Grade 8 MCAS Review on Grade 7 Life Science Units

1. Grade 8 MCAS Review April 28, 2015

2. Grade 7 Life Science Units • Scientific Inquiry • Classification of Living Things • Cells • Genetics • Evolution & Biodiversity • Ecology • Human Body Systems

3. MCAS Review Sequence • Use this power point along with the Grade 7 Life Science Video links to review and complete the twenty-five (25) questions on the MCAS Packet you have been provided. • Follow this power point in order along with the videos to complete the questions. • Save the Scientific Inquiry videos for the end. • Good luck on your Grade 8 Science MCAS Exam!!

4. Standards 1-4 Classification and Cells • Watch the Classification and Cell Video(s). • Review the next set of slides. • Answer questions 1 – 6 and the Open Response Question in your MCAS Review Packet. • Good luck!

5. Classification • Organisms are classified into specific groups (Kingdoms) according to their common characteristics, such as: • Their ability to make food (Autotroph or Heterotroph) • Whether or not they have a nucleus (Eukaryote or Prokaryote). IMPORTANT: Organisms with a nucleus are Eukaryotes—Organisms without a nucleus are Prokaryotes. • Whether they are unicellular or multicellular. • See next slide for examples and characteristics of organisms in all Six Kingdoms of Life.

6. Classification • There are Six (6) Kingdoms of Life. • Animalia • Plantae • Fungi • Protista • Eubacteria • Archaebacteria

7. Classification

8. Cells and Living Things • Cell Theory: • All living things are composed of cells. • Cells are the basic units of structure and function in living things. • New cells are produced from existing cells.

9. Cells and Living Things

10. Cells and Living Things • Within most cells there are membrane-enclosed structures called organelles. • Can anyone list an organelle?

11. Cells and Living Things • Cell Wall Cell Membrane • Nucleus Mitochondria • Ribosome Lysosome • Chloroplast Endoplasmic Reticulum • Golgi Body/Apparatus Vacuole • Centriole

12. Cells

13. Cells and Living Things

14. Cells and Living Things • Speaking of Cells, Organelles and Glucose…let’s look at a very important cellular process…one of the most important on the biosphere…does anyone know which process produces the oxygen and glucose that we need to survive? • Did you say PHOTOSYNTHESIS?? • Great work!!

15. Photosynthesis Where? In Plant Cells What Organelle? Chloroplast Why? 1. To provide energy In the form of glucose to all living things. 2. To produce oxygen for living things.

16. Cellular Respiration • Once the glucose and oxygen are produced by photosynthesis, these molecules needs to be broken down into energy for the cells to use and waste material for the cells to get rid of.

17. Cellular Transport

18. Types of Cell Division • Meiosis what about Mitosis? • Meiosis produces gametes with ½ number of chromosomes. • Mitosis is the process of cell division that produces an identical replacement cell – such as a skin cell, muscle cell, etc. It has the same number of chromosomes as the original cell. It has too!

19. Standards 7-10Genetics and Heredity • Watch the Genetics Videos. • View the next series of slides. • Answer questions 11-15. • Good luck!

20. Genetics and Heredity • All living things contain cells. • All cells contain DNA—deoxyribonucleic acid—whether contained in a nucleus (as in eukaryotes) or not (as in prokaryotes). • DNA contains the genetic information that is passed from one generation to the next.

21. Genetics and Heredity • DNA is a molecule shaped like a twisted double helix. • DNA structure: (1) Deoxyribose Sugar (2) Nitrogenous base (Adenine, Thymine, Guanine or Cytosine) (3) Phosphate Group. • These three (3) parts are referred to as a nucleotide.

22. Genetics and Heredity Base Pairing Rule The “rungs” of a DNA ladder are made up of the nitrogen bases. The base pairing rule establishes the match up of nitrogen bases. Guanine will always Match up with Cytosine. C with G Thymine will always Match up with Adenine. T with A

23. Genetics and Heredity • DNA Replication is the process in which one original strand of DNA unwinds and becomes two new identical strands of DNA. • The process of DNA replication is an important part of Cell Division – Mitosis and Meiosis.

24. Genetics and Heredity • Sometimes a mutation in a sequence of DNA occurs. • Mutations are not always harmful—in fact they could help an organism survive. • Mutations acquired in an organism’s lifetime cannot be passed on---only mutations on genes or chromosomes can be passed on to future generations.

25. Genetics and Heredity • Traits are passed on from parents to offspring on genes. • A gene is a section of a chromosome. Each chromosome contains many genes – approximately 30,000 genes in humans. • Humans have 23 pairs of chromosomes – 22 autosomes (numbered 1-22) and a pair of sex chromosomes XX for girls and XY for boys. • Each of these chromosomes contains the different genes that code for your specific traits such as eye color and hair color.

26. Genetics and Heredity • The passing on of traits from parents to offspring occurs during the cellular process of Meiosis. • Meiosis is the process in which the number of chromosomes is divided in half to produce gametes. • The resulting gametes (egg and sperm cells) will fertilize and produce a zygote. • The zygote (developing embryo) will again contain 23 pairs of chromosomes.

27. Genetics and Heredity • What’s a Punnett Square? • A Punnettsquare is a chart which shows/predicts all possible gene combinations in a cross of parents (whose genes are known). • Punnett squares are named for an English geneticist, Reginald Punnett.

