dean - 1 Sample exam questions: Dean Unit, Biology 2290F/G...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Sample exam questions: Dean Unit, Biology 2290F/G (Answers start on page 6) (These are sample exam questions. There are more questions than on the exam) Question 1 : Chlorella is a unicellular alga that grows well in liquid culture media. Using a haemacytometer, the cell density in a Chlorella culture was determined to be 5.625 x 10 7 cells/ml. To make a standard curve of its absorbance at 750 nm (A 750 ) against the number of cells per milliliter, the culture was diluted 15-fold . As shown in the table below, this diluted sample gave an A 750 reading of 0.390. Complete the table to show (i) the number of cells per milliliter (#cells/ml) that correspond to each A 750 reading , and (ii), the volumes of diluted culture and water in the blank spaces in columns 1 and 2 of the table. All tubes contain a total volume of 5.0 ml ( 4 marks ) ml diluted culture ml water #cells/ml A 750 5.0 0 0.390 0.234 0.117 0.039 Question 2 : The following table shows the contents of the experimental reaction mixture used to determine the rate of photoreduction of DCPIP at 25 cm from a 100 watt lamp. 2 x 10 -4 M Reaction buffer Distilled Chloroplast Tube # DCPIP (ml) pH 7.0 (ml) water (ml) preparation ( l) 1. Experimental 2.0 2.0 6.0 * 2. Dark Control * 3. Blank * (* volume to be determined) (a) Complete the table to show the contents of tubes numbered 2 and 3 ( 2 marks ) Chloroplasts were isolated according to the Biology 2290 protocol. Fifty (50) l of this preparation was added to 5.0 ml of 80% (v/v) acetone, the tube was shaken to dissolve the chlorophyll and centrifuged at 1300 x g for 3 minutes. The supernatant was transferred to a cuvette and its A 652 was determined to be 0.720 . (b) What is the appropriate blank for this A 652 determination? __________ ___________ ________________________________________( 1 mark )
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Sample exam questions: Dean Unit, Biology 2290F/G (Answers start on page 6) (These are sample exam questions. There are more questions than on the exam) The concentration of chlorophyll in the chloroplast preparation was determined from the following equation: A 652 x 5 . 34 100 = mg of chlorophyll/ml of chloroplast preparation. (c) A volume of chloroplast preparation that contains 50 g of chlorophyll was added to each tube in the preceding table. Calculate the required volume in l and include this value in the table at the start of this question (Show calculation, 2 marks ). In the experiment, the following data were obtained: (i) Experimental (tube #1, 25 cm from lamp) . (ii) Control (dark) (tube #2). Time (min) A600 A600 Time (min) A600 A600 0 0.860 0 0.860 2 0.460 2 0.760 The absorption coefficient (E) for DCPIP in the conditions of the experiment was 18,000 litres/mole.cm. (d) Calculate the rate of photoreduction of DCPIP in tube #1 in moles of DCPIP
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/01/2011 for the course BIOLOGY Biology 22 taught by Professor Dr.dean,krajnyk,zabulionis during the Fall '10 term at UWO.

Page1 / 10

dean - 1 Sample exam questions: Dean Unit, Biology 2290F/G...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online