryonic origins, in two different organisms, we can observe their genetic and thus evolutionary relationships. Analogous organs (those which have similar functions and appearance but different genetic origin) can’t be used. The early land vertebrates were amphibians and possessed a limb structure called the pentadactyl limb; a limb with five fingers or toes. All vertebrates that descended from these early amphibians, including reptiles, birds and mammals, have limbs that have evolved from this same basic pentadactyl pattern. They also illustrate the phenomenon known as adaptive radiation, since the basic limb plan has been adapted to meet the requirements of different niches. There are two diagrams of the forelimbs of several different vertebrates. Figure 1 (you’ll find at the table) shows the generalized pentadactyl limb of an early land vertebrate. Note the names and relative position of the bones in this diagram. Figure 2 (on the following page) shows the forelimbs of several modern vertebrates. Compare each modern forelimb to that of the early vertebrate and colour the bones as indicated below: Humerus Radius Ulna Carpals Metacarpals Phalanges

Upper arm Lower arm on “thumbs-side” of limb Lower arm opposite to radius Wrist Palm Fingers

Red Blue Yellow Green Orange Violet

These bones are all examples of homologous structures and are therefore derived from similar genes. You can see that the basic physical pattern of bones composing the forelimbs is the same in all the animals. This is explainable is we accept that all of the vertebrates living today, including the examples shown here, are descended from the first ancestral vertebrates, which have passed along the basic gene pattern for forelimbs structure from generation to generation.

Questions: 1. Briefly describe the purpose of the major anatomical change that has taken place in each of the limb examples below (ie. What is the function of the forelimb?): a) Human: _____________________________________________________________________ b) bird: ________Flying_____________________________________________________ c) Seal: ________Grooming and Swimming ______________________________________________ d) Horse: _______Braking and turning________________________________________________ e) Sloth: ________hanging_________________________________________________________ f) Bat: __________Flying__________________________________________________________

Forelimbs of Modern Vertebrates

Note: the radius and ulna are fused together in some animals (Figure 2)

2. Observe the metacarpals and the carpals of the sloth and human. These bones perform the same function in these animals. Do you expect them to be similar? Are they?

I think sloth and human are similar but not the same. In the diagram above, they have very similar structures, but because the bones are used for different purposes, they are still different.

3. Compare the metacarpals and carpals of the bird and bat. Are these bones modified in the same ways? Describe how these modifications support the… Bird wing: They use their wings to fly, and their structure is similar as the bats.

Bat wing: They use their wings to fly as well, but their forelimbs are their wings, and their wings are very similar to human fingers. 4. Based on your observations in questions 3 and 4, which pair of organisms (birds and bats or humans and sloths) are more closely related? Support your answer.

Humans and sloths are more closely related because firstly, Bats, humans and sloths are mammals, but birds are not. Also, the forelimbs of bats are their wings. The forelimbs and wings of the bird are separated. 5. How are homologous structures, such as forelimbs of vertebrates evidence for evolution? In the picture, the bones of some animals are very similar, so it can indicate that they may have the same ancestry. Perhaps in the process of evolution, due to different ecological environments, different evolutions will be carried out to better adapt to the environment. 6. Now examine the skeletons of a human, turtle, snake, dog and chicken. Use the rating scale to compare the skeletons to the human skeleton. Compare the shape, number of parts, and other characteristics as you see fit. Add one feature of your own choosing. Anatomical Feature

Dog

Snake

Turtle

Chicken

4

1

1

1

4

1

1

3

3

1

1

4

2

1

1

2

4

1

1

1

Teeth Ribs Rating Scale: 5 = most like the human skeleton 4 = very similar to human 3 = somewhat like the human 2 = only slightly like the human 1 = dissimilar to the human skeleton

Thumbs Collar bones Skull

1. Give 2 examples of vestigial structures in animals. Hind leg bones in whales, and the wings on flightless birds. 2. Describe how the vestigial hind limbs of modern whales provide anatomical evidence for their evolution.