28. Genetics and Heredity • DNA is located on genes. • Genes are sections of chromosomes. • The different forms of genes are called alleles. • Each allele combination represents a person’s traits. Alleles can represent dominant or recessive traits. • A dominant trait is represented by a capital letter – example “A”. A recessive trait is represented by a lower case letter “a”. • A genotype refers to a person’s genetic makeup. A phenotype refers to an organism’s physical appearance.

29. Genetics and Herdity • A dominant trait is represented by a capital letter – example “A”. A recessive trait is represented by a lower case letter “a”. • A genotype refers to a person’s genetic makeup. • For example, AA would represent a person’s genotype and that person would have two (2) dominant alleles for that trait. This person would be homozygous or a purebred for that particular trait. • Aa would represent a person who has one dominant allele and one recessive allele. This person would be heterozygous or a hybrid for that trait. • If a person has the genotype “aa” this person would also be homozygous or a purebred, however, they would have two (2) recessive alleles.

30. Genetics and Heredity • A pedigree is a chart that shows how traits have been passed on through several generations. • A series of symbols is used to represent dominant and recessive traits and males and females. 

31. Genetics and Heredity • A karyotype is a “picture” of an individual’s chromosomes. • A karyotype shows all 23 pairs of human chromosomes and creates a “map” of all of the person’s genes . 

32. Genetics and Heredity • Dominant vs. Recessive Traits. • A dominant trait will always be expressed in an organism. Example: Say that the letter “T” represents the dominant form of the allele for tallness. If an organism has the genotype “TT” or “Tt”, then the organism will be tall. • A recessive trait will only be expressed when there are two alleles for that trait. The organisms genotype would look like “tt” and the organism would be short.

33. Parents: Aa and Aa A is dominant = freckles. A is recessive = no freckles. Offspring: Which ones will have freckles?

34. Standard 6 • Watch the Human Body Systems Video. • View the next set of slides. • Answer questions 7-10 in your MCAS packet. • Good luck!

35. Human Body Systems • Let’s review how multicellular organisms (like humans) are organized: • Cells, tissues, organs, organ systems, ORGANISM. • There are eleven (11) human body systems. • They all work together to maintain homeostasis. What’s that?? • Can anyone name a few systems??

36. Human Body Systems

37. Standards 10 and 11Evolution and Biodiversity • Watch the Evolution and Biodiversity Videos. • View the next set of slides. • Answer questions 16-18 in your MCAS Review Packet. • Good luck!

38. Evolution and Biodiversity • Everything has evolved including humans. • Evolution has occurred over millions of years. • Evolution is a change in species over time. • There is specific evidence of evolution: • Fossils, Vestigial Structures, Embryology, DNA/ Chemical Evidence & Homologous Structures

39. Evolution and Biodiversity • All of these types of evidence demonstrate that organisms have shared a common ancestor. • Fossil evidence can be found in sedimentary rock. • Two ways to date fossils: • Relative Dating – Uses law of superposition • Absolute Dating - Uses radioactive dating

40. Evolution and Biodiversity • Which layer contains the oldest fossil?

41. Evolution and Biodiversity • Those organisms that have been best suited to their environments have survived over time. • Some organisms have specific “adaptations” or physical traits that allow them to survive and reproduce offspring over other organisms. • This is referred to as “natural selection” or survival of the fittest. • Natural selection results in evolution. The organisms with the best traits will pass on these traits to their offspring.

42. Standards 12 – 18Ecology and Evolution • Watch the two (2) Ecology Videos, and, if you have to, watch the Evolution video again! • View the next set of slides. • Answer questions 19-25 in your MCAS Review Packet. • Good Luck!

43. Ecology • All living organisms interact with each other and their environment. • Just like there are levels of organization in the human body, there are ecological levels of organization. • From the smallest to largest: organism, population, community, ecosystem and biosphere.

44. Ecology • The biotic factors are the living organisms in an environment, such as plants, animals, humans. The abiotic factors are the non-living things in the environment, such as rocks, streams, air and temperature. • The way that living organisms can interact with each other varies. There are several different scenarios.

45. Ecology • There is symbiosis – when at least one organism benefits. • There are three (3) types of symbiosis: • Commensalism – One organism benefits and the other doesn’t benefit or get harmed. • Mutualism – Both organisms benefit. WIN WIN • Parasitism – One organism benefits and the other gets harmed.

46. Ecology • There are also classic predator – prey relationships – such as a Hawk and a mouse. • Finally, there is competition – when organisms compete with each other for limited resources, such as: food, water or living space.

47. Ecology • Every organism has its role in the environment: • Decomposers – these break down old living organisms. These include: bacteria and fungi. • Producers – these are autotrophs, such as plants, which make food for themselves and others. • Consumers – there are many levels – first, second and third – these eat the producers and other living organisms.

48. Ecology Decomposers

49. Ecology • Food Chain – A food chain shows the one-way (arrows in only one direction—the direction in which the energy is transferred)transfer of energy (food) within an ecosystem. • Food Web – A food web is a series of interconnected food chains. 

50. Scientific Inquiry • Watch the Scientific Inquiry Videos.