IB Biology Quarter 1 Exam Review

1. IB Biology Quarter 1 Exam Review IB topics 1 (statistical analysis) & 2.1 (cell theory)

2. Guidelines • Get into a group of 4 • Designate a recorder (you may rotate) • In order to get points, your answer must be written on the dry erase board • When time is called, each group will raise their answer/board up • If your answer is correct, award yourself a point (we’re on the honor policy ) • I will take away points for disruptive behavior • 1 minute per question

3. Topic 2.1 • List the three main principles of the cell theory • All organisms are composed of one or more cells • Cells are the smallest units of life • All cells come from pre-existing cells

4. IB Topic 2.1 • Describe the work of Robert Hooke. • First described cells in 1665 while observing cork with a microscope he built.

5. IB topic 2.1 • Describe the work of Antoine van Leeuwenhoek. • Observed the first living cells are referred to them as “animalcules,” meaning, little animals

6. IB Topic 2.1 • Describe the work of Mathais Schleiden and Theodor Schwann • Schleiden: botanist; stated that plants are made of cells (1838) • Schwann: zoologist; made similar statement about animals

7. IB topic 2.1 • Describe the work of Louis Pasteur. Which principle of the cell theory did he give provide evidence? • 1860s; after sterilizing chicken broth by boiling, Pasteur showed that living organisms would not spontaneously reappear • Only after exposure to pre-existing cells was life able to re-establish itself in the sterilized chicken broth • Cell theory principle; cells come from pre-existing cells

8. IB topic 2.1 • Compare light microscopes and electron microscopes • Light: passes light through the living or dead specimen to create an image • Electron: uses electron; provides us with the greatest magnification (over 100,000x) and resolution

9. IB topic 2.1 • Put the following cells in order from smallest to biggest: • Bacteria, viruses, molecules, membranes, and organelles • (Smallest) molecules  membranes  viruses  bacteria  organelles (Biggest)

10. IB topic 2.1 • Convert the following: • 1 mm = _____ µm • 1 µm = ______ nm • 1000 µm • 1000 nm

11. IB Topic 2.1 • Convert the following: • 50 mm = _____ µm • 750 µm = _____ mm • .250 mm = _____ nm • Answers • 50,000 µm • .750 mm • .250 x 1000 x 1000 = 250,000 nm

12. IB topic 2.1 • State the equation for linear magnification • Magnification = size of image / actual size

13. IB topic 2.1 • If a white blood cell has a diameter of 2 µm and a student shows it with a diameter of 20 mm in a drawing, what is the magnification of the drawing? • 10,000x • Image = 20 mm (convert to µm) = 20,000 • Actual = 2 µm

14. IB Topic 2.1 • As a cell increases in size, which increases faster: surface area or volume? • Volume

15. IB Topic 2.1 • Explain why the surface area to volume ratio is a limiting factor to cell size. • As a cell grows, volume increases faster than surface area • The surface area to volume ratio decreases • This means there is less surface area to bring in needed materials and to rid the cell of waste than a small cell (diffusion slows down) • To prevent this, cells are limited as to the size they can attain and still be able to carry out the functions of life; modifications: long & thin; folding

16. IB Topic 2.1 • What is the equation for: • Surface area of a cub • Volume of a cube • Surface area to volume ratio • SA = L x W x 6 • Volume = L x W x H • Ratio • Surface area divided by volume : volume divided by volume

17. IB topic 1 – Stats • Define error bar • A graphical representation of the variability of data • Used to show the range of data or the standard deviation on a graph

18. IB topic 1 – Stats • What is standard deviation used for? • To summarize the spread of values around the mean

19. IB topic 1 – Stats • What causes a high standard deviation? • A wide range of data points

20. IB topic 1 – Stats • What is a t-test used for? • Deducing the significant difference between two sets of data

21. IB topic 1 – Stats • When using a t-test, what is the level of confidence that is considered a significant difference when comparing two sets of data? • 95%

22. IB topic 1 – Stats • How do you calculate the degrees of freedom? • Sum of two sample sizes – 2

23. IB topic 1 – Stats • An experiment was performed which measured the size of salmon that spawned in two different streams. Fifty salmon were sampled for each stream. The value of t was found to be 1.29. What is the confidence level of this particular test? • Confidence level = 80% • Degrees of freedom = 50 + 50 – 2 = 98 • T value = 1.29 • Probability = 20%

24. IB topic 1 – Stats • Compare correlation and causation • Observation  correlation • Data/experimentation  causation • Correlation does not mean causation

25. IB topic 1 – Stats • When using the t-test to compare two sets of data, the p-value of the data according to the t-table is 0.05. What is the probability that chance alone can produce the difference seen? How confident can I be in my data? • 5% probability (due to chance) • 95% confident the difference is significant (real)

26. IB topic 1 – Stats • When using a mathematical correlation test, the value of r signifies the correlation. The value of r can vary from ___ to ____ to ___. What does these values tell us? • -1 to 0 to +1 • -1 = negative correlation • 0 = no correlation • +1 = positive correlation

27. IB topic 1 – Stats • What is the average and standard deviation of the following set of data: • 4, 5, 6, 6, 6, 5, 5, 4, 3, • Average = 4.88 • Standard Deviation = 1.05

28. IB topic 1 – Stats • What percentage of values lie within 1 SD of the mean? What about 2 SD of the mean? • 68% • 95%

29. Your Test Tomorrow • IB Topic 1 – Statistical Analysis • IB Topic 2.1 – Cell Theory (up to page 19) • 33 multiple choice questions • 1 short answer • You need a calculate and a pencil