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Life Science 2 nd Semester Exam Review. Basic Concepts.

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Presentation on theme: "Life Science 2 nd Semester Exam Review. Basic Concepts."— Presentation transcript:

1 Life Science 2 nd Semester Exam Review

2 Basic Concepts

3 Structure of Ecosystems/Levels of Organization Organism – individual living (biotic) thing Population – group of organisms, all of one species, which live in the same place and the same time Community – all the populations of different species, same place, same time Ecosystem – Populations of plant and animals that interact with each other in a given area and with the abiotic parts (non-living) Biosphere – The portion of Earth that supports life


5 Has Nucleus No Nuclear Membrane Ribosomes and DNA

6 Cell Structure

7 Cell Structures 1. Cell wall: rigid layer of nonliving material that surrounds the cells of plants –Made of cellulose –Protects and supports the cells


9 2. Cell membrane: Boundary that protects the cell from the environment & controls what comes in and out –All cells have –Like a screen door


11 3. Nucleus: control center for the cell

12 4. Ribosomes: grain like bodies on the ER & in the cytoplasm

13 5.Endoplasmic Reticulum: (called ER) carry proteins and materials within the cell

14 6. Golgi Body: receives and packages proteins from ER and distributes around cell and body (mailroom)

15 7. Cytoplasm: clear gelatinous fluid inside a cell

16 8. Vacuoles: storage area of the cell Plant has one large vacuole Stores food, waste, & enzymes

17 9. Mitochondria = powerhouse of the cell; where cell energy comes from.

18 10. Chloroplasts: ONLY IN PLANTS captures sunlight and produces food for the cell

19 11. Flagella = used for movement

20 12. Cilia = used for movement; tiny hair-like structures; found on cells that need to move mucus



23 D. Absence of a nuclear membrane

24 B. Viruses require a host cell to reproduce.

25 C. flagellum

26 B. flagella


28 Questions they (OGT) has asked the last 4 years.

29 D. Place the rabbit in a cage with a heated floor.

30 B. D.


32 Evolution Charles Darwin (1809-1882) 1.Natural Selection a.“Only the strongest survive” 2.Darwin hypothesized that when animals had traits that helped them live, they would pass them on to their offspring. 3.Animals who did not possess these traits died.

33 Darwin’s Example 1.Darwin noted the different beak structures of finches depended on the island they came from. 2.Finches who lived on islands plentiful in nuts and berries had different beaks than finches who lived on islands plentiful in insects.

34 Even though all these birds are finches they developed different beaks depending on the plentiful food source of specific islands.

35 Examples of Natural Selection 1.Galapagos Iguanas a.Some iguanas have evolved to eat algae. b.Some iguanas have developed large claws to help them cling to rock. c.These iguanas evolved from other iguanas because they need those two traits to survive. d.The algae eating, long clawed iguanas passed these trait on to their young. e.Iguanas not having that trait. Everyday green iguana Galapagos marine iguana

36 Other adaptations 1.Camaflouge a. Enables species to blend in with their surroundings. Can you find the snake’s head?

37 2. Mimicry – enables a species to look like other species What part of the plant is this? It’s not part of the plant at all, it’s an insect.

38 Darwin Hypothetical 1.Let’s say there was a new “killer” virus that affected dogs. 2.This flu bug only affected dogs with long hair. So, if a dog had long hair (more than ¾ inch long) it would get the virus and die. 3.In 20 years, will all dogs have long or short hair? WHY? All dogs would have short hair because all the long hair dogs have died from the virus. There would only be short haired dogs mating with short hair dogs. You could say all dogs with short hair were “naturally selected” to live. The dog species has evolved from having both short and long hair to having only short hair.

39 1.Populations evolve not individuals.

40 B.

41 C. Had a higher survival rate than light moths in the same area


43 One last thing the OGT might get you on…… Jean Baptiste Lamarck (1744-1821) –Came before Darwin –Had some of the same ideas as Darwin –No one ever believed him. –Died in obscurity and poverty.

44 Genetics 1. The dominant trait will always be visible 2. Dominant-always masks the recessive; represented by uppercase letter (T, H, D, R) 3.Recessive-will be masked by dominant; represented by lowercase letter (t, h, d, r) -For a recessive trait to be visible, there must be two (tt, hh, dd, rr)

45 Pedigrees XYXX FatherMother DaughterSon c CC XX cC XY C C

46 Down Syndrome Karyotype

47 Darwin’s Background Born in England, 1809 Studied Medicine at Edinburgh University Transferred to Cambridge University Studied to be a Minister Library of Congress, Prints and Photographs Division [reproduction number, e.g., LC-USZ61-104].