The vestigial hindlimbs of modern whales provide anatomical evidence for their evolution from a carnivorous, four footed, terrestrial ancestors. When terrestrial organism evolves, some mammals will move back to water. By the late Eocene, whales were fully marine and had lost almost all traces of their former terrestrial life. Their hind limbs became useless but can still be seen in modern whales.

3. In terms of natural selection explain how structures that were once useful to an organism could become vestigial.

When some structures are useless, they could become vestigial. But they were performed some important functions in the organism in the past. For example, the human tailbone. Mammals use it to balance the body, transmit signals and support the body. Because humans walk upright, So, the tails become useless.

4. Suggest why a vestigial structure, once it has been reduced to a certain size, may not disappear altogether. I think there are two reasons. Firstly, even if they are useless, the genes that make up the residual structure will continue to be passed on. Secondly, Evolution is a very slow gradual process and will not disappear suddenly. Likewise, vestigial structures do not mean that they are completely useless. In some cases, they still function in the body, so they cannot disappear completely.

PART D: Biochemical Comparisons This is the newest and in some ways the best and most powerful evidence to establish evolutionary relationships. The previous methods each studied the end result of an organisms gene being expressed, ie. a one or shell or embryo. This method studies the immediate product of gene action, a protein molecule. You will learn in detail how a gene (a piece of DNA) makes a specific protein molecule in a cell in our next unit and in Biology 12. For now, all that you need to know is that the order of nucleotides in DNA determines the type and order of amino acids in a protein molecule. Any change in the order of nucleotides in the DNA will result in a change in the amino acid sequence of the protein that the piece of DNA (a gene) codes for. A change in the DNA is called a mutation and mutations occur randomly and unpredictably. Organisms which are the same species, and thus reproduce together, will all possess the same mutations after a few generations. Organisms which don’t reproduce with each other (and therefore separate species) will have different, unique mutations. If one species evolved into two separate species, their gene pools become isolated and they begin to accumulate their own mutations. The longer they have evolved apart, the more differences in their gene pools one would expect. Therefore, when we study amino acid differences in the same protein between species (which is technically fairly simple to do) we are really studying changes in DNA over time. A protein molecule common to all vertebrates is the blood protein hemoglobin. Look at the amino acid sequences shown on the chart. These sequences are portions of the hemoglobin molecule of five organisms. You will analyze this data to see how biologists use this technique to measure evolution and evolutionary rates and then answer the questions below.

Questions 1. Compare the amino-acid sequence of hemoglobin molecules of the human, gorilla, chimpanzee and horse. Count the number of amino acids that differ between the organisms and list them in the table below. 2. Based on these results, which two animals appear to be most closely related in terms of amino acid Number of Amino Acid Sequence sequences? Differences Chimpanzee and Man Number of Differences Organisms in the Sequence 3. What biological process results in changes in DNA? 1 Man and gorilla Mutation will result in changes in DNA. 4 Man and Horse 4. If two organisms have very similar but not identical 6 Gorilla and Horse DNA sequences in their genes, what could you conclude and why? 1 Gorilla and Chimpanzee These two species are closely related if they 0 have very similar but not identical DNA Chimpanzee and Man sequences in their genes. If they have 5 similar sequence, then they should make Horse with Chimpanzee similar proteins. 5. If two organisms have some DNA in common, but a lot that are different, what would you conclude and why? This means that they are not closely related, but there are still some connections between the two species. Because only a small part of them are the same. 6. If two organisms have few DNA sequences in common, what would you conclude? This means that they have nothing to do with each other or are too far apart. Because there are not too many same sequences between them.

Embryological Comparisons Actual Photographs

Human embryo at 7 weeks

Fish Embryo

Chicken embryo

Cat embryo

dolphin embryo

(Figure 1)

Vestigial Structures...