48 Charles Darwin Wrote in 1859“On the Origin of Species by Means of Natural Selection”Wrote in 1859:“On the Origin of Species by Means of Natural Selection” Two main points:Two main points: 1.Species were not created in their present form, but evolved from ancestral species. 2.Proposed a mechanism for evolution: NATURAL SELECTION

49 Chapter 15 Darwin’s Voyage Section 1 History of Evolutionary Thought 21AC-2256-43A7-8F70- 367D66017CFC&blnFromSearch=1&productcode=US

50 Example of Natural Selection

51 Analogous Structures Different structure design, same purpose.

52 Homologous Structures Different uses, same design

53 What is Convergent Evolution? Different unrelated species demonstrate similar traits in response to environment.

54 What is divergent Evolution? Common ancestor Develop different traits

55 II. Mendel’s Legacy A.Observed 7 traits (a genetically determined variant of a characteristic) of Garder Peas A.Height B.Flower position C.Pod color D.Pod appearance E.Seed texture F.Seed color G.Flower color


57 XI. Homozygous dominant x Homozygous recessive Purple is dominant over white PP (purple) x pp (white) P P pp PP PP pp PP P P p p p p Genotypic ratio = 4:0 Phenotypic ratio = 4 purple : 0 white

58 Purple is dominant over white PP (purple) x Pp (purple) P P pp PP PP pP PP P P P P p p Genotypic ratio = 2:2 Phenotypic ratio = 4 purple : 0 white XII. Homozygous dominant x heterozygous

59 Purple is dominant over white Pp (purple) x Pp (purple) P p PP p P PP P p P p p p Genotypic ratio = 1:3:1 Phenotypic ratio = 3 purple : 1 white XIII. heterozygous x heterozygous

60 P r PR r R RR R r R r r r Genotypic ratio = 1:3:1 Phenotypic ratio = 1 red: 2 pink: 2 white XIV. Incomplete dominance In roses (R = red, Rr = pink, rr = white)

61 XV. Co-Dominance In guinea pigs (B = black, Bb = black and white, bb = white)


63 c.taxonomy. The science of classifying living things is called a.identification.c.taxonomy. b.classification.d.speciation.

64 c.become more similar in appearance. As we move through the biological hierarchy from the kingdom to species level, organisms a.vary more and more. b.are less and less related to each other. c.become more similar in appearance. d.always are members of the same order.

65 c.Quercus. The organism Quercus phellos is a member of the genus a.Plantae.c.Quercus. b.phellos.d.Protista.

66 d.toxicodendron. Poison ivy is also known as Rhus toxicodendron. Its species identifier is a.poison.c.ivy. b.Rhus.d.toxicodendron.

67 d.Acer rubrum. The red maple is also known as Acer rubrum. Its scientific name is maple.c.rubrum. b.Acer.d.Acer rubrum.

68 c.kingdom, phylum, class, order, family, genus, species. The correct order of the biological hierarchy from kingdom to species is a.kingdom, class, family, order, phylum, genus, species. b.kingdom, phylum, order, family, class, genus, species. c.kingdom, phylum, class, order, family, genus, species. d.kingdom, class, order, phylum, family, genus, species.

69 b.species. The lowest hierarchy level in biological classification is the b.species.d.order.

70 d.species Which of the following is the least inclusive classification group? a.classc.phylum b.genusd.species

71 Refer to the illustration above. A branching diagram like the one shown is called a a.phenetic tree. tree. b.cladogram. d.homology. b.cladogram.

72 d.the Galápagos Islands. Darwin drew ideas for his theory from observations of organisms on a.the Samoan Islands. b.Manhattan Island. c.the Hawaiian Islands. d.the Galápagos Islands.

73 c.because of natural selection. According to Darwin, evolution occurs a.only through artificial selection. b.during half-life periods of 5,715 years. c.because of natural selection. rapidly that it can be observed easily.

74 c.the idea that species are permanent and unchanging. When Darwin published his first book about evolution, he included all of the following ideas except a.the idea that species change slowly over time. b.the idea that some organisms reproduce at a greater rate than others. c.the idea that species are permanent and unchanging. d.the idea that some species become better suited to their environment than others.

75 d.species change over time by natural selection. The major idea that Darwin presented in his book The Origin of Species was that a.species change over time and never compete with each other. b.animals change, but plants remain the same over time. c.species may change in small ways but cannot give rise to new species. d.species change over time by natural selection.

76 b.organisms with traits well suited to their environment survive and reproduce more successfully than organisms less suited to the same environment. Natural selection is the process by which a.the age of selected fossils is calculated. b.organisms with traits well suited to their environment survive and reproduce more successfully than organisms less suited to the same environment. c.acquired traits are passed on from one generation to the next. d.All of the above

77 c.adaptation. The process by which a population becomes better suited to its environment is known as a.accommodation.c.adaptation. b.variation.d.acclimation.

78 a.had a common ancestor. The species of finches that Darwin observed differed in the shape of their beaks. According to Darwin, all of these species probably a.had a common ancestor. b.had migrated from Africa. c.had descended from similar birds in Africa. d.ate the same diet.

79 d.become increasingly different as each population becomes adapted to its own environment. Populations of the same species living in different places not vary. b.always show balancing selection. c.are genetically identical to each other. d.become increasingly different as each population becomes adapted to its own environment.

80 b.must compete for resources. Since natural resources are limited, all organisms a.must migrate to new habitats. b.must compete for resources. c.display vestigial structures. d.have inherited characteristics.

81 Refer to the illustration above. The bones labeled “X” can be referred to as a.vestigial structures. b.sequential structures. c.homologous structures. d.fossil structures. c.homologous structures.

82 a.share a common ancestor. Homologous structures in organisms provide evidence that the organisms b.must have lived at different times. c.have a skeletal structure. d.are now extinct.

